JP4103550B2 - Vehicle steering system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle steering apparatus configured to be able to apply a force from an actuator to an operation member such as a steering wheel, as in a steer-by-wire (SBW) system.
[0002]
[Prior art]
For example, the mechanical coupling between the steering wheel and the steering mechanism for steering the steering wheel is eliminated, the steering wheel operating angle is detected, and the torque from the steering actuator is detected based on the detection result. A system (so-called steer-by-wire (SBW) system) that achieves steering of a steering wheel by providing the steering mechanism to the steering mechanism has been proposed (for example, Patent Document 1 below).
[0003]
The steering actuator is controlled by a control device including a microcomputer. That is, while the ignition key switch of the vehicle is on, detection signals of the operation angle sensor for detecting the operation angle of the steering wheel and the turning angle sensor for detecting the turning angle of the steering wheel are input to the control device. ing. Based on these input signals, the control device controls the steering actuator so that the turning angle of the steering wheel corresponds to the operation angle of the steering wheel.
[0004]
On the other hand, in order to apply an operational reaction force to the steering wheel, a reaction force actuator is attached to the steering shaft. The control device applies an operation reaction force to the steering wheel by driving and controlling the reaction force actuator according to an operation angle or the like.
[0005]
[Patent Document 1]
JP 2000-198453 A [Patent Document 2]
Japanese Patent Laid-Open No. 10-324120 [Patent Document 3]
Japanese Patent Laid-Open No. 11-20427
[Problems to be solved by the invention]
The driver uses the following information consciously or unconsciously to drive the vehicle.
(1) Tire condition (Wear condition: Decrease in grip)
(2) Road conditions (slippery roads, irregular roads, wavy roads, bottled roads)
(3) Vehicle abnormalities (abnormalities, looseness and wear of each part of the drive system and undercarriage parts) (4) Information received from the driving infrastructure is a driver of vision, hearing, seat vibration and operation end. It is detected from the reaction force when operating (steering wheel, control stick, etc.).
[0007]
However, in the steer-by-wire system in which the steering gear and the handle column are not directly connected, the steering torque transmission system differs from the case of the normal type steering mechanism in which the steering wheel to the steering mechanism are mechanically connected. The actual value of the axial force and torque cannot be fed back to the driver via the steering wheel.
For this reason, the above information tends to be insufficiently transmitted to the driver. This is not limited to steer-by-wire systems, but various technologies to improve vehicle comfort and exercise performance (steer-by-wire technology as well as improved braking systems, drive systems, suspension systems, etc.) ) Is a common problem, and may increase driving stress.
[0008]
Accordingly, an object of the present invention is to provide a vehicle steering apparatus that can appropriately transmit necessary information to a driver and thereby provide a comfortable driving environment.
[0009]
[Means for Solving the Problems and Effects of the Invention]
The invention according to claim 1 for achieving the above object is a steering mechanism for turning the steering wheel (5, 29) in accordance with the operation of the operation member (1, 22) operated by the driver. (4, 6, 7, 24) is a vehicle steering device, and for transmitting information to the driver, an actuator (9, 40) for applying a reaction torque to the operation member, At least one sensor (S1 to S12) that detects a physical quantity related to exercise and outputs a detection signal according to the detection result, a specifying means (14) for specifying a tire located outside the steering direction , and the sensor outputs A signal analyzing means (14, C, A2) for analyzing a detection signal to be output and outputting an analysis result, and a control means (14) for controlling the actuator based on the analysis result output by the signal analyzing means. See The sensor includes a right stress sensor (SR) that detects a stress of the right sidewall portion (52R) of the tire, and a left stress sensor (SL) that detects a stress of the left sidewall portion (52L) of the tire, The control means is based on a first-order time differential value or a second-order time differential value of a difference (ΔT) in a detection value (ΔT) between the right stress sensor and the left stress sensor of the tire located outside the steering direction of the tire specified by the specifying means. A vehicle steering apparatus that controls driving of the actuator . The alphanumeric characters in parentheses indicate corresponding components in the embodiments described later. The same applies hereinafter.
[0010]
According to this configuration, the physical quantity related to the motion of the vehicle sensor for detecting the (operating member operation, the operation of the steering mechanism, the operation of the brake mechanism, drive kinematic system operation. Including those for such as load of the tire) The detection result is analyzed, and the actuator is controlled based on the analysis result. That is, for example, the frequency characteristic of the detection signal of the sensor is analyzed, and the reaction torque controlled according to the result is applied to the operation member. As a result, information related to the movement of the vehicle can be transmitted to the driver via the operation member, so various technologies (steer-by-wire, etc.) are adopted to enhance the comfort and movement performance of the vehicle. Even if it is done, necessary information can be appropriately transmitted to the driver.
Further, the actuator is controlled according to the first-order time differential value (tire load change speed) or the second-order time differential value (tire load change acceleration) of the stress difference between the left and right sidewall portions of the tire, so that the operation member is interposed. Thus, the tire ground contact surface transient information can be transmitted to the driver.
[0011]
In the invention according to claim 2, the first determination means (A11, A12) for determining whether or not the analysis result by the signal analysis means satisfies a predetermined first determination condition, and the first determination means, When it is determined that the analysis result of the signal analysis means satisfies the first determination condition (YES in A11, YES in A12), teaching means (19, 70) that gives the driver a teaching corresponding to the determination result The vehicle steering apparatus according to claim 1, further comprising:
[0012]
According to this configuration, when it is determined that the analysis result (for example, frequency characteristics) by the signal analysis unit satisfies the first determination condition, the driver is provided with the teaching corresponding to the determination result. On the other hand, the occurrence of an abnormality can be appropriately communicated.
The teaching means may be one that generates voice and teaches the driver, or may teach the driver by lamp display or message display.
[0013]
The invention according to claim 3 further includes second determination means (A11, A16) for determining whether an analysis result by the signal analysis means satisfies a predetermined second determination condition, wherein the control means includes: When the second determination means determines that the analysis result of the signal analysis means satisfies the second determination condition (NO in A11, YES in A16), the actuator is controlled according to the analysis result. The vehicle steering apparatus according to claim 1 or 2, wherein the vehicle steering apparatus is (A18).
[0014]
According to this configuration, when the analysis result (for example, frequency characteristics) by the signal analysis unit satisfies the predetermined second determination condition, the actuator is controlled according to the analysis result. Thereby, for example, when the analysis result indicates an abnormality, the occurrence of the abnormality can be appropriately transmitted to the driver via the operation member by controlling the actuator according to the degree of the abnormality.
The invention according to claim 4 is a means (A6, A7, A9) for determining whether or not there is an abnormality in the steering system or the turning system. The vehicle steering apparatus according to any one of claims 1 to 3, further comprising means (A10) for adding to the target reaction force torque value.
The invention according to claim 5 is a means (A6, A11, A12, A16, A17) for determining whether or not there is an abnormality in the suspension system. The vehicle steering apparatus according to any one of claims 1 to 4, further comprising means (A18) for adding the target reaction force torque value.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a conceptual diagram for explaining a configuration of a vehicle steering apparatus according to a first embodiment of the present invention. This vehicle steering device eliminates the mechanical coupling between the steering wheel 1 and the steering mechanism, and the operation of the steering actuator 2 driven in accordance with the rotation operation of the steering wheel 1 is performed on the steering shaft supported by the housing 3. 4 is converted to a linear motion in the vehicle width direction, and the steering is achieved by converting the linear motion of the steered shaft 4 into the steered motion of the front left and right wheels 5 for steering. A wire (SBW) system.
[0016]
The steering actuator 2 includes an electric motor such as a brushless motor, for example. The driving force (rotational force of the output shaft) of the steering actuator 2 is generated by an axial direction (vehicle width direction) of the steered shaft 4 by a motion conversion mechanism (for example, a ball screw mechanism) provided in association with the steered shaft 4. ) Is converted to linear motion. This linear motion of the steered shaft 4 is transmitted to the tie rods 6 that protrude from both ends of the steered shaft 4, and further causes the knuckle arm 7 connected to the king pin P to rotate via the tie rod 6. Thereby, turning of the wheel 5 supported by the knuckle arm 7 is achieved. The steering shaft 4, the tie rod 6, the knuckle arm 7, and the like constitute a steering mechanism for steering the steering wheel 5.
[0017]
The steering wheel 1 is connected to a rotating shaft 8 that is rotatably supported with respect to the vehicle body. A reaction force actuator 9 for applying an operation reaction force to the steering wheel 1 is attached to the rotating shaft 8. The reaction force actuator 9 includes an electric motor such as a brushless motor having an output shaft integrated with the rotary shaft 8.
An elastic member 10 made of a spiral spring or the like is coupled to the end of the rotating shaft 8 on the opposite side of the steering wheel 1 from the vehicle body. The elastic member 10 returns the steering wheel 1 to the straight-ahead steering position by the elastic force when the reaction force actuator 9 is not applying torque to the steering wheel 1.
[0018]
In order to detect the operation input value of the steering wheel 1, an operation angle sensor S <b> 1 for detecting the operation angle of the steering wheel 1 is provided in association with the rotary shaft 8. The rotating shaft 8 is provided with a torque sensor S2 for detecting an operation torque applied to the steering wheel 1. On the other hand, in relation to the steered shaft 4, a steered angle sensor S3 for detecting the steered angle (tire angle) of the steering wheel 5 and an axial force sensor for detecting the axial force acting on the steered shaft 4. S4 is provided.
[0019]
In addition to these sensors, a vehicle speed sensor S5 that detects the vehicle speed, a longitudinal acceleration sensor S6 that detects the longitudinal acceleration of the vehicle, a lateral acceleration sensor S7 that detects the lateral acceleration of the vehicle, and a yaw rate sensor S8 that detects the yaw rate of the vehicle. , A stroke sensor S9 for detecting the stroke (displacement) of the shock absorber, a brake fluid pressure sensor S10 for detecting the brake hydraulic pressure, a load sensor S11 for detecting the load of the vehicle, and a drive current supplied to the steering actuator 2 from the drive circuit 17 A current detection unit S12 (a force acting on the steered shaft 4 can be indirectly detected by detecting a drive current) is provided.
[0020]
Further, as will be described later, the left side stress sensor SL and the right side stress sensor SR that detect the stress acting on the left and right sidewall portions of the tire W, and the tire W are disposed inside the tire W attached to the wheel 5. An air pressure sensor SP for detecting air pressure is provided.
The detection signals of the sensors S1 to S12, SL, SR, and SP are input to a control device 14 including an electronic control unit (ECU) having a configuration including a microcomputer. However, the detection signals of the stress sensors SL and SR and the air pressure sensor SP are received by the control device 14 by wireless communication via the antenna 14a.
[0021]
The control device 14 controls the operation angle detected by the operation angle sensor S1, the turning angle detected by the turning angle sensor S3, the vehicle speed detected by the vehicle speed sensor S5, and the tire stress detected by the stress sensors SL and SR. The steering command value is set based on the tire pressure detected by the air pressure sensor SP, and the steering actuator 2 is controlled via the drive circuit 17 based on the steering command value.
Since there is no mechanical coupling between the steering wheel 1 and the steering mechanism, VGR (Variable Gear) that variably sets the ratio (transmission ratio, gear ratio) between the rotation amount of the steering wheel 1 and the steering amount of the wheel 5 Ratio) function can be realized. That is, for example, the control device 14 sets the gear ratio based on the vehicle speed detected by the vehicle speed sensor S5 and the tire load detected by the stress sensors SL, SR and / or the air pressure sensor SP, and this gear ratio. And a steering command value corresponding to a voltage to be applied to the steering actuator 2 is set based on the operation angle of the steering wheel 1.
[0022]
On the other hand, the control device 14 reacts via the drive circuit 18 so that an appropriate reaction force in the direction opposite to the operation direction of the steering wheel 1 is generated based on the detection signals output from the sensors S1 to S12. The force actuator 9 is controlled.
Further, for example, an alarm device 19 provided on an instrument panel of the vehicle is connected to the control device 14. The alarm device 19 may be composed of an alarm sound generator, or may be composed of an alarm display device that performs alarm display (lamp display or message display). Based on the output signals of the sensors S11 to S12 (particularly the turning angle sensor S3, the vehicle speed sensor S5, and the stroke sensor S9), the control device 14 may, for example, perform a predetermined abnormality or traveling state (running on a rough road, generating flutter, When an unbalance occurrence or the like is detected, an alarm is generated from the alarm device 19.
[0023]
FIG. 2 is a schematic cross-sectional view for explaining the configuration of the tire W of the steering wheel 5. The tire W includes a tread portion 51 that contacts a road surface, and a pair of sidewall portions 52L and 52R coupled to both side portions of the tread portion 51. A right stress sensor SR is disposed on the inner wall surface of the right sidewall portion 52R in the traveling direction of the vehicle, and a left stress sensor is disposed on the inner wall surface of the left sidewall portion 52L in the traveling direction of the vehicle. SL is arranged. An air pressure sensor SP is disposed on the inner wall surface of the tread portion 51. In addition, for example, the stress sensor SA may be embedded in the tread portion 51 as necessary.
[0024]
The right side stress sensor SR and the left side stress sensor SL detect the stress applied to the right side wall part 52R and the left side wall part 52L, respectively. A sensor part such as a strain gauge and a detection signal of this sensor part are wirelessly transmitted. A transponder unit for transmission and a power storage unit that converts the rotational motion of the tire W into electric energy and stores the electric energy, and operates by the electric energy accumulated in the power storage unit. Similarly, the air pressure sensor SP is arranged inside the tire W, a sensor unit for detecting the internal air pressure of the tire W, a transponder unit for wirelessly transmitting a detection signal of the sensor unit, and rotation of the tire W And a power storage unit that converts motion into electrical energy and stores the electrical energy, and is operated by the electrical energy stored in the power storage unit. A signal transmitted from the transponder unit is taken into the control device 14 from the antenna 14a.
[0025]
As the stress sensor and the air pressure sensor as described above, for example, known ones as disclosed in Patent Document 2 and Patent Document 3 can be adopted.
FIG. 3 is an illustrative view for explaining deformation of the tire W during cornering. FIG. 3A shows the cross-sectional shapes of the left and right tires WL and WR when leftward steering is performed on a road surface with a relatively small friction coefficient, and FIG. 3B shows road surface friction. The cross-sectional shapes of the left and right tires WL and WR when leftward steering is performed on a road surface having a relatively large coefficient are shown. 3A and 3B, the cross-sectional shapes of the tires WL and WR are shapes as viewed from the rear in the traveling direction of the vehicle.
[0026]
Of the left and right tires WL, WR, the deformation of the left tire WL on the inside in the steering direction is relatively small, and the deformation of the right tire WR on the outside in the steering direction is large. In both the left and right tires WL and WR, the deformation at the left sidewall portion that is inside the steering direction is small, and the deformation at the right sidewall portion that is outside the steering direction is large. This deformation increases as the road surface friction coefficient increases. Therefore, in this embodiment, the control device 14 identifies a tire located on the outer side in the steering direction based on the output signal of the turning angle sensor S3 and is mounted on the tire (the right tire WR in the example of FIG. 3). Refer to the outputs of the left and right stress sensors SL, SR. More specifically, the stress To of the outer side wall part detected by the right side stress sensor SR that detects the stress of the right side wall part 52R on the outer side in the steering direction and the stress of the left side wall part 52L on the inner side in the steering direction are determined. A difference ΔT (= To−Ti) from the stress Ti of the inner sidewall portion detected by the detected left stress sensor SL is obtained. Further, the control device 14 obtains a first-order time differential value (stress change rate, tire load change rate) or a second-order time differential value (stress change acceleration, tire load change acceleration) of the stress difference ΔT between the left and right sidewall portions, The steering actuator 2 and the reaction force actuator 9 are driven and controlled based on the tire load change speed or the tire load change acceleration thus obtained.
[0027]
FIG. 4 is a control characteristic diagram showing an example of a control mode of the reaction force actuator 9 by the control device 14. The control device 14 sets a reaction force actuator drive target value that changes, for example, linearly within a certain range in accordance with, for example, a tire load change speed or a tire load change acceleration in a tire outside the steering direction. A control signal is given to the drive circuit 18 so that the drive target value is achieved. In the characteristic diagram of FIG. 4, a reaction force actuator drive target value that linearly increases with an increase in the tire load change speed or the tire load change acceleration is set for a tire load change speed or a tire load change acceleration that is greater than a certain value. In addition, the larger the vehicle speed detected by the vehicle speed sensor S5, the larger the reaction force actuator drive target value is set.
[0028]
As a result, the greater the change speed or change acceleration of the load applied to the tire, the greater the reaction force is transmitted to the driver via the steering wheel 1, and the greater the vehicle speed, the greater reaction force is transmitted to the driver via the steering wheel 1. Will be transmitted to.
FIG. 5 is a conceptual diagram showing how information is exchanged between the driver, the vehicle, and the road surface. For example, a disturbance such as a cross wind is applied to the vehicle from the road surface, and information such as traffic conditions is provided to the vehicle as, for example, ITS (Intelligent Transport Systems) electronic information from the infrastructure arranged in the road traffic network. Furthermore, road surface conditions such as a narrow road, a cant road, a wavy road and a snowy road are transmitted to the vehicle through the tire.
[0029]
On the other hand, from the vehicle to the driver, the control device 14 (ECU: electronic control unit) controls the reaction force actuator 9 (reaction force control) through the steering wheel 1 together with the road surface information (low frequency information). The tire ground contact surface transient information is transmitted. Further, through the above-described alarm device 19, instability information and warning of the steering system are transmitted to the driver by display or sound.
The reaction force actuator 9 is controlled based on the torque generated by the steering actuator 2 and the output of the turning angle sensor S3, so that road surface information as low frequency information can be transmitted to the driver via the steering wheel. it can. In addition to this control, as described above, the reaction force actuator 9 is controlled in accordance with the tire load change speed or the tire load change acceleration, so that tire ground contact surface transient information is transmitted to the driver via the steering wheel 1. Is done.
[0030]
The instability information of the steering system transmitted by the alarm device 19 includes the occurrence of tire imbalance and shimmy. These pieces of information may be transmitted to the driver through the control of the reaction force actuator 9, but it is more effective to visually or audibly transmit the driver to the driver using the alarm device 19 to promote maintenance. is there.
The control device 14 controls vibrations of the steering system (flutter, shimmy, etc. due to poor maintenance of consumables / mechanical parts and abnormal control due to abnormal signals), tire / suspension vibration (vibration due to unbalance), etc. Alternatively, displacement sensor signals (signals from the operation angle sensor S1, the steering angle sensor S3, the stroke sensor S9, etc.) and acceleration sensor signals (front-rear acceleration sensor S6, lateral) provided in each component (part for detecting a physical quantity related to vehicle motion) Based on the acceleration sensor S7) and the analysis results (differential values, integral values, frequency characteristics obtained by vibration power spectrum analysis, etc.) obtained by analyzing these signals by signal processing, the driver The presence or absence of information to be transmitted to is determined. Further, if there is information to be transmitted to the driver, it is determined whether the information should be transmitted to the driver as an operation reaction force or visually or audibly via the alarm device 19. The information is transmitted to the driver by a method according to the determination result.
[0031]
The control device 14 further controls the steering actuator 2 according to the output of the operation angle sensor S1 and the like and the tire load detected by the stress sensors SL and SR and the air pressure sensor SP (steering control).
On the other hand, in addition to the information transmitted from the alarm device 19 or the steering wheel 1, the driver feels the acceleration G on the vehicle, and also feels the vehicle speed V, yaw rate γ, roll φ, and pitch τ. Based on these pieces of information, the driver operates the steering wheel 1 to perform predictive control, tracking control, and compensation control.
[0032]
Predictive control is control that the driver predicts the next situation, and tracking control is control that tries to track this target with the vehicle behavior intended by the driver as a target. Is a control for compensating for disturbances such as crosswinds. These controls are based on the driver's knowledge about driving the vehicle, but this knowledge can be stratified into a skill base, a rule base and an intelligent base. Skill-based driving knowledge is knowledge that has been acquired by the body and is knowledge that is unconsciously transferred to action based on information perceived by the five senses. The rule-based driving knowledge is knowledge that is transferred to an action according to a determination result based on a driver's memory (for example, whether or not a certain condition is met), that is, knowledge about a patterned action. Intelligent-based driving knowledge is not knowledge about patterned behavior, but advanced knowledge that is transferred to behavior through conscious, abstract and logical thinking.
[0033]
For example, the road surface information transmitted from the steering wheel 1 to the driver as low-frequency information works on the rule-based knowledge and prompts the driver to drive a pattern. On the other hand, the tire ground contact surface transient information transmitted from the steering wheel 1 to the driver is used for more advanced judgment (whether it is a limit point from which the steering torque can be removed, etc.) by working on the knowledge of the intelligent base. It is done.
[0034]
FIG. 6 is a flowchart for explaining processing executed by the control device 14 to transmit information to the driver by the control of the reaction force actuator 9 or the alarm device 19. First, detection signals output from the sensors S1 to S12 are captured (step A1), and then signal processing (step A2) is performed on the detection signals of these sensors S1 to S12. Specifically, differentiation processing, integration processing, signal periodicity analysis, envelope detection, frequency characteristic analysis by spectrum analysis, and the like are performed. More specifically, the vibration frequency of the output signal of the turning angle sensor S3 (steering angle vibration frequency), the vibration frequency of the output signal of the stroke sensor S9 (shock absorber vibration frequency), and the output signal of the turning angle sensor S3. A differential value (steering angular velocity) is obtained. Further, the lateral acceleration (lateral G) detected by the lateral acceleration sensor S7, the yaw rate detected by the yaw rate sensor S8, the shock absorber stroke detected by the stroke sensor S9, and the brake hydraulic pressure detected by the brake hydraulic pressure sensor S10. Each vibration frequency is required.
[0035]
Furthermore, the control device 14 has a plurality of vehicle speed ranges determined in advance by the vehicle speed V detected by the vehicle speed sensor S5 (in this embodiment, 0 km / h <V ≦ 30 km / h, 30 km / h <V ≦ 60 km / h, 60 km / The processing is branched depending on which of the four vehicle speed ranges h <V ≦ 90 km / h and 90 km / h <V (steps A3, A4, A5).
For example, when the vehicle speed V is a value within the vehicle speed range of 0 km / h <V ≦ 30 km / h (YES in step A3), it is determined whether the turning angular vibration frequency is equal to or higher than a predetermined threshold value of 5 Hz ( Step A6). If this determination is affirmative, there is a possibility that an abnormality of the steering system or the steering system has occurred, so that the lateral acceleration (lateral G) detected by the lateral acceleration sensor S7 is further detected by the yaw rate sensor S8. The vibration frequency of one or more of the predetermined yaw rate, the shock absorber stroke detected by the stroke sensor S9, and the brake hydraulic pressure detected by the brake hydraulic pressure sensor S10 is set to a predetermined threshold. It is determined whether the value is 2 Hz or less (step A7). If this determination is denied, it is assumed that there is no abnormality in the steering system or the steering system, and the target reaction force torque for driving the reaction force actuator 9 is the normal reaction force torque value (when there is no abnormality). Set to a certain Ta (step A8) and return. The normal target reaction force torque value reflects the tire load detected by the stress sensors SL and SR and the air pressure sensor SP.
[0036]
On the other hand, if it is determined in step A7 that the vibration frequency of one or more of the lateral acceleration, yaw rate, shock absorber stroke, and brake fluid pressure is 2 Hz or less, the steering system or It is determined that there is an abnormality in the turning system (step A9). In this case, the control device 14 converts the target reaction force torque for driving the reaction force actuator 9 to the normal target reaction force torque value Ta and the correction torque value Tb (correction torque when the steering system or the steering system is abnormal). Is set to a value Ta + Tb (step A10), and the process returns.
[0037]
The correction torque value Tb is determined according to the vibration frequency of the determination target value determined to be 2 Hz or less in step A7, for example, and is determined to be larger as the vibration frequency is larger. Further, the correction torque value Tb may be further determined according to the vehicle speed and the turning angle, and may be determined to be larger as the vehicle speed is higher and larger as the turning angle is larger.
If the turning angular vibration frequency is less than 5 Hz (NO in step A6), there is a possibility of a suspension system abnormality or the like. Further, whether or not the shock absorber vibration frequency is 1 Hz or more which is a predetermined first threshold value. Is determined (step A11). When the shock absorber vibration frequency is 1 Hz or more, it is further determined whether or not the turning angular velocity is 5 rad / sec or less which is a predetermined threshold value (step A12). If this determination is affirmative, it is determined that either flutter or unbalance occurs while traveling on a rough road (step A13), and these abnormalities are notified to the driver through the alarm device 19 (step A14). ). Then, the target reaction force torque for controlling the reaction force actuator 9 is set to the normal target reaction force torque value Ta (step A15), and the process returns.
[0038]
Even when the turning angular frequency is less than 5 Hz, when the shock absorber vibration frequency is less than 1 Hz (NO in step A11), or the turning angular frequency is less than 5 Hz and the shock absorber vibration frequency is 1 Hz or more. When the turning speed exceeds 5 rad / sec (NO in step A12), the shock absorber vibration frequency is a predetermined second threshold value in order to check whether there is any abnormality in the suspension system. It is determined whether the frequency is 10 Hz or higher (step A16). If this determination is affirmed, it is determined that there is an abnormality in the suspension system (step A17), and the control device 14 uses the target reaction force torque for driving the reaction force actuator 9 as the normal target reaction force torque. The value Ta + Tc obtained by adding the correction torque value Tc (correction torque when the suspension system is abnormal) to the value Ta is set (step A18), and the process returns.
[0039]
The correction torque value Tc is determined according to, for example, the shock absorber vibration frequency, and is determined to be larger as the shock absorber vibration frequency is larger, for example. Further, the correction torque value Tc may be further determined according to the vehicle speed and the turning angle, and may be determined to be larger as the vehicle speed is higher and larger as the turning angle is larger.
If the above determination in Step A16 is negative, it is assumed that there is no abnormality in the suspension system, and the target reaction force torque for driving the reaction force actuator 9 is the target reaction force torque value at normal time (when there is no abnormality). Set to a certain Ta (step A19) and return.
[0040]
In the vehicle speed range of 30 km / h <V ≦ 60 km / h, 60 km / h <V ≦ 90 km / h, 90 km / h <V, the type of vibration frequency to be determined is appropriately selected, and the threshold for each vibration frequency is selected. After the value is set appropriately, the same processing as described above is performed.
As a result of such processing, regarding the abnormality of the steering system, the steering system and the suspension system, the steering reaction force applied to the steering wheel 1 is made different from the normal value (Ta) through the steering wheel 1. It is transmitted to the driver. On the other hand, information such as occurrence of flutter and occurrence of unbalance during rough road traveling is notified to the driver via the alarm device 19 without passing through the steering wheel 1. In this way, since an appropriate transmission route is selected according to the type of abnormality that has occurred, information transmission to the driver is performed smoothly, driving stress can be reduced, and a comfortable driving environment can be achieved. realizable.
[0041]
Moreover, in this embodiment, the reaction force actuator 9 is controlled in accordance with the tire load directly detected by the left and right stress sensors SL, SR and the air pressure sensor SP attached to the tire. . Therefore, since appropriate reaction force control can be performed regardless of the mechanical configuration of the steering mechanism, it is possible to reduce or eliminate vehicle adaptation technology that makes reaction force control different for each vehicle type or vehicle. it can. Thereby, the development period of the vehicle steering device can be greatly shortened.
[0042]
In addition, since the load state of the tire W is directly detected by the left and right stress sensors SL, SR and the air pressure sensor SP, and the reaction force control is performed using this, complicated calculation processing is not required. The reaction force actuator 9 can be controlled with high-speed response on the order of 10 milliseconds. Therefore, tire ground contact surface transient information such as a grip limit situation in which the tire W loses gripping power can be transmitted to the driver via the steering wheel 1.
[0043]
FIG. 7 is a schematic diagram showing a schematic configuration of the vehicle steering apparatus according to the second embodiment of the present invention. The vehicle steering device 21 includes a first steering shaft 23 connected to a steering wheel 22 as an operation member so as to be integrally rotatable, and a steering mechanism provided coaxially with the first steering shaft 23, such as a rack and pinion mechanism. And a planetary gear mechanism 26 as a planetary transmission mechanism constituting a differential transmission mechanism for allowing differential rotation between the first and second steering shafts 23 and 25. Prepare.
[0044]
The steering mechanism 24 includes a steering shaft 27 that extends in the left-right direction of the vehicle, and a knuckle arm 30 that is coupled to both ends of the steering shaft 27 via tie rods 28 and supports steering wheels 29. Prepare. The steered shaft 27 is supported by a housing 31 and is slidable in the axial direction, and a steering actuator 32 made of an electric motor is coaxially incorporated in the middle of the steered shaft 27. The drive rotation of the steering actuator 32 is converted into sliding of the turning shaft 27 by a motion conversion mechanism such as a ball screw mechanism, and the turning of the wheel 29 is achieved by the sliding of the turning shaft 27.
[0045]
A rack 27a is formed in a part of the steered shaft 27, and a pinion 34 provided at an end of the second steering shaft 25 and rotating integrally with the second steering shaft 25 is engaged with the rack 27a. ing. When the steering actuator 32 fails, when the second steering shaft 25 is driven to rotate according to the operation of the steering wheel 22, the rotation of the second steering shaft 25 is caused to slide on the turning shaft 27 by the pinion 34 and the rack 27a. The wheel 29 is steered.
[0046]
The planetary gear mechanism 26 includes a plurality of sun gears 35 that are connected to the end of the first steering shaft 23 so as to be integrally rotatable, and are rotatably held by a carrier 36 that is an output side to mesh with the sun gear 35. Planetary gears 37 and ring gears 38 as ring members having inner teeth 38a meshing with the planetary gears 37 on the inner periphery.
The ring gear 38 forms, for example, a worm wheel by forming external teeth 38b. The external teeth 38b are drivingly connected to a reaction force actuator 40 for applying an operation reaction force to the steering wheel 22 via a drive transmission gear 39 made of, for example, a worm. The reaction force actuator 40 is composed of, for example, an electric motor, and its casing is fixed at an appropriate position on the vehicle body.
[0047]
The steering actuator 32 and the reaction force actuator 40 are controlled by a control device C (ECU: electronic control unit) including a CPU 61, a ROM 62 storing a control program, a RAM 63 used as a work area for arithmetic processing, and the like. ing.
The first steering shaft 23 has a steering angle sensor S1 as a steering angle detection means for detecting a steering angle by the steering wheel 22, and a steering torque detection means for detecting a steering torque input from the steering wheel 22. A torque sensor S2 is provided. Detection signals from the steering angle sensor S1 and the torque sensor S2 are input to the control device C.
[0048]
Further, the turning shaft 27 detects the turning position of the wheel 29 by detecting the axial position of the turning shaft 27, and the axial force acting on the turning shaft 27. Is detected, and detection signals from the turning angle sensor S3 and the axial force sensor S4 are also input to the control device C. Further, a detection signal from a vehicle speed sensor S5 for detecting the vehicle speed is input to the control device C.
[0049]
In addition to these, the control device C includes a longitudinal acceleration sensor S6 for detecting the longitudinal acceleration of the vehicle, a lateral acceleration sensor S7 for detecting the lateral acceleration of the vehicle, and the yaw rate of the vehicle, as in the case of the first embodiment. Is supplied to the yaw rate sensor S8 for detecting the stroke, the stroke sensor S9 for detecting the stroke (displacement) of the shock absorber, the brake hydraulic pressure sensor S10 for detecting the brake hydraulic pressure, the load sensor S11 for detecting the load of the vehicle, and the steering actuator 32. Detection signals output from the current detection unit S12 that detects the drive current are respectively input. Further, as in the case of the first embodiment described above, a tire air pressure sensor SP, a left stress sensor SL, and a right stress sensor SR are provided in the tire of the wheel 29 as tire load detection means. . The output signals of these sensors are taken into the control device C from the antenna Ca by wireless communication.
[0050]
The control device C outputs a control signal to drive circuits 48 and 49 as drive units for driving the steering actuator 32 and the reaction force actuator 40 based on the input signals from the sensors.
The control device C constantly monitors whether the steering system is operating normally. More specifically, the occurrence of abnormality in at least one of the turning angle sensor 46 and the steering actuator 32 is monitored.
[0051]
If there is no abnormality in the turning system, the control device C causes the reaction force actuator 40 to generate torque for applying to the steering wheel 22 a steering reaction force corresponding to the road surface reaction force.
Further, the control device C sets the voltage command value of the steering actuator 32 in accordance with the operation amount of the steering wheel 22, and gives the control signal corresponding to the voltage command value to the drive circuit 48, so that the steering actuator 32 is controlled. Drive control. Although the steering wheel 22 and the steering mechanism 24 are coupled via the planetary gear mechanism 26, the reaction force actuator 40 does not substantially restrain the rotation of the ring gear 38, and the steering reaction force is applied to the steering wheel 22. In the state of operating only for giving, the steering torque applied to the steering wheel 22 is not substantially transmitted to the steering mechanism 24. In that sense, the configuration shown in FIG. 7 can also be said to be a steer-by-wire (SBW) type vehicle steering device, and the same variable gear as in the first embodiment described above. Ratio control is possible.
[0052]
In this embodiment, the control device C is detected by the stress sensors SL, SR and / or the air pressure sensor SP according to the characteristics as shown in FIG. 4 in the same manner as the control device 14 of the first embodiment described above. The reaction force actuator 40 is controlled based on the applied tire load. As a result, not only low frequency information indicating road surface conditions but also high frequency information such as tire ground contact surface transient information can be transmitted to the driver via the steering wheel 22.
[0053]
Furthermore, like the control device 14 in the first embodiment described above, the control device C executes the processing as shown in FIG. 6 to process the signals of the sensors to obtain the vibration frequency and the like. On the basis of this, abnormalities in the steering system, the steering system, and the suspension system are transmitted to the driver by reaction force control, and information on the occurrence of flutter and unbalance during rough road traveling is provided by the alarm device 70 (first implementation). The driver is informed via a similar configuration to the alarm device 19 in the embodiment.
[0054]
When an abnormality occurs in the steering system, the control device C stops the control of the steering actuator 32 to put the steering actuator 32 in a free rotation state, and restricts the rotation of the ring gear 38 by the reaction force actuator 40, and the steering wheel It is assumed that the steering torque applied to 22 is transmitted to the steering mechanism 24. At this time, the steering assist can be performed by the control of the reaction force actuator 40, and the variable control of the gear ratio can be performed.
[0055]
As mentioned above, although two embodiment of this invention was described, this invention can be implemented also with another form. For example, as shown in FIGS. 1 and 7, an operation unit 75 may be connected to the control units 14 and C, and the magnitude of the reaction force of the operation may be adjusted by an operation from the operation unit 75.
Further, for example, in a normal electric power steering apparatus in which a steering wheel and a steering mechanism are coupled by a steering shaft in which a torsion bar is interposed and a steering assist force is applied to the steering mechanism from an electric motor, By providing an actuator that applies force to the wheel and an alarm device, it is possible to transmit information to the driver by properly using the steering wheel or the alarm device according to the type of abnormality or the like.
[0056]
A similar configuration can also be adopted in a power steering device configured to generate hydraulic pressure by a pump driven by an electric motor and transmit a driving force generated by a power cylinder operated by the hydraulic pressure to a steering mechanism. is there.
In addition, various design changes can be made within the scope of matters described in the claims.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram for explaining a configuration of a vehicle steering apparatus according to a first embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view for explaining the configuration of a tire for a steering wheel.
FIG. 3 is an illustrative view for explaining deformation of a tire during cornering.
FIG. 4 is a control characteristic diagram showing an example of a control mode of a reaction force actuator.
FIG. 5 is a conceptual diagram showing how information is exchanged among a driver, a vehicle, and a road surface.
FIG. 6 is a flowchart for explaining processing executed by the control device in order to transmit information to the driver through control of the reaction force actuator or an alarm device.
FIG. 7 is a schematic diagram showing a schematic configuration of a vehicle steering apparatus according to a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering actuator 4 Steering shaft 5 Wheel 9 Reaction force actuator 14 Control device 14a Antenna 17 Drive circuit 18 Drive circuit 19 Alarm 21 Vehicle steering device 22 Steering wheel 24 Steering mechanism 26 Planetary gear mechanism 27 Steering shaft 27a Rack 29 Wheel 32 Steering actuator 34 Pinion 35 Sun gear 36 Carrier 37 Planetary gear 38 Ring gear 39 Drive transmission gear 40 Reaction force actuator 44 Steering angle sensor 45 Torque sensor 46 Steering angle sensor 47 Vehicle speed sensor 48 Drive circuit 51 Tread part 52L Left side Wall portion 52R Right side wall portion 70 Alarm C Control device Ca Antenna SA Stress sensor SL Left side stress sensor SP Air pressure sensor SR Right side stress sensor W Tire WL Left side tire WR Right side tire S1 Operation angle sensor S2 Torque sensor S3 Steering angle sensor S4 Axial force sensor S5 Vehicle speed sensor S6 Longitudinal acceleration sensor S7 Lateral acceleration sensor S8 Yaw rate sensor S9 Shock absorber stroke sensor S10 Brake fluid pressure sensor S11 Load sensor S12 Current detection unit

Claims (5)

A vehicle steering apparatus for operating a steering mechanism for turning a steering wheel according to an operation of an operation member operated by a driver,
An actuator for applying a reaction torque to the operating member for information transmission to the driver;
At least one sensor for detecting a physical quantity related to the motion of the vehicle and outputting a detection signal according to the detection result;
A specifying means for specifying a tire located outside the steering direction;
A signal analyzing means for analyzing the detection signal output by the sensor and outputting an analysis result;
The signal analysis means on the basis of the analysis result is outputted, seen including a controller for controlling the actuator,
The sensor includes a right stress sensor that detects a stress of a right sidewall portion of the tire, and a left stress sensor that detects a stress of a left sidewall portion of the tire,
The control means includes the actuator based on a first-order time differential value or a second-order time differential value of a difference between detected values of the right stress sensor and the left stress sensor of the tire that is outside the steering direction of the tire specified by the specifying means. A vehicle steering apparatus characterized by controlling the drive of the vehicle. First determination means for determining whether an analysis result by the signal analysis means satisfies a predetermined first determination condition;
And a teaching means for providing the driver with a teaching corresponding to the determination result when the first determination means determines that the analysis result of the signal analysis means satisfies the first determination condition. The vehicle steering apparatus according to claim 1, wherein A second determination unit that determines whether the analysis result by the signal analysis unit satisfies a predetermined second determination condition;
The control means controls the actuator according to the analysis result when the second determination means determines that the analysis result of the signal analysis means satisfies the second determination condition. The vehicle steering apparatus according to claim 1, wherein the vehicle steering apparatus is a vehicle steering apparatus.   Means for determining whether there is an abnormality in the steering system or the steering system;
  The vehicle steering apparatus according to any one of claims 1 to 3, further comprising means for adding a correction torque value to a normal target reaction force torque value when it is determined that there is an abnormality.   Means for determining whether there is an abnormality in the suspension system;
  The vehicle steering apparatus according to any one of claims 1 to 4, further comprising means for adding a correction torque value to a normal target reaction force torque value when it is determined that there is an abnormality.

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