Control device for vehicle

Abstract

To prevent a vehicle from turning when an abnormality occurs in either of left and right parking brakes.SOLUTION: A control device 50 detects an abnormality in each of left and right parking brakes 95, and controls a vehicle 100 so as to suppress the rotation of the wheel on the side where the abnormality has occurred in the parking brake 95 when a drive command is output to the respective parking brakes 95 and an abnormal condition such that an abnormality has occurred in one of the parking brakes 95 is satisfied.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] The vehicle disclosed in Patent Document 1 is equipped with a parking brake for parking. A parking brake is provided for each of the left and right rear wheels. The parking brake is electrically operated. When an occupant operates an operation switch, driving power is supplied to an actuator. Then, the actuator activates the parking brake. This makes it impossible for the rear wheels to rotate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-076490 A Summary of the Invention [Problem to be solved by the invention]

[0004] Assume that a vehicle such as that described in Patent Document 1 is parked on a slope using the parking brake, and one of the left and right parking brakes is malfunctioning. When one of the parking brakes malfunctions, the wheels on the side with the normal parking brake cannot rotate, while the wheels on the side with the malfunctioning parking brake can rotate. In this case, the vehicle will turn under its own weight around the wheel braked by the normal parking brake. [Means for solving the problem]

[0005] A vehicle control device for solving the above problems is applied to a vehicle having parking brakes that are provided corresponding to each of the left and right wheels and that disable the wheels from rotating when activated, and detects the occurrence of an abnormality in each of the left and right parking brakes, and when an abnormality condition is satisfied that a drive command has been output to each of the parking brakes and an abnormality condition has occurred in one of the parking brakes, controls equipment in the vehicle other than the parking brakes so as to suppress rotation of the wheel on the side of the parking brake where the abnormality has occurred. Effect of the Invention

[0006] With the above configuration, if an abnormality occurs in either the left or right parking brake, the vehicle can be prevented from turning. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of a vehicle. [Diagram 2] FIG. 2 is an explanatory diagram of the steering angle. [Diagram 3] FIG. 3 is a flowchart showing the procedure of the handling process. [Figure 4] FIG. 4 is a schematic diagram showing a state in which a vehicle is positioned on an uphill road. [Diagram 5] FIG. 5 is a schematic diagram showing a state in which a vehicle turns. [Figure 6] FIG. 6 is a schematic diagram showing a state in which the front wheels are steered. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of a vehicle control device will be described with reference to the drawings. <Overall vehicle configuration> As shown in Fig. 1, the vehicle 100 is equipped with a drive source 90 for the vehicle 100. One example of the drive source 90 for the vehicle 100 is an internal combustion engine. Another example of the drive source 90 for the vehicle 100 is a motor generator. The drive force output by the drive source 90 for the vehicle 100 is transmitted to rear wheels 82, which are drive wheels.

[0009] The vehicle 100 is equipped with four service brakes 92. The service brakes 92 are provided corresponding to each of the four wheels on the front, rear, left and right sides. The service brakes 92 are hydraulic. That is, the service brakes 92 operate according to hydraulic pressure to brake each wheel. The service brakes 92 are, for example, disc brakes.

[0010] The vehicle 100 is provided with two parking brakes 95. The parking brakes 95 are provided corresponding to the left and right rear wheels 82, respectively. The parking brakes 95 are electrically operated. The parking brakes 95 are provided with brake shoes and an actuator 96. The brake shoes are located inside a brake drum that rotates integrally with the rear wheels 82. The actuator 96 is provided with a motor and a reduction gear mechanism. The actuator 96 presses the brake shoes against the brake drum or moves the brake shoes away from the brake drum in response to the driving of the motor. When the brake shoes are pressed against the brake drum, the rear wheels 82 cannot rotate. This state is the ON state of the parking brake 95. On the other hand, when the brake shoes are separated from the brake drum, the rear wheels 82 can rotate. This state is the OFF state of the parking brake 95.

[0011] Vehicle 100 is equipped with steering system 10. Steering system 10 is equipped with steering wheel 11, input shaft 12, output shaft 13, steered shaft 14, adjustment device 15, steering device 16, and conversion mechanism 17. Steering wheel 11 rotates integrally with input shaft 12. Input shaft 12 is connected to output shaft 13 via adjustment device 15. Output shaft 13 is connected to steered shaft 14 via conversion mechanism 17. Conversion mechanism 17 converts the rotational movement of output shaft 13 into linear movement of steered shaft 14. Both ends of steered shaft 14 are connected to left and right front wheels 81 via tie rods. When steered shaft 14 moves in response to the movement of steering wheel 11, the steering angle F of left and right front wheels 81 changes.

[0012] The angular position of the front wheel 81 when the vehicle 100 travels straight is referred to as the neutral position L. Also, a portion of the front wheel 81 that is located forward of a central axis 81V of the front wheel 81 in a top view of the vehicle 100 is referred to as the forward portion 81A. In Figures 1 and 2, the forward portion 81A is indicated by diagonal lines. As shown in Figure 2, the steering angle F of the front wheel 81 is the inclination angle of the angular position M of the forward portion 81A with respect to the neutral position L.

[0013] As shown in Fig. 1, the adjustment device 15 is located between the input shaft 12 and the output shaft 13. The adjustment device 15 is equipped with a motor. When the motor is driven, the output shaft 13 rotates relative to the input shaft 12. This relative rotation makes it possible to adjust the ratio of the steering angle F of the front wheels 81 to the rotation angle H of the handlebars 11.

[0014] The turning device 16 includes a motor 16A and a transmission mechanism 16B. The motor 16A is connected to the turning shaft 14 via the transmission mechanism 16B. The transmission mechanism 16B converts the rotational motion of the motor 16A into linear motion of the turning shaft 14. Therefore, when the turning shaft 14 moves linearly in response to the drive of the motor 16A, the rudder angle F of the left and right front wheels 81 changes. The turning device 16 constitutes a steering device. As can be seen from the configuration of the steering system 10 described above, in this embodiment, the front wheels 81 can be steered but the rear wheels 82 cannot be steered.

[0015] The vehicle 100 includes a control device 50. The control device 50 is a computer equipped with a processing circuit. The processing circuit includes a CPU and a memory. The memory stores in advance various programs in which processes to be executed by the CPU are described, and various data necessary for the CPU to execute the programs. The CPU executes the programs stored in the memory to function 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, as functional units, a drive system control unit 51, a brake control unit 52, a steering control unit 53, and an application execution unit 54. Each of these functional units performs its own dedicated process and exchanges information with each other. The processes performed by each of these functional units may be realized by separate control devices.

[0016] The drive system control unit 51 controls the drive source 90 of the vehicle 100. The brake control unit 52 controls each parking brake 95 and each service brake 92. The steering control unit 53 controls the adjustment device 15 and the steering device 16. The application execution unit 54 executes an application stored in the memory, thereby outputting motion requests regarding the vehicle 100 to the drive system control unit 51, the brake control unit 52, and the steering control unit 53. An application is a type of program. An example of an application is an AD application. The AD application realizes an automatic driving function that causes the vehicle 100 to drive autonomously.

[0017] The vehicle 100 includes, as information detection devices, two current sensors 72, four wheel speed sensors 73, a yaw rate sensor 74, a steering wheel angle sensor 75, a position acquirer 76, and a camera 77. The current sensors 72 are provided corresponding to the two parking brakes 95, respectively. In FIG. 1, one of the two current sensors 72 is shown as a representative. The current sensor 72 detects a current value (hereinafter, referred to as a motor current value A) flowing through a motor of an actuator 96 in the parking brake 95. The wheel speed sensors 73 are provided corresponding to the front, rear, left and right wheels, respectively. In FIG. 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 the rotation speed of the 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 may always 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 acquirer 76 acquires information relating to the current position coordinates G of the vehicle 100 from a global positioning satellite. The camera 77 acquires image information J of the surroundings of the vehicle 100. Each information detection device repeatedly outputs the information it has detected or acquired to the control device 50. Then, the control device 50 repeatedly acquires information from each information detection device.

[0018] The vehicle 100 includes a start switch 78 and a parking switch 79. The start switch 78 is sometimes called an ignition switch or a system activation switch. The start switch 78 is a switch for activating a main system of the control device 50. The start switch 78 is turned on or off in response to an operation by the occupant. When the start switch 78 is on, the control device 50 is in an activated state. When the start switch 78 is off, the control device 50 is basically in a stopped state. However, even when the start switch 78 is off, some of the functional units of the control device 50 can continue processing as necessary. 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 an operation by the occupant.

[0019] <Functions of the brake control unit> The brake control unit 52 switches the operation state of the parking brakes 95 according to the operation state of the parking switch 79. When the parking switch 79 is operated to be 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 brakes 95 from an off state to an on state. When the brake control unit 52 outputs the drive command, the parking brakes 95 are driven. That is, in the parking brakes 95, a current flows through the motor of the actuator 96. At the same time, the actuator 96 operates to press the brake shoe against the brake drum. As a result, the parking brakes 95 disable the rotation of the rear wheels 82. That is, the parking brakes 95 are turned on. The brake control unit 52 can grasp the switching state of the parking brakes 95 based on, for example, the motor current value A.

[0020] 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 an on state to an off state. When the brake control unit 52 outputs the release command, the parking brake 95 is released. That is, in the parking brake 95, a current flows through the motor of the actuator 96. At the same time, the actuator 96 operates to separate the brake shoe from the brake drum. This allows the parking brake 95 to rotate the rear wheels 82. That is, the parking brake 95 is in an off state.

[0021] 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. The brake control unit 52 monitors the presence or absence of an abnormality in the parking brake 95 when switching the parking brake 95 from an OFF state to an ON state. Specifically, the brake control unit 52 monitors the motor current value A when outputting a drive command. Then, when the state in which the motor current value A is equal to or less than the threshold continues for a predetermined 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 or the like as a value that can grasp that the motor of the actuator 96 is not able to output a torque in a normal state. The predetermined time is determined in advance by experiments or the like as a value that can determine that the abnormal state of the current value is not a temporary state such as noise but is clearly continuing. The brake control unit 52 of this embodiment detects, as an abnormality, a situation in which the parking brake 95 does not switch to the ON state despite outputting a drive command. The brake control unit 52 monitors the presence or absence of an abnormality for each of the left and right parking brakes 95 individually. When the brake control unit 52 detects the occurrence of an abnormality in the parking brake 95, it switches an abnormality flag from OFF to ON. An abnormality flag is prepared for each parking brake 95. When the brake control unit 52 detects the occurrence of an abnormality in the parking brake 95, it turns on a notification lamp provided in the vehicle compartment.

[0022] <Handling> When the brake control unit 52 outputs a drive command to each parking brake 95, the steering control unit 53 repeatedly determines whether or not an abnormality condition is satisfied until each parking brake 95 is switched to an ON state. The abnormality condition is a state in which a drive command is output to each parking brake 95 by the brake control unit 52 and an abnormality occurs in either the left or right parking brake 95. The state in which a drive command is output means a state in which a drive command is output. After the brake control unit 52 once outputs a drive command, the steering control unit 53 treats the state as a state in which a drive command is output until the brake control unit 52 next outputs a release command, even if the output of the drive command is subsequently interrupted. In other words, the requirement in the abnormality condition that a drive command is output to each parking brake 95 corresponds to a requirement of a period from when the brake control unit 52 outputs a drive command to each parking brake 95 until when the brake control unit 52 outputs a 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 abnormality condition is met, the steering control unit 53 identifies the side of the parking brake 95 on which the abnormality has occurred, between "left" and "right," as the abnormal side. The steering control unit 53 also identifies the side opposite the abnormal side as the normal side. Then, the steering control unit 53 starts a countermeasure process. The countermeasure process is a process for dealing with an abnormality when an abnormality occurs in either the left or right parking brake 95.

[0023] As shown in FIG. 3, when the steering control unit 53 starts the countermeasure processing, it first executes the processing of step S10. In step S10, the steering control unit 53 judges whether or not the turning condition is satisfied. The turning 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 specified value SK, and the absolute value of the wheel speed S detected by the second wheel speed sensor is less than the specified value SK. The first wheel speed sensor is the 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 the wheel speed sensor 73 that detects the wheel speed S of the rear wheel 82 on the normal side. The specified value SK is a value that can grasp the turning of the vehicle 100 and is determined in advance through experiments, etc. The turning of the vehicle 100 will be described in the section on the operation of the embodiment described later. The steering control unit 53 judges whether or not the turning condition is satisfied based on the latest detection information of the first wheel speed sensor and the second wheel speed sensor. If the turning condition is not satisfied, the steering control unit 53 advances the process to step S100.

[0024] In step S100, the steering control unit 53 judges whether the time elapsed since the start of the countermeasure process has reached a set time. The set time is determined in advance through experiments, etc., as a length of time that can be determined to be clear that the vehicle 100 will not turn. If the set time has not yet elapsed since the start of the countermeasure process (step S100: NO), the steering control unit 53 returns to the process of step S10. Then, the steering control unit 53 executes the process of step S10 again. Regarding these steps S10 and S100, if the set time has elapsed without the turning condition being satisfied (step S10: NO, step S100: YES), the steering control unit 53 ends the countermeasure process at that point in time. On the other hand, if the turning condition is satisfied (step S10: YES) before the set time has elapsed (step S100: NO), the steering control unit 53 advances the process to step S20.

[0025] In step S20, the steering control unit 53 calculates control information for performing turning inhibition control. The turning inhibition control is a control for suppressing the rotation of the rear wheel 82 on the abnormal side. The turning inhibition control of this embodiment is a control performed with the steering device 16 as the control target. Here, the steering control unit 53 handles the positive and negative of the steering angle F under the following rules while the countermeasure processing is being executed. That is, the steering control unit 53 regards the neutral position L as zero degrees, and handles the abnormal side with respect to the neutral position L as a positive value, and the normal side with respect to the neutral position L as a negative value. Under this handling, in the turning inhibition control, the steering control unit 53 increases the steering angle F of the left and right front wheels 81 toward the abnormal side compared to the time when the occurrence of the abnormality of the parking brake 95 is detected. The steering angle F of the front wheels 81 at the time when the occurrence of the abnormality of the parking brake 95 is detected is substantially the same as the steering angle F of the front wheels 81 at the time when step S20 is executed. Here, the angular position of the front wheels 81 at the time when the occurrence of an abnormality in the parking brake 95 is detected is referred to as the reference position. In the turning suppression control, the steering control unit 53 steers the front portion 81A of the front wheels 81 toward the abnormal side with respect to the reference position.

[0026] Now, the control information for performing the turning suppression control is specifically the target rotation amount and the target rotation direction of the motor 16A in the steering device 16. When calculating these pieces of 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 of 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 premise for the steering control unit 53 to calculate the target rotation amount, the memory of the control device 50 stores a steering map in advance. The steering map represents the correspondence 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 above-mentioned speed difference ΔS. The other variable is the required steering amount ΔF. The required steering amount ΔF is the amount of change in the steering angle F of the front wheels 81 required to stop the rotation of the abnormal rear wheels 82 and thus the turning of the vehicle 100. The required steering amount ΔF is based on the premise that the front wheels 81 are steered from the reference position to the abnormal side. Both the speed difference ΔS and the required steering amount ΔF are positive values. In the steering map, the larger the speed difference ΔS, the larger the required steering amount ΔF. The steering control unit 53 uses this steering map to calculate the control information. Specifically, the steering control unit 53 applies the latest speed difference ΔS calculated above to the steering map. Then, the steering control unit 53 calculates the required steering amount ΔF corresponding to the latest speed difference ΔS based on the steering map. Then, the steering control unit 53 converts the calculated required steering amount ΔF into the rotation amount of the motor 16A based on a predetermined relational expression. The steering control unit 53 calculates the converted rotation amount of the motor 16A as the target rotation amount. When the steering control unit 53 calculates the target rotation amount, it determines the target rotation direction of the motor 16A. Here, in this embodiment, the rotation direction of the motor 16A and the steering of the front wheels 81 have the following correspondence relationship. Now, assume that the front wheels 81 are in the neutral position L. At this time, when the motor 16A rotates in a first direction, the front portion 81A of the front wheels 81 is steered to the left with respect to the neutral position L. On the other hand, when the motor 16A rotates in a second direction that is the opposite direction to the first direction, the front portion 81A of the front wheels 81 is steered to the right with respect to the neutral position L.The memory of the control device 50 stores in advance such a correspondence relationship between the rotation direction of the motor 16A and the steering of the front wheels 81. Based on this correspondence relationship, the steering control unit 53 determines a target rotation direction of the motor 16A so that the front wheels 81 are steered to the abnormal side. That is, when the abnormal side is "left", the steering control unit 53 determines the target rotation direction to be a first direction. On the other hand, when the abnormal side is "right", the steering control unit 53 determines the target rotation direction to be a 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.

[0027] In step S30, the steering control unit 53 executes turning suppression control based on the control information calculated in step S20. That is, the steering control unit 53 controls the motor 16A so that the motor 16A rotates by the target rotation amount toward the target rotation direction determined in step S20. After this, the steering control unit 53 advances the process to step S40.

[0028] In step S40, the steering control unit 53 judges whether or not 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 a specified value SK, and the absolute value of the wheel speed S detected by the second wheel speed sensor is less than a specified value SK. The steering control unit 53 judges whether or not the stop condition is satisfied based on the latest detection information of the first wheel speed sensor and the second wheel speed sensor. If 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 executes 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. Then, when the stop condition is satisfied (step S40: YES), the steering control unit 53 ends the countermeasure process. Note that the stop condition may be satisfied when the process proceeds to step S40 for the first time after the start of the countermeasure process. In this case, the steering control unit 53 ends the countermeasure processing at that point.

[0029] Here, the parking switch 79 is often turned on immediately before the occupant finishes using the vehicle 100 and turns off the start switch 78. In relation to this, the start switch 78 may be turned off while the countermeasure processing is being executed. In this case, the steering control unit 53 is set to function as follows. That is, the steering control unit 53 continues to run and executes a series of processes of the countermeasure processing until the countermeasure processing is completed. Then, when the countermeasure processing is completed, the steering control unit 53 enters a stopped state in which no processing is performed. Like the steering control unit 53, the brake control unit 52 continues its own processing until the steering control unit 53 completes the countermeasure processing.

[0030] In addition, the steering control unit 53 ends the countermeasure processing in the middle of its execution in the following cases. That is, when a release command is output by the brake control unit 52 in the middle of its execution, the steering control unit 53 ends the countermeasure processing at that point. In this case, the steering control unit 53 moves to another process requested by the occupant or an application.

[0031] <Operation of the embodiment> Now, as shown in FIG. 4, it is assumed that the vehicle 100 is located on an uphill road with a fairly steep gradient. Then, it is assumed that the occupant turns on the parking switch 79 to park the vehicle 100 on this uphill road. Then, the brake control unit 52 outputs a drive command to each parking brake 95. At this time, as shown in FIG. 5, it is assumed that the left parking brake 95 among the left and right parking brakes 95 operates normally, but an abnormality occurs in the right parking brake 95, and the parking brake 95 does not operate normally. In this case, the right rear wheel 82 shown by the dashed line in FIG. 5 is not braked by the parking brake 95. At this time, if no action is taken, the vehicle 100 turns rightward about the left rear wheel 82, which is the normal side, as an axis, as shown by the dashed line in FIG. 5.

[0032] In order to prevent such turning, the steering control unit 53 of this embodiment performs turning suppression control through the countermeasure processing. That is, as shown in FIG. 6, the steering control unit 53 controls the steering device 16 to turn the front portion 81A of the left and right front wheels 81 to the right with respect to the reference position. Then, the steering control unit 53 increases the steering angle F of the left and right front wheels 81 toward the right. When the left and right front wheels 81 are turned toward the right, a force acting in the opposite direction to the abnormal turning direction acts on the vehicle 100. The abnormal turning direction is the direction in which the vehicle 100 tries to turn around the normal rear wheel 82 as an axis. The force acting in the opposite direction to the abnormal turning direction acts on the vehicle 100, thereby preventing the vehicle 100 from turning. Note that, regarding the countermeasure processing, the steering control unit 53 finely adjusts the steering angle F of the front wheels 81 until the turning of the vehicle 100 stops by repeating the processing of steps S20, S30, and S40. Accordingly, the steering angle F of the front wheels 81 is at an optimal position for preventing the vehicle 100 from turning.

[0033] <Effects of the embodiment> (1) As described in the operation of the above embodiment, in this embodiment, if an abnormality occurs in either the left or right parking brake 95, the front wheels 81 are steered to prevent the vehicle 100 from turning.

[0034] (2) Even if an abnormality occurs in either the left or right parking brake 95, the vehicle 100 may not turn, for example, when the road surface gradient is gentle. If the vehicle 100 does not turn, there is no need to execute the turning inhibition control. Therefore, in this embodiment, the turning inhibition control is executed after it is determined through the processing of step S10 that the vehicle 100 has actually started to turn. In this way, it is possible to prevent turning inhibition control from being executed unnecessarily. This makes it possible to eliminate the processing burden on the control device 50 associated with the execution of the turning inhibition control, and the power consumption of the steering device 16 associated with the execution of the turning inhibition control.

[0035] (3) When performing turning suppression control, if the change amount of the steering angle F of the front wheels 81 is too small, the turning of the vehicle 100 cannot be stopped. On the other hand, if the change amount of the steering angle F of the front wheels 81 is too large, there is a risk that the vehicle 100 will turn in the opposite direction to the abnormal turning direction. In this embodiment, the steering angle F of the front wheels 81 is changed by an amount commensurate with the amount of turning of the vehicle 100 in the abnormal turning direction. Therefore, the turning of the vehicle 100 can be appropriately stopped.

[0036] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modified examples can be implemented in combination with each other to the extent that there is no technical contradiction.

[0037] The method of detecting an abnormality in the parking brake 95 is not limited to the example of the above embodiment. For example, when the motor current value A is greater than a predetermined upper limit value, it may be determined that an abnormality has occurred in the parking brake 95. For example, a variable reflecting the transition of the motor current value A, such as a differential value of the motor current value A, may be used to detect an abnormality in the parking brake 95. A variable other than the motor current value A may be used to detect an abnormality in the parking brake 95. For example, the temperature of the motor of the actuator 96 may be used as a variable other than the motor current value A in detecting an abnormality in the parking brake 95. Then, when the temperature of the motor is out of the allowable range, it may be determined that an abnormality has occurred in the parking brake 95. In this case, a temperature sensor that detects the temperature of the motor may be provided in the vehicle 100. The method of detecting an abnormality in the parking brake 95 is not limited to a method that can detect a situation in which the parking brake 95 does not switch to the on state, but may be a method that can determine that the parking brake 95 is not normal.

[0038] The period during which the parking brake 95 is monitored for abnormality is not limited to when the parking brake 95 is switched from the OFF state to the ON state. For example, the parking brake 95 may be constantly monitored for abnormality when the start switch 78 is ON.

[0039] When steering the front wheels 81 with the turning suppression control, it is not essential to increase the amount of change in the steering angle F of the front wheels 81 as the speed difference ΔS increases. For example, the front wheels 81 may be steered to the maximum angle position allowed for the front wheels 81 regardless of the size of the speed difference ΔS. For example, in cases where the road gradient is relatively small, such a method of dealing with the situation can also prevent the vehicle 100 from turning.

[0040] When steering the front wheels 81 in the turning suppression control, it is not essential to determine the amount of change in the steering angle F of the front wheels 81 using the detection information of 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 of the yaw rate sensor 74. In this case, it is considered 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 becomes zero.

[0041] The process of step S10 may be omitted. In other words, regardless of whether the turning condition is satisfied or not, the turning suppression control may be executed when the abnormal condition is satisfied. For example, when the abnormal condition is satisfied, the front wheels 81 may be steered to the maximum angle position allowed for the front wheels 81, as in the above modification.

[0042] The adjustment device 15 may be used as the steering device to be controlled in the turning suppression control of step S30, instead of the turning device 16. The adjustment device 15 may be controlled to increase the steering angle F of the front wheels 81 toward the abnormal side.

[0043] When the equipment to be controlled by the turning suppression control (hereinafter, referred to as the target equipment) is changed from that in the above embodiment as in the above modified example, the control information calculated in step S20 can be changed accordingly.

[0044] The target device of the turning inhibition control is not limited to a steering device capable of changing 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 that can suppress the rotation of the abnormal rear wheel 82. The content of the control performed in the turning inhibition control is not limited to steering the front wheels 81. The turning inhibition control only requires that the rotation of the rear wheels 82 be suppressed. For example, the vehicle 100 may be equipped with a steering lock device. The steering lock device may be adopted as the target device. The steering lock device is a device that fixes the left and right front wheels 81 at the neutral position L. In the turning inhibition control, the front wheels 81 may be fixed at zero degrees by activating this device. If the front wheels 81 are not steered, the vehicle 100 will not turn even if an abnormality occurs in either the left or right parking brake 95. For example, the drive source 90 of the vehicle 100 may be adopted as the target device. In the turning suppression control, the driving force of the driving source 90 of the vehicle 100 may be applied to the rear wheel 82 to suppress rotation of the abnormal rear wheel 82. If the start switch 78 of the vehicle 100 is on, the driving source 90 of the vehicle 100 is in operation, and therefore the driving source 90 of the vehicle 100 may function as the target device. For example, the service brake 92 may be used as the target device. In the turning suppression control, the parking brake 95 in which an abnormality has occurred may apply a braking force to the rear wheel 82 that is to be braked. The service brake 92 may apply a braking force to all the wheels on the front, rear, left, and right sides.

[0045] Depending on the target device, for example, when a steering lock device is used as the target device, the process of step S40 may not be necessary in the countermeasure process. In such a case, the process of step S40 may be abolished, and the countermeasure process may be terminated when the turning suppression control is terminated.

[0046] The configuration of the parking brake 95 is not limited to the example in the above embodiment. The parking brake 95 may be an electric brake that can disable the wheels from rotating when driven. The parking brakes 95 may be provided corresponding to the left and right front wheels 81, and the left and right rear wheels 82 may be configured to be steerable. In this case, when an abnormality occurs in one of the left and right parking brakes 95 while the vehicle 100 is on a downhill road, the vehicle 100 may turn around the normal front wheel 81 as an axis. In order to prevent the vehicle 100 from turning in this way, rotation suppression control may be performed when an abnormality condition is satisfied. In this case, the content of the rotation suppression control may be anything that can suppress the rotation of the abnormal front wheel 81.

[0047] The AD application may be configured to realize the following. In the following, the contents of various processes actually performed by the control device 50 will be described mainly with reference to the AD application. Note that, as in the above embodiment, it is assumed here that the parking brake 95 is provided corresponding to the rear wheels 82 and the front wheels 81 are steerable.

[0048] The AD application constantly monitors the parking brake 95 for abnormalities while the vehicle 100 is traveling. If no abnormality occurs in each parking brake 95, the AD application permits parking on a slope. On the other hand, if an abnormality occurs in either the left or right parking brake 95, the AD application prohibits parking on a slope. That is, if an abnormality occurs in either the left or right parking brake 95, the AD application ensures that the vehicle is parked on a flat road. When parking 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 a curb on the road. At this time, the AD application ensures that the curb is located on the abnormal side with respect to the vehicle 100. After that, the AD application outputs a drive command to each parking brake 95, and steers the left and right front wheels 81 to the abnormal side to bring the abnormal side front wheel 81 into contact with the curb. This brings the abnormal side front wheel 81 into a state supported by the curb. [Explanation of symbols]

[0049] 16... Steering device 50... Control device 73... Wheel speed sensor 81... Front wheel 82... Rear wheel 95... Parking brake 100... Vehicle

Claims

1. This is applied to a vehicle having a parking brake that is provided for each of the left and right wheels and that disables the rotation of the wheels by driving the parking brake. Detecting an occurrence of an abnormality in each of the left and right parking brakes; When a drive command is output to each of the parking brakes and an abnormality condition is satisfied that an abnormality has occurred in any of the parking brakes, control a device other than the parking brake in the vehicle so as to suppress rotation of the wheel on the side where the parking brake abnormality has occurred; Do Vehicle control device.

2. The wheels on which the parking brake is provided are rear wheels, the vehicle has a steering device capable of changing the steering angle of left and right front wheels, When the side on the left or right where the parking brake malfunctions is defined as the abnormal side, The control for suppressing the rotation of the rear wheel on the abnormal side is a control for increasing the steering angle of the left and right front wheels toward the abnormal side from the point in time when the occurrence of the parking brake abnormality was detected. The vehicle control device according to claim 1 .

3. the vehicle has wheel speed sensors provided corresponding to the left and right rear wheels, When a turning condition is satisfied, that is, 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 predetermined value and the absolute value of the other is less than the predetermined value, and when the abnormality condition is satisfied, control is performed to suppress rotation of the rear wheel on the abnormal side. The vehicle control device according to claim 2.

4. The greater 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, the greater the amount of change in the steering angle of the left and right front wheels. The vehicle control device according to claim 3.

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