Control device

Abstract

A braking control device 100 comprises: a moment estimating unit 123 that, in a situation in which an abnormality has occurred in only one of electric braking devices 62L and 62R of rear wheels 22L and 22R, estimates a moment generated in a vehicle 10 on the basis of the position and attitude information of the wheel to which the normally-operating electric braking device can apply a parking braking force; and an adjusting unit 124 that transmits, to an electric steering device 40, a first steering angle adjustment signal for adjusting the steering angle in the direction that cancels out the moment.

Description

Control device

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

[0002] Conventionally, a vehicle having two parking brakes that individually apply parking braking force to two rear wheels has been known. In a situation where such a vehicle parks on an uphill road, if an abnormality occurs in one of the two parking brakes, there is a risk that the vehicle cannot maintain parking. Specifically, a yaw moment centered on a wheel with a normally functioning parking brake, a moment proportional to the vehicle weight and the gradient of the uphill road, may act on the vehicle, causing the vehicle to move in the direction in which the moment acts.

[0003] Therefore, when an abnormality occurs in one of the two parking brakes, the control device described in Patent Document 1 predicts the direction in which the yaw moment acts based on the position of the rear wheel to which parking braking force can be normally applied among the two rear wheels. Subsequently, the control device changes the front wheel steering angle in a direction that cancels out the yaw moment based on the prediction result. Thus, even when an abnormality occurs in one of the two parking brakes, the control device maintains the parking of the vehicle.

[0004] Japanese Unexamined Patent Application Publication No. 2007-137182

[0005] There is still room for improvement in the above control device in terms of maintaining the parking of the vehicle.

[0006] A control device for solving the above problems is applied to a vehicle comprising: a plurality of wheels; two electric parking brake devices that apply parking braking force to two wheels that form a pair on the left and right among the plurality of wheels by maintaining the position of the friction material while pressing the friction material against a rotating body that rotates with the wheels; an electric steering device that adjusts the steering angle of two wheels that form a pair on the left and right among the plurality of wheels; and a posture information detection unit that detects posture information including the tilt of the vehicle in the longitudinal direction and the tilt in the lateral direction, wherein, in a situation in which a malfunction occurs in only one of the two parking brake devices, a moment estimation unit that estimates the moment generated in the vehicle based on the posture information and the position of the wheel to which the normal parking brake device can apply the parking braking force; and an adjustment unit that transmits a first steering angle adjustment signal to the steering device for adjusting the steering angle in a direction that cancels out the moment.

[0007] The control system can improve the vehicle's parking performance.

[0008] Figure 1 is a schematic diagram of a vehicle equipped with a braking control device. Figure 2 is a schematic diagram of the electric braking device of the vehicle in Figure 1. Figure 3 is a side view of a vehicle parked on a road surface that slopes in the longitudinal direction. Figure 4 is a top view of the vehicle in Figure 3. Figure 5 is a top view of the vehicle in Figure 3. Figure 6 is a side view of a vehicle parked on a road surface that slopes in the lateral direction. Figure 7 is a top view of the vehicle in Figure 6. Figure 8 is a top view of the vehicle in Figure 6. Figure 9 is a flowchart showing the processing flow executed by the braking control device in Figure 1 when parking. Figure 10 is a flowchart showing the processing flow executed by the braking control device in Figure 1 when driving is resumed. Figures 11(a) to 11(d) are timing charts showing various parameters that change over time during parking and driving resumption.

[0009] The following describes one embodiment in which the "vehicle control device" is specifically defined as a vehicle braking control device. <Configuration of this embodiment> As shown in Figure 1, the vehicle 10 includes a plurality of wheels 20, a steering member 31, a braking operation member 32, an electric steering device 40, a plurality of braking mechanisms 50, and a plurality of electric braking devices 60. The vehicle 10 also includes a plurality of sensors 81 to 83 and a switch 84, a steering control device 90, and a braking control device 100.

[0010] The multiple wheels 20 include front wheels 21L, 21R and rear wheels 22L, 22R. The front wheels 21L, 21R include a left front wheel 21L and a right front wheel 21R, which form a pair on the left and right sides, and the rear wheels 22L, 22R include a left rear wheel 22L and a right rear wheel 22R, which form a pair on the left and right sides. The steering member 31 is a member operated by the driver when turning the vehicle 10. An example of the steering member 31 is a steering wheel. The braking operation member 32 is a member operated by the driver when adjusting the deceleration of the vehicle 10. An example of the braking operation member 32 is a brake pedal.

[0011] <Electric Steering Device> The electric steering device 40 adjusts the steering angle of the front wheels 21L and 21R (hereinafter referred to as "front wheel steering angle") based on the power of an electric motor (not shown). When the front wheel steering angle is adjusted by the electric steering device 40, the vehicle 10 becomes capable of turning. In this embodiment, of the multiple wheels 20, only the front wheels 21L and 21R are steering wheels. In other embodiments, of the multiple wheels 20, only the rear wheels 22L and 22R may be steering wheels, or all wheels 20 may be steering wheels. The electric steering device 40 corresponds to the "steering device".

[0012] <Braking Mechanism> Multiple braking mechanisms 50 are provided for each of the multiple wheels 20. In other words, there are as many braking mechanisms 50 as there are wheels 20. Each braking mechanism 50 has a rotating body 51 and a friction material 52. For example, the rotating body 51 is a brake disc, and the friction material 52 is a brake pad. The rotating body 51 rotates together with the wheel 20. Therefore, when the friction material 52 is pressed against the rotating body 51, a braking force is applied to the wheel 20. Hereafter, the force with which the friction material 52 is pressed against the rotating body 51 will be called the "pressing force". In the braking mechanism 50, the higher the pressing force, the greater the braking force applied to the wheel 20. In other words, the pressing force and the braking force are correlated.

[0013] <Electric Brake System 60> Multiple electric brake systems 60 are provided for each of the multiple wheels 20. In other words, there are as many electric brake systems 60 as there are wheels 20. The multiple electric brake systems 60 include electric brake systems 61L and 61R for the front wheels and electric brake systems 62L and 62R for the rear wheels. Specifically, the electric brake systems 61L and 61R for the front wheels include an electric brake system 61L for the left front wheel and an electric brake system 61R for the right front wheel, while the electric brake systems 62L and 62R for the rear wheels include an electric brake system 62L for the left rear wheel and an electric brake system 62R for the right rear wheel.

[0014] The front electric brakes 61L and 61R have the function of applying normal braking force, which is the braking force for decelerating the vehicle 10, to the front wheels 21L and 21R, respectively. On the other hand, the rear electric brakes 62L and 62R have the function of applying normal braking force to the rear wheels 22L and 22R, respectively, and the function of applying parking braking force, which is the braking force for parking the vehicle 10, to the rear wheels 22L and 22R, respectively. In other words, the front electric brakes 62L and 62R correspond to "normal braking devices". On the other hand, the rear electric brakes 62L and 62R correspond to both "normal braking devices" and "parking braking devices". In this respect, the front electric brakes 61L and 61R can be said to be configured in a way that omits the function of applying parking braking force from the rear electric brakes 62L and 62R. Based on these points, the electric braking systems 62L and 62R for the rear wheels will be explained in detail below, and the explanation of the electric braking systems 61L and 61R for the front wheels will be omitted.

[0015] When a normal braking force is applied to a wheel, the friction material 52 is pressed against the rotating body 51 that rotates with the wheel. On the other hand, when a parking braking force is applied to a wheel, the position of the friction material 52 is maintained while it is pressed against the rotating body 51 that rotates with the wheel.

[0016] As shown in Figure 2, the electric brakes 62L and 62R for the rear wheels include an electric motor 71, a reduction mechanism 72, a linear motion conversion mechanism 73, a piston 74, and a brake maintenance mechanism 75.

[0017] The electric motor 71 has an output shaft 711 that rotates when power is supplied. The reduction mechanism 72 reduces the rotational motion of the output shaft 711 of the electric motor 71 and outputs it to the linear motion conversion mechanism 73. The reduction mechanism 72 has, for example, a plurality of gears that mesh with each other. The linear motion conversion mechanism 73 has a screw shaft 731 and a nut 732. The screw shaft 731 rotates based on the power transmitted from the reduction mechanism 72. The nut 732 is screwed onto the screw shaft 731. Thus, in the linear motion conversion mechanism 73, when the screw shaft 731 rotates, the nut 732 moves linearly in the axial direction of the screw shaft 731.

[0018] The piston 74 is connected to the nut 732. Therefore, when the nut 732 moves in a linear motion, the piston 74 moves in a linear motion in the same direction as the nut 732. When the piston 74 moves forward in the direction approaching the rotating body 51, the pressing force increases. On the other hand, when the piston 74 moves backward in the direction away from the rotating body 51, the pressing force decreases.

[0019] Thus, when the output shaft 711 of the electric motor 71 is rotated in one direction (hereinafter referred to as the "increasing direction"), the piston 74 moves forward, increasing the pressing force. On the other hand, when the output shaft 711 of the electric motor 71 is rotated in the opposite direction to the increasing direction (hereinafter referred to as the "decreasing direction"), the piston 74 moves backward, decreasing the pressing force. Therefore, the electric brakes 62L and 62R for the rear wheels can adjust the pressing force by controlling the electric motor 71. In other words, the electric brakes 62L and 62R for the rear wheels can adjust the braking force applied to the corresponding rear wheels 22L and 22R by controlling the electric motor 71.

[0020] The braking maintenance mechanism 75 includes a ratchet gear 751, a pawl member 752, and a solenoid 753. The ratchet gear 751 is fixed to the output shaft 711 of the electric motor 71 in a state that allows it to rotate integrally with the gear. The pawl member 752 is displaceable between a locked position in which it engages with the ratchet gear 751 and a retracted position in which it retracts from the ratchet gear 751. The pawl member 752 is biased in the direction from the locked position to the retracted position by a coil spring (not shown) or the like. When the pawl member 752 is in the locked position, it restricts the rotation of the output shaft 711 and the ratchet gear 751 in the decreasing direction. On the other hand, when the pawl member 752 is in the locked position, it does not restrict the rotation of the output shaft 711 and the ratchet gear 751 in the increasing direction. The solenoid 753 is a power source for displacing the pawl member 752 to the locked position. In other words, when power is supplied to the solenoid 753, the electromagnetic force generated by the solenoid 753 moves the pawl member 752 to the locking position. If the pawl member 752 is locked to the ratchet gear 751 in the locking position, the pawl member 752 will remain in the locking position even if the power supply to the solenoid 753 is stopped. In this way, the braking maintenance mechanism 75 maintains a state in which braking force is applied to the corresponding rear wheels 22L and 22R, even when the power supply to the electric motor 71 is stopped.

[0021] The front wheel electric brakes 61L and 61R are equipped with an electric motor 71, a reduction mechanism 72, a linear motion conversion mechanism 73, and a piston 74. In other words, the front wheel electric brakes 61L and 61R differ from the rear wheel electric brakes 62L and 62R in that they do not have a brake maintenance mechanism 75.

[0022] <Sensors and Switches> As shown in Figure 1, the multiple sensors 81 to 83 output signals to the braking control device 100 according to the detection results. The brake sensor 81 outputs a detection signal according to the driver's operation of the braking operation member 32. The steering angle sensor 82 outputs a detection signal according to the driver's operation of the steering member 31. The acceleration sensor 83 outputs a detection signal according to the acceleration of the vehicle 10 in the longitudinal and lateral directions. The parking brake switch 84 outputs a signal to the braking control device 100 according to the operation status of the switch. The parking brake switch 84 is operated by the driver to switch the parking brake on and off.

[0023] <Steering Control Device> The steering control device 90 controls the electric steering device 40. The steering control device 90 is a processing circuit having a CPU and memory. The steering control device 90 is configured to send and receive various information with the braking control device 100 via the in-vehicle network. The steering control device 90 acquires the steering amount of the steering member 31 based on the detection signal of the steering angle sensor 82. Subsequently, the steering control device 90 calculates a target steering amount, which is a target value of the steering amount, based on the steering amount. If the vehicle 10 is equipped with a driving control device that has an automatic driving function, the steering control device 90 may acquire the target steering amount transmitted from the driving control device. Then, the steering control device 90 controls the electric steering device 40 based on the target steering amount.

[0024] <Braking Control Device> As shown in Figure 1, the braking control device 100 includes a processing circuit 110 having a CPU 111 and a memory 112. The memory 112 stores control programs executed by the CPU 111 and various types of information. When the CPU 111 executes the control programs stored in the memory 112, the processing circuit 110 functions as an acquisition unit 121, a braking control unit 122, a moment estimation unit 123, and an adjustment unit 124.

[0025] <Acquisition Unit> The acquisition unit 121 acquires the braking operation amount, which is the amount operated by the braking operation member 32, based on the detection signal from the brake sensor 81. The acquisition unit 121 also acquires the longitudinal acceleration and lateral acceleration of the vehicle 10 based on the detection signal from the acceleration sensor 83. The acquisition unit 121 acquires attitude information based on the longitudinal acceleration and lateral acceleration of the vehicle 10. The attitude information includes the road surface gradient θ, which is the gradient of the road surface on which the vehicle 10 is located. More specifically, the attitude information includes the road surface gradient θ in the longitudinal direction and the road surface gradient θ in the left-right direction. In other words, the attitude information includes the tilt of the vehicle 10 in the longitudinal direction and the tilt in the left-right direction. In this respect, the acceleration sensor 83 corresponds to an "attitude information detection unit" that detects attitude information.

[0026] Furthermore, the acquisition unit 121 acquires parking brake requests and parking brake release requests based on detection signals from the parking brake switch 84, etc. A parking brake request is a request to turn on the parking brake, and a parking brake release request is a request to turn off the parking brake.

[0027] <Braking Control Unit> When a normal braking request occurs, the braking control unit 122 performs a normal braking process that applies normal braking force to multiple wheels 20. When a parking braking request occurs, the braking control unit 122 performs an apply process that applies parking braking force to the rear wheels 22L and 22R. When a parking braking release request occurs, the braking control unit 122 performs a release process that releases the parking braking force applied to the rear wheels 22L and 22R.

[0028] In normal braking processing, the braking control unit 122 calculates the required normal braking force, which is the required value of the normal braking force. The required normal braking force is, for example, a braking force proportional to the braking operation amount. If the vehicle 10 is equipped with an automatic driving control device, the braking control unit 122 may obtain the required normal braking force transmitted from the driving control device. Subsequently, the braking control unit 122 calculates the target pressing force, which is the target value of the pressing force, based on the required braking force. If the target pressing force is high, the braking control unit 122 rotates the output shafts 711 of the electric motors 71 of the multiple electric brake devices 60 in the increasing direction. In this way, the braking control unit 122 increases the pressing force by advancing the piston 74. On the other hand, if the target pressing force is low, the braking control unit 122 rotates the output shafts 711 of the electric motors 71 of the multiple electric brake devices 60 in the decreasing direction. In this way, the braking control unit 122 decreases the pressing force by retracting the piston 74.

[0029] In the apply process, the braking control unit 122 sets the pressing force corresponding to the requested parking braking force to the target pressing force. The requested parking braking force is a braking force equal to or greater than the parking maintenance braking force required to maintain the vehicle 10 in a stopped position. Next, the braking control unit 122 rotates the output shaft 711 of the electric motor 71 of the rear wheel electric brake devices 62L and 62R in an increasing direction. In this way, the braking control unit 122 increases the pressing force by advancing the piston 74. When the pressing force increases to the target pressing force, the braking control unit 122 stops the rotation of the output shaft 711 of the electric motor 71. In other words, the braking control unit 122 drives the electric motor 71 so that the rotation angle of the electric motor 71 is maintained. Next, the braking control unit 122 displaces the claw member 752 to the locked position by supplying power to the solenoid 753 of the braking maintenance mechanism 75. After that, the braking control unit 122 stops supplying power to the electric motor 71 and the solenoid 753. In this way, by maintaining the pressing force at the target pressing force, the condition in which the required parking braking force is applied to the rear wheels 22L and 22R is maintained.

[0030] In the release process, the braking control unit 122 slightly rotates the output shaft 711 of the electric motor 71 of the rear wheel electric brakes 62L and 62R in the increasing direction. This causes the pawl member 752 to move away from the ratchet gear 751, displacing the pawl member 752 to the retracted position. Subsequently, the braking control unit 122 rotates the output shaft 711 of the electric motor 71 in the decreasing direction until the piston 74 returns to its initial position. In this way, the pressing force is relieved, and the required parking braking force applied to the rear wheels 22L and 22R is eliminated.

[0031] <Moment Estimation Unit> Consider the case where the apply process is performed with the vehicle 10 stopped on an inclined road surface. In this case, if parking braking force is applied to both rear wheels 22L and 22R, the vehicle 10 will be parked. However, if parking braking force is not applied to at least one of the rear wheels 22L and 22R, there is a possibility that the vehicle 10 will not be parked.

[0032] Hereafter, a situation in which an abnormality occurs in one of the rear-wheel electric braking devices 62L or 62R, preventing the abnormal electric braking device from applying parking braking force to the corresponding rear wheels 22L or 22R, will be referred to as a "specific situation." A specific situation occurs, for example, when an abnormality occurs in the electric motor 71 or the solenoid 753 in the abnormal electric braking device. In this embodiment, if a specific situation occurs due to an abnormality in the electric motor 71, the abnormal electric braking device may be unable to apply both normal braking force and parking braking force to the corresponding rear wheels 22L or 22R. Also, if a specific situation occurs due to an abnormality in the solenoid 753, the abnormal electric braking device may be able to apply normal braking force to the corresponding rear wheels 22L or 22R, but may be unable to apply parking braking force to the corresponding rear wheels 22L or 22R. Hereafter, under specific circumstances, the wheel 20 corresponding to the electric braking system that has malfunctioned will be referred to as the "malfunctioning wheel," and the wheel 20 corresponding to the electric braking system that has not malfunctioned will be referred to as the "normal wheel." In other words, the malfunctioning wheel is one of the rear wheels 22L or 22R to which parking braking force cannot be applied, and the normal wheel is the other of the rear wheels 22L or 22R to which parking braking force can be applied.

[0033] In this embodiment, the vehicle 10 is equipped with one processing circuit 110, but in other embodiments, the vehicle 10 may be equipped with a processing circuit 110 and a CPU 111 for each electric braking device. In this case, the specific situation may include a situation in which an abnormality occurs in the processing circuit 110 and CPU 111 for controlling one of the rear electric braking devices 62L and 62R. The specific situation may also include a situation in which an abnormality occurs in an electric motor drive circuit (not shown) for controlling one of the rear electric braking devices 62L and 62R.

[0034] Referring to Figures 3 to 5, consider the case where vehicle 10 is parked on a road surface that slopes in the front-to-back direction. More specifically, consider the case where the apply process is executed when the rear of vehicle 10 is positioned vertically below the front of vehicle 10, as shown in Figure 3, and under specific conditions. The solid arrows shown in Figures 4 and 5 represent the component of vehicle weight F that is aligned with the road surface (hereinafter also referred to as the "slope component Fp of vehicle weight"), as shown in Figure 3.

[0035] As shown in Figure 4, if a malfunction occurs in the electric brake system 62L for the left rear wheel, parking braking force will not be applied to the malfunctioning left rear wheel 22L even if the apply process is executed. Therefore, as shown in Figure 4, a moment M is generated around an axis perpendicular to the contact surface of the normal right rear wheel 22R, which tends to turn the vehicle 10 to the left. Thus, depending on the magnitude of the generated moment M, the vehicle 10 may move in the direction in which the moment M acts. On the other hand, as shown in Figure 5, if a malfunction occurs in the electric brake system 62R for the right rear wheel, parking braking force will not be applied to the malfunctioning right rear wheel 22R even if the apply process is executed. Therefore, as shown in Figure 5, a moment M is generated around an axis perpendicular to the contact surface of the normal left rear wheel 22L, which tends to turn the vehicle 10 to the right. Thus, depending on the magnitude of the generated moment M, the vehicle 10 may move in the direction in which the moment M acts.

[0036] Referring to Figures 6 to 8, consider the case where vehicle 10 is parked on a road surface that slopes from side to side. More specifically, consider the case where the apply process is executed when the left side of vehicle 10 is positioned vertically below the right side of vehicle 10, as shown in Figure 6. The solid arrows shown in Figures 7 and 8 represent the slope component Fp of the vehicle weight F, as shown in Figure 6.

[0037] As shown in Figure 7, if a malfunction occurs in the electric brake system 62L for the left rear wheel, parking braking force will not be applied to the malfunctioning left rear wheel 22L even if the apply process is executed. Therefore, as shown in Figure 7, a moment M is generated around an axis perpendicular to the contact surface of the normal right rear wheel 22R, which tends to turn the vehicle 10 to the left. Thus, depending on the magnitude of the generated moment M, the vehicle 10 may move in the direction in which the moment M acts. On the other hand, as shown in Figure 8, if a malfunction occurs in the electric brake system 62R for the right rear wheel, parking braking force will not be applied to the malfunctioning right rear wheel 22R even if the apply process is executed. Therefore, as shown in Figure 8, a moment M is generated around an axis perpendicular to the contact surface of the normal left rear wheel 22L, which tends to turn the vehicle 10 to the left. Thus, depending on the magnitude of the generated moment M, the vehicle 10 may move in the direction in which the moment M acts.

[0038] As described above, when the apply process is performed under specific conditions, the direction of the moment M generated in the vehicle 10 is determined by the direction of the road surface inclination and the position of the normal wheels. Also, the magnitude of the moment M generated in the vehicle 10 is determined by the vehicle weight F and the magnitude of the road surface gradient θ. Therefore, the moment estimation unit 123 estimates the moment M generated in the vehicle 10 based on the attitude information and the position of the normal wheels under specific conditions. Here, when estimating the moment M, the moment estimation unit 123 may use the vehicle weight F that takes into account the weight of the occupants and luggage, or it may use the vehicle weight F that does not take into account the weight of the occupants and luggage. In the latter case, since the vehicle weight F can be treated as a constant, the moment estimation unit 123 can estimate the magnitude and direction of the moment M without using the vehicle weight F.

[0039] The road surface on which the vehicle 10 is parked may be inclined in both the longitudinal and lateral directions. In this case, the moment estimation unit 123 may individually estimate the moment generated by the inclination component Fp of the vehicle weight in the longitudinal direction and the moment generated by the inclination component Fp of the vehicle weight in the lateral direction. Subsequently, the moment estimation unit 123 may estimate the moment M actually generated in the vehicle 10 by adding the two individually estimated moments. Alternatively, the moment estimation unit 123 may directly estimate the moment M generated by the inclination component Fp of the vehicle weight in both the longitudinal and lateral directions, i.e., the moment M actually generated in the vehicle 10.

[0040] <Adjustment Unit> The adjustment unit 124 adjusts the normal braking force applied to the wheels 20 when the vehicle 10 is parked and when the vehicle 10 is driven again, and also adjusts the steering angle of the front wheels.

[0041] The processing details of the adjustment unit 124 when the vehicle 10 is parked will now be explained. As shown in Figures 4, 7, and 8, consider the case where a moment M is generated that causes the vehicle 10 to turn to the left when the apply process is executed. In this case, as shown by the dashed line in the figure, the movement of the vehicle 10 can be suppressed by adjusting the front wheel steering angle to the left, which is the direction that cancels out the moment M. Similarly, as shown in Figure 5, consider the case where a moment M is generated that causes the vehicle 10 to turn to the right. In this case, as shown by the dashed line in the figure, the movement of the vehicle 10 can be suppressed by adjusting the front wheel steering angle to the right, which is the direction that cancels out the moment M.

[0042] By adjusting the front-wheel steering angle, it is possible to cancel the moment M for turning the vehicle 10 because the frictional force between the front wheels 21L and 21R and the road surface increases about the axis orthogonal to the ground contact surface of the normal wheels. In other words, about the axis orthogonal to the ground contact surface of the normal wheels, the moment M corresponding to the inclined surface component Fp of the vehicle weight and the moment corresponding to the frictional force between the front wheels 21L and 21R and the road surface are balanced. In this regard, when the moment M for turning the vehicle 10 is large, the adjustment amount of the front-wheel steering angle required to suppress the movement of the vehicle 10 tends to be larger than when the moment M is small.

[0043] Therefore, the adjustment unit 124 transmits a first steering angle adjustment signal for adjusting the front-wheel steering angle in a direction to cancel the moment M generated in the vehicle 10 to the electric power steering device 40 via the steering control device 90 under specific circumstances. In this case, the steering control device 90 changes the front-wheel steering angle based on the received first steering angle adjustment signal.

[0044] Even when the application process is executed under specific circumstances, if the road surface on which the vehicle 10 is located is flat, no moment M for turning the vehicle 10 is generated in the vehicle 10. Also, even when the application process is executed under specific circumstances, if the magnitude of the gradient of the road surface on which the vehicle 10 is located is very small, no moment M sufficient to move the vehicle 10 is generated in the vehicle 10. Therefore, the adjustment unit 124 determines whether or not the magnitude of the road surface gradient θ is equal to or greater than a predetermined gradient determination value θth on the road surface where the vehicle 10 is stopped. Then, when the magnitude of the road surface gradient θ is equal to or greater than the gradient determination value θth, the adjustment unit 124 transmits the first steering angle adjustment signal to the steering control device 90. On the other hand, when the magnitude of the road surface gradient θ is less than the gradient determination value θth, the adjustment unit 124 does not transmit the first steering angle adjustment signal to the steering control device 90. This includes prohibiting the transmission of the first steering angle adjustment signal to the steering control device 90. The magnitude of the road surface gradient θ here preferably represents a comprehensive gradient considering both the gradient with respect to the longitudinal direction and the gradient with respect to the lateral direction of the road surface.

[0045] If the front wheel steering angle is adjusted based on the first steering angle adjustment signal while the occupants, including the driver, are in the vehicle 10, the occupants may feel uncomfortable. Therefore, it is preferable that the adjustment unit 124 transmits the first steering angle adjustment signal to the steering control device 90 after detecting an exit operation, which is the action of an occupant getting out of the vehicle 10, when a parking brake request occurs. For example, the adjustment unit 124 detects an exit operation when the operation of the braking operation member 32 is released, when the ignition switch is turned off, when the detection signal of the seat sensor is turned off, when the doors of the vehicle 10 are opened, and when the vehicle doors are locked. Alternatively, the adjustment unit 124 may detect an exit operation after a predetermined time has elapsed since these events occurred.

[0046] The adjustment unit 124 transmits a first steering angle adjustment signal to the steering control device 90 when the apply process is executed under specific conditions. Subsequently, the steering control device 90 causes the electric steering device 40 to adjust the front wheel steering angle. Therefore, if normal braking force is not applied to the wheels 20 during the period from when the apply process is started until the adjustment of the front wheel steering angle based on the first steering angle adjustment signal is completed, there may be insufficient moment to counteract the moment M that would cause the vehicle 10 to turn. In other words, if normal braking force is not applied to the wheels 20 during the period from when the apply process is started until the adjustment of the front wheel steering angle based on the first steering angle adjustment signal is completed, the vehicle 10 may move.

[0047] Therefore, it is preferable that the adjustment unit 124 transmits a first braking force adjustment signal to the electric braking device 60 corresponding to at least one wheel 20, excluding the normal wheel, to apply normal braking force to that wheel 20 during the period from when the apply process is started until the adjustment of the front wheel steering angle based on the first steering angle adjustment signal is completed. In this embodiment, the adjustment unit 124 transmits the first braking force adjustment process before the apply process is started.

[0048] In addition, when the apply process is executed, that is, when a parking brake request occurs, it is highly likely that normal braking force has already been applied to a plurality of wheels 20 according to a request from the driver or the driving control device. In such a situation, when the adjustment unit 124 transmits the first braking force adjustment signal, the electric braking devices 61L and 61R for the front wheels are controlled from the state of being controlled according to a request from the driver or the driving control device to the state of being controlled by a signal from the adjustment unit 124. That is, even if the driver releases the operation of the braking operation member 32 after the adjustment unit 124 transmits the first braking force adjustment signal, the normal braking force applied to the front wheels 21L and 21R is not released.

[0049] Further, when it becomes unnecessary to apply the normal braking force, the adjustment unit 124 transmits a second braking force adjustment signal for canceling the normal braking force to the corresponding electric braking device 60. The case where it becomes unnecessary to apply the normal braking force includes, in addition to the case where the adjustment of the front wheel steering angle based on the first steering angle adjustment signal is completed, the case where both of the electric braking devices 62L and 62R for the rear wheels are operating normally and the case where the magnitude of the road surface gradient θ is less than the gradient determination value θth.

[0050] The processing content of the adjustment unit 124 when the vehicle 10 resumes driving will be described. In the apply process based on a parking brake request from the driver, when the front wheel steering angle is adjusted based on the first steering angle adjustment signal, the front wheel steering angle can become a steering angle unintended by the driver. Therefore, it is preferable that the front wheel steering angle has returned to the original steering angle by the time the driver resumes driving the vehicle 10. Thus, when the adjustment unit 124 detects a boarding operation, which is an operation in which a passenger boards the vehicle 10, the adjustment unit 124 transmits a second steering angle adjustment signal for returning the front wheel steering angle to the steering angle before the adjustment based on the first steering angle adjustment signal to the electric steering device 40 via the steering control device 90. The adjustment unit 124 detects a boarding operation, for example, when a driver carrying a mobile device approaches the vehicle 10, when the vehicle door is unlocked, when the vehicle door performs an opening operation, when the detection signal of the seating sensor turns on, and when the ignition switch turns on. In this regard, when the boarding operation of the passenger is detected, it is highly likely that the vehicle 10 will start moving.

[0051] Immediately after the adjustment unit 124 detects the occupant getting into the vehicle, the driver may not be operating the braking operation member 32. Therefore, if the front wheel steering angle returns to its original angle by transmitting the second steering angle adjustment signal immediately after detecting the occupant getting into the vehicle, there may be insufficient moment to counteract the moment M that would cause the vehicle 10 to turn. In other words, if the front wheel steering angle is returned to its original angle by transmitting the second steering angle adjustment signal immediately after detecting the occupant getting into the vehicle, the vehicle 10 may move.

[0052] Therefore, when the adjustment unit 124 transmits a second steering angle adjustment signal, it transmits a first braking force adjustment signal to the electric braking device 60 corresponding to at least one wheel 20 other than the normal wheel. For example, when the adjustment unit 124 detects a user getting on the vehicle, it may transmit the first braking force adjustment signal before transmitting the second steering angle adjustment signal. Also, when it is no longer necessary to apply normal braking force to at least one wheel 20 other than the normal wheel, the adjustment unit 124 transmits a second braking force adjustment signal to the electric braking device 60 corresponding to that wheel 20. When it is no longer necessary to apply normal braking force, for example, when the driver operates the braking operation member 32.

[0053] <Processing flow performed by the braking control device> Referring to Figure 9, the processing flow performed by the braking control device 100 when parking the vehicle 10 will be explained. In other words, this process is performed when a parking brake request occurs while the vehicle 10 is stopped.

[0054] As shown in Figure 9, when a parking brake request occurs, the braking control device 100 performs an apply process (S11). Then, the electric brakes 62L and 62R for the rear wheels apply parking braking force to the rear wheels 22L and 22R.

[0055] The braking control device 100 then determines whether the electric brakes 62L and 62R for the rear wheels are operating normally (S12). More specifically, the braking control device 100 determines whether parking braking force is applied to both the left rear wheel 22L and the left rear wheel 22R. For example, the braking control device 100 can determine whether the electric brakes 62L and 62R for the rear wheels are operating normally by determining whether a pressing force corresponding to the required parking braking force is generated in each of the electric brakes 62L and 62R for the rear wheels.

[0056] If both the rear-wheel electric braking devices 62L and 62R are functioning normally (S12: YES), that is, if the vehicle 10 can be kept parked without adjusting the front wheel steering angle, the braking control device 100 terminates this process.

[0057] In step S12, if an abnormality occurs in one of the rear-wheel electric brakes 62L or 62R (S12: NO), that is, if a specific condition occurs, the braking control device 100 determines whether the magnitude of the road surface gradient θ is less than the gradient determination value θth (S13). If an abnormality occurs in one of the rear-wheel electric brakes 62L or 62R, it is preferable for the braking control device 100 to notify the driver that an abnormality has occurred in one of the rear-wheel electric brakes 62L or 62R.

[0058] If the magnitude of the road surface gradient θ is less than the gradient determination value θth (S13: YES), that is, if the parking of the vehicle 10 can be maintained with only the parking braking force applied by the normal electric brake system 60 without adjusting the front wheel steering angle, the braking control device 100 terminates this process. On the other hand, if the magnitude of the road surface gradient θ is greater than or equal to the gradient determination value θth (S13: NO), that is, if there is a possibility that the parking of the vehicle 10 cannot be maintained without adjusting the front wheel steering angle, the braking control device 100 transmits a first braking force adjustment signal to the electric brake systems 61L and 61R for the front wheels (S14). Then, the electric brake systems 61L and 61R for the front wheels apply normal braking force to the front wheels 21L and 21R. Subsequently, the braking control device 100 identifies the normal wheels based on the determination result of step S12 (S15). More specifically, the braking control device 100 identifies the wheel 20 to which parking braking force is applied among the rear wheels 22L and 22R as a normal wheel.

[0059] Next, the braking control device 100 estimates a moment M around an axis perpendicular to the contact surface of the normal wheel, based on the attitude information and the position of the normal wheel, which is a moment M that would cause the vehicle 10 to turn (S16). After that, the braking control device 100 calculates the amount of adjustment of the front wheel steering angle necessary to counteract the moment M estimated in step S16 (S17). Next, the braking control device 100 determines whether or not it has detected the occupant disembarking (S18). If the occupant disembarking cannot be detected (S18: NO), the braking control device 100 proceeds to step S18. In other words, the braking control device 100 waits for the occupant to disembark. If the occupant disembarking can be detected (S18: YES), the braking control device 100 transmits a first steering angle adjustment signal, including the amount of adjustment of the front wheel steering angle, to the electric steering device 40 (S19). Then, the electric steering device 40 adjusts the steering angle of the front wheels based on the first steering angle adjustment signal. As a result, even without applying normal braking force to the front wheels 21L and 21R, the movement of the vehicle 10 is suppressed by the moment M estimated in step S16.

[0060] Subsequently, the braking control device 100 stores the amount of adjustment to the front wheel steering angle (S20). Furthermore, the braking control device 100 turns on a steering angle adjustment flag indicating whether or not the front wheel steering angle has been adjusted (S21). The steering angle adjustment flag is off when this process starts. In other words, the steering angle adjustment flag is turned on only when the front wheel steering angle is adjusted. Then, the braking control device 100 transmits a second braking force adjustment signal to the electric brakes 61L and 61R for the front wheels (S22). As a result, the electric brakes 61L and 61R for the front wheels release the normal braking force that was applied to the front wheels 21L and 21R. After that, the braking control device 100 terminates this process.

[0061] In step S12 of the flowchart above, it is possible that an abnormality has occurred in both the rear wheel electric braking devices 62L and 62R. In this case, it is preferable that the braking control device 100 notifies the driver of the abnormality through the vehicle 10's display and warning lights. Furthermore, it is preferable that the braking control device 100 prompts the driver to move to a flat surface or to set wheel chocks on the wheels 20.

[0062] In step S19 of the flowchart above, there may be cases where simply adjusting the front wheel steering angle is insufficient to counteract the moment M estimated in step S16. In this case, it is preferable for the braking control device 100 to notify the driver that the above situation has occurred via the vehicle's display and warning lights. Furthermore, it is preferable for the braking control device 100 to encourage the driver to move to a flat surface or to set wheel chocks on the wheels 20.

[0063] Referring to Figure 10, the processing flow executed by the braking control device 100 after the parking of the vehicle 10 is completed will be explained. As shown in Figure 10, the braking control device 100 determines whether or not it has detected the boarding motion of an occupant (S31). If it cannot detect the boarding motion of an occupant (S31: NO), the braking control device 100 terminates this process. On the other hand, if it has detected the boarding motion of an occupant (S31: YES), the braking control device 100 determines whether or not the steering angle adjustment flag is on (S32). If the steering angle adjustment flag is off (S32: NO), that is, if the front wheel steering angle was not adjusted in the most recent apply process, the braking control device 100 terminates this process. On the other hand, if the steering angle adjustment flag is on (S32: YES), that is, if the front wheel steering angle was adjusted in the most recent apply process, the braking control device 100 transmits a first braking force adjustment signal to the electric brakes 61L and 61R for the front wheels (S33). Then, the electric braking devices 61L and 61R for the front wheels apply normal braking force to the front wheels 21L and 21R.

[0064] Subsequently, the braking control device 100 calculates a return adjustment amount, which is the amount of adjustment to the front wheel steering angle, in order to return the front wheel steering angle to the steering angle before the most recent apply process was executed (S34). For example, the return adjustment amount for the front wheel steering angle is the value obtained by inverting the sign of the adjustment amount for the front wheel steering angle in the most recent apply process that is stored. Then, the braking control device 100 transmits a second steering angle adjustment signal, which includes the return adjustment amount for the front wheel steering angle, to the electric steering device 40 (S35). The electric steering device 40 then adjusts the front wheel steering angle based on the second steering angle adjustment signal. As a result, the front wheel steering angle returns to the front wheel steering angle before the most recent apply process was executed. Then, the braking control device 100 turns off the steering angle adjustment flag (S36). Subsequently, the braking control device 100 terminates this process.

[0065] <Operation and Effects of This Embodiment> Referring to Figures 11(a) to (d), the operation when parking a vehicle 10 on an inclined road surface will be described. The magnitude of the road surface gradient θ on the road surface where the vehicle 10 is located is greater than or equal to the gradient determination value θth.

[0066] As shown in Figure 11, when a parking brake request occurs at timing t11, the braking control device 100 starts the apply process. As a result, parking brake force is applied to the rear wheels 22L and 22R. As shown in Figure 11(a), under specific circumstances where a malfunction occurs in one of the rear electric brake devices 62L and 62R, parking brake force is not applied to one of the rear wheels 22L and 22R, as shown by the solid line. However, as shown by the dashed line, parking brake force is applied to the other rear wheel 22L and 22R.

[0067] At timing t11, when it becomes clear that the apply process is being executed under specific conditions, the braking control device 100 transmits a first braking force adjustment signal to the electric brakes 61L and 61R for the front wheels, thereby applying normal braking force to the front wheels 21L and 21R. In the case shown in Figure 11(b), normal braking force corresponding to the braking operation amount has already been applied before timing t11. In other words, at timing t11, the system transitions from a state where braking force corresponding to the braking operation amount is applied to a state where braking force corresponding to the first braking force adjustment signal is applied.

[0068] At timing t11 or later, the braking control device 100 estimates the moment M generated in the vehicle 10 based on the attitude information and the position of the normal wheels. At timing t12, when the braking control device 100 detects the occupant's disembarking motion, it transmits a first steering angle adjustment signal to the electric steering device 40. In this way, the braking control device 100 starts adjusting the front wheel steering angle. Here, the adjustment of the front wheel steering angle starts after the occupant's disembarking motion is detected. Therefore, the braking control device 100 can suppress causing discomfort to the occupant of the vehicle 10 by adjusting the front wheel steering angle. In particular, when the disembarking motion is an action that moves the occupant far away from the vehicle 10, the braking control device 100 can further suppress causing discomfort to the occupant of the vehicle 10 by adjusting the front wheel steering angle.

[0069] At timing t13, the adjustment of the front wheel steering angle is completed. Therefore, the braking control device 100 releases the normal braking force applied to the front wheels 21L and 21R by transmitting a second braking force adjustment signal to the electric brakes 61L and 61R for the front wheels. In this way, the braking control device 100 can maintain the parking of the vehicle 10 even under specific conditions by adjusting the front wheel steering angle based on attitude information and the position of the normal wheels. In other words, the braking control device 100 can improve the parking performance of the vehicle 10.

[0070] The period from timing t13 to timing t21 is the period during which the occupant is away from the vehicle 10. At timing t21, when the braking control device 100 detects the occupant getting into the vehicle, it transmits a first braking force adjustment signal to the electric brakes 61L and 61R for the front wheels. As a result, normal braking force is applied to the front wheels 21L and 21R. At timing t22, the braking control device 100 transmits a second steering angle adjustment signal to the electric steering device 40 in order to return the front wheel steering angle adjusted in the most recent apply process back to its original steering angle. As a result, the front wheel steering angle begins to change. At timing t23, the front wheel steering angle returns to the steering angle at timing t12.

[0071] In this manner, the braking control device 100 applies normal braking force to the front wheels 21L and 21R while returning the front wheel steering angle to its pre-adjustment position. Therefore, the braking control device 100 can suppress the movement of the vehicle 10 due to the moment M generated in the vehicle 10 when returning the front wheel steering angle to its pre-adjustment position. Furthermore, in this embodiment, the occupant's boarding action is the action of the occupant approaching the vehicle 10. Therefore, the braking control device 100 can return the front wheel steering angle to its pre-adjustment position before the occupant boards the vehicle 10. As a result, the driver is less likely to feel any discomfort when resuming driving the vehicle 10.

[0072] At timing t23 or later, the braking control device 100, for example, when the driver starts operating the braking operation member 32, transitions from a state in which braking force corresponding to the first braking force adjustment signal is applied to a state in which braking force corresponding to the amount of braking operation is applied. In addition, the braking control device 100 executes a release process when a request to release the parking brake occurs.

[0073] <Examples of Modifications> This embodiment can be implemented with the following modifications. This embodiment and the following examples of modifications can be combined with each other to the extent that they do not contradict each other technically.

[0074] - When the braking control device 100 performs the apply process under specific conditions, it does not need to determine whether or not to transmit the first steering angle adjustment signal based on the magnitude of the road surface gradient θ. For example, in the flowchart shown in Figure 9, the process in step S13 may be omitted.

[0075] - The larger the estimated moment M, the higher the probability that the vehicle 10 will move after the apply process is executed. Therefore, the braking control device 100 may determine whether or not to transmit the first steering angle adjustment signal based on the estimated moment M. In this case, the braking control device 100 can determine whether or not to transmit the first steering angle adjustment signal more accurately.

[0076] - The braking control device 100 adjusts the front wheel steering angle based on the first steering angle adjustment signal, but does not have to adjust the front wheel steering angle based on the second steering angle adjustment signal. In this case, the driver needs to pay attention to the direction in which the vehicle 10 will move when resuming driving the parked vehicle 10. In this respect, it is preferable that the braking control device 100 prompts the driver to pay attention to this matter via the vehicle 10's display and speaker, etc. Alternatively, the braking control device 100 may adjust the front wheel steering angle based on the second steering angle adjustment signal in the release process executed in response to the occurrence of a parking brake release request. In other words, the trigger for the braking control device 100 to transmit the second steering angle adjustment signal does not have to be the occupant getting into the vehicle.

[0077] - When both the front wheels 21L, 21R and the rear wheels 22L, 22R are steering wheels, the first steering angle adjustment signal and the second steering angle adjustment signal may be signals for adjusting the steering angles of both the front wheels 21L, 21R and the rear wheels 22L, 22R. In this case, the adjustment amounts for the front wheel steering angles and the rear wheel steering angles may be equal or different.

[0078] - The amount of adjustment of the front wheel steering angle by the second steering angle adjustment signal may be smaller than the amount of adjustment of the front wheel steering angle by the first steering angle adjustment signal. In other words, the second steering angle adjustment signal only needs to be a signal that brings the steering angle closer to the steering angle before the adjustment based on the first steering angle adjustment signal is made.

[0079] - When the braking control device 100 performs the apply process under specific circumstances, it does not need to transmit the first braking force adjustment signal to the electric brakes 61L and 61R for the front wheels. In other words, the braking control device 100 may adjust the front wheel steering angle based on the first steering angle adjustment signal without applying parking braking force to the front wheels 21L and 21R. In this case, it is preferable to quickly adjust the front wheel steering angle based on the first steering angle adjustment signal so that the vehicle 10 does not move due to the moment M generated in the vehicle 10.

[0080] - When a parking brake request occurs, the braking control device 100 may promptly transmit the first steering angle adjustment signal without waiting for the occupants to disembark. In other words, in the flowchart shown in Figure 9, the process in step S18 can be omitted.

[0081] The braking control device 100 may estimate the moment M generated in the vehicle 10 or calculate the amount of adjustment for the front wheel steering angle even when the magnitude of the road surface gradient θ is less than the gradient determination value θth. In other words, in the flowchart shown in Figure 9, the processing in step S13 may be a processing after step S17. Thus, the braking control device 100 may not transmit the first steering angle adjustment signal to the electric steering device 40 when the road surface gradient θ is less than the gradient determination value θth.

[0082] - If the front wheel steering angle is not adjusted even after the braking control device 100 transmits the first steering angle adjustment signal, it is preferable to notify the driver of this fact. In this case, the braking control device 100 may instruct the driver to operate the steering member 31 in the direction specified by the first steering angle adjustment signal.

[0083] - If the braking control device 100 transmits a first braking force adjustment signal but does not apply normal braking force to the front wheels 21L and 21R, it is preferable to notify the driver of this fact. In this case, the braking control device 100 may instruct the driver to operate the braking operating member 32 until the adjustment of the front wheel steering angle based on the first steering angle adjustment signal is completed.

[0084] - When the braking control device 100 performs an apply process under specific circumstances, if it determines that the vehicle 10 may move even if the front wheel steering angle is adjusted, it may calculate the amount to adjust the front wheel steering angle so that the vehicle 10 moves in a safe direction. For example, in the above case, the braking control device 100 may calculate the amount to adjust the front wheel steering angle so that the vehicle 10 moves toward the shoulder of the road and parking space.

[0085] - During the execution of the apply process, if the period between transmitting the first braking force adjustment signal and transmitting the second braking force adjustment signal is long, the temperature of the front wheel electric brakes 61L and 61R may rise. Therefore, if the temperature of the front wheel electric brakes 61L and 61R rises after transmitting the first braking force adjustment signal, the braking control device 100 may promptly transmit the first steering angle adjustment signal and the second braking force adjustment signal. In this case, the braking control device 100 may also notify the occupants of this fact.

[0086] - When vehicle 10 is parked on a downhill slope, the ground contact load on the rear wheels 22L and 22R is smaller than when vehicle 10 is parked on an uphill slope or a flat road. Therefore, even if the same amount of parking braking force is applied to the rear wheels 22L and 22R, it is more difficult to maintain the parking position of vehicle 10 when it is parked on a downhill slope than when it is parked on an uphill slope or a flat road. Therefore, when vehicle 10 is parked on a downhill slope, the braking control device 100 may make it easier to maintain the parking position of vehicle 10 by adjusting the front wheel steering angle based on the first steering angle adjustment signal.

[0087] - The above embodiment is an embodiment in which the "control device" is embodied in the braking control device 100, but the "control device" may also be embodied in the steering control device 90, the driving control device, or other control devices of the vehicle 10.

[0088] The braking control device 100 is not limited to a processing circuit 110 that includes a CPU 111 and a memory 112 and executes software processing. For example, the braking control device 100 may include a dedicated hardware circuit that executes at least a part of the various processes performed in the above embodiment. An example of a dedicated hardware circuit is an ASIC. ASIC is an abbreviation for "Application Specific Integrated Circuit". In other words, the braking control device 100 may have any of the following configurations (a) to (c).

[0089] (a) A processing circuit comprising a processing unit that executes all of the above processes according to a program, and a program storage device such as memory for storing the program. (b) A processing circuit comprising a processing unit and a program storage device that execute a part of the above processes according to a program, and a dedicated hardware circuit that executes the remaining processes.

[0090] (c) A processing circuit equipped with dedicated hardware circuits to perform all of the above processing. Here, there may be multiple software execution devices equipped with processing units and program storage devices, and multiple dedicated hardware circuits.

[0091] As used herein, the expression "at least one" means "one or more" of the desired options. For example, as used herein, if there are two options, the expression "at least one" means "only one option" or "both of the two options." As another example, as used herein, the expression "at least one" means "only one option" or "any combination of two or more options" if there are three or more options.

Claims

1. A control device applied to a vehicle comprising: a plurality of wheels; two electric parking brake devices that apply parking braking force to two wheels in a pair, left and right, by maintaining the position of the friction material while pressing it against a rotating body that rotates with the wheels; an electric steering device that adjusts the steering angle of two wheels in a pair, left and right, among the plurality of wheels; and a posture information detection unit that detects posture information including the tilt of the vehicle in the longitudinal direction and the tilt in the lateral direction, wherein, in a situation in which a malfunction occurs in only one of the two parking brake devices, the control device comprises: a moment estimation unit that estimates the moment generated in the vehicle based on the posture information and the position of the wheels to which the normal parking brake device can apply the parking braking force; and an adjustment unit that transmits a first steering angle adjustment signal to the steering device for adjusting the steering angle in a direction that cancels out the moment.

2. The control device according to claim 1, wherein the vehicle further comprises an electric conventional braking device, which is a device different from the parking brake device, and which applies conventional braking force to the plurality of wheels by pressing a friction material against a rotating body that rotates with the wheels, and in a situation in which a malfunction occurs in only one of the two parking brake devices, the adjustment unit transmits a first braking force adjustment signal to the conventional braking device for applying conventional braking force to at least one of the plurality of wheels, excluding the wheel to which the normal parking brake device is applying parking braking force, until the steering device completes the adjustment of the steering angle based on the first steering angle adjustment signal.

3. In a situation in which a malfunction occurs in only one of the two parking brake devices, the control device according to claim 2, wherein the adjustment unit transmits the first braking force adjustment signal to the normal brake device and transmits a second steering angle adjustment signal to the steering device to return the steering angle to the steering angle before the adjustment based on the first steering angle adjustment signal is made, if there is a high probability that the vehicle will start moving.

4. In a situation in which a malfunction occurs in only one of the two parking brake devices, the control device according to any one of claims 1 to 3, wherein the adjustment unit does not transmit the first steering angle adjustment signal to the steering device if the gradient of the road surface on which the vehicle is stopped is less than the gradient determination value.

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