Vehicle control device

Abstract

The invention relates to a vehicle control device. The vehicle control device applied to a vehicle includes a processor, the vehicle including parking brakes provided in association with left and right wheels, and configured to be driven to bring the wheels into a non-rotatable state. The processor is configured to acquire abnormality occurrence information on each of the left and right parking brakes. The processor is configured to output a drive command to each of the parking brakes when an abnormality condition is satisfied in which one of the parking brakes has an abnormality. A device other than the parking brake in the vehicle is controlled to suppress rotation of the wheel provided with the parking brake having the abnormality.

Description

Technical Field

[0001] The invention relates to a vehicle control device. Background Art

[0002] The vehicle disclosed in Japanese Unexamined Patent Application Publication No. 2007-076490 (JP 2007-076490 A) includes a parking brake for parking. The parking brake is provided in association with the left and right rear wheels. The parking brake is electrically driven. When the occupant operates the operating switch, driving power is supplied to the actuator. The actuator then drives the parking brake. Therefore, the rear wheels enter a non-rotatable state. Summary of the invention

[0003] Assume that the vehicle is parked on a slope using the parking brake as in JP 2007-076490 A, and the right or left parking brake fails. When one of the parking brakes fails in this way, the wheel with the normal parking brake cannot rotate, but the wheel with the failed parking brake can rotate. In this case, the vehicle rotates around the wheel braked by the normal parking brake due to its own weight.

[0004] By means of the first aspect of the present disclosure, a vehicle control device applied to a vehicle includes a processor, the vehicle includes a parking brake, the parking brake is provided in association with left and right wheels, and is configured to be driven to put the wheels into a non-rotatable state. The processor is configured to obtain abnormality occurrence information about each of the left and right parking brakes. The processor is configured to control a device other than the parking brake in the vehicle to suppress the rotation of the wheel provided with the parking brake having the abnormality when an abnormal condition that a drive command is output to each of the parking brakes and one of the parking brakes has an abnormality is satisfied.

[0005] In the vehicle control device according to the first aspect of the present disclosure, the wheel provided with the parking brake may be a rear wheel. The vehicle may include a steering device configured to change the steering angle of the left and right front wheels. The processor may be configured to perform control to increase the steering angle of the left and right front wheels to an abnormal side compared to the steering angle when the occurrence of the abnormality in the parking brake is detected. The abnormal side may be the side of the left and right parking brakes where the parking brake has the abnormality.

[0006] In the vehicle control device according to the first aspect of the present disclosure, the vehicle may include a wheel speed sensor provided in association with the left and right rear wheels. The processor may be configured to, when a rotation condition is satisfied that an absolute value of one of the wheel speeds detected by the left and right wheel speed sensors is equal to or greater than a first prescribed value and an absolute value of the other of the wheel speeds is less than a second prescribed value and the abnormal condition is satisfied, perform the control of increasing the steering angle of the left and right front wheels to the abnormal side compared to the steering angle when the occurrence of the abnormality in the parking brake is detected.

[0007] In the vehicle control device according to the first aspect of the present disclosure, the first prescribed value and the second prescribed value may be the same value.

[0008] In a vehicle control device according to the first aspect of the present disclosure, the processor can be configured to set a larger change in the steering angle of the left and right front wheels as the difference between the absolute value of one of the wheel speeds detected by the left and right wheel speed sensors and the absolute value of the other of the wheel speeds increases.

[0009] With the above configuration, when the right or left parking brake has an abnormality, the rotation of the vehicle can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, wherein like reference numerals represent like elements, and wherein:

[0011] Figure 1 is a schematic configuration diagram of a vehicle;

[0012] Figure 2 is an illustration of the steering angle;

[0013] Figure 3 is a flowchart showing the processing procedure of the addressing process;

[0014] Figure 4 is a schematic diagram showing a vehicle located on an uphill road;

[0015] Figure 5 is a schematic diagram showing a rotating vehicle; and

[0016] Figure 6 is a schematic diagram showing the rotating front wheels. DETAILED DESCRIPTION

[0017] A vehicle control device according to an embodiment will be described below with reference to the accompanying drawings.

[0018] The overall structure of the vehicle

[0019] like Figure 1 As shown, the vehicle 100 includes a driving source 90 for the vehicle 100. An example of the driving source 90 for the vehicle 100 is an internal combustion engine. Another example of the driving source 90 for the vehicle 100 is an electric generator. The driving force output by the driving source 90 for the vehicle 100 is transmitted to the rear wheels 82 as driving wheels.

[0020] The vehicle 100 includes four service brakes 92. The service brakes 92 are provided in association with the four left and right front wheels and the rear wheels. The service brakes 92 are hydraulic brakes. That is, the service brakes 92 brake each wheel by operating based on hydraulic pressure. Examples of the service brakes 92 include disc brakes.

[0021] The vehicle 100 includes two parking brakes 95. The parking brakes 95 are provided in association with the left and right rear wheels 82. The parking brakes 95 are electrically driven. Each parking brake 95 includes a brake shoe and an actuator 96. The brake shoe is positioned inside a brake drum that rotates with the rear wheels 82. The actuator 96 includes a motor and a reduction gear mechanism. The actuator 96 pushes the brake shoe against the brake drum or moves the brake shoe away from the brake drum in response to the drive of the motor. When the brake shoe is pushed against the brake drum, the rear wheel 82 cannot rotate. In this state, the parking brake 95 is turned on. When the brake shoe moves away from the brake drum, the rear wheel 82 can rotate. In this state, the parking brake 95 is disconnected.

[0022] The vehicle 100 includes a steering system 10. The steering system 10 includes a steering wheel 11, an input shaft 12, an output shaft 13, a steering operating shaft 14, an adjustment device 15, a steering operating device 16, and a conversion mechanism 17. The steering wheel 11 rotates together with the input shaft 12. The input shaft 12 is connected to the output shaft 13 via the adjustment device 15. The output shaft 13 is connected to the steering operating shaft 14 via the conversion mechanism 17. The conversion mechanism 17 converts the rotational motion of the output shaft 13 into the linear motion of the steering operating shaft 14. Both ends of the steering operating shaft 14 are connected to the left and right front wheels 81 via tie rods. When the steering operating shaft 14 is operated in response to the operation of the steering wheel 11, the steering angle F of the left and right front wheels 81 changes.

[0023] The angular position of the front wheel 81 when the vehicle 100 is traveling straight is referred to as the "neutral position L". The portion of the front wheel 81 positioned on the front side of the center axis 81V of the front wheel 81 in the top view of the vehicle 100 will be referred to as the "front portion 81A". Figure 1 and Figure 2 In FIG. 8 , the front portion 81A is hatched. Figure 2As shown, the steering angle F of the front wheel 81 is the inclination angle of the angular position M of the front part 81A relative to the neutral position L.

[0024] like Figure 1 As shown, the adjustment device 15 is positioned between the input shaft 12 and the output shaft 13. The adjustment device 15 includes a motor. When the motor is driven, the output shaft 13 rotates relative to the input shaft 12. Through the relative rotation, the ratio of the steering angle F of the front wheels 81 and the rotation angle H of the steering wheel 11 can be adjusted.

[0025] The steering operating device 16 includes a motor 16A and a transmission mechanism 16B. The motor 16A is connected to the steering operating shaft 14 via the transmission mechanism 16B. The transmission mechanism 16B converts the rotational motion of the motor 16A into the linear motion of the steering operating shaft 14. Therefore, when the steering operating shaft 14 is linearly operated in response to the drive of the motor 16A, the steering angle F of the left and right front wheels 81 changes. The steering operating device 16 constitutes a steering device. As can be seen from the configuration of the above-mentioned steering system 10, in this embodiment, the front wheels 81 can rotate, but the rear wheels 82 cannot rotate.

[0026] The vehicle 100 includes a control device 50. The control device 50 is a computer including a processing circuit (processor). The processing circuit includes a central processing unit (CPU) and a memory. The memory pre-stores various programs describing the processing to be performed by the CPU and various types of data required for the CPU to execute the programs. By executing the programs stored in the memory, the CPU functions as a drive system control unit 51, a brake control unit 52, a steering control unit 53, and an application execution unit 54. That is, the control device 50 includes a drive system control unit 51, a brake control unit 52, a steering control unit 53, and an application execution unit 54 as functional units. These functional units perform dedicated processing and exchange information with each other. The processing to be performed by these functional units can be implemented by a separate control device.

[0027] The drive system control unit 51 controls a drive source 90 for the vehicle 100. The brake control unit 52 controls a parking brake 95 and a service brake 92. The steering control unit 53 controls the adjustment device 15 and the steering operation device 16. The application execution unit 54 outputs a motion request related to the vehicle 100 to the drive system control unit 51, the brake control unit 52, and the steering control unit 53 by executing an application stored in a memory. An application is a type of program. An example of an application is an autonomous driving (AD) application. The AD application implements an autonomous driving function that causes the vehicle 100 to travel automatically.

[0028] The vehicle 100 includes two current sensors 72, four wheel speed sensors 73, a yaw rate sensor 74, a steering wheel angle sensor 75, a position acquisition device 76, and a camera 77 as information detection devices. The current sensor 72 is provided in association with the two parking brakes 95. Figure 1 In FIG. 1 , one of the two current sensors 72 is shown as a representative. The current sensor 72 detects the current value (hereinafter referred to as "motor current value A") flowing through the motor of the actuator 96 in the parking brake 95. The wheel speed sensor 73 is provided in association with the left and right front wheels and the rear wheels. Figure 1 , one of the four wheel speed sensors 73 is shown as a representative. The wheel speed sensor 73 detects a wheel speed S which is a rotation speed of a wheel. The wheel speed sensor 73 detects a positive value when the vehicle 100 moves forward, and detects a negative value when the vehicle 100 moves backward. The wheel speed sensor 73 can continuously detect a positive value regardless of the traveling direction of the vehicle 100. The yaw rate sensor 74 detects the yaw rate Y of the vehicle 100. The steering wheel angle sensor 75 detects the rotation angle H of the steering wheel 11. The position acquisition device 76 acquires information about the current position coordinates G of the vehicle 100 from the global positioning satellite. The camera 77 acquires imaging information J about the surroundings of the vehicle 100. Each information detection device repeatedly outputs information detected or acquired by itself to the control device 50. The control device 50 repeatedly acquires information from each information detection device.

[0029] The vehicle 100 includes a start switch 78 and a parking switch 79. The start switch 78 is also called an "ignition switch" or a "system start switch". The start switch 78 is a switch for starting the main system of the control device 50. The start switch 78 is turned on or off in response to the operation of the occupant. When the start switch 78 is turned on, the control device 50 is in an activated state. When the start switch 78 is turned off, the control device 50 is basically in a stopped state. Even when the start switch 78 is turned off, some functional units of the control device 50 can continue to process as needed. The parking switch 79 is a switch for switching the operating state of the parking brake 95. The parking switch 79 is turned on or off in response to the operation of the occupant.

[0030] Function of the brake control unit

[0031] The brake control unit 52 switches the operating state of the parking brake 95 based on the operating state of the parking switch 79. When the parking switch 79 is turned on, the brake control unit 52 outputs a drive command to the actuator 96 of each parking brake 95. The drive command is a command to switch the parking brake 95 from disconnection to connection. When the brake control unit 52 outputs the drive command, the parking brake 95 is driven. That is, in the parking brake 95, current flows through the motor of the actuator 96. At the same time, the actuator 96 operates to push the brake shoe against the brake drum. Therefore, the parking brake 95 puts the rear wheel 82 into a non-rotatable state. That is, the parking brake 95 is turned on. The brake control unit 52 can grasp the switching state of the parking brake 95, for example, based on the motor current value A.

[0032] When the parking switch 79 is turned off, the brake control unit 52 outputs a release command to the actuator 96 of each parking brake 95. The release command is a command to switch the parking brake 95 from on to off. When the brake control unit 52 outputs the release command, the parking brake 95 is released. That is, in the parking brake 95, current flows through the motor of the actuator 96. At the same time, the actuator 96 operates to move the brake shoe away from the brake drum. Therefore, the parking brake 95 puts the rear wheel 82 into a rotatable state. That is, the parking brake 95 is disconnected.

[0033] The brake control unit 52 may output a drive command or a release command based on a motion request from the application execution unit 54. When the parking brake 95 is switched from off to on, the brake control unit 52 monitors an abnormality of the parking brake 95. Specifically, when the brake control unit 52 outputs a drive command, the brake control unit 52 monitors the motor current value A. When the motor current value A continues to be equal to or less than the threshold value for a predetermined period of time, the brake control unit 52 detects the occurrence of an abnormality in the parking brake 95. The threshold value is determined in advance by experiments, etc. as a value that can be used to grasp that the motor of the actuator 96 cannot output normal torque. The predetermined time period is determined in advance by experiments, etc. as a value that can be used to determine that the abnormal state of the current value is not a temporary state caused by noise, etc. but a value that is obviously continuous. The brake control unit 52 of the present embodiment basically detects a situation in which the parking brake 95 is not switched on even if a drive command is output as an abnormality. The brake control unit 52 monitors the abnormality of each of the left and right parking brakes 95 individually. When the occurrence of an abnormality in the parking brake 95 is detected, the brake control unit 52 switches the abnormality flag from off to on. An abnormality flag is prepared for each parking brake 95. When the occurrence of an abnormality in the parking brake 95 is detected, the brake control unit 52 turns on a notification lamp provided in the vehicle compartment.

[0034] Coping

[0035] When the brake control unit 52 outputs a drive command to each parking brake 95, the steering control unit 53 repeatedly determines whether an abnormal condition is satisfied until each parking brake 95 is switched to on. The abnormal condition is that the brake control unit 52 outputs a drive command to each parking brake 95 and the right or left parking brake 95 has an abnormality. The state of outputting a drive command means the state of outputting a drive command from the brake control unit 52. Once the brake control unit 52 outputs a drive command, even if the output of the drive command is interrupted later, the steering control unit 53 processes the current state as the state of outputting a drive command until the brake control unit 52 subsequently outputs a release command. That is, in an abnormal condition, the requirement to output a drive command to each parking brake 95 corresponds to the requirement for the time period from the brake control unit 52 outputting a drive command to each parking brake 95 (from the start of the output) to the output of the release command. The steering control unit 53 can grasp the occurrence of an abnormality in the parking brake 95 by referring to the abnormality flag set by the brake control unit 52. When the abnormal condition is met, the steering control unit 53 identifies the "right" or "left" parking brake 95 with the abnormality as the abnormal side. The steering control unit 53 identifies the side opposite to the abnormal side as the normal side. Then, the steering control unit 53 starts the response process. The response process is a process for responding to the abnormality when an abnormality occurs in the right or left parking brake 95.

[0036] like Figure 3 As shown, when the handling process starts, the steering control unit 53 first performs the process of step S10. In step S10, the steering control unit 53 determines whether the rotation condition is satisfied. The rotation condition is that the absolute value of the wheel speed S detected by the first wheel speed sensor is equal to or greater than the prescribed value SK and the absolute value of the wheel speed S detected by the second wheel speed sensor is less than the prescribed value SK. The prescribed value SK may be a first prescribed value and a second prescribed value less than the first prescribed value. In this case, the rotation condition is that the absolute value of the wheel speed S detected by the first wheel speed sensor may be equal to or greater than the first prescribed value SK, and the absolute value of the wheel speed S detected by the second wheel speed sensor is less than the second prescribed value SK. The first wheel speed sensor is a wheel speed sensor 73 that detects the wheel speed S of the rear wheel 82 on the abnormal side. The second wheel speed sensor is a wheel speed sensor 73 that detects the wheel speed S of the rear wheel 82 on the normal side. The prescribed value SK is determined in advance by experiments or the like as a value that can be used to grasp the rotation of the vehicle 100. The rotation of the vehicle 100 will be described later in the "Operation of the Embodiment" section. The steering control unit 53 determines whether the turning condition is satisfied based on the latest detection information from the first wheel speed sensor and the second wheel speed sensor. When the steering control unit 53 determines that the turning condition is not satisfied, the process proceeds to step S100.

[0037] In step S100, the steering control unit 53 determines whether the time period that has passed since the start of the response process has reached the set time period. The set time period is determined in advance through experiments or the like as a length of time that can be used to clearly determine that the vehicle 100 has not turned. When the set time period has not passed since the start of the response process (step S100: No), the steering control unit 53 returns to the process of step S10. Then, the steering control unit 53 performs the process of step S10 again. With respect to steps S10 and S100, when the set time period has passed without satisfying the turning condition (step S10: No, step S100: Yes), the steering control unit 53 terminates the response process. When the turning condition is satisfied before the set time period has passed (step S100: Yes), the steering control unit 53 advances the process to step S20.

[0038] In step S20, the steering control unit 53 calculates control information for performing the rotation suppression control. The rotation suppression control is a control for suppressing the rotation of the rear wheel 82 on the abnormal side. The rotation suppression control of the present embodiment is performed on the steering operation device 16 as the control target. During the handling process, the steering control unit 53 processes the sign of the steering angle F according to the following rule. That is, the steering control unit 53 processes the neutral position L as zero degrees, the abnormal side relative to the neutral position L as a positive value, and the normal side relative to the neutral position L as a negative value. In the rotation suppression control by such processing, the steering control unit 53 increases the steering angle F of the left and right front wheels 81 to the abnormal side compared to when the occurrence of the abnormality in the parking brake 95 is detected. The steering angle F of the front wheel 81 when the occurrence of the abnormality in the parking brake 95 is detected is substantially the same as the steering angle F of the front wheel 81 at the time of step S20. The angular position of each front wheel 81 when the occurrence of the abnormality in the parking brake 95 is detected will be referred to as a "reference position". In the turning suppression control, the steering control unit 53 turns the front portion 81A of each front wheel 81 to the abnormal side with respect to the reference position.

[0039] The control information for executing the rotation suppression control is specifically the target rotation amount and target rotation direction of the motor 16A in the steering operation device 16. In calculating the control information, the steering control unit 53 first calculates the speed difference ΔS. The speed difference ΔS is the absolute value of the difference between the absolute value of the wheel speed S detected by the first wheel speed sensor and the absolute value of the wheel speed S detected by the second wheel speed sensor. The steering control unit 53 calculates the speed difference ΔS based on the latest detection information from the first wheel speed sensor and the second wheel speed sensor. After calculating the speed difference ΔS, the steering control unit 53 calculates the target rotation amount. As a prerequisite for the steering control unit 53 to calculate the target rotation amount, the memory of the control device 50 stores a steering operation map in advance. The steering operation map represents the corresponding relationship between the following two variables. One variable is the difference between the absolute values ​​of the rotation speeds of the left and right rear wheels 82, that is, the speed difference ΔS. The other variable is the necessary steering operation amount ΔF. The necessary steering operation amount ΔF is the change amount of the steering angle F of each front wheel 81 required to stop the rotation of the rear wheel 82 on the abnormal side and thus stop the rotation of the vehicle 100. The necessary steering operation amount ΔF is based on the premise that each front wheel 81 rotates from the reference position to the abnormal side. The speed difference ΔS and the necessary steering operation amount ΔF both take positive values. In the steering operation map, the necessary steering operation amount ΔF increases as the speed difference ΔS increases. The steering control unit 53 calculates control information by using the steering operation map. Specifically, the steering control unit 53 applies the latest speed difference ΔS calculated above to the steering operation map. The steering control unit 53 calculates the necessary steering operation amount ΔF associated with the latest speed difference ΔS based on the steering operation map. The steering control unit 53 converts the calculated necessary steering operation amount ΔF into the rotation amount of the motor 16A based on a predetermined relationship expression. The steering control unit 53 calculates the converted rotation amount of the motor 16A as the target rotation amount. After calculating the target rotation amount, the steering control unit 53 determines the target rotation direction of the motor 16A. In the present embodiment, the rotation direction of the motor 16A and the rotation of each front wheel 81 have the following corresponding relationship. Assume that the front wheel 81 is in the neutral position L. When the motor 16A rotates in a first direction, the front portion 81A of the front wheel 81 rotates to the left relative to the neutral position L. When the motor 16A rotates in a second direction opposite to the first direction, the front portion 81A of the front wheel 81 rotates to the right relative to the neutral position L. The memory of the control device 50 pre-stores the correspondence between the rotation direction of the motor 16A and the rotation of the front wheel 81. Based on the correspondence, the steering control unit 53 determines the target rotation direction of the motor 16A to rotate the front wheel 81 to the abnormal side. That is, when the abnormal side is "left", the steering control unit 53 sets the target rotation direction to the first direction. When the abnormal side is "right", the steering control unit 53 sets the target rotation direction to the second direction.After determining the target rotation amount and target rotation direction of the motor 16A, the steering control unit 53 advances the process to step S30.

[0040] In step S30, the steering control unit 53 performs rotation suppression control based on the control information calculated in step S20. That is, the steering control unit 53 controls the motor 16A to rotate by the target rotation amount in the target rotation direction determined in step S20. Then, the steering control unit 53 advances the process to step S40.

[0041] In step S40, the steering control unit 53 determines whether the stop condition is satisfied. The stop condition is that the absolute value of the wheel speed S detected by the first wheel speed sensor is less than the prescribed value SK and the absolute value of the wheel speed S detected by the second wheel speed sensor is less than the prescribed value SK. The steering control unit 53 determines whether the stop condition is satisfied based on the latest detection information from the first wheel speed sensor and the second wheel speed sensor. When the stop condition is not satisfied (step S40: No), the steering control unit 53 returns to the process of step S20. In this case, the steering control unit 53 performs the processes of steps S20, S30 and S40 again. The steering control unit 53 repeats the processes of steps S20, S30 and S40 until the stop condition is satisfied. When the stop condition is satisfied (step S40: Yes), the steering control unit 53 terminates the response process. When the process proceeds to step S40 for the first time after the response process starts, the stop condition may be satisfied. In this case, the steering control unit 53 terminates the response process at this point.

[0042] The parking switch 79 is usually turned on immediately before the occupant finishes using the vehicle 100, and the start switch 78 is turned off. In this regard, the start switch 78 may be turned off during the coping process. In this case, the steering control unit 53 is set to function as follows. That is, the steering control unit 53 continues to be activated and performs a series of processes for the coping process until the coping process is completed. After the coping process is completed, the steering control unit 53 enters a stop state in which no process is performed. Similar to the steering control unit 53, the braking control unit 52 continues its processing until the steering control unit 53 completes the coping process.

[0043] In the following case, the steering control unit 53 terminates the coping process during the coping process. That is, when the brake control unit 52 outputs a release command during the coping process, the steering control unit 53 terminates the coping process. In this case, the steering control unit 53 shifts to another process requested by the occupant or the application.

[0044] Operation of the Embodiment

[0045] like Figure 4As shown in FIG. 1 , it is assumed that the vehicle 100 is located on an uphill road with a relatively large slope. It is assumed that the occupant turns on the parking switch 79 to park the vehicle 100 on the uphill road. Then, the brake control unit 52 outputs a drive command to the parking brake 95. Figure 5 As shown, it is assumed that, of the left and right parking brakes 95, the left parking brake 95 operates normally, but the right parking brake 95 has an abnormality and does not operate normally. In this case, Figure 5 The right rear wheel 82 shown by the dotted line in FIG. 8 is not braked by the parking brake 95. If no action is taken at this time, the vehicle 100 rotates to the right around the left rear wheel 82 on the normal side, as shown in FIG. Figure 5 As shown by the double-dotted line in .

[0046] In order to prevent such rotation, the steering control unit 53 of the present embodiment performs rotation suppression control by means of a corresponding process. Figure 6 As shown, the steering control unit 53 controls the steering operation device 16 to turn the front part 81A of the left and right front wheels 81 to the right relative to the reference position. Then, the steering control unit 53 increases the steering angle F of the left and right front wheels 81 to the right. When the left and right front wheels 81 turn to the right, a force is applied to the vehicle 100 in a direction opposite to the abnormal turning direction. The abnormal turning direction is the direction in which the vehicle 100 will turn around the rear wheel 82 on the normal side. The turning of the vehicle 100 can be prevented by applying a force to the vehicle 100 in a direction opposite to the abnormal turning direction. Regarding the coping process, the steering control unit 53 finely adjusts the steering angle F of the front wheels 81 by repeating the processes of steps S20, S30, and S40 until the turning of the vehicle 100 stops. Therefore, the steering angle F of the front wheels 81 is optimized to prevent the turning of the vehicle 100.

[0047] Effects of the Embodiments

[0048] (1) As described in “Operation of Embodiment”, in the present embodiment, when the right or left parking brake 95 has an abnormality, the rotation of the vehicle 100 can be prevented by rotating the front wheels 81 .

[0049] (2) Even if the right or left parking brake 95 has an abnormality, the vehicle 100 may not turn, for example, when the road slope is gentle. When the vehicle 100 does not turn, there is no need to perform the turn suppression control. In the present embodiment, after grasping that the vehicle 100 has actually started to turn through the processing of step S10, the turn suppression control is performed. In this way, unnecessary turn suppression control can be prevented. Therefore, the processing load of the control device 50 related to the turn suppression control and the power consumption of the steering operation device 16 related to the turn suppression control can be eliminated.

[0050] (3) When the rotation suppression control is performed, if the amount of change in the steering angle F of the front wheels 81 is too small, the rotation of the vehicle 100 cannot be stopped. If the amount of change in the steering angle F of the front wheels 81 is too large, the vehicle 100 may turn in the direction opposite to the abnormal rotation direction. In the present embodiment, the steering angle F of the front wheels 81 is changed by an amount corresponding to the amount of rotation of the vehicle 100 in the abnormal rotation direction. Therefore, the rotation of the vehicle 100 can be stopped appropriately.

[0051] Variations

[0052] The above embodiment can be modified as follows. The above embodiment and the following modifications can be combined with each other as long as no technical contradiction occurs.

[0053] -The method for detecting an abnormality in the parking brake 95 is not limited to the example of the above-mentioned embodiment. For example, when the motor current value A is greater than a predetermined upper limit value, a determination can be made that the parking brake 95 has an abnormality. For example, an abnormality in the parking brake 95 can be detected by using a variable that reflects the transition of the motor current value A (such as a differential value of the motor current value A). An abnormality in the parking brake 95 can be detected by using a variable other than the motor current value A. For example, the temperature of the motor of the actuator 96 can be used as a variable other than the motor current value A to detect an abnormality in the parking brake 95. When the temperature of the motor is outside the allowable range, a determination can be made that the parking brake 95 has an abnormality. In this case, it is appropriate for the vehicle 100 to include a temperature sensor that detects the temperature of the motor. The method for detecting an abnormality in the parking brake 95 is not limited to a method capable of detecting a situation where the parking brake 95 is not switched to on, but can be any method capable of making a determination that the parking brake 95 is abnormal.

[0054] The timing of monitoring the abnormality of the parking brake 95 is not limited to the timing of switching the parking brake 95 from off to on. For example, when the start switch 78 is on, the abnormality of the parking brake 95 may be continuously monitored.

[0055] - When the front wheel 81 is turned by the turn suppression control, it is not necessary to increase the amount of change of the steering angle F of the front wheel 81 as the speed difference ΔS increases. For example, the front wheel 81 can be turned to the maximum angular position allowed by the front wheel 81 regardless of the size of the speed difference ΔS. For example, in the case where the road slope is small to a certain extent, the turning of the vehicle 100 can be prevented by taking such an action.

[0056] - When the front wheels 81 are turned by the turning suppression control, it is not necessary to determine the amount of change in the steering angle F of the front wheels 81 by using the detection information from the wheel speed sensor 73. For example, the amount of change in the steering angle F of the front wheels 81 may be determined based on the detection information from the yaw rate sensor 74. In this case, it is conceivable to determine the amount of change in the steering angle F of the front wheels 81 so that the yaw rate Y of the vehicle 100 reaches zero.

[0057] - The processing of step S10 may be omitted. That is, when the abnormal condition is satisfied, the rotation suppression control may be performed regardless of whether the rotation condition is satisfied. For example, when the abnormal condition is satisfied, the front wheel 81 may be rotated to the maximum angular position allowed by the front wheel 81, as in the above-mentioned modification example.

[0058] - The adjustment device 15 may be used as the steering device to be controlled in the steering suppression control in step S30 instead of the steering operating device 16. By controlling the adjustment device 15, the steering angle F of the front wheels 81 can be increased to the abnormal side.

[0059] - As in the above-described modification, when the device to be controlled in the rotation suppression control (hereinafter referred to as "target device") is changed from that in the above-described embodiment, it is appropriate to change the control information calculated in step S20 accordingly.

[0060] -The target device of the rotation suppression control is not limited to the steering device that can change the steering angle F of the left and right front wheels 81. The target device may be any device other than the parking brake 95 as long as the device can suppress the rotation of the rear wheel 82 on the abnormal side. The control performed in the rotation suppression control is not limited to the control of rotating the front wheel 81. It is only necessary to suppress the rotation of the rear wheel 82 by the rotation suppression control. For example, the vehicle 100 may include a steering wheel locking device. The steering wheel locking device may be used as the target device. The steering wheel locking device fixes the left and right front wheels 81 at the neutral position L. In the rotation suppression control, the front wheel 81 can be fixed at zero degrees by operating the device. As long as the front wheel 81 does not rotate, the vehicle 100 will not rotate even if the right or left parking brake 95 has an abnormality. For example, the drive source 90 for the vehicle 100 may be used as the target device. In the rotation suppression control, the rotation of the rear wheel 82 on the abnormal side can be suppressed by applying the driving force of the drive source 90 for the vehicle 100 to the rear wheel 82. At the same time when the start switch 78 of the vehicle 100 is turned on, the driving source 90 for the vehicle 100 is driven. Therefore, the driving source 90 for the vehicle 100 can be used as a target device. For example, the service brake 92 can be used as a target device. In the rotation suppression control, the braking force can be applied to the rear wheel 82 to be braked by the parking brake 95 having an abnormality. The service brake 92 can apply the braking force to all the left and right front wheels and rear wheels.

[0061] - Depending on the target device, the processing of step S40 in the countermeasure process may not be necessary, such as when a steering wheel lock device is used as the target device. In this case, the processing of step S40 may be omitted, and the countermeasure process may be terminated with the completion of the rotation suppression control.

[0062] - The configuration of the parking brake 95 is not limited to the example of the above-described embodiment. It is only necessary to electrically drive the parking brake 95, and the wheels can be brought into a non-rotatable state by driving the parking brake 95.

[0063] -The parking brake 95 may be provided in association with the left and right front wheels 81, and the left and right rear wheels 82 may be rotatable. In this case, when the right or left parking brake 95 has an abnormality while the vehicle 100 is on a downhill road, the vehicle 100 may rotate around the front wheel 81 on the normal side. In order to prevent such rotation of the vehicle 100, rotation suppression control may be performed when an abnormal condition is satisfied. The rotation suppression control in this case may be any control capable of suppressing the rotation of the front wheel 81 on the abnormal side.

[0064] -AD application may be an application that implements the following. Various processes actually performed by the control device 50 will be described below as being performed by the AD application. It is assumed that the parking brake 95 is provided in association with the rear wheels 82, and the front wheels 81 are rotatable as in the above-described embodiment.

[0065] While the vehicle 100 is traveling, the AD application continuously monitors the abnormality of the parking brake 95. When each parking brake 95 has no abnormality, the AD application allows parking on a slope. When the right or left parking brake 95 has an abnormality, the AD application prohibits parking on a slope. That is, when the right or left parking brake 95 has an abnormality, the AD application always parks the vehicle on a flat road. When the vehicle is parked on a flat road in response to an abnormality in the parking brake 95, the AD application uses information from the camera 77 to stop the vehicle 100 at a position adjacent to the curb on the road. At this time, the AD application positions the curb on the abnormal side of the vehicle 100. Then, the AD application outputs a drive command to each parking brake 95, and turns the left and right front wheels 81 to the abnormal side so that the front wheels 81 on the abnormal side are in contact with the curb. Therefore, the front wheels 81 on the abnormal side are supported by the curb.

Claims

1. A vehicle control device applied to a vehicle, the vehicle comprising a parking brake, the parking brake being provided in association with left and right wheels and configured to be driven to put the wheels into a non-rotatable state, the vehicle control device being characterized by comprising a processor, the processor being configured to: acquiring abnormality occurrence information about each of the left and right parking brakes; and When an abnormal condition is satisfied in which a drive command is output to each of the parking brakes and one of the parking brakes has an abnormality, devices other than the parking brakes in the vehicle are controlled to suppress rotation of the wheel provided with the parking brake having the abnormality.

2. The vehicle control device according to claim 1, characterized in that: The wheel provided with the parking brake is a rear wheel; The vehicle includes a steering device configured to change a steering angle of left and right front wheels; and The processor is configured to perform control of increasing the steering angle of the left and right front wheels toward an abnormal side, compared to the steering angle when the occurrence of the abnormality in the parking brake is detected, the abnormal side being a side of the left and right parking brakes where the parking brake has the abnormality.

3. The vehicle control device according to claim 2, characterized in that: The vehicle includes wheel speed sensors provided in association with the left and right rear wheels; and The processor is configured to, when a rotation condition is satisfied that the absolute value of one of the wheel speeds detected by the left and right wheel speed sensors is equal to or greater than a first prescribed value and the absolute value of the other of the wheel speeds is less than a second prescribed value and the abnormal condition is satisfied, perform the control of increasing the steering angle of the left and right front wheels to the abnormal side compared to the steering angle when the occurrence of the abnormality in the parking brake is detected.

4. The vehicle control device according to claim 3, characterized in that: The first prescribed value and the second prescribed value are the same value.

5. The vehicle control device according to claim 3, characterized in that: The processor is configured to set a larger amount of change in the steering angle of the left and right front wheels as a difference between the absolute value of one of the wheel speeds detected by the left and right wheel speed sensors and the absolute value of the other of the wheel speeds increases.

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