JP7067169B2 - Steering control device - Google Patents

Description

The present invention relates to a steering control device.

Conventionally, as a vehicle steering device, an electric power steering device (EPS) including an actuator whose drive source is a motor is known. Some of these EPSs detect the steering angle of the steering wheel (steering wheel steering angle) in correspondence with the rotation angle of the motor (motor absolute angle) acquired in the absolute angle in the range exceeding 360 °. Various controls are performed based on the control steering angle (control angle) indicated by the absolute angle of the motor. As an example of control based on the control steering angle, for example, in Patent Document 1, the impact of the end contact is alleviated by increasing the steering reaction force before the rack end, which is the end of the rack shaft, hits the rack housing. Things are disclosed. Further, the control steering angle is detected, for example, by accumulating (counting) the number of rotations with the angle in the steering neutral position as a reference (origin).

Japanese Unexamined Patent Publication No. 2015-20506

By the way, in the configuration in which the absolute angle of the motor is detected corresponding to the steering angle, for example, the rotation of the motor is detected by continuing the power supply from the in-vehicle battery to the control device even when the ignition is off, and the steering angle is changed. Even when it changes, the correspondence between the steering angle and the absolute motor angle is maintained. However, if the power supply to the control device is cut off due to, for example, battery replacement, the rotation of the motor cannot be detected, so that the correspondence between the steering angle and the absolute angle of the motor cannot be maintained, and the correspondence is made to correspond to the steering angle. The absolute angle of the motor cannot be detected. Therefore, when the correspondence between the steering angle and the absolute motor angle disappears, these correspondences can be memorized (learned) so that the accurate motor absolute angle corresponding to the actual steering angle can be obtained. The creation of technology was required.

It should be noted that such a problem is not limited to EPS, but also when, for example, in a steer-by-wire type steering device, the absolute angle of the motor that is the drive source of the steering actuator that steers the steering wheel is detected in correspondence with the steering angle. It can happen as well.

An object of the present invention is to provide a steering control device capable of acquiring an accurate motor absolute angle corresponding to an actual steering angle.

The steering control device that solves the above problems targets a steering device to which a motor torque that reciprocates the steering shaft of the steering mechanism by an actuator that uses a motor as a drive source is applied, and the steering shaft is either left or right. The steering shaft is determined by the end position determination unit that determines whether or not the motor is in the end position, the motor absolute angle detection unit that detects the rotation angle of the motor at an absolute angle exceeding the range of 360 °, and the end position determination unit. When it is determined that the motor is at either the left or right end position, the motor absolute angle detected by the motor absolute angle detection unit is set as the end position corresponding motor angle corresponding to the left or right end position. Equipped with a corresponding motor angle setting unit.

For example, it is conceivable to determine whether or not the vehicle is in a straight-ahead state, and set the absolute motor angle when it is determined to be in a straight-ahead state as a reference angle corresponding to the steering neutral position. However, the stroke amount from the steering neutral position to the left end position and the stroke amount from the steering neutral position to the right end position are slightly different due to dimensional variations of each component constituting the steering device. There is. As a result, the end position corresponding motor angle estimated based on the motor absolute angle with respect to the steering neutral position may actually deviate from the motor absolute angle at which the steering axis is at the end position. In this respect, according to the above configuration, since the motor absolute angle when it is determined that the steering shaft is at the end position is set as the end position corresponding motor angle, an accurate end position corresponding motor angle can be set.

In the steering control device, it is preferable that the motor absolute angle detecting unit corrects and detects the motor absolute angle based on the mechanical elastic deformation of the steering mechanism generated by the torque applied to the steering mechanism.

According to the above configuration, it is possible to set a more accurate end position corresponding motor angle in consideration of the elastic deformation of the steering mechanism when it is determined that the steering shaft is at the end position.
In the steering control device, after the end position corresponding motor angle setting unit sets the end position corresponding motor angle, the motor absolute angle having the same sign as the end position corresponding motor angle and having a large absolute value is the motor absolute angle. When detected by the detection unit, it is preferable to update the absolute motor angle as a new end position corresponding motor angle.

When the end position determination unit makes a determination based on, for example, torque or the angular velocity of the motor, if the steering wheel hits a curb or the like, even if the steering shaft is not actually at the end position, it is in front of it. There is a risk that the position will be erroneously determined to be at the end position, and the end position corresponding motor angle may also be set to an inaccurate angle. In this regard, according to the above configuration, even if the end position corresponding motor angle is set once, it is updated when the motor absolute angle having the same sign as the end position corresponding motor angle and having a large absolute value is detected, which is erroneous. It is possible to suppress the setting of the motor angle corresponding to the end position.

In the steering control device, the average value of the left and right end position corresponding motor angles set by the end position corresponding motor angle setting unit is defined as an offset angle, and the angle obtained by subtracting the offset angle from the detected motor absolute angle is used. It is preferable to include a control steering angle origin setting unit that is set as the origin of the control steering angle indicated by the absolute angle of the motor.

According to the above configuration, the origin corresponding to the steering neutral position can be easily set.
In the steering control device, in the control steering angle origin setting unit, the sum of the absolute values of the left and right end position corresponding motor angles set by the end position corresponding motor angle setting unit covers the entire stroke range of the steering shaft. If it is less than the stroke threshold based on the corresponding motor absolute angle range, it is preferable not to set the origin.

For example, when the steering wheel hits a rim stone or the like, it is determined that the steering axis is at the end position, and if the wrong end position corresponding motor angle is set, the sum of the absolute values of the left and right end position corresponding motor angles is calculated. It is smaller than the absolute motor angle range corresponding to the entire stroke range of the steering shaft. Based on this point, in the above configuration, if the sum of the absolute values of the set left and right end position corresponding motor angles is less than the stroke threshold value based on the motor absolute angle range, the origin of the control steering angle is not set, which is incorrect. It is possible to suppress setting the origin of the control steering angle.

The steering control device includes a motor control unit that controls the drive of the motor so that the motor torque becomes a torque command value, and the motor control unit has a motor angle corresponding to the end position in which the absolute value of the control steering angle is the end position. End contact relaxation control that reduces the absolute value of the torque command value based on the increase in the absolute value of the control steering angle when the absolute value of the steering angle near the end near the steering neutral position is exceeded by the first angle. In the control steering angle origin setting unit, after the left and right end position corresponding motor angles are set, the motor absolute angle is closer to the steering neutral position side than the left and right end position corresponding motor angles. It is preferable that the origin is set based on the left and right end position corresponding motor angles after approaching the first angle or more, and the motor control unit executes the end contact relaxation control after setting the origin.

According to the above configuration, immediately after setting the motor angles corresponding to the left and right end positions, that is, by setting the origin of the control steering angle while the steering axis is still in the end position, end contact relaxation control is executed and the actuator is operated. Therefore, it is possible to prevent the steering reaction force from being suddenly applied.

The steering control device includes a motor control unit that controls the drive of the motor so that the motor torque becomes a torque command value, and the motor control unit has a motor angle corresponding to the end position in which the absolute value of the control rudder angle is the end position. When the rudder angle near the end near the steering neutral position is exceeded by the first angle, the end contact relaxation control is performed to reduce the absolute value of the torque command value based on the increase in the absolute value of the control rudder angle. The absolute angle of the motor at a plurality of timings when the end position determination unit determines that the steering axis is at either the left or right end position when the origin of the control steering angle is not set. A provisional end position corresponding steering angle setting unit for setting a provisional end position corresponding steering angle on either the left or right side based on a plurality of one end position corresponding motor angles is provided, and the motor control unit is provided with the motor absolute angle. When the angle to the rudder angle corresponding to the provisional end position is less than the second angle, it is preferable to perform provisional end contact relaxation control to reduce the absolute value of the torque command value based on the decrease of the angle.

For example, depending on the running condition of the vehicle, it is assumed that the end hit of only one of the left and right sides is repeatedly generated. However, if both the left and right end hits do not occur, the origin of the control steering angle is not set and the end hit relaxation control is not executed, so that the impact of the end hits may cause discomfort to the driver. Further, considering the case where the motor angle corresponding to either the left or right end position is set by, for example, the steering wheel hitting a curb or the like, it is set only by the motor angle corresponding to the end position set by one end pad. The end position corresponding motor angle may not correspond exactly to the actual end position.

In this regard, according to the above configuration, the origin of the control steering angle is not set, for example, the appropriate motor angle corresponding to both the left and right end positions is not set, or the motor angle corresponding to only one of the left and right ends is set. Even in this state, it is possible to set an appropriate provisional end position corresponding steering angle corresponding to the actual end position by using the motor angle corresponding to one of a plurality of left and right ends. Then, by performing the provisional end-hit relaxation control based on the rudder angle corresponding to the provisional end position, even when the end-hit of only one of them is repeated in a state where the origin of the control rudder angle is not set, the one is the same. The impact of the end pad can be mitigated.

In the steering control device, in the provisional end position corresponding steering angle setting unit, after the plurality of one end position corresponding motor angles are set, the motor absolute angle is on the steering neutral position side with respect to the provisional end position corresponding steering angle. After approaching the second angle or more, the provisional end position corresponding steering angle is set based on the plurality of one-end position corresponding motor angles, and the motor control unit sets the provisional end position corresponding steering angle. It is preferable to execute the provisional end guess relaxation control.

According to the above configuration, the provisional end contact relaxation control is executed by setting the provisional end position corresponding steering angle immediately after setting the plurality of motor angles corresponding to one end position, that is, while the steering axis is still in the end position. Therefore, it is possible to prevent the steering reaction force from being suddenly applied by the actuator.

In the steering control device, it is preferable that the provisional end position corresponding steering angle setting unit sets the average value of the plurality of one-end position corresponding motor angles as the provisional end position corresponding steering angle.

According to the above configuration, the rudder angle corresponding to the provisional end position can be preferably set.
In the steering control device, the provisional end position corresponding steering angle setting unit is one of the plurality of one end position corresponding motor angles as the plurality of one end position corresponding motor angles that are the basis of the provisional end position corresponding steering angle. And the other one of the plurality of motor angles corresponding to one end position set after the absolute angle of the motor has changed by a predetermined steering amount or more indicating that the turning back steering has been performed after setting the one. It is preferable to use it.

According to the above configuration, since the other one of the motor angles corresponding to one end position is set after the switchback steering is performed after setting one of the motor angles corresponding to one end position, the other one of the motor angles corresponding to one end position is set. After the vehicle moves from the situation where one is set, it is more likely that another one will be set. Thereby, for example, it is possible to suppress that any one of the plurality of motor angles corresponding to one end position is set in a state where the steering wheel hits the curb, and the provisional end position corresponding steering angle is set based on these.

In the steering control device, the provisional end position corresponding rudder angle setting unit is the provisional end position corresponding steering when the difference between one of the plurality of motor angles corresponding to one end position and the other one is equal to or less than a predetermined difference. It is preferable to set the angle.

Since the end position is predetermined for each steering device, when a plurality of motor angles corresponding to one end position are set while the steering shaft is at the end position, the difference between them becomes a small value. On the other hand, the absolute motor angle when the steering wheel hits the curb differs depending on the situation, so if the motor angle corresponding to one end position is set while the steering wheel hits the curb, these differences will be large. .. Therefore, as in the above configuration, when the difference between one of the plurality of motor angles corresponding to one end position and the other one is equal to or less than a predetermined difference, by setting the provisional end position corresponding steering angle, for example, one of the plurality of ones. When one of the end position corresponding motor angles is set in a state where the steering wheel hits the curb, it is possible to suppress the setting of the provisional end position corresponding steering angle.

In the steering control device, the end position determination unit has a steering shaft when the angular velocity of the motor is equal to or lower than a predetermined angular velocity indicating a stopped state and the torque applied to the steering mechanism is equal to or higher than the predetermined torque. It is preferable to determine that it is in the end position.

According to the above configuration, it can be easily and accurately determined that the steering shaft is at the end position.

According to the present invention, it is possible to obtain an accurate absolute motor angle corresponding to an actual steering angle.

Schematic diagram of the electric power steering device. The block diagram of the steering control device of 1st Embodiment. A map showing the relationship between the current correction value of end guess relaxation control and the control steering angle. The flowchart which shows the processing procedure of the control steering angle calculation part of 1st Embodiment. The block diagram of the control steering angle calculation part of 1st Embodiment. The schematic diagram which shows the relationship between the mechanical elastic deformation of a steering mechanism, and the absolute angle of a motor. The flowchart which shows the processing procedure of setting of the motor angle corresponding to an end position. A flowchart showing a processing procedure for setting the control steering angle origin. The block diagram of the steering control device of the 2nd Embodiment. The flowchart which shows the processing procedure of the control steering angle calculation part of 2nd Embodiment. A map showing the relationship between the current correction value of the provisional end guess relaxation control and the control steering angle. The block diagram of the control steering angle calculation part of 2nd Embodiment. A flowchart showing a processing procedure for setting a plurality of motor angles corresponding to one end position. A flowchart showing a processing procedure for setting a rudder angle corresponding to a provisional end position. The block diagram of the current command value calculation part of 3rd Embodiment. The block diagram of the current command value calculation part of 4th Embodiment.

(First Embodiment)
Hereinafter, the first embodiment of the steering control device will be described with reference to the drawings.
As shown in FIG. 1, the electric power steering device (EPS) 1 as a steering device to be controlled includes a steering mechanism 4 that steers the steering wheel 3 based on the operation of the steering wheel 2 by the driver. .. Further, the EPS 1 includes an EPS actuator 5 as an actuator that applies an assist force for assisting the steering operation to the steering mechanism 4, and a steering control device 6 that controls the operation of the EPS actuator 5.

The steering mechanism 4 is inserted through a steering shaft 11 to which the steering wheel 2 is fixed, a rack shaft 12 as a steering shaft that reciprocates in the axial direction according to the rotation of the steering shaft 11, and a rack shaft 12 that can reciprocate. It is provided with a substantially cylindrical rack housing 13. The steering shaft 11 is configured by connecting a column shaft 14, an intermediate shaft 15, and a pinion shaft 16 in order from the steering wheel 2 side.

The rack shaft 12 and the pinion shaft 16 are arranged in the rack housing 13 at a predetermined crossing angle, and the rack teeth 12a formed on the rack shaft 12 and the pinion teeth 16a formed on the pinion shaft 16 are meshed with each other. As a result, the rack and pinion mechanism 17 is configured. Further, tie rods 19 are rotatably connected to both ends of the rack shaft 12 via rack ends 18 formed of ball joints provided at the shaft ends thereof. The tip of the tie rod 19 is connected to a knuckle (not shown) to which the steering wheel 3 is assembled. Therefore, in EPS 1, the rotation of the steering shaft 11 accompanying the steering operation is converted into the axial movement of the rack shaft 12 by the rack and pinion mechanism 17, and this axial movement is transmitted to the knuckle via the tie rod 19. The steering angle of the steering wheel 3, that is, the traveling direction of the vehicle is changed.

The position where the rack end 18 abuts on the left end of the rack housing 13 is the position where the maximum steering is possible in the right direction, and the same position corresponds to the rack end position as the right end position. Further, the position where the rack end 18 abuts on the right end of the rack housing 13 is a position where maximum steering is possible in the left direction, and the same position corresponds to the rack end position as the left end position.

The EPS actuator 5 includes a motor 21 which is a drive source, and a reduction mechanism 22 such as a worm and wheel which is connected to the motor 21 and also connected to the column shaft 14. Then, the EPS actuator 5 decelerates the rotation of the motor 21 by the deceleration mechanism 22 and transmits it to the column shaft 14, thereby applying the motor torque Tm to the steering mechanism 4 as an assist force. A three-phase brushless motor is used for the motor 21 of the present embodiment.

The steering control device 6 is connected to a vehicle speed sensor 31 that detects the vehicle speed V of the vehicle and a torque sensor 32 that detects the steering torque Ts applied to the steering shaft 11 by the steering of the driver. Further, the steering control device 6 is connected to a rotation sensor 33 as a motor relative angle detecting unit that detects the rotation angle θmc of the motor 21 at a relative angle within a range of 360 °. The steering torque Ts and the angle of rotation θmc are detected as positive values when steering in one direction (right in this embodiment) and negative values when steering in the other direction (left in this embodiment). do. Then, the steering control device 6 operates the EPS actuator 5 by supplying driving power to the motor 21 based on the signal indicating each state amount input from each of these sensors and the signal indicating the state amount of the motor 21. That is, the assist force applied to the steering mechanism 4 is controlled.

As shown in FIG. 2, the steering control device 6 includes a microcomputer 41 as a motor control unit that outputs a control signal, and a drive circuit 42 that supplies drive power to the motor 21 based on the control signal. The drive circuit 42 of the present embodiment employs a well-known PWM inverter having a plurality of switching elements (for example, FETs and the like). The control signal output by the microcomputer 41 defines the on / off state of each switching element. As a result, each switching element is turned on and off in response to the control signal, and the energization pattern for the motor coil of each phase is switched, so that the DC power of the battery 43 is converted into the three-phase drive power and output to the motor 21. Will be done. Each control block shown below is realized by a computer program executed by the microcomputer 41. Each state quantity is detected in a predetermined sampling cycle (detection cycle), and each of the following is performed in each predetermined calculation cycle. Each arithmetic process shown in the control block is executed.

The vehicle speed V, steering torque Ts, and rotation angle θmc of the motor 21 are input to the microcomputer 41. Further, each phase current value I of the motor 21 detected by the current sensor 45 provided on the connection line 44 between the drive circuit 42 and the motor coil of each phase is input to the microcomputer 41. In FIG. 2, for convenience of explanation, the connection line of each phase and the current sensor 45 of each phase are shown together as one. Then, the microcomputer 41 outputs a control signal based on each of these state quantities.

Specifically, the microcomputer 41 has a current command value calculation unit 51 that calculates a target value of power supply to the motor 21, that is, a current command value Id *, Iq * corresponding to the target assist force, and a current command value Id *, Iq *. A control signal output unit 52 that outputs a control signal based on the above is provided. Further, the microcomputer 41 calculates 360 ° by accumulating (counting) the number of rotations based on the rotation angle θmc of the motor 21 with the angle in the state where the rack shaft 12 is in the steering neutral position as the origin (zero degree). It is equipped with a control steering angle calculation unit 53 that calculates the control steering angle θs indicated by an absolute angle in the range exceeding the range, an angular velocity calculation unit 54 that calculates the angular velocity ωm of the motor 21 by differentiating the rotation angle θmc, and a memory 55. There is. The control rudder angle θs is a positive value when the rotation angle is one direction from the steering neutral position and a negative value when the rotation angle is the other direction, as in the rotation angle θmc of the motor 21. The command value is a positive value when assisting steering in one direction and a negative value when assisting steering in the other direction.

The current command values Id * and Iq * are target values of the current to be supplied to the motor 21, and indicate the current command value on the d-axis and the current command value on the q-axis in the d / q coordinate system, respectively. Of these, the q-axis current command value Iq * corresponds to the torque command value, which is the target value of the output torque of the motor 21. In this embodiment, the d-axis current command value Id * is fixed to zero.

Specifically, the current command value calculation unit 51 includes a basic assist calculation unit 61 that calculates the basic current command value Ias *, which is a basic component of the q-axis current command value Iq *, and a current correction value Ira for the basic current command value Ias *. It is provided with a current correction value calculation unit 62 for calculating *. Steering torque Ts and vehicle speed V are input to the basic assist calculation unit 61. Then, the basic assist calculation unit 61 calculates the basic current command value Is * based on the steering torque Ts and the vehicle speed V. Specifically, the basic assist calculation unit 61 calculates the basic current command value Ias * having a larger value (absolute value) as the absolute value of the steering torque Ts is larger and the vehicle speed V is slower. The basic current command value Is * calculated in this way is input to the subtractor 63.

The current correction value calculation unit 62 calculates the current correction value Ira * based on the control steering angle θs output from the control steering angle calculation unit 53, which will be described later. When the control steering angle θs is not output from the control steering angle calculation unit 53, the current correction value calculation unit 62 does not calculate the current correction value Ira * or outputs zero as the current correction value Ira *. The current correction value Ira * is a correction component that corrects the basic current command value Ias * so that the steering reaction force is applied to the steering shaft 11, and by outputting the current correction value Ira *, the impact of the end contact is applied. Execute end guess relaxation control to alleviate. The current correction value calculation unit 62 has, for example, a map as shown in FIG. 3, and calculates the current correction value Ira * from the control steering angle θs based on this map. In this map, the near-end rudder whose absolute value is smaller than the control steering angle θs at the rack end position (end position corresponding motor angle θma_le, θma_re) where the rack end 18 abuts on the rack housing 13 is the first angle θ1. The angle θne is set. The first angle θ1 is set to a relatively small angle so that the steering angle θne near the end is not too far from the rack end position. The current correction value Ira * has a larger steering reaction as the absolute value of the control steering angle θs becomes larger when the absolute value of the control steering angle θs becomes larger than the absolute value of the steering angle θne near the end according to this map. It is calculated so that the force is applied. The current correction value Ira * calculated in this way is input to the subtractor 63.

The subtractor 63 obtains the q-axis current command value Iq * by subtracting the current correction value Ira * calculated by the current correction value calculation unit 62 from the basic current command value Ias * calculated by the basic assist calculation unit 61. Calculate. Then, the subtractor 63 outputs the calculated q-axis current command value Iq * to the control signal output unit 52. As a result, the microcomputer 41 has a q-axis current that becomes a torque command value based on an increase in the absolute value of the control steering angle θs when the absolute value of the control steering angle θs exceeds the absolute value of the steering angle θne near the end. End guess relaxation control is performed to reduce the absolute value of the command value Iq *.

The control signal output unit 52 outputs a control signal by executing current feedback control in the d / q coordinate system based on the current command values Id *, Iq *, each phase current value I, and the rotation angle θmc of the motor 21. Generate. Specifically, the control signal output unit 52 maps each phase current value I on the d / q coordinates based on the rotation angle θmc, so that the d-axis current, which is the actual current value of the motor 21 in the d / q coordinate system, is present. Calculate the value and the q-axis current value. Then, the control signal output unit 52 performs current feedback control so that the d-axis current value follows the d-axis current command value Id * and the q-axis current value follows the q-axis current command value Iq *. By doing so, a control signal is generated. When this control signal is output to the drive circuit 42, drive power corresponding to the control signal is supplied to the motor 21. As a result, the drive of the motor 21 is controlled so that the output torque of the motor 21 follows the torque command value corresponding to the q-axis current command value Iq *.

Next, the calculation of the control steering angle θs by the control steering angle calculation unit 53 will be described.
Steering torque Ts, rotation angle θmc of the motor 21, angular velocity ωm, and each phase current value I are input to the control steering angle calculation unit 53, and the control steering angle calculation unit 53 controls the control steering angle based on these state quantities. Calculate θs. Here, the control steering angle θs is a motor absolute angle θma represented by an absolute angle in the range exceeding 360 ° by integrating the rotation speed of the motor 21 with the angle in the steering neutral position as the origin. The control steering angle calculation unit 53 calculates the control steering angle θs (motor absolute angle θma) by counting the rotation speed from the rotation angle θmc of the motor 21 and the origin. The origin of the control steering angle θs is stored in the memory 55 in association with the steering neutral position of the steering mechanism 4. By the way, if the power supply to the microcomputer 41 is cut off due to, for example, replacement of the battery 43, the rotation of the motor 21 cannot be detected, so that the correspondence cannot be maintained when the rudder angle changes, and the rudder of the steering mechanism 4 cannot be maintained. The origin of the control rudder angle θs associated with the angle disappears. Therefore, the control rudder angle calculation unit 53 sets the origin of the control rudder angle θs when the origin is not set.

When setting the origin of the control rudder angle θs, the control rudder angle calculation unit 53 first sets the motor absolute angle θma when the rack shaft 12 is at the left and right rack end positions as the motor angles θma_le and θma_re corresponding to the left and right end positions. .. Then, the origin of the control steering angle θs is set based on the motor angles θma_le and θma_re corresponding to the left and right end positions. When the origin is set, the control steering angle calculation unit 53 calculates the control steering angle θs by counting the rotation speed θmc of the acquired motor 21 and the rotation speed from the origin, and calculates the current correction value. Output to unit 62.

Specifically, as shown in the flowchart of FIG. 4, when the control steering angle calculation unit 53 acquires various state quantities (step 101), a control flag indicating that the origin of the control steering angle θs should be set is set. It is determined whether or not it has been done (step 102). It should be noted that this control flag is preset so as to be set when the power supply to the steering control device 6 is stopped and then the power supply is started again.

Then, when the control flag is not set (step 102: NO), the control steering angle calculation unit 53 calculates the control steering angle θs and outputs it to the current correction value calculation unit 62 (step 103). On the other hand, when the control flag is set (step 102: YES), the left and right end position corresponding motor angles θma_le and θma_re are set (step 104), and then the origin of the control steering angle θs is set. (Step 105).

Next, the setting of the motor angles θma_le and θma_re corresponding to the left and right end positions will be described.
As shown in FIG. 5, the control rudder angle calculation unit 53 includes a motor absolute angle calculation unit 71 as a motor absolute angle detection unit, an output switching unit 72, an end position determination unit 73, and an end position corresponding motor angle setting unit. It includes 74 and a control steering angle origin setting unit 75.

The rotation angle θmc of the motor 21, the steering torque Ts, and each phase current value I are input to the motor absolute angle calculation unit 71. Then, the motor absolute angle calculation unit 71 subtracts the mechanical elastic deformation generated in the steering mechanism 4 from the elementary motor absolute angle calculated from the rotation angle θmc of the motor 21 and the rotation speed from the origin. Calculate θma. When the origin of the control steering angle θs is not set in the memory 55, the motor absolute angle calculation unit 71 of the present embodiment temporarily sets the rack position when the power is first supplied to the steering control device 6. The motor absolute angle θma is calculated by storing it as the origin and integrating the number of rotations from the origin.

Specifically, the motor absolute angle calculation unit 71 sums the steering torque Ts given to the driver and the motor torque Tm calculated based on the phase current value I, which is the actual current value detected by the current sensor 45. That is, the pinion shaft torque Tp, which is the total value of the torque applied to the steering mechanism 4, is calculated. Then, the motor absolute angle calculation unit 71 calculates the motor absolute angle θma corrected based on the mechanical elastic deformation of the steering mechanism 4 caused by the pinion shaft torque Tp applied to the steering mechanism 4.

Here, as shown in FIG. 6, when the steering operation is normally performed by the driver, the steering wheel 3 is steered according to the pinion shaft torque Tp applied to the steering mechanism 4, and the motor absolute angle θma increases. do. Then, from a position slightly exceeding the motor absolute angle θma corresponding to the actual rack end position, the motor absolute angle θma hardly increases even if the pinion shaft torque Tp increases. This is because the rack shaft 12 is located at the rack end position, so that the pinion shaft torque Tp increases, and the motor is mechanically elastically deformed by twisting the steering shaft 11 constituting the steering mechanism 4 or compressing the rack shaft 12. This is because 21 rotates only slightly. Further, even in a state where the rack shaft 12 reciprocates due to the steering operation, the steering mechanism 4 is elastically deformed according to the pinion shaft torque Tp, and the calculated motor absolute angle θma is the actual rack shaft 12 The value deviates in the steering direction from the motor absolute angle θma corresponding to the position of. Since the slope of the pinion shaft torque Tp with respect to the absolute motor angle θma is proportional to the elastic coefficient K of the steering mechanism 4, the base point is the absolute motor angle obtained by integrating the rotation speed from the origin into the rotation angle θmc of the motor 21. In addition, the motor absolute angle θma at the position where the pinion shaft torque Tp becomes zero according to the inclination substantially coincides with the actual rack end position.

Based on this, the motor absolute angle calculation unit 71 calculates the rotation (K × Tp) of the motor 21 based on the elastic deformation obtained by multiplying the elasticity coefficient K of the steering mechanism 4 by the pinion shaft torque Tp from the elementary motor absolute angle. The subtracted value is detected as the motor absolute angle θma. In the present embodiment, the elastic modulus K of the steering mechanism 4 is obtained in advance by an experiment, a simulation, or the like using an actual model of the steering mechanism 4.

As shown in FIG. 5, the motor absolute angle θma calculated in this way is output to the output switching unit 72. Before setting the origin of the control steering angle θs, the output switching unit 72 outputs the motor absolute angle θma to the end position corresponding motor angle setting unit 74 and the control steering angle origin setting unit 75. After setting the origin of the control steering angle θs, the motor absolute angle θma based on the rotation speed from the origin, that is, the control steering angle θs is output to the current correction value calculation unit 62.

Steering torque Ts, each phase current value I, and angular velocity ωm are input to the end position determination unit 73. Then, in the end position determination unit 73, when the angular velocity ωm of the motor 21 is equal to or higher than the predetermined angular velocity ωth and the pinion shaft torque Tp is equal to or higher than the predetermined torque Tth for a predetermined time or longer, the rack shaft 12 is left or right. It is determined that the rack end is at the rack end position, and a determination signal S indicating that effect is output to the end position corresponding motor angle setting unit 74. The predetermined angular velocity ωth is a value indicating that the motor 21 is stopped, and is set to a value slightly larger than zero in consideration of the influence of signal noise and the like. Further, the predetermined torque Tth is set to an appropriate value larger than zero, which indicates the torque at which the steering wheel 3 can be steered on a normal road surface.

The end position corresponding motor angle setting unit 74 determines the steering direction based on the input code of the motor absolute angle θma, and determines the motor absolute angle θma when it is determined that the rack shaft 12 is at the left rack end position. Set as the motor angle θma_le corresponding to the left end position. Further, the end position corresponding motor angle setting unit 74 sets the motor absolute angle θma when it is determined that the rack shaft 12 is at the right rack end position as the right end position corresponding motor angle θma_re. Further, even after the left and right end position corresponding motor angles θma_le and θma_re are once set in the end position corresponding motor angle setting unit 74, the motor absolute angle θma having the same sign as the end position corresponding motor angles θma_le and θma_re and having a large absolute value is obtained. When detected, this motor absolute angle θma is updated as new end position corresponding motor angles θma_le and θma_re.

Next, the procedure for setting the end position corresponding motor angles θma_le and θma_re will be described.
As shown in the flowchart of FIG. 7, when the control steering angle calculation unit 53 acquires various state quantities (step 201), it determines whether or not the steering is left steering based on the calculated code of the motor absolute angle θma (step 201). Step 202). In the case of left steering (step 202: YES), it is determined whether or not the absolute value of the angular velocity ωm of the motor 21 is equal to or less than the predetermined angular velocity ωth (step 203). Subsequently, when the absolute value of the angular velocity ωm is equal to or less than the predetermined angular velocity ωth (step 203: YES), it is determined whether or not the absolute value of the pinion shaft torque Tp is equal to or greater than the predetermined torque Tth (step 204). When the pinion shaft torque Tp is equal to or greater than the predetermined torque Tth (step 204: YES), the left end counter Cl is incremented (step 205: Cl = Cl + 1), and the left end counter Cl is equal to or greater than the predetermined counter Cth. Whether or not it is determined (step 206). On the other hand, when the absolute value of the angular velocity ωm is larger than the predetermined angular velocity ωth (step 203: NO), and when the absolute value of the pinion shaft torque Tp is less than the predetermined torque Tth (step 204: NO), the left end counter. Reset Cl (step 207: Cl = 0).

Subsequently, when the left end counter Cl becomes equal to or higher than the predetermined counter Cth due to a further cut by the driver while the rack shaft 12 is at the left rack end position (step 206: YES), this time. It is determined whether or not the absolute value of the motor absolute angle θma calculated in the calculation cycle is larger than the absolute value of the left end position corresponding motor angle θma_le stored in the memory 55 (step 208). In the memory 55, zero is set as the initial value of the motor angles θma_le and θma_re corresponding to the left and right end positions. When the absolute value of the motor absolute angle θma is larger than the absolute value of the motor angle θma_le corresponding to the left end position (step 208: YES), the motor absolute angle θma is set as the motor angle θma_le corresponding to the left end position. Then, the left end counter Cl is reset (step 209). On the other hand, when the left end counter Cl is less than the predetermined counter Cth (step 206: NO), and when the absolute value of the motor absolute angle θma is equal to or less than the absolute value of the left end position corresponding motor angle θma_le (step 208: NO). ), Do not set / update the motor angle θma_le corresponding to the left end position.

If the control steering angle calculation unit 53 is not steering to the left (step 202: NO), the control steering angle calculation unit 53 determines whether or not the steering is to the right (step 210). In the case of right steering (step 210: YES), the end position determination is performed in the same manner as in steps 203 and 204 (steps 211 and 212). If the end position determination is established (steps 211,212: YES), the right end counter Cr is incremented (step 213: Cr = Cr + 1), and it is determined whether or not the right end counter Cr is equal to or greater than the predetermined counter Cth. (Step 214). On the other hand, if the end position determination is not established (steps 211,212: NO), the right end counter Cr is reset (step 215: Cr = 0).

When the right end counter Cr becomes equal to or higher than the predetermined counter Cth (step 214: YES), the absolute value of the motor absolute angle θma calculated in the current calculation cycle is stored in the memory 55. It is determined whether or not the angle θma_re is larger than the absolute value (step 216). When the absolute value of the motor absolute angle θma is larger than the absolute value of the motor angle θma_le corresponding to the left end position (step 216: YES), the motor absolute angle θma is set as the motor angle θma_re corresponding to the right end position. Then, the right end counter Cr is reset (step 217). On the other hand, when the right end counter Cr is less than the predetermined counter Cth (step 214: NO), and when the absolute value of the motor absolute angle θma is equal to or less than the absolute value of the right end position corresponding motor angle θma_re (step 216: NO). ), Do not set / update the motor angle θma_re corresponding to the right end position. If the steering is not right-handed (step 210: NO), the processes of steps 203 to 209 and steps 211 to 217 are not performed.

Next, the setting of the origin of the control steering angle θs will be described.
The control steering angle origin setting unit 75 has a steering neutral position rather than the end position corresponding motor angles θma_le and θma_re for which the detected motor absolute angle θma is set or updated after the end position corresponding motor angles θma_le and θma_re are set or updated. After approaching the first angle θ1 or more to the side, the origin of the control steering angle θs is set based on the end position corresponding motor angles θma_le and θma_re stored in the memory 55.

Specifically, as shown in FIG. 8, when the control steering angle origin setting unit 75 acquires various state quantities (step 301), the motor absolute angle θma is the first angle than the left and right end position corresponding motor angles θma_le and θma_re. Determine whether or not it is close to the steering neutral position by θ1 or more. Specifically, it is determined whether or not the motor absolute angle θma is within the origin setting permission range (−θne ≦ θma ≦ θne) away from the rack end position (step 302). When the motor absolute angle θma is within the origin setting permission range (step 302: YES), the stroke width Wma, which is the sum of the absolute values of the motor angles θma_le and θma_re corresponding to the left and right end positions, is calculated (step 303). Then, it is determined whether or not the stroke width Wma is larger than the stroke threshold value Wth indicating the motor absolute angle range corresponding to the entire stroke range of the rack shaft 12 (step 304). The stroke threshold value Wth is set to a value slightly smaller than the motor absolute angle range. If the absolute motor angle θma is not within the origin setting permission range (step 302: NO), the processes of steps 303 to 307 are not executed.

When the stroke width Wma is larger than the stroke threshold value Wth (step 304: YES), the control steering angle origin setting unit 75 calculates the average value of the left and right end position corresponding motor angles θma_le and θma_re as the offset angle Δθ (step 304: YES). Step 305). Then, the angle (θma−Δθ) obtained by subtracting the offset angle from the detected motor absolute angle θma is set as the origin of the control steering angle θs (step 306), indicating that the origin of the control steering angle θs should be set. Reset the control flag (step 307). When the stroke width Wma is equal to or less than the stroke threshold value Wth (step 304: NO), the processes of steps 305 to 307 are not executed.

As described above, according to the present embodiment, the following effects can be obtained.
(1) The motor absolute angle θma when it is determined that the rack shaft 12 is at the rack end position is set as the motor angles θma_le and θma_re corresponding to the left and right end positions. Therefore, for example, the absolute motor angle when it is determined to be in a straight-ahead state is set as the origin corresponding to the steering neutral position, and the motor angles θma_le and θma_re corresponding to the end position are set more accurately than when the motor angle corresponding to the end position is estimated. can.

(2) The motor absolute angle calculation unit 71 acquires the motor absolute angle θma at an angle corrected based on the mechanical elastic deformation caused by the pinion shaft torque Tp applied to the steering mechanism 4, so that it is more accurate. End position compatible motor angles θma_le and θma_re can be set.

(3) The steering mechanism 4 converts the rotation of the steering shaft 11 connecting the column shaft 14, the intermediate shaft 15, and the pinion shaft 16 into the reciprocating motion of the rack shaft 12 via the rack and pinion mechanism 17 and transmits the rotation. The EPS actuator 5 applies the motor torque Tm of the motor 21 to the column shaft 14. As described above, in the present embodiment, the motor torque Tm is transmitted to the steering wheel 3 via the column shaft 14, the intermediate shaft 15, the pinion shaft 16, the rack shaft 12, and the like, so that not only the compression of the rack shaft 12 but also, for example, is performed. The elastic deformation of the steering mechanism 4 tends to increase due to the applied torque such as the twist of the intermediate shaft 15. Therefore, the effect of setting the motor absolute angle θma corrected based on the elastic deformation generated in the steering mechanism 4 as the end position corresponding motor angles θma_le and θma_re is great.

(4) When the end position determination unit 73 makes a determination based on the pinion shaft torque Tp and the angular velocity ωm of the motor 21 as in the present embodiment, if the steering wheel 3 hits a curb or the like, the rack shaft is actually used. Even if 12 is not at the rack end position, it may be erroneously determined that the 12 is at the rack end position at a position in front of it. As a result, the end position corresponding motor angles θma_le and θma_re may also be set to inaccurate angles. In this respect, in the present embodiment, even if the end position corresponding motor angles θma_le and θma_re are once set, when the motor absolute angle θma having the same sign as the end position corresponding motor angles θma_le and θma_re and having a large absolute value is detected. Since it is updated, it is possible to prevent the wrong end position corresponding motor angles θma_le and θma_re from being set.

(5) Since the average value of the motor angles θma_le and θma_re corresponding to the left and right end positions is set as the offset angle Δθ, and the angle obtained by subtracting the offset angle Δθ from the motor absolute angle θma is set as the origin of the control steering angle θs, it is easy. The origin corresponding to the steering neutral position can be set.

(6) For example, when the steering wheel 3 hits a curb or the like, it is determined that the rack shaft 12 is at the rack end position, and when the wrong end position corresponding motor angles θma_le and θma_re are set, the left and right end positions are supported. The stroke width Wma, which is the sum of the absolute values of the motor angles θma_le and θma_re, becomes smaller than the stroke threshold value Wth. Based on this point, since the origin is not set when the stroke width Wma is less than the stroke threshold value Wth, it is possible to suppress the setting of the origin of the erroneous control steering angle θs.

(7) The steering control device 6 has a q-axis which is a torque command value based on an increase in the absolute value of the control steering angle θs when the absolute value of the control steering angle θs exceeds the absolute value of the steering angle θne near the end. End guess relaxation control is performed to reduce the absolute value of the current command value Iq *. Then, when setting the origin of the control steering angle θs, after the left and right end position corresponding motor angles θma_le and θma_re are set, the motor absolute angle θma is closer to the steering neutral position side than the end position corresponding motor angles θma_le and θma_re. After approaching the first angle θ1 or more, the origin is set based on the motor angles θma_le and θma_re corresponding to the left and right end positions. Therefore, immediately after setting the left and right end position corresponding motor angles θma_le and θma_re, that is, by setting the origin of the control rudder angle θs while the rack shaft 12 is still in the rack end position, end contact relaxation control is executed. It is possible to prevent the steering reaction force from being suddenly applied by the EPS actuator 5.

(8) The rack shaft 12 is at the rack end position when the angular velocity ωm of the motor 21 is equal to or less than the predetermined angular velocity ωth indicating a stopped state and the pinion shaft torque Tp applied to the steering mechanism 4 is equal to or higher than the predetermined torque Tth. Therefore, it can be easily and accurately determined that the rack shaft 12 is at the rack end position.

(Second Embodiment)
Next, a second embodiment of the steering control device will be described with reference to the drawings. For convenience of explanation, the same components are designated by the same reference numerals as those in the first embodiment, and the description thereof will be omitted.

As shown in FIG. 9, the current command value calculation unit 51 of the present embodiment includes a provisional current correction value calculation unit 81 in addition to the basic assist calculation unit 61 and the current correction value calculation unit 62. Further, in addition to calculating the control rudder angle θs as in the first embodiment, the control rudder angle calculation unit 53 has a plurality of left and right end pads in a state where the origin of the control rudder angle θs is not set. The provisional end position corresponding rudder angle θma_xe represented by the motor absolute angle θma at the rack end position in the direction in which the end contact is performed is set when the rotation is performed. Then, the provisional end separation angle θsx, which is the value obtained by subtracting the motor absolute angle θma from the steering angle θma_xe corresponding to the provisional end position, is output to the provisional current correction value calculation unit 81, and the provisional current correction value calculation unit 81 outputs the provisional current correction value. Make Irb * output. After setting the origin of the control rudder angle θs, the control rudder angle calculation unit 53 does not calculate the provisional end separation angle θsx, but calculates only the control rudder angle θs.

Specifically, as shown in the flowchart of FIG. 10, the control steering angle calculation unit 53 performs the control steering angle origin setting process in step 105, and then the first and second end position corresponding motor angles θma_x1, A plurality of motor angle setting processes corresponding to one end position for setting ma_x2 are performed (step 401), and a rudder angle setting process corresponding to the provisional end position is performed (step 402). Then, the provisional end separation angle θsx is calculated based on the steering angle θma_xe corresponding to the provisional end position set in step 402 (step 403). The processes other than steps 401 to 403 are performed in the same manner as in the first embodiment.

The provisional current correction value calculation unit 81 calculates the provisional current correction value Irb * based on the provisional end separation angle θsx and the angular velocity ωm output from the control steering angle calculation unit 53. If the provisional end separation angle θsx is not output from the control steering angle calculation unit 53, the provisional current correction value calculation unit 81 does not calculate the provisional current correction value Irb *, or sets zero as the provisional current correction value Irb *. Output. The provisional current correction value Irb * is a correction component that corrects the basic current command value Is * so that the steering reaction force is applied to the steering shaft 11, and the provisional current correction value Irb * is output to the subtractor 63. Then, the provisional end contact relaxation control for alleviating the impact of the end contact is executed.

The provisional current correction value calculation unit 81 has a map as shown in FIG. 11, for example, and calculates the provisional current correction value Irb * from the provisional end separation angle θsx and the angular velocity ωm based on this map. In this map, the larger the absolute value of the provisional end separation angle θsx is closer to zero, and the larger the absolute value of the angular velocity ωm is, the larger the provisional current correction value Irb * is set to be calculated. When the absolute value of θsx becomes the second angle θ2 or more, the provisional current correction value Irb * is set to be zero. The second angle θ2 is an angle from the steering angle θma_xe corresponding to the provisional end position to the steering angle θnxe near the provisional end closer to the steering neutral position than the steering angle θma_xe corresponding to the provisional end position, and the steering angle θnxe near the provisional end is provisional. The rudder angle corresponding to the end position is set to a relatively small angle so as not to be too far from the rudder angle θma_xe. The size of the second angle θ2 of the present embodiment is set to be equal to the size of the first angle θ1. That is, the current command value calculation unit 51 performs the provisional end guess relaxation control when the angle of the motor absolute angle θma to the steering angle θnxe near the provisional end is less than the second angle θ2.

In the subtractor 63, in addition to the basic current command value Ias *, the current correction value Ira * or the provisional current depends on whether the control steering angle calculation unit 53 calculates the control steering angle θs or the provisional end separation angle θsx. The correction value Irb * is input. Then, the subtractor 63 calculates the q-axis current command value Iq * by subtracting the current correction value Ira * or the provisional current correction value Irb * from the basic current command value Ias * calculated by the basic assist calculation unit 61. do. As a result, the microcomputer 41 has a q-axis current that becomes a torque command value based on an increase in the absolute value of the control steering angle θs when the absolute value of the control steering angle θs exceeds the absolute value of the steering angle θne near the end. End contact relaxation control that reduces the absolute value of the command value Iq *, or when the provisional end separation angle θsx becomes less than the second angle θ2, the torque command value becomes the torque command value based on the decrease in the provisional end separation angle θsx. Temporary end guess relaxation control is executed to reduce the absolute value of the shaft current command value Iq *.

Next, the setting of the steering angle θma_xe corresponding to the provisional end position will be described.
As shown in FIG. 12, in addition to each block of the first embodiment, the control steering angle calculation unit 53 of the present embodiment has an end position corresponding motor angle setting unit 91 and a provisional end position corresponding steering angle setting unit 92. And a provisional end separation angle calculation unit 93.

On the other hand, the determination signal S and the motor absolute angle θma are input to the end position corresponding motor angle setting unit 91. On the other hand, the end position corresponding motor angle setting unit 91 is connected to the memory 55. On the other hand, when the end position corresponding motor angle θma_le or θma_re is set in the memory 55 by the end position corresponding motor angle setting unit 74, the end position corresponding motor angle setting unit 91 has the end position corresponding motor angle θma_le, One of θma_re is set as the first motor angle θma_x1 corresponding to one end position, which is one of the motor angles corresponding to one end position. Further, the motor angle setting unit 91 corresponding to one end position has changed the absolute motor angle θma by a predetermined steering amount θth or more indicating that the turning back steering has been performed after setting the first one end position corresponding motor angle θma_x1. Later, the motor absolute angle θma when the determination signal S indicating that the rack shaft 12 is at the end position in the same direction is input is set as the second one end position corresponding motor angle θma_x2. The predetermined steering amount θth is set to, for example, about half of the stroke threshold value Wth, that is, the steering amount from the rack end position to the steering neutral position, and is set to a value sufficiently larger than the detection error of the rotation sensor 33. Will be done.

Specifically, as shown in the flowchart of FIG. 13, the end position corresponding motor angle setting unit 91 executes the processes of steps 501 to 514 as the processes of step 401. On the other hand, when the end position corresponding motor angle setting unit 91 acquires various state quantities (step 501), it determines whether or not the control flag is set (step 502), and when the control flag is set (step 502). Step 502: YES), it is determined whether or not the provisional flag is set (step 503). The provisional flag is a flag indicating whether or not the first and second end position corresponding motor angles θma_x1 and ma_x2, which are the basis of the provisional end position corresponding steering angle θma_xe, are set in the memory 55, and is sent to the steering control device 6. It has been reset when the power supply is resumed. If the control flag is not set (step 502: NO) and the provisional flag is set (step 503: YES), the subsequent processes of step 402 are not executed.

Subsequently, the one-sided end position corresponding motor angle setting unit 91 determines whether or not the first one end position corresponding motor angle θma_x1 is set when the provisional flag is not set (step 503: NO). (Step 504). If the first one-sided end position corresponding motor angle θma_x1 is not set (step 504: NO), whether or not one of the left and right end position corresponding motor angles θma_le and θma_re set in step 104 is set. Is determined (step 505). When either the left or right end position corresponding motor angle θma_le or θma_re is set (step 505: YES), the angle is set as the first one end position corresponding motor angle θma_x1 (step 506). When the power supply to the steering control device 6 is stopped and then the power supply is started again, either one of the end position corresponding motor angles θma_le and θma_re is set in the memory 55 first. Therefore, in the state where the first one-sided end position corresponding motor angle θma_x1 is not set, the state where both the end position corresponding motor angles θma_le and θma_re are set in the memory 55 does not occur. On the other hand, when the motor angle θma_x1 corresponding to the first one end position is set (step 504: YES), the process proceeds to step 507 without executing the process of step 506. If either the left or right end position corresponding motor angles θma_le and θma_re are not set (step 505: NO), the subsequent processing of step 402 is not executed.

Subsequently, in step 507, the one-end position corresponding motor angle setting unit 91 determines whether or not the steering direction is the same as the end direction of the first one end position corresponding motor angle θma_x1 based on the sign of the motor absolute angle θma. To judge. When the steering direction is the same as the end direction of the motor angle θma_x1 corresponding to the first one end position (step 507: YES), it is determined whether or not the learning permission flag is set (step 508). The learning permission flag determines whether or not the motor absolute angle θma when the rack shaft 12 is determined to be at the rack end position by the end position determination unit 73 may be set as the second one end position corresponding motor angle θma_x2. This flag indicates that the flag is reset when the power supply to the steering control device 6 is resumed.

On the other hand, when the learning permission flag is not set (step 508: NO), the end position corresponding motor angle setting unit 91 is the absolute value of the value obtained by subtracting the motor absolute angle θma from the first one end position corresponding motor angle θma_x1. Is larger than the predetermined steering amount θth (step 509). When the absolute value of the subtracted value is larger than the predetermined steering amount θth (step 509: YES), the learning permission flag is set (step 510). If the absolute value of the subtracted value is equal to or less than the predetermined steering amount θth (step 509: NO), the learning permission flag is not set.

On the other hand, when the learning permission flag is set (step 508: YES), it is determined whether or not the determination signal S indicating that the rack shaft 12 is at the rack end position is input (step 511). Then, when the determination signal S indicating that the rack shaft 12 is at the rack end position is input (step 511: YES), the motor absolute angle θma in the same calculation cycle is set as the second one end position corresponding motor angle θma_x2. It is set (step 512), the provisional flag is set (step 513), and the learning permission flag is reset (step 514).

As shown in FIG. 12, the provisional end position corresponding steering angle setting unit 92 is the first one end when both the first and second one end position corresponding motor angles θma_x1 and θma_x2 are set in the memory 55. The difference α between the position-corresponding motor angle θma_x1 and the second end position-corresponding motor angle θma_x2 is calculated. Then, when the difference α is equal to or less than the predetermined difference αth, the provisional end position corresponding steering angle setting unit 92 sets the average value of the first and second end position corresponding motor angles θma_x1 and ma_x2 as the provisional end position corresponding steering angle. Calculate as θma_xe. The predetermined difference αth is zero in consideration of the detection error of the rotation sensor 33, the variation in the correction amount of the motor absolute angle θma based on the mechanical elastic deformation caused by the detection error of the torque sensor 32, and the like. It is set to a slightly larger value than. Subsequently, the provisional end position corresponding steering angle setting unit 92 is closer to the steering neutral position side by the second angle θ2 or more than the provisional end position corresponding steering angle θma_xe calculated by the motor absolute angle θma, and the provisional end position The corresponding steering angle θma_xe is set in the memory 55.

Specifically, as shown in the flowchart of FIG. 14, the provisional end position corresponding steering angle setting unit 92 executes the processes of steps 601 to 610 as the processes of step 402. When the provisional end position corresponding steering angle setting unit 92 acquires various state quantities (step 601), the provisional end position corresponding steering angle setting unit 92 determines whether or not the provisional end position corresponding steering angle θma_xe is set (step 602). If the steering angle θma_xe corresponding to the provisional end position is set (step 602: YES), the subsequent processing of step 403 is not executed. On the other hand, when the provisional end position corresponding steering angle θma_xe is not set (step 602: NO), whether or not the first and second end position corresponding motor angles θma_x1 and θma_x2 are set in the memory 55. Is determined (step 603). If the motor angles θma_x1 and θma_x2 corresponding to the first and second end positions are not set (step 603: NO), the subsequent steps 403 are not executed. On the other hand, when the motor angles θma_x1 and θma_x2 corresponding to the first and second end positions are set (step 603: YES), it is determined whether or not the provisional end position corresponding steering angle θma_xe has been calculated. (Step 604). If the provisional end position corresponding steering angle θma_xe has not been calculated yet (step 604: NO), the difference α between the first one end position corresponding motor angle θma_x1 and the second one end position corresponding motor angle θma_x2 is the predetermined difference αth. It is determined whether or not it is as follows (step 605). When the difference α is equal to or less than the predetermined difference αth (step 605: YES), the average value of the first one end position corresponding motor angle θma_x1 and the second one end position corresponding motor angle θma_x2 is used as the provisional end position corresponding steering angle. The calculation is performed as θma_xe (step 606), and the process proceeds to step 607. If the steering angle θma_xe corresponding to the provisional end position has already been calculated (step 604: YES), the process proceeds to step 607 without executing the processes of steps 605 and 606.

Subsequently, in step 607, the provisional end position corresponding steering angle setting unit 92 determines whether or not the absolute value of the value obtained by subtracting the motor absolute angle θma from the provisional end position corresponding steering angle θma_xe is the second angle θ2 or more, that is. It is determined whether or not the absolute motor angle θma is closer to the steering neutral position side than the steering angle θma_xe corresponding to the provisional end position by the second angle θ2 or more. When the motor absolute angle θma is closer to the steering neutral position side than the steering neutral position θ2 by the second angle θ2 or more (step 607: YES), the calculated provisional end position corresponding steering angle θma_xe is set in the memory 55. (Step 608). On the other hand, if the motor absolute angle θma is not closer to the steering neutral position side than the steering angle θma_xe corresponding to the provisional end position by the second angle θ2 or more (step 607: NO), the process of step 608 is not executed.

Further, when the difference α is larger than the predetermined difference αth (step 605: NO), the provisional end position corresponding steering angle setting unit 92 has one of the first and second end position corresponding motor angles θma_x1 and ma_x2. The larger one is updated as the first one end position corresponding motor angle θma_x1, and the other is deleted (step 609). Then, the provisional flag is reset (step 610).

As shown in FIG. 12, the motor absolute angle θma is input to the provisional end separation angle calculation unit 93. Then, when the provisional end position corresponding steering angle θma_xe is set in the memory 55, the provisional end separation angle calculation unit 93 subtracts the motor absolute angle θma from the provisional end position corresponding steering angle θma_xe to obtain the provisional end separation. It is output to the provisional current correction value calculation unit 81 as the angle θsx. As a result, the provisional current correction value Irb * is output from the provisional current correction value calculation unit 81, and the provisional end guess relaxation control is executed. The provisional end separation angle calculation unit 93 sets the provisional end separation angle θsx when the provisional end position corresponding steering angle θma_xe is not set in the memory 55 and when the origin of the control steering angle θs is set. It does not calculate and does not output to the provisional current correction value calculation unit 81.

Next, the action and effect of this embodiment will be described. In this embodiment, in addition to the effects of (1) to (8) of the first embodiment, the following effects are obtained.
(9) In the steering control device 6 of the present embodiment, when the origin of the control steering angle θs is not set, the steering angle corresponding to the provisional end position is based on the motor angles θma_x1 and ma_x2 corresponding to the first and second end positions. θma_xe was set, and provisional end guess relaxation control was performed to reduce the absolute value of the q-axis current command value Iq *, which is the torque command value, based on the decrease in the provisional end separation angle θsx.

Here, for example, depending on the traveling condition of the vehicle, it is assumed that the end contact of only one of the left and right ends is repeatedly generated. However, if both the left and right end hits do not occur, the origin of the control steering angle θs is not set and the end hit relaxation control is not executed, so that the impact of the end hits may cause discomfort to the driver. Further, considering the case where the motor angles θma_le and θma_re corresponding to either the left or right end position are set by, for example, the steering wheel 3 hitting a curb or the like, only the end position corresponding motor angle set by one end contact is taken into consideration. Then, there is a possibility that the set end position corresponding motor angle does not exactly correspond to the actual end position.

In this regard, in the present embodiment, the origin of the control steering angle θs is not set, for example, the appropriate motor angles θma_le and θma_re corresponding to both the left and right ends are not set, or the motor corresponding to only one of the left and right ends is supported. Even when the angles θma_le and θma_re are set, the appropriate provisional end position corresponding rudder angle θma_xe corresponding to the actual rack end position is set based on the motor angles θma_x1 and ma_x2 corresponding to the first and second end positions. can. Then, by performing the provisional end-hit relaxation control based on the rudder angle θma_xe corresponding to the provisional end position, even when only one of the end-hits is repeated while the origin of the control rudder angle θs is not set. The impact of the one end pad can be mitigated.

(10) The steering angle setting unit 92 corresponding to the provisional end position calculates the steering angle θma_xe corresponding to the provisional end position, and then the motor absolute angle θma is the second angle θ2 or more on the steering neutral position side with respect to the steering angle θma_xe corresponding to the provisional end position. The rudder angle θma_xe corresponding to the provisional end position was set after approaching. Therefore, immediately after setting the motor angles θma_x1 and ma_x2 corresponding to the first and second end positions, that is, by setting the provisional end position corresponding rudder angle θma_xe while the rack shaft 12 is still in the end position, the provisional end contact relaxation is relaxed. The control is executed, and it is possible to prevent the EPS actuator 5 from suddenly applying a steering reaction force.

(11) The provisional end position corresponding steering angle setting unit 92 sets the average value of the first and second end position corresponding motor angles θma_x1 and ma_x2 as the provisional end position corresponding steering angle θma_xe, so that the provisional end position corresponding steering angle θma_xe can be set appropriately.

(12) The provisional end position corresponding rudder angle setting unit 92 sets the first one end position corresponding motor angle θma_x1 and the first one end position corresponding motor angle θma_x1 and then sets the predetermined steering amount θth or more and the motor absolute angle θma. The provisional end position corresponding rudder angle θma_xe is set using the second one end position corresponding motor angle θma_x2 that was set after the change. Therefore, the second one-sided end position corresponding motor angle θma_x2 is set after the first one-sided end position corresponding motor angle θma_x1 is set and then the switchback steering is performed. Therefore, the first one-sided end position corresponding motor angle θma_x1 is set. There is a high possibility that the second one-end position corresponding motor angle θma_x2 will be set after the vehicle has moved from the above situation. As a result, for example, both the first and second end position corresponding motor angles θma_x1 and ma_x2 are set in a state where the steering wheel 3 hits the curb, and the provisional end position corresponding steering angle θma_xe is set based on these. Can be suppressed.

(13) The provisional end position corresponding steering angle setting unit 92 is the provisional end position when the difference α between the first one end position corresponding motor angle θma_x1 and the second one end position corresponding motor angle θma_x2 is equal to or less than the predetermined difference αth. The corresponding rudder angle θma_xe is set.

Here, since the rack end position is predetermined for each EPS 1, when the motor angles θma_x1 and ma_x2 corresponding to the first and second end positions are set while the rack shaft 12 is at the rack end position, These differences α are small values. On the other hand, since the motor absolute angle θma when the steering wheel 3 hits the curb differs depending on the situation, when the first and second end position corresponding motor angles θma_x2 are set while the steering wheel 3 hits the curb. In, these differences α become large. Therefore, as in the present embodiment, when the difference α is equal to or less than the predetermined difference αth, by setting the provisional end position corresponding steering angle θma_xe, for example, the first one end position corresponding motor angle θma_x1 can be set by the steering wheel 3. It is possible to prevent the provisional end position corresponding rudder angle θma_xe from being set when it is set in a state of hitting a curb.

(Third Embodiment)
Next, a third embodiment of the steering control device will be described with reference to the drawings. The main difference between this embodiment and the first embodiment is that in the first embodiment, the end guess relaxation control is executed by subtracting the current correction value Ira * from the basic current command value Ias *. In the present embodiment, the control is executed by performing a guard process on the basic current command value Ias *. Therefore, for convenience of explanation, the same components are designated by the same reference numerals as those in the first embodiment, and the description thereof will be omitted.

As shown in FIG. 15, the current command value calculation unit 51 of the present embodiment includes a basic assist calculation unit 61 and a guard processing unit 101 that limits the basic current command value Ias * based on the control steering angle θs. The current correction value calculation unit 62 of the first embodiment is not provided.

The basic current command value Is * output from the basic assist calculation unit 61 and the control steering angle θs output from the control steering angle calculation unit 53 (see FIG. 2) are input to the guard processing unit 101. The guard processing unit 101 limits the absolute value of the basic current command value Ias * to the current limit value Iga or less, and outputs it as the q-axis current command value Iq *. Then, when the absolute value of the control steering angle θs exceeds the end-near steering angle θne, the guard processing unit 101 reduces the absolute value of the current limit value Iga based on the increase.

Specifically, the guard processing unit 101 has a map as shown in FIG. 15, for example, and calculates the current limit value Iga according to the control steering angle θs based on this map. In this map, the current limit value Iga is set to the predetermined current value Imax until the absolute value of the control rudder angle θs exceeds the rudder angle θne near the end, and the absolute value of the control rudder angle θs is the absolute value of the rudder angle θne near the end. When it becomes larger than the value, the absolute value of the current limit value Iga becomes smaller as the absolute value of the control rudder angle θs becomes larger. The predetermined current value Imax is set to a value that does not limit the maximum value of the basic current command value Ias * calculated by the basic assist calculation unit 61, that is, the basic current command value Ias *.

Then, the guard processing unit 101 calculates the current limit value Iga according to the control steering angle θs, and when the absolute value of the input basic current command value Ias * is equal to or less than the current limit value Iga, the basic current command value. The value of Ias * is output as it is as the q-axis current command value Iq *. On the other hand, when the absolute value of the input basic current command value Ias * is larger than the current limit value Iga, the value of the basic current command value Ias * is limited to the value of the current limit value Iga and the q-axis current command value. Output as Iq *. When the control steering angle θs is not output from the control steering angle calculation unit 53, the guard processing unit 101 outputs the value of the basic current command value Ias * as it is as the q-axis current command value Iq *. As a result, the microcomputer 41 has a q-axis current that becomes a torque command value based on an increase in the absolute value of the control steering angle θs when the absolute value of the control steering angle θs exceeds the absolute value of the steering angle θne near the end. The end guess relaxation control that reduces the absolute value of the command value Iq * is executed.

As described above, this embodiment has the same effects as those of (1) to (8) of the first embodiment.
(Fourth Embodiment)
Next, a fourth embodiment of the steering control device will be described with reference to the drawings. The main difference between the present embodiment and the second embodiment is that in the second embodiment, the provisional end guess relaxation control is executed by subtracting the provisional current correction value Irb * from the basic current command value Is *. On the other hand, in the present embodiment, the control is executed by applying a provisional guard process to the basic current command value Ias *. Therefore, for convenience of explanation, the same components are designated by the same reference numerals as those in the second embodiment, and the description thereof will be omitted.

As shown in FIG. 16, the current command value calculation unit 51 of the present embodiment includes a basic assist calculation unit 61, a guard processing unit 111 that limits the basic current command value Ias * based on the control steering angle θs, and guard processing. It is provided with a provisional guard processing unit 112 that limits the later basic current command value Ias ** based on the provisional end separation angle θsx. The current correction value calculation unit 62 and the provisional current correction value calculation unit 81 of the second embodiment are not provided.

The guard processing unit 111 is configured in the same manner as the guard processing unit 101 of the third embodiment, and limits the basic current command value Ias * based on the control steering angle θs. The provisional guard processing unit 112 includes a basic current command value Is ** after guard processing, a provisional end separation angle θsx output from the control steering angle calculation unit 53 (see FIG. 9), and an angular velocity calculation unit 54 (see FIG. 9). ) Outputs the angular velocity ωm. The provisional guard processing unit 112 limits the absolute value of the basic current command value Ias ** after the guard processing to the provisional current limit value Igb or less, and outputs it as the q-axis current command value Iq *. Then, when the absolute value of the provisional end separation angle θsx becomes less than the second angle θ2, the provisional guard processing unit 112 reduces the absolute value of the provisional current limit value Igb based on the decrease.

Specifically, the provisional guard processing unit 112 has a map as shown in FIG. 16, for example, and calculates a provisional current limit value Igb according to the provisional end separation angle θsx based on this map. In this map, the provisional current limit value Igb is set so that the closer the absolute value of the provisional end separation angle θsx is to zero, the smaller the absolute value of the current limit value Iga. Further, the provisional current limit value Igb is set so that the provisional current limit value Igb becomes the predetermined current value Imax when the absolute value of the provisional end separation angle θsx becomes the second angle θ2 or more. Further, the provisional current limit value Igb is set so that the smaller the absolute value of the angular velocity ωm, the longer the range in which the predetermined current value Imax becomes after the absolute value of the provisional end separation angle θsx becomes less than the second angle θ2. ing.

Then, the provisional guard processing unit 112 calculates the provisional current limit value Igb according to the provisional end separation angle θsx, and the absolute value of the input basic current command value Is ** after the guard processing is equal to or less than the provisional current limit value Igb. In the case of, the value of the basic current command value Ias * is output as it is as the q-axis current command value Iq *. On the other hand, when the absolute value of the input basic current command value Is ** after the guard processing is larger than the provisional current limit value Igb, the value of the basic current command value Is * is changed to the value of the provisional current limit value Igb. It is limited and output as the q-axis current command value Iq *. When the provisional end separation angle θsx is not output from the control steering angle calculation unit 53, the provisional guard processing unit 112 uses the value of the basic current command value Is ** after the guard processing as it is as the q-axis current command value Iq *. Is output as. As a result, the microcomputer 41 has an absolute value of the q-axis current command value Iq * which becomes a torque command value based on the decrease of the provisional end separation angle θsx when the provisional end separation angle θsx becomes less than the second angle θ2. Perform provisional end-guessing mitigation control to reduce.

As described above, this embodiment has the same effects as those of (1) to (8) of the first embodiment and (9) to (13) of the second embodiment.
Each of the above embodiments can be modified and implemented as follows. Each embodiment and the following modifications can be implemented in combination with each other within a technically consistent range.

-In the second and fourth embodiments, the sizes of the first angle θ1 and the second angle θ2 may be set to be different from each other.
In the second embodiment, the provisional current correction value calculation unit 81 calculates the provisional current correction value Irb * based on the provisional end separation angle θsx output from the control steering angle calculation unit 53. However, the present invention is not limited to this, for example, when the motor absolute angle θma is output from the control steering angle calculation unit 53 and the absolute value of the motor absolute angle θma exceeds the absolute value of the steering angle θnxe near the provisional end. The provisional current correction value Irb * may be calculated. Further, the end distance angle, which is the difference between the end position corresponding motor angles θma_le and θma_re and the control steering angle θs, is output from the control steering angle calculation unit 53 to the current correction value calculation unit 62. May calculate the current correction value Ira * based on the end separation angle. Needless to say, the configuration for calculating the current correction value Ira * based on the end separation angle can also be applied to the first embodiment.

-In the second embodiment, the provisional current correction value calculation unit 81 calculates the provisional current correction value Irb * as the angular velocity ωm increases, but the provisional current correction value is not limited to this, and the provisional end separation is not limited to this, for example, regardless of the angular velocity ωm. The provisional current correction value Irb * may be calculated based only on the angular velocity θsx. Further, the current correction value calculation unit 62 may calculate a larger current correction value Ira * as the angular velocity ωm is larger. Needless to say, the configuration for calculating the current correction value Ira * based on the angular velocity ωm can also be applied to the first embodiment.

In the fourth embodiment, the provisional guard processing unit 112 has a provisional current limit value Igb of a predetermined current after the absolute value of the provisional end separation angle θsx becomes less than the second angle θ2 as the absolute value of the angular velocity ωm becomes smaller. The range of the value Imax was set to be long. However, the present invention is not limited to this, and the provisional current limit value Igb may be calculated based only on the provisional end separation angle θsx, regardless of, for example, the angular velocity ωm. Further, for the guard processing unit 101, the smaller the absolute value of the angular velocity ωm, the longer the range in which the current limit value Iga becomes the predetermined current value Imax after the absolute value of the control steering angle θs exceeds the steering angle θne near the end. May be set to. Needless to say, the configuration for calculating the current limit value Iga based on the angular velocity ωm can also be applied to the third embodiment.

-In the third and fourth embodiments, a compensation amount (for example, a damping compensation amount) for the purpose of improving the steering feeling may be applied to the basic current command value Ias *. In this case, guard processing or provisional guard processing may be performed on the command value after applying the compensation amount to the basic current command value Ias *.

-In the second and fourth embodiments, even if the difference α between the first one-sided end position corresponding motor angle θma_x1 and the second one-sided end position corresponding motor angle θma_x2 is larger than the predetermined difference αth, the provisional end position is based on these. The corresponding steering angle θma_xe may be set.

-In the second and fourth embodiments, the average value of the motor angles θma_x1 and ma_x2 corresponding to the first and second end positions is set as the steering angle θma_xe corresponding to the provisional end position. However, the present invention is not limited to this, and for example, the first one end position corresponding motor angle θma_x1 may be set as it is as the provisional end position corresponding steering angle θma_xe, and the method for calculating the provisional end position corresponding steering angle θma_xe can be appropriately changed. ..

-In the second and fourth embodiments, the predetermined steering amount θth indicating that the turning back steering is performed after setting the second one-sided end position corresponding motor angle θma_x2 and the first one-sided end position corresponding motor angle θma_x1. As described above, the motor absolute angle θma may be set before the change.

-In the second and fourth embodiments, the steering angle θma_xe corresponding to the provisional end position is calculated and set at the same time, and the motor absolute angle θma is closer to the steering neutral position side than the provisional end position corresponding steering angle θma_xe by the second angle θ2 or more. The provisional end guess relaxation control may be executed before.

In each of the above embodiments, the control steering angle calculation unit 53 sets the origin of the control steering angle θs based on whether or not a control flag indicating that the origin of the control steering angle θs should be set is set. However, it is not limited to this. For example, the origin of the control steering angle θs may be set by using a predetermined operation by the user as a trigger, and the mode may be appropriately changed. Further, the control flag may be set, for example, when the ignition is turned on / off a predetermined number of times or more, and the setting can be changed as appropriate.

-In each of the above embodiments, the end position determination of whether or not the rack shaft 12 is at the rack end position is performed based on the angular velocity ωm of the motor 21 and the pinion shaft torque Tp, but the end position is not limited to this, and for example, the pinion shaft torque. The end position may be determined based only on Tp. Further, for example, the end position may be determined using the angular acceleration of the motor 21. In this case, for example, the angular acceleration of the motor 21 can be used instead of the angular velocity ωm. Further, a contact sensor may be provided on the rack end 18, and the end position determination may be performed based on the signal of the sensor, and the determination mode may be appropriately changed.

-In each of the above embodiments, the origin of the control steering angle θs may be set immediately after the left and right end position corresponding motor angles θma_le and θma_re are set.
-In each of the above embodiments, it is determined whether or not the stroke width Wma is less than the stroke threshold value Wth, but the origin of the control steering angle θs is determined without determining whether or not the stroke width Wma is less than the stroke threshold value Wth. May be set.

-In each of the above embodiments, the average value of the left and right end position corresponding motor angles θma_le and θma_re is set as the offset angle Δθ, and the angle obtained by subtracting the offset angle Δθ from the motor absolute angle θma corresponds to the steering neutral position of the control steering angle θs. Set as the origin. However, not limited to this, the method of calculating the origin corresponding to the steering neutral position of the control steering angle θs can be appropriately changed.

-In each of the above embodiments, once the end position corresponding motor angles θma_le and θma_re are set, the motor absolute angle θma having the same sign as the end position corresponding motor angles θma_le and θma_re and having a large absolute value is detected thereafter. However, the end position corresponding motor angles θma_le and θma_re may not be updated.

In each of the above embodiments, the value obtained by subtracting the rotation (K × Tp) of the motor 21 based on the elastic deformation obtained by multiplying the elastic modulus K of the steering mechanism 4 by the pinion shaft torque Tp from the absolute angle of the elementary motor is used as the motor. Detected as an absolute angle θma. However, not limited to this, the rotation of the motor 21 based on the elastic deformation is estimated in consideration of components other than the pinion shaft torque Tp, for example, the angular acceleration of the motor 21, and this estimated rotation is calculated from the absolute angle of the elementary motor. It may be detected as the motor absolute angle θma by subtracting.

In each of the above embodiments, the motor absolute angle calculation unit 71 acquires the motor absolute angle θma at an angle corrected based on the mechanical elastic deformation caused by the pinion shaft torque Tp applied to the steering mechanism 4. However, the present invention is not limited to this, and it is not necessary to make corrections based on mechanical elastic deformation.

-In each of the above embodiments, the end contact relaxation control is performed based on the control steering angle θs indicated by the motor absolute angle θma with the steering neutral position as the origin, but the origin of the control steering angle θs is not limited to this. May be, for example, either the left or right rack end position, and can be changed as appropriate.

-In each of the above embodiments, the end contact relaxation control is performed based on the control steering angle θs, but the control is not limited to this, for example, a control that assists the steering wheel 2 to smoothly return to the neutral position when the steering wheel 2 is turned back. May be performed based on the control steering angle θs, and various controls can be performed based on the control steering angle θs.

-In each of the above embodiments, the steering control device 6 targets EPS 1 in a form in which the EPS actuator 5 applies the motor torque Tm to the column shaft 14, but the control device 6 is not limited to this, and the rack is not limited to this, for example, via a ball screw nut. A steering device of a type that applies a motor torque Tm to the shaft 12 may be controlled. Further, not limited to EPS, a steering unit operated by the driver, a steering unit that steers the steering wheel, and a steer-by-wire type steering device that is mechanically separated are targeted for control and are provided in the steering unit. The control steering angle may be calculated based on the rotation angle of the motor of the steering actuator.

Next, the technical ideas that can be grasped from each of the above embodiments and other examples will be added below together with their effects.
(B) The steering mechanism converts the rotation of the steering shaft formed by connecting the column shaft, the intermediate shaft and the pinion shaft into the reciprocating motion of the rack shaft as the steering shaft via the rack and pinion mechanism and transmits the rotation. The actuator is a steering control device that applies the motor torque of the motor to the column shaft. In the above configuration, since the motor torque is transmitted to the steering wheel via the column shaft, the intermediate shaft, the pinion shaft, the rack shaft, etc., not only the compression of the rack shaft but also the torque applied such as the twist of the intermediate shaft causes the torque. The elastic deformation of the steering mechanism tends to increase. Therefore, the effect of setting the motor absolute angle corrected based on the elastic deformation generated in the steering mechanism as the end position corresponding motor angle is great.

1 ... Electric power steering device (EPS), 3 ... Steering wheel, 4 ... Steering mechanism, 5 ... EPS actuator (actuator), 6 ... Steering control device, 11 ... Steering shaft, 12 ... Rack shaft, 13 ... Rack housing, 14 ... Column axis, 15 ... Intermediate axis, 16 ... Pinion axis, 17 ... Rack and pinion mechanism, 18 ... Rack end, 21 ... Motor, 43 ... Battery, 53 ... Control steering angle calculation unit, 55 ... Memory, 61 ... Basic assist Calculation unit, 62 ... Current correction value calculation unit, 71 ... Motor absolute angle calculation unit, 73 ... End position determination unit, 74 ... End position corresponding motor angle setting unit, 75 ... Control steering angle origin setting unit, 81 ... Temporary current correction Value calculation unit, 91 ... On the other hand, end position corresponding motor angle setting unit, 92 ... provisional end position corresponding steering angle setting unit, 93 ... provisional end separation angle calculation unit, 101, 111 ... guard processing unit, 112 ... provisional guard processing unit, Δθ ... offset angle, θs ... control steering angle, θsx ... provisional end separation angle, θth ... predetermined steering amount, θ1 ... first angle, θ2 ... second angle, θma ... motor absolute angle, θmc ... rotation angle, θne ... end Near steering angle, θnxe… Temporary end near steering angle, θma_le… Left end position corresponding motor angle, θma_re… Right end position corresponding motor angle, θma_x1… First one end position corresponding motor angle, θma_x2… Second one end position Corresponding motor angle, ωm ... angular speed, Tm ... motor torque, Tp ... pinion shaft torque, Ts ... steering torque, Tth ... predetermined torque, Id * ... d-axis current command value, Iq * ... q-axis current command value, Iga ... current Limit value, Igb ... Temporary current limit value, Ias * ... Basic current command value, Ira * ... Current correction value, Irb * ... Temporary current correction value, Wma ... Stroke width, Wth ... Stroke threshold, α ... Difference, αth ... Predetermined Difference.

Claims (10)

The control target is a steering device to which a motor torque is applied to reciprocate the steering shaft of the steering mechanism by an actuator whose drive source is a motor.
An end position determination unit that determines whether or not the steering axis is at either the left or right end position,
A motor absolute angle detection unit that detects the rotation angle of the motor with an absolute angle exceeding the range of 360 °,
When the end position determination unit determines that the steering axis is at either the left or right end position, the motor absolute angle detected by the motor absolute angle detection unit corresponds to the left or right end position. The end position compatible motor angle setting unit that is set as the end position compatible motor angle, and the end position compatible motor angle setting unit
The average value of the left and right end position corresponding motor angles set by the end position corresponding motor angle setting unit is used as the offset angle, and the angle obtained by subtracting the offset angle from the detected motor absolute angle is defined as the motor absolute angle. The control steering angle origin setting unit that is set as the origin of the indicated control steering angle,
A motor control unit that controls the drive of the motor so that the motor torque becomes a torque command value is provided.
When the absolute value of the control steering angle exceeds the absolute value of the steering angle near the end close to the steering neutral position by the first angle from the motor angle corresponding to the end position, the motor control unit has an absolute value of the control steering angle. The end contact relaxation control that reduces the absolute value of the torque command value based on the increase in the value is performed.
After the left and right end position corresponding motor angles are set, the control steering angle origin setting unit approaches the motor absolute angle closer to the steering neutral position side than the left and right end position corresponding motor angles by the first angle or more. After that, the origin is set based on the motor angles corresponding to the left and right end positions.
The motor control unit is a steering control device that executes the end contact relaxation control after setting the origin . In the steering control device according to claim 1,
The motor absolute angle detecting unit is a steering control device that corrects and detects the motor absolute angle based on the mechanical elastic deformation of the steering mechanism generated by the torque applied to the steering mechanism. In the steering control device according to claim 1 or 2.
After setting the end position corresponding motor angle, the end position corresponding motor angle setting unit detects the motor absolute angle having the same sign as the end position corresponding motor angle and having a large absolute value by the motor absolute angle detection unit. In some cases, a steering control device that updates the absolute motor angle as a new end position corresponding motor angle. The steering control device according to any one of claims 1 to 3 .
In the control steering angle origin setting unit, the sum of the absolute values of the left and right end position corresponding motor angles set by the end position corresponding motor angle setting unit corresponds to the entire stroke range of the steering shaft. A steering control device that does not set the origin when it is less than the stroke threshold based on. In the steering control device according to any one of claims 1 to 4 .
When the origin of the control steering angle is not set, the motor absolute angles at a plurality of timings at which the steering axis is determined to be at either the left or right end position by the end position determination unit. It is equipped with a provisional end position corresponding steering angle setting unit that sets the provisional end position corresponding steering angle on either the left or right side based on the one end position corresponding motor angle.
When the angle of the absolute angle of the motor to the rudder angle corresponding to the provisional end position becomes less than the second angle, the motor control unit reduces the absolute value of the torque command value based on the decrease of the angle. Steering control device that performs end contact relaxation control. In the steering control device according to claim 5 ,
After the plurality of motor angles corresponding to one end position are set, the provisional end position corresponding steering angle setting unit has the second angle or more on the steering neutral position side of the provisional end position corresponding steering angle. After approaching, the provisional end position corresponding steering angle is set based on the plurality of motor angles corresponding to one end position.
The motor control unit is a steering control device that executes the provisional end contact relaxation control after setting the steering angle corresponding to the provisional end position. In the steering control device according to claim 5 or 6 .
The provisional end position corresponding steering angle setting unit is a steering control device that sets an average value of the plurality of motor angles corresponding to one end position as the provisional end position corresponding steering angle. In the steering control device according to any one of claims 5 to 7 .
The provisional end position corresponding steering angle setting unit sets one of the plurality of one end position corresponding motor angles and the one as the plurality of one end position corresponding motor angles which are the basis of the provisional end position corresponding steering angle. A steering control device using the other one of the plurality of motor angles corresponding to one end position, which is set after the absolute angle of the motor has changed by a predetermined steering amount or more indicating that the turn-back steering has been performed. The steering control device according to any one of claims 5 to 8 .
The provisional end position corresponding steering angle setting unit is a steering control that sets the provisional end position corresponding steering angle when the difference between one of the plurality of motor angles corresponding to one end position and the other one is equal to or less than a predetermined difference. Device. In the steering control device according to any one of claims 1 to 9 .
The end position determination unit determines that the steering shaft is at the end position when the angular velocity of the motor is equal to or lower than a predetermined angular velocity indicating a stopped state and the torque applied to the steering mechanism is equal to or higher than the predetermined torque. Steering control device.

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