JP6247898B2 - Automatic braking device - Google Patents

Description

  The technology of the present disclosure relates to an automatic braking device that automatically brakes a vehicle.

  2. Description of the Related Art An automatic braking device is known that automatically brakes a host vehicle regardless of a driver's operation when a collision between the host vehicle and an obstacle such as another vehicle is predicted. For example, as described in Patent Document 1, the automatic braking device has a predetermined threshold value that is calculated from a relative distance between the host vehicle and the obstacle and a relative speed between the host vehicle and the obstacle. When it is below, the brake device is driven to brake the host vehicle.

JP 2012-196997 A

By the way, the automatic braking device normally stops the vehicle by driving each brake so that the driving amount of the left wheel brake and the driving amount of the right wheel brake are the same. However, even if the driving amount of the left wheel brake and the driving amount of the right wheel brake are the same, the braking force generated on the left wheel and the braking force generated on the right wheel due to, for example, changes over time in the members constituting the brake. there is also to be different and power. When the left wheel braking force is greater than the right wheel braking force, the left turning force acts on the vehicle, while the right wheel braking force is greater than the left wheel braking force. The right turning force acts on the vehicle. In such a case, when the automatic braking device automatically stops the vehicle, the trajectory of the vehicle from when the brake device is activated until the vehicle stops is greatly different from the direction in which the driver is operating the vehicle. .

  An object of the technology of the present disclosure is to provide an automatic braking device that can suppress a difference between a driver's operation and a vehicle trajectory.

One aspect of the automatic braking device according to the technology of the present disclosure includes a time calculation unit that calculates a predicted collision time of a vehicle with respect to an object, and a collision determination unit that determines whether or not the predicted collision time is a predetermined time threshold value or less. And a drive unit that drives the brake device when the collision determination unit determines that the predicted collision time is equal to or less than the time threshold. Further, the automatic braking device includes a movement amount calculation unit that calculates a movement amount of the vehicle in the intersecting direction using acceleration in a direction intersecting the front-rear direction of the vehicle in a state where the brake device is driven. A distance determination unit that determines whether or not the movement amount calculated by the movement amount calculation unit is equal to or greater than a predetermined distance threshold; and a release condition that releases driving of the brake device by the driving unit. Includes a drive canceling unit that cancels the driving when the canceling condition is satisfied, including that the distance determining unit determines that is equal to or greater than the distance threshold. The automatic braking device includes a vehicle speed acquisition unit that acquires a vehicle speed that is a speed of the vehicle, a steering angle acquisition unit that acquires a steering angle of a steering wheel, and the vehicle
A turning state acquisition unit that acquires the turning state of the vehicle, a target calculation unit that calculates a target turning state using the vehicle speed acquired by the vehicle speed acquisition unit and the steering angle acquired by the steering angle acquisition unit; . The automatic braking device includes a state determination unit that determines whether the turning state of the vehicle acquired by the turning state acquisition unit is different from the target turning state calculated by the target calculation unit, When the distance determining unit determines that the amount of movement is less than the distance threshold, and when the state determining unit determines that the turning state of the vehicle is different from the target turning state, the turning state of the vehicle And a braking force control unit that controls the braking force of the brake device so that a difference between the target turning state and the target turning state is reduced .

  According to one aspect of the automatic braking device in the technology of the present disclosure, since the movement of the vehicle based on the automatic driving of the brake device is suppressed, the turning of the vehicle due to the automatic driving of the brake device is suppressed. Therefore, the difference between the driver's operation and the vehicle trajectory can be suppressed.

Further , according to the above aspect, when the brake device is automatically driven, the difference between the actual turning state of the vehicle and the target turning state is reduced, so that the driver can operate even when the brake device is driven. The difference between the operation and the trajectory of the vehicle can be suppressed.

  In another aspect of the automatic braking device according to the technique of the present disclosure, the state determination unit determines whether or not a difference between the turning state of the vehicle and the target turning state is equal to or greater than a predetermined threshold value. In the drive release unit, the distance determination unit determines that the movement amount is less than the distance threshold, and a difference between the turning state of the vehicle and the target turning state is equal to or greater than a predetermined threshold value. When the state determination unit determines that there is, the driving of the brake device by the driving unit is released.

  According to another aspect of the automatic braking device of the technology of the present disclosure, braking is performed even when a difference between an actual turning state of the vehicle and a target turning state, that is, a turning state based on a driver's operation is opened. The drive of the device is released. Therefore, there are more opportunities for the difference between the driver's operation and the vehicle trajectory to be suppressed.

In another aspect of the automatic braking device according to the technology of the present disclosure, a curvature radius in a traveling locus of the vehicle is used as the turning state of the vehicle, and the movement amount calculation unit uses the curvature radius to cross the intersecting direction. And the amount of movement of the vehicle in the intersecting direction is calculated using the result of calculating the acceleration in the intersecting direction.

  According to another aspect of the automatic braking device according to the technique of the present disclosure, the turning state of the vehicle is also used for calculating acceleration for obtaining the movement amount, and therefore, the type of data used by the automatic braking device is reduced. be able to.

The state determination unit further determines which of the braking force of the right wheel and the braking force of the left wheel is greater from the turning state of the vehicle and the target turning state. Further, the braking force control unit is configured of the braking force of the right wheel and the braking force of the left wheel, to reduce the magnitude of the braking force which the state determiner determines that relatively large, the state determination It approaches the magnitude of the braking force determined to be relatively small.

  According to another aspect of the automatic braking device in the technology of the present disclosure, the magnitude of the braking force on the right wheel approaches the magnitude of the braking force on the left wheel, or the magnitude of the braking force on the left wheel is the right wheel. Approaches the magnitude of the braking force at Therefore, the difference between the two braking forces can be reliably reduced. Therefore, the difference between the driver's operation and the vehicle trajectory can be reliably suppressed.

It is a block diagram which shows the structure of the vehicle carrying the automatic braking device in 1st Embodiment of the automatic braking device of this indication. It is a functional block diagram which shows the structure of the automatic braking device in 1st Embodiment. It is a flowchart which shows the procedure of the process which the automatic braking device in 1st Embodiment performs. It is an operation view for explaining the operation of the automatic braking device in the first embodiment. It is a functional block diagram which shows the structure of the automatic braking device in 2nd Embodiment of the automatic braking device of this indication. It is a figure which shows an example of the map which the automatic braking device in 2nd Embodiment memorize | stores. It is a flowchart which shows a part of procedure of the process which the automatic braking device in 2nd Embodiment performs. It is an operation view for explaining the operation of the automatic braking device in the second embodiment.

[First Embodiment]
A first embodiment embodying an automatic braking device will be described with reference to FIGS. 1 to 4. Below, the structure of the vehicle carrying an automatic braking device, the structure of an automatic braking device, the procedure of the process which an automatic braking device performs, and the effect | action of an automatic braking device are demonstrated in order.

[Vehicle configuration]
A configuration of a vehicle equipped with an automatic braking device will be described with reference to FIG.
As shown in FIG. 1, the vehicle 10 has, for example, two right wheels and two left wheels, and one of the two right wheels is a front right wheel 11a, and the other is a rear right wheel 11c. Of the two left wheels, one is the front left wheel 11b and the other is the rear left wheel 11d. The vehicle 10 includes brakes 12a, 12b, 12c, and 12d that brake the vehicle while suppressing the rotation of each of the four wheels. Each brake may be a drum brake or a disc brake.

  Each brake is connected to a brake actuator 13 that applies a braking force for braking the vehicle to each brake. The brake actuator 13 may be configured to apply air pressure to each brake as a braking force, or may be configured to apply hydraulic pressure to each brake as a braking force. The brake actuator 13 has a mechanism for adjusting the braking force applied to each brake by adjusting the air pressure or hydraulic pressure applied to each brake. Each brake and brake actuator 13 is an example of a brake device.

  The vehicle 10 is equipped with an automatic braking device 14 that controls the drive amount by which the brake actuator 13 drives each brake. The automatic braking device 14 is connected to a steering sensor 15, a millimeter wave radar 16, a vehicle speed sensor 17, and a yaw rate sensor 18.

  The steering sensor 15 measures the steering angle of the steering wheel mounted on the vehicle 10 and outputs the measured value to the automatic braking device 14. The millimeter wave radar 16 measures the relative position and relative speed between the vehicle 10 and an obstacle located around the vehicle 10, for example, another vehicle, and outputs these measured values to the automatic braking device 14. For example, the vehicle speed sensor 17 measures the rotational speed of each wheel and outputs the measured value to the automatic braking device 14. The yaw rate sensor 18 measures the yaw rate, which is the angular velocity of the rotational motion about the vertical axis passing through the center of gravity of the vehicle 10, and outputs the measured value to the automatic braking device 14.

[Configuration of automatic braking system]
The configuration of the automatic braking device 14 will be described with reference to FIG.
As shown in FIG. 2, the automatic braking device 14 includes a time calculation unit 21, a collision determination unit 22, a control signal generation unit 23, a drive unit 24, a movement amount calculation unit 25, and a distance determination unit 26. Among these, the time calculation unit 21 inputs the measurement value of the relative distance and the measurement value of the relative speed which are the measurement values of the millimeter wave radar 16 as input values, and the movement amount calculation unit 25 measures the measurement of the vehicle speed sensor 17. The vehicle speed that is the value and the yaw rate that is the measurement value of the yaw rate sensor are input as input values. The drive unit 24 outputs a drive signal directed to the brake actuator 13 constituting the brake device.

The time calculation unit 21 calculates the collision prediction time using the relative distance and the relative speed. The time calculation unit 21 calculates the collision prediction time by dividing the relative distance by the relative speed.
The collision determination unit 22 determines whether or not the predicted collision time calculated by the time calculation unit 21 is equal to or less than a time threshold that is a predetermined threshold in time. The time threshold is several seconds, for example.

  The control signal generation unit 23 generates a control signal for controlling the driving of the brake actuator 13 constituting the brake device based on the determination result of the collision determination unit 22. When the collision determination unit 22 determines that the predicted collision time is equal to or less than the time threshold, the control signal generation unit 23 causes the brake actuator 13 so that the right wheel drive amount and the left wheel drive amount of the vehicle 10 are the same. A control signal for driving is generated. The control signal generation unit 23 outputs the generated control signal toward the drive unit 24. On the other hand, when the collision determination unit 22 determines that the predicted collision time is greater than the time threshold, the control signal generation unit 23 performs a control signal for releasing the driving of the brake actuator 13 by the automatic braking device 14 or the driving signal. A control signal for maintaining the stop is generated, and the generated control signal is output to the drive unit 24.

  The drive unit 24 generates a drive signal for driving the brake device in a drive state corresponding to the control signal output from the control signal generation unit 23. The drive unit 24 outputs a drive signal toward the brake actuator 13 of the brake device. Accordingly, the brake device is automatically driven by the automatic braking device 14. Or the drive of a brake device is cancelled | released or the stop of the drive of a brake device is maintained.

  When the collision determination unit 22 determines that the predicted collision time is equal to or less than the time threshold, the movement amount calculation unit 25 uses the yaw rate and the vehicle speed to determine the distance between the travel locus of the center of gravity of the vehicle and the turning center, that is, The actual radius of curvature, which is the actual radius of curvature, is calculated. The movement amount calculation unit 25 calculates the actual curvature radius by dividing the vehicle speed by the yaw rate. When the vehicle speed is V (m / s), the yaw rate is Y (rad / s), and the actual curvature radius is Ra (m), the movement amount calculation unit 25 uses the following equation to calculate the actual curvature radius. Ra is calculated.

Ra = V / Y
The movement amount calculation unit 25 calculates an acceleration in a direction that intersects the front-rear direction of the vehicle 10, and calculates a movement amount in a direction that intersects the front-rear direction of the vehicle 10 using the calculated acceleration. The acceleration may be, for example, a lateral acceleration that is an acceleration acting in the lateral direction perpendicular to the front-rear direction of the vehicle 10 or a centripetal acceleration that is an acceleration acting in the center direction of the turning of the vehicle 10. When the acceleration is centripetal acceleration and the centripetal acceleration is A, the movement amount calculation unit 25 calculates the centripetal acceleration by applying the vehicle speed V and the actual curvature radius Ra to the following equations.

A ⁼ V 2 / Ra
When the acceleration is a lateral acceleration, the movement amount calculating unit 25 calculates the lateral acceleration by correcting the acceleration calculated using the vehicle speed and the actual curvature radius Ra with the gravity center side slip angle. The center-of-gravity point side slip angle is an angle formed by the traveling direction of the center-of-gravity point of the vehicle 10 and the center line of the vehicle that extends along the longitudinal direction of the vehicle 10 and passes through the center-of-gravity point of the vehicle 10. .

  The movement amount calculation unit 25 calculates a movement amount that is a distance that the vehicle 10 moves in a direction that intersects the front-rear direction of the vehicle 10 using the calculated acceleration. The movement amount calculation unit 25 calculates the movement amount by, for example, second-order integration of acceleration.

  The distance determination unit 26 determines whether or not the movement amount calculated by the movement amount calculation unit 25 is greater than or equal to a distance threshold that is a predetermined threshold in distance. For example, when the vehicle 10 is a large vehicle such as a large bus or a large truck, the distance threshold is preferably about 1 m. When a large vehicle travels in one of two lanes that face each other and the amount of movement of the large vehicle exceeds the distance threshold, the large vehicle may collide with a vehicle traveling in the opposite lane, or the opposite lane By moving in the opposite direction, there is a high possibility that it will protrude from the lane.

  The control signal generation unit 23 generates a control signal for controlling the driving of the brake actuator 13 based on the result determined by the distance determination unit 26. The control signal generation unit 23 includes that the distance determination unit 26 determines that the movement amount of the vehicle 10 is equal to or greater than the distance threshold as a condition for releasing the driving of the brake actuator 13.

  When the distance determination unit 26 determines that the amount of movement of the vehicle 10 is equal to or greater than the distance threshold, the control signal generation unit 23 generates a control signal for releasing the drive of the brake actuator 13 and sends it to the drive unit 24. Output. The drive unit 24 outputs a drive release signal for releasing the drive of the brake device to the brake actuator 13 in accordance with the control signal output from the control signal generation unit 23. Thereby, the drive part 24 cancels | releases the drive of the brake actuator 13 based on the result judged by the collision judgment part 22, and cancels the drive of a brake device.

  On the other hand, when the distance determination unit 26 determines that the movement amount of the vehicle 10 is less than the distance threshold, the control signal generation unit 23 does not generate a control signal for releasing the drive of the brake actuator 13. As a result, the driving of the brake actuator 13 based on the determination of the collision determination unit 22 is continued, and the driving of the brake device is continued. The control signal generation unit 23 is an example of a drive release unit.

[Procedure for automatic braking system processing]
With reference to FIG. 3, the procedure of the process which the automatic braking device 14 performs is demonstrated. Note that the automatic braking device 14 repeatedly performs the following processing every predetermined time.

  As shown in FIG. 3, the automatic braking device 14 calculates the collision prediction time using the relative distance and the relative speed (step S <b> 11), and the automatic braking device 14 calculates the calculated collision prediction time that is equal to or less than the time threshold. Whether or not (step S12). When it is determined that the predicted collision time is equal to or less than the time threshold (step S12: YES), the automatic braking device 14 generates a drive signal for the brake actuator 13 and outputs the drive signal to the brake actuator 13 (step S13).

  When the brake actuator 13 is driven, that is, when the brake device is driven, the automatic braking device 14 calculates the actual curvature radius using the vehicle speed and the yaw rate, and uses the vehicle speed and the actual curvature radius to calculate the vehicle longitudinal direction. Acceleration in the direction that intersects with is calculated (step S14). The automatic braking device 14 uses the acceleration calculated in step S14 to calculate a movement amount in a direction intersecting with the front-rear direction of the vehicle (step S15), and determines whether the calculated movement amount is equal to or greater than a distance threshold. Judgment is made (step S16). When the automatic braking device 14 determines that the amount of movement is equal to or greater than the distance threshold (step S16: YES), the automatic braking device 14 generates a drive release signal and outputs it to the brake actuator 13 (step S17). When the automatic braking device 14 finishes the process of step S17, the series of processes from step S11 to step S17 are temporarily ended.

  When the automatic braking device 14 determines in step S12 that the predicted collision time is longer than the time threshold (step S12: NO), the automatic braking device 14 releases the driving of the brake device or stops the driving of the braking device. A drive signal for maintenance is generated and output to the brake actuator 13. Thereafter, the automatic braking device 14 once ends a series of processes. On the other hand, when the automatic braking device 14 determines in step S16 that the movement amount is less than the distance threshold value, the automatic braking device 14 ends the series of processes without performing the subsequent processes.

[Operation of automatic braking system]
The operation of the automatic braking device 14 will be described with reference to FIG.
As shown in FIG. 4, when the host vehicle 31 is traveling along the first lane 41 extending along one direction, the host vehicle 31 travels in front of the host vehicle 31 along the first lane 41. The vehicle approaches the forward vehicle 32. As a result, when the predicted collision time, which is the time taken for the host vehicle 31 to collide with the preceding vehicle 32, becomes equal to or less than the time threshold, the brake device provided in the host vehicle 31 is driven by the automatic braking device 14.

  When the brake device is automatically driven and the amount of movement in the direction intersecting the traveling direction of the host vehicle 31 is equal to or greater than the distance threshold, the drive of the brake device is released. For this reason, the host vehicle 31 traveling along the direction in which the first lane 41 extends is less likely to receive a force for turning in either the left-right direction. Therefore, the host vehicle 31 can be prevented from moving in a direction greatly deviating from the first lane 41 by moving in a direction crossing the traveling direction. That is, the host vehicle 31 is likely to be positioned at the front position 31a on the first lane 41 as long as the driver is driving the host vehicle 31 along the direction in which the first lane 41 extends. As a result, the difference between the driver's operation and the vehicle trajectory can be suppressed.

  On the other hand, when the brake device is automatically driven and the drive of the brake device is not stopped even when the above-described movement amount is equal to or greater than the distance threshold, the vehicle travels along the direction in which the first lane 41 extends. The host vehicle 31 receives a force for turning in one of the left and right directions.

  For example, when the braking force on the right wheel is larger than the braking force on the left wheel and the vehicle 31 receives a force that turns the vehicle 31 to the right, the driver holds the vehicle 31 in the first lane 41. Even if the vehicle 31 travels along the extending direction, the host vehicle 31 travels from the first lane 41 toward the second lane 42. The second lane 42 is a lane that extends in the same direction as the first lane 41 and in which the vehicle travels in a direction opposite to the first lane 41. As a result, the host vehicle 31 enters the second lane 42 beyond the center line 43 that divides the first lane 41 and the second lane 42, and most of the host vehicle 31 is located on the second lane 42. It will be located in the turning position 31b. As a result, the difference between the driver's operation and the vehicle trajectory becomes large. As a result, the possibility of collision with the oncoming vehicle 33 traveling along the direction in which the second lane 42 extends increases.

  On the other hand, when the vehicle 31 receives a force for turning the vehicle 31 in the left direction because the magnitude of the braking force at the left wheel is larger than the magnitude of the braking force at the right wheel, the driver holds the vehicle 31 in the first lane 41. Even if the vehicle 31 travels along the extending direction, the host vehicle 31 travels in a direction away from the center line 43. As a result, the host vehicle 31 is positioned at the left turn position 31c, which is a position where most of the host vehicle 31 deviates from the first lane 41. As a result, the difference between the driver's operation and the vehicle trajectory becomes large. Eventually, for example, when the first lane 41 is partitioned by a side wall extending in the same direction as the first lane, the possibility of the host vehicle 31 colliding with the side wall increases.

As described above, according to the automatic braking device in the first embodiment, the following effects can be obtained.
(1) Since the movement of the vehicle 10 based on the automatic driving of the brake device is suppressed, the turning of the vehicle 10 due to the automatic driving of the brake device is suppressed. Therefore, the difference between the driver's operation and the vehicle trajectory can be suppressed.

The first embodiment described above can be implemented with appropriate modifications as follows.
If the vehicle 10 is configured to include a lateral acceleration sensor that is a sensor that measures acceleration in a direction crossing the front-rear direction of the vehicle 10, the movement amount calculation unit 25 inputs and inputs the lateral acceleration as an input value. A configuration in which the lateral acceleration is second-order integrated to calculate the movement amount may be used.

  The vehicle 10 may include an even number of wheels of 6 or more. When the vehicle 10 is, for example, a large truck or a large bus, a configuration including three right wheels arranged along the front-rear direction of the vehicle 10 and three left wheels arranged along the front-rear direction of the vehicle 10 may be used.

  Each of the steering sensor 15, the millimeter wave radar 16, the vehicle speed sensor 17, and the yaw rate sensor 18 is an example of a measurement sensor, and the vehicle 10 is configured to include a sensor that measures the same measurement object as each of these sensors. May be. Alternatively, the vehicle 10 may have a configuration in which data related to a measurement target is obtained from another vehicle by inter-vehicle communication.

The automatic braking device 14 may be configured to have a plurality of time threshold values in the collision prediction time. For example, the automatic braking device 14 has two time threshold values, and when the predicted collision time is less than or equal to a relatively large time threshold value, warns the driver using a lamp or a buzzer, and relatively The brake device is driven with a small driving amount. The automatic braking device 14 drives the brake device with a relatively large driving amount when the predicted collision time is equal to or less than a relatively small time threshold. In such a configuration, when the collision prediction time is less than or equal to a relatively small time threshold, the processing described using FIG. 3 may be performed, or when the collision prediction time is less than or equal to a relatively large time threshold, The same processing may be performed, or the same processing may be performed in any case.

  The automatic braking device 14 may be configured to have three time threshold values. The automatic braking device 14 warns when the predicted collision time is below the maximum time threshold, and drives the brake device with a relatively small drive amount when the predicted collision time is below the second smallest time threshold. When the collision prediction time is equal to or shorter than the smallest collision prediction time, the brake device may be driven with a relatively large driving amount.

[Second Embodiment]
A second embodiment in which the automatic braking device is embodied will be described with reference to FIGS. The automatic braking device according to the second embodiment is different from the automatic braking device according to the first embodiment in that processing that is performed when the above-described movement amount is smaller than the distance threshold is added. Therefore, in the following, in order to explain these differences in detail, the configuration of the automatic braking device, the procedure of processing performed by the automatic braking device, and the operation of the automatic braking device will be described in order. Moreover, below, the same code | symbol is attached | subjected with respect to the structure equivalent to the automatic braking device of 1st Embodiment, and detailed description about these structures is abbreviate | omitted.

[Configuration of automatic braking system]
The configuration of the automatic braking device 14 will be described with reference to FIG.
As shown in FIG. 5, the automatic braking device 14 includes a target calculation unit 21, a collision determination unit 22, a control signal generation unit 23, a drive unit 24, a movement amount calculation unit 25, and a distance determination unit 26. A calculation unit 51 and a state determination unit 52 are provided.

  The target calculation unit 51 inputs the steering angle of the steering wheel, which is a measured value of the steering sensor 15, and the vehicle speed, which is a measured value of the vehicle speed sensor 17, as input values. The target calculation unit 51 is an example of a vehicle speed acquisition unit and a steering angle acquisition unit. The target calculation unit 51 calculates a target curvature radius that is a target curvature radius using the steering angle and the vehicle speed. That is, the target curvature radius is a curvature radius estimated from the amount of operation of the steering wheel by the driver.

  When the vehicle speed is V (m / s), the steering angle is S (deg), and the target curvature radius is Rt (m), the target calculation unit 51 calculates the target curvature radius Rt using the following equation. calculate. Note that α and β below are predetermined constants.

Rt = (V × α + β) / S
The state determination unit 52 determines whether the actual turning state of the vehicle 10 is different from the target turning state of the vehicle 10. For example, when the turning state is a radius of curvature in the travel locus of the vehicle 10, the state determination unit 52 calculates the actual curvature radius Ra calculated by the movement amount calculation unit 25 and the target curvature radius Rt calculated by the target calculation unit 51. Determine whether they are different. The state determination unit 52 is an example of a turning state acquisition unit.

  The state determination unit 52 further determines whether or not the difference between the actual turning state and the target turning state is equal to or greater than a predetermined threshold value. When the turning state is, for example, a radius of curvature in the travel locus of the vehicle 10, the state determination unit 52 determines whether or not the difference between the actual curvature radius Ra and the target curvature radius Rt is equal to or less than a predetermined threshold value.

  When the state determination unit 52 determines whether or not the radius difference ΔR that is the difference between the actual curvature radius Ra and the target curvature radius Rt is greater than or equal to a threshold value, for example, the braking force stored in the storage unit of the automatic braking device 14 Use a map. The state determination unit 52 applies the actual curvature radius Ra and the target curvature radius Rt to the braking force map, and determines whether or not the radius difference ΔR is greater than or equal to a threshold value.

  Further, the state determination unit 52 applies the actual curvature radius Ra and the target curvature radius Rt to the braking force map when the previously described threshold is the first threshold, and the radius difference ΔR is greater than the first threshold. It may be determined whether or not the second threshold value is less than the first threshold value.

  The control signal generator 23 controls the braking force of the brake device to reduce the difference between the actual turning state of the vehicle 10 and the target turning state of the vehicle 10. However, when the control signal generation unit 23 reduces the difference between the actual turning state and the target turning state, the distance determination unit 26 determines that the movement amount of the vehicle 10 is less than the distance threshold. The state determination unit 52 needs to determine that the actual turning state is different from the target turning state.

  The control signal generation unit 23 inputs the result determined by the distance determination unit 26 and the result determined by the state determination unit 52, and based on these results, determines the difference between the actual turning state and the target turning state. A corresponding control signal is generated to control the driving of the brake device. The control signal generator 23 has a function of generating a signal for controlling the driving amount of the brake device, in addition to a function of generating a signal for controlling whether or not to drive the brake device. That is, the control signal generation unit 23 generates a control signal for releasing the driving of the brake device using the result determined by the state determination unit 52. In addition, the control signal generation unit 23 calculates the drive amount of the brake actuator 13 for reducing the above-described difference in the turning state using the determination result of the state determination unit 52, and the brake actuator 13 is calculated with the calculated drive amount. A control signal for driving is generated and output to the drive unit 24.

  For example, when the turning state is the radius of curvature in the travel locus of the vehicle, the control signal generation unit 23 generates a signal for controlling the driving amount of the brake device, and the actual curvature radius Ra in the vehicle 10 and the vehicle 10 The difference from the target curvature radius Rt at is reduced. The control signal generation unit 23 is an example of a braking force control unit.

  The drive unit 24 generates a drive release signal and outputs it to the brake actuator 13 when a control signal for releasing the drive of the brake device is input from among the control signals output by the control signal generation unit 23. . On the other hand, the drive unit 24 generates a drive correction signal and inputs it to the brake actuator 13 when a control signal for driving the brake device with a drive amount calculated from the control signals output by the control signal generation unit 23 is input. Output toward.

[Braking force map]
An example of the braking force map stored in the storage unit of the automatic braking device 14 will be described with reference to FIG. In the following description, when the actual curvature radius Ra is smaller than the target curvature radius Rt in the braking force map, that is, when the actual turning amount is larger than the target turning amount, the collision determination unit 22 An example in which the driving of the brake device based on the determined result is released will be described.

  As shown in FIG. 6, the braking force map 61 is a two-dimensional map in which the vertical axis 62 is the actual curvature radius Ra, and the horizontal axis 63 is the target curvature radius. We are in a cross.

  The yaw rate sensor 18 outputs a positive value as a measurement value when the vehicle 10 turns to the left, and outputs a negative value as a measurement value when the vehicle 10 turns to the right. Therefore, the actual curvature radius Ra is also a positive value when the vehicle 10 turns to the left, and a negative value when the vehicle 10 turns to the right.

  The steering sensor 15 outputs a positive value as a measured value when the steering wheel turns to the left, and outputs a negative value as a measured value when the vehicle 10 turns to the right. Therefore, the target curvature radius Rt is also a positive value when the vehicle 10 turns to the left, and a negative value when the vehicle 10 turns to the right.

  In each of the actual curvature radius Ra and the target curvature radius Rt, the amount of turning at the travel distance of the vehicle 10 decreases as the absolute value increases regardless of the positive value or the negative value. The running track approaches a straight line.

  In the two-dimensional region defined by the vertical axis 62 and the horizontal axis 63, a first straight line 64, a second straight line 65, and a third straight line 66 are set. The second straight line 65 is a straight line having a smaller inclination than the first straight line 64, and the third straight line 66 is a straight line having a smaller inclination than the second straight line.

  The first straight line 64 is a set of points where the actual curvature radius Ra and the target curvature radius Rt are equal. When the radius point P, which is a point specified by the actual curvature radius Ra and the target curvature radius Rt, is equal to or smaller than the first straight line 64 and larger than the second straight line 65, the automatic braking device 14 determines the collision determination unit 22. Based on the result, the drive of the brake device is continued. That is, the automatic braking device 14 is based on the result determined by the collision determination unit 22 when the radius point P is included in one of the two drive areas defined by the first straight line 64 and the second straight line 65. Continue driving.

  The second straight line 65 is a set of points in which the absolute value of the actual curvature radius Ra is smaller by a predetermined length than the absolute value of the target curvature radius Rt, and the radius difference ΔR is a predetermined length or more. It is a set. When the radius point P is equal to or smaller than the second straight line 65 and larger than the third straight line 66, the automatic braking device 14 corrects the driving amount of the brake device so that the radius difference ΔR becomes small, and the brake device The braking force due to is corrected.

  In the braking force map 61, the distance between the first straight line 64 and the second straight line 65 decreases as the turning amount of the vehicle 10 increases. That is, as the turning amount of the vehicle 10 increases, the radius point P is included in one of the two correction regions even if the radius difference ΔR is small. Therefore, even if the turning amount of the vehicle changes, the vehicle has a relatively large turning amount of the vehicle 10 as compared with the configuration in which the radius point P is included in one of the two correction regions when the radius difference ΔR is the same. 10 turns are further suppressed. On the other hand, when the turning amount of the vehicle 10 is relatively small, the braking force of the vehicle 10 is not suppressed too much.

  That is, each of the points constituting the second straight line 65 is a threshold for determining whether or not the automatic braking device 14 corrects the driving amount of the braking device, and is the second of the two thresholds described above. It is a threshold value. The automatic braking device 14 corrects the drive amount of the brake device when the radius point P is included in one of the two correction regions defined by the second straight line 65 and the third straight line 66.

  For example, when the actual curvature radius Ra and the target curvature radius Rt are positive values and the radius point is included in one correction region, the magnitude of the braking force on the right wheel is larger than the magnitude of the braking force on the left wheel. Therefore, the vehicle 10 receives a force for turning right. Thereby, the actual curvature radius Ra becomes smaller than the target curvature radius Rt.

  At this time, the automatic braking device 14 reduces, for example, the driving amount of the braking device with respect to the right wheel by a predetermined amount to reduce the magnitude of the braking force at the right wheel by a predetermined amount, and the actual curvature radius Ra. And the difference between the target curvature radius Rt.

  On the other hand, when the actual curvature radius Ra and the target curvature radius Rt are negative values and the radius point P is included in the other correction region, the magnitude of the braking force on the left wheel is equal to the braking force on the right wheel. Since it is larger than the size, the vehicle 10 receives a force to turn left. Thereby, the absolute value of the actual curvature radius Ra becomes smaller than the absolute value of the target curvature radius Rt.

  At this time, the automatic braking device 14 reduces, for example, the driving amount of the braking device with respect to the left wheel by a predetermined amount to reduce the braking force at the left wheel by a predetermined amount, and the actual curvature radius Ra and the target radius The difference from the radius of curvature Rt is reduced.

  Thus, when the brake device is automatically driven, the difference between the actual curvature radius Ra and the target curvature radius Rt of the vehicle 10 is reduced, so that even when the brake device is driven, the driver's operation and the vehicle The difference between the tracks can be suppressed.

  Also, in order to bring the magnitude of the relatively large braking force closer to the magnitude of the relatively small braking force, compared to the configuration in which the magnitude of the relatively small braking force is brought closer to the magnitude of the relatively large braking force. The difference between the two braking forces can be reliably reduced. Therefore, the difference between the driver's operation and the vehicle trajectory can be reliably suppressed.

  The third straight line 66 is a set of points where the absolute value of the actual curvature radius Ra is smaller by a predetermined length than the absolute value of the target curvature radius Rt, and the set of points where the radius difference ΔR is greater than or equal to the predetermined length. is there. The radius point P is equal to or less than the third straight line 66, and the automatic braking device 14 releases the driving of the brake device. That is, each of the points constituting the third straight line 66 is a threshold for determining whether or not the automatic braking device 14 releases the driving of the brake device, and is a first threshold of the two thresholds described above. It is. The automatic braking device 14 releases the driving of the brake device when the radius point P is included in one of the two release regions defined by the third straight line 66 and the horizontal axis 63.

  In the braking force map 61, the distance between the second straight line 65 and the third straight line 66 decreases as the turning amount of the vehicle 10 increases. That is, as the turning amount of the vehicle 10 increases, the radius point P is included in one of the two release regions even if the radius difference ΔR is small. Therefore, even if the turning amount of the vehicle changes, the vehicle 10 has a relatively large turning amount compared to the configuration in which the radius point P is included in one of the two release regions when the radius difference ΔR is the same. 10 turns are further suppressed. On the other hand, when the turning amount of the vehicle 10 is relatively small, the braking force of the vehicle 10 is not suppressed too much.

  As described above, the driving of the brake device is also released when the difference between the actual curvature radius Ra of the vehicle 10 and the target curvature radius Rt, that is, the curvature radius based on the operation of the driver, is increased. Therefore, there are more opportunities for the difference between the driver's operation and the vehicle trajectory to be suppressed.

[Procedure for automatic braking system processing]
The processing procedure of the automatic braking device 14 will be described with reference to FIG. The plurality of processes shown in FIG. 7 are a series of processes performed before the series of processes are ended when the determination in step S16 is NO in the processes shown in FIG.

  As shown in FIG. 7, the automatic braking device 14 calculates the target curvature radius Rt using the steering angle and the vehicle speed (step S21). The automatic braking device 14 applies the calculated target curvature radius Rt and the actual curvature radius Ra calculated in step S14 to the braking force map, and the automatic braking device 14 has the radius point P in one of the two driving regions. It is determined whether it is included (step S22). When the automatic braking device 14 determines that the radius point P is included in one of the two drive regions (step S22: YES), the series of processes is temporarily ended.

  On the other hand, when the automatic braking device 14 determines that the radius point P is not included in any of the two drive regions (step S22: NO), the radius point P is in any of the two correction regions in the braking force map. It is judged whether it is included in (step S23). When the automatic braking device 14 determines that the radius point P is included in one of the two correction regions (step S23: YES), the automatic braking device 14 generates a drive correction signal and outputs it to the brake actuator 13 (step S24). . When the automatic braking device 14 ends the process of step S24, the series of processes is temporarily ended.

  When the automatic braking device 14 determines that the radius point P is not included in any of the two correction regions (step S23: NO), it generates a drive release signal and outputs it to the brake actuator 13 ( Step S25). When the automatic braking device 14 ends the process of step S25, the series of processes is temporarily ended.

[Operation of automatic braking system]
The operation of the automatic braking device 14 will be described with reference to FIG.
As shown in FIG. 8, when the host vehicle 71 travels along a lane 81 extending along one direction, the host vehicle 71 travels in front of the host vehicle 71 along the lane 81. Get closer to. As a result, when the predicted collision time, which is the time taken for the host vehicle 71 to collide with the forward vehicle 72, becomes equal to or less than the time threshold, the brake device provided in the host vehicle 71 is driven by the automatic braking device 14.

  When the brake device is driven automatically and the radius point P is included in one of the two correction regions, the larger of the braking force on the right wheel and the braking force on the left wheel is controlled. The magnitude of power is reduced. Thereby, the difference between the actual curvature radius Ra and the target curvature radius Rt is reduced. Therefore, the traveling locus of the host vehicle 71 is less likely to receive a force that turns in either the right or left direction with respect to the direction along the direction in which the lane 81 that is the traveling direction of the host vehicle 71 extends. Therefore, as long as the driver is driving the host vehicle 71 along the direction in which the lane 81 extends, the host vehicle 71 is likely to be positioned at the front position 71 a on the lane 81. As a result, even when the brake device is driven, the difference between the driver's operation and the vehicle trajectory can be suppressed.

  Further, when the brake device is automatically driven and the radius point P is included in one of the two release regions, the drive of the brake device is released. Therefore, the traveling locus of the host vehicle 71 does not receive a force that turns in either the right or left direction when the brake device is automatically driven. Therefore, the difference between the driver's operation and the vehicle trajectory can be suppressed.

  On the other hand, even when the brake device is automatically driven and the radius point P is included in one of the two correction regions, when the braking force of the brake device is not corrected, along the direction in which the lane 81 extends. The traveling own vehicle 71 receives a force to turn in either the left or right direction.

  Even when the brake device is automatically driven and the radius point P is included in the release region, when the drive of the brake device is not released, the host vehicle 71 traveling along the direction in which the lane 81 extends is Receives more force to turn in either the left or right direction.

  For example, when the host vehicle 71 receives a force for turning rightward, even if the driver runs the host vehicle 71 along the direction in which the lane 81 extends, Drive in the direction. Thereby, the own vehicle 71 will be located in the right turn position 71b.

  On the other hand, when the host vehicle 71 receives a force for turning leftward, even if the driver runs the host vehicle 71 along the direction in which the lane 81 extends, the host vehicle 71 is left with respect to the direction in which the lane 81 extends. Drive in the direction. Thereby, the own vehicle 71 will be located in the left turn position 71c.

As described above, according to the automatic braking device of the second embodiment, in addition to the effect (1) described above, the effects listed below can be obtained.
(2) Since the difference between the actual curvature radius Ra and the target curvature radius Rt of the vehicle 10 is reduced when the brake device is automatically driven, the driver's operation and the vehicle 10 can be performed even when the brake device is driven. The difference between the trajectory can be suppressed.

  (3) The driving of the brake device is also released when the difference between the actual curvature radius Ra of the vehicle 10 and the target curvature radius Rt, that is, the curvature radius based on the driver's operation, is increased. Therefore, there are more opportunities for the difference between the driver's operation and the trajectory of the vehicle 10 to be suppressed.

(4) Since the actual curvature radius Ra of the vehicle 10 is also used for calculating acceleration for determining the amount of movement, the types of data used by the automatic braking device 14 for calculation can be reduced.
(5) Since the magnitude of the relatively large braking force is brought close to the magnitude of the relatively small braking force, the difference between the two braking forces can be reliably reduced. Therefore, the difference between the driver's operation and the trajectory of the vehicle 10 can be reliably suppressed.

Note that the second embodiment can be implemented with appropriate modifications as follows.
In order to reduce the radius difference ΔR, the automatic braking device 14 uses the braking force determined by the state determination unit 52 to be relatively small and the braking force determined by the state determination unit 52 to be relatively large. You may approach the size. However, when the automatic braking device 14 is driven so as to have a braking force that is close to the upper limit value of the braking force of the braking device, the magnitude of the braking force that is relatively small enough to reduce the radius difference ΔR is relatively large. In some cases, it may not be possible to approach a large braking force. Therefore, as described in the embodiment, the automatic braking device 14 is preferably configured so that the magnitude of the relatively large braking force approaches the magnitude of the relatively small braking force.

  The first threshold value that is a threshold value for determining whether or not to release the drive of the brake device changes according to the turning amount of the vehicle 10 and the target turning amount. Not limited to this, the first threshold value may be constant regardless of the turning amount of the vehicle 10 and the target turning amount.

  The state determination unit 52 uses the radius of curvature in the travel locus of the vehicle 10 as the turning state of the vehicle 10, but may use information on the yaw rate of the vehicle 10 or the turning state obtained from the GPS as the turning state. . In such a configuration, when the state determination unit 52 determines that the difference between the actual yaw rate measured by the yaw rate sensor 18 and the target yaw rate calculated using the vehicle speed and the steering angle is equal to or greater than a predetermined threshold value, What is necessary is just to cancel the drive of a brake device. Alternatively, when the state determination unit 52 determines that the difference between the information regarding the turning state obtained from the GPS and the turning state calculated using the vehicle speed and the steering angle is equal to or greater than a predetermined threshold, the driving of the brake device is performed. Can be canceled.

  The automatic braking device 14 is configured such that when the state determination unit 52 determines that the difference between the turning state of the vehicle 10 and the target turning state is equal to or greater than a predetermined threshold, the process for releasing the driving of the brake device is not performed. But you can.

  When the state determination unit 52 determines that the difference between the actual yaw rate measured by the yaw rate sensor 18 and the target yaw rate calculated using the vehicle speed and the steering angle is different, the control signal generation unit 23 The configuration may be such that a control signal for correcting the drive amount of the brake device after the brake device is driven based on the determination result of the collision determination unit 22 is generated so that the difference is reduced.

  The automatic braking device 14 may not be configured to control the driving amount of the brake device to correct the braking force of the brake device by a predetermined magnitude when the radius point P is included in one of the two correction regions. Good. As the difference between the turning state of the vehicle 10 and the target turning state increases, the automatic braking device 14 increases the drive amount when the brake device is driven based on the determination result of the collision determination unit 22 and the corrected drive. The structure which enlarges the difference with quantity may be sufficient. According to such a configuration, since the rate of correction of the braking force changes according to the difference between the actual turning state of the vehicle 10 and the target turning state, the rate of correction of the braking force is more appropriate to the state of the vehicle 10. Become a proportion.

  The second threshold value, which is a threshold value for determining whether to correct the braking force, changes according to the turning amount of the vehicle 10 and the target turning amount. Not limited to this, the second threshold value may be constant regardless of the turning amount of the vehicle 10 and the target turning amount.

  The state determination unit 52 applies the actual turning state and the target turning state to the braking force map 61 described above, and determines whether or not the actual turning state and the target turning state are different. Not necessarily. The state determination unit 52 may be configured to determine whether or not the actual turning state and the target turning state are different by calculation.

  The state determination unit 52 applies the actual turning state and the target turning state to the braking force map 61 to determine which of the right wheel braking force and the left wheel braking force is greater. It does not have to be a configuration to do. The state determination unit 52 may be configured to determine which of the braking force of the right wheel and the braking force of the left wheel is greater by calculation.

  The automatic braking device 14 corrects the drive amount of the brake device and releases the drive of the brake device only when the actual curvature radius Ra is larger than the target curvature radius Rt. Not limited to this, the automatic braking device 14 may be configured to correct the driving amount of the brake device and release the driving of the brake device even when the actual curvature radius Ra is smaller than the target curvature radius Rt. According to such a structure, the opportunity which can suppress the difference between a driver | operator's operation and the locus | trajectory of the vehicle 10 can be increased.

  Alternatively, the automatic braking device 14 may be configured to correct the drive amount of the brake device and release the drive of the brake device only when the actual curvature radius Ra is smaller than the target curvature radius Rt. Even in such a configuration, when the actual curvature radius Ra is smaller than the target curvature radius Rt, at least the difference between the driver's operation and the trajectory of the vehicle 10 can be suppressed.

  DESCRIPTION OF SYMBOLS 10 ... Vehicle, 11a ... Front right wheel, 11b ... Front left wheel, 11c ... Rear right wheel, 11d ... Rear left wheel, 12a, 12b, 12c, 12d ... Brake, 13 ... Brake actuator, 14 ... Automatic brake device, 15 ... Steering Sensors: 16 millimeter wave radar, 17 vehicle speed sensor, 18 yaw rate sensor, 21 time calculation unit, 22 collision determination unit, 23 control signal generation unit, 24 drive unit, 25 movement amount calculation unit, 26 ... Distance judgment unit 31, 71 ... Own vehicle, 31a, 71a ... Forward position, 31b, 71b ... Right turn position, 31c, 71c ... Left turn position, 32 ... Forward vehicle, 33 ... Oncoming vehicle, 41 ... First Lane ... 42 ... 2nd lane, 43 ... center line, 51 ... target calculation part, 52 ... state determination part, 61 ... braking force map, 62 ... vertical axis, 63 ... horizontal axis, 64 ... first straight line, 65 ... first 2 straight lines 66 ... third linear, 81 ... lane.

Claims (4)

A time calculation unit for calculating a predicted collision time of the vehicle against the object;
A collision determination unit that determines whether the collision prediction time is equal to or less than a predetermined time threshold;
A drive unit that drives a brake device when the collision determination unit determines that the predicted collision time is equal to or less than the time threshold;
A movement amount calculation unit for calculating a movement amount of the vehicle in the intersecting direction using acceleration in a direction intersecting the front-rear direction of the vehicle in a state where the brake device is driven;
A distance determination unit that determines whether the movement amount calculated by the movement amount calculation unit is equal to or greater than a predetermined distance threshold;
The release condition for releasing the driving of the brake device by the drive unit includes that the distance determining unit determines that the movement amount is equal to or greater than the distance threshold, and the drive is released when the release condition is satisfied. A drive release unit to
A vehicle speed acquisition unit that acquires a vehicle speed that is the speed of the vehicle;
A steering angle acquisition unit for acquiring the steering angle of the steering wheel;
A turning state acquisition unit for acquiring a turning state of the vehicle;
A target calculation unit that calculates a target turning state using the vehicle speed acquired by the vehicle speed acquisition unit and the steering angle acquired by the steering angle acquisition unit;
A state determination unit that determines whether the turning state of the vehicle acquired by the turning state acquisition unit is different from the target turning state calculated by the target calculation unit;
When the distance determining unit determines that the amount of movement is less than the distance threshold, and when the state determining unit determines that the turning state of the vehicle is different from the target turning state, the turning of the vehicle A braking force control unit that controls a braking force of the brake device so that a difference between the state and the target turning state is reduced . The state determination unit
Determining whether the difference between the turning state of the vehicle and the target turning state is equal to or greater than a predetermined threshold;
The drive release unit is
The distance determining unit determines that the amount of movement is less than the distance threshold, and the state determining unit determines that the difference between the turning state of the vehicle and the target turning state is equal to or greater than a predetermined threshold value. when an automatic braking system according to claim 1 for releasing the drive of the braking device by the driver. As the turning state of the vehicle, a radius of curvature in the traveling locus of the vehicle is used ,
The movement amount calculation unit
Calculating the direction of the acceleration the intersecting with the radius of curvature using the calculated result of the direction of acceleration the intersection of claim 1 or 2 for calculating the amount of movement in the crossing direction of the vehicle Automatic braking device. The state determination unit
From the turning state of the vehicle and the target turning state, it is further determined which of the braking force of the right wheel and the braking force of the left wheel is greater,
The braking force control unit
The braking force of the right wheel and of the braking force of the left wheel, to reduce the magnitude of the braking force which the state determiner determines that relatively large, it is determined that the state determining section is relatively small The automatic braking device according to any one of claims 1 to 3 , wherein the automatic braking device approaches a magnitude of a braking force.

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