Vehicle control device and vehicle control method
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ADVICS CO LTD
- Filing Date
- 2025-12-17
- Publication Date
- 2026-08-06
Smart Images
Figure JP2025044018_06082026_PF_FP_ABST
Abstract
Description
Vehicle control device and vehicle control method
[0001] The present disclosure relates to a vehicle control device and a vehicle control method.
[0002] Patent Document 1 discloses a control device that executes a deceleration correction control for suppressing a change in the posture of a vehicle at the time of vehicle stop by reducing the braking force when the vehicle with the braking force applied thereto is about to stop.
[0003] Japanese Patent Application Laid-Open No. 2016-28913
[0004] Even when the vehicle is stopped by applying a braking force, the drive device of the vehicle applies a driving force to the vehicle. Therefore, if the driving force applied from the drive device to the vehicle when the vehicle is about to stop is not considered, when the vehicle is stopped by applying a braking force to the vehicle, the actual stop position of the vehicle may deviate from the target stop position.
[0005] A vehicle control device according to an aspect of the present disclosure includes a gradient estimation unit configured to calculate a gradient estimation value that is an estimated value of a gradient of a road surface on which the vehicle travels, a required deceleration acquisition unit configured to acquire a required deceleration that is a required value of a deceleration of the vehicle, a determination unit configured to determine whether or not the stop of the vehicle can be maintained by applying a braking force corresponding to the required deceleration to the vehicle when the vehicle stops based on the gradient estimation value, and a setting unit configured to set a target driving force that is a target value of a driving force applied to the vehicle. The setting unit executes a first setting process of setting the target driving force to be smaller as the required deceleration is larger when it is determined by the determination unit that the stop of the vehicle cannot be maintained in a situation where the road surface is not a downhill road, and executes a second setting process of setting the target driving force to be smaller than the target driving force set when the first setting process is executed when it is determined by the determination unit that the stop of the vehicle can be maintained.
[0006] A vehicle control method according to another aspect of the present disclosure includes: calculating a gradient estimate, which is an estimated value of the gradient of the road surface on which the vehicle is traveling; obtaining a required deceleration, which is a required value of the degree of deceleration of the vehicle; determining, based on the gradient estimate, whether the vehicle can be kept stopped by applying a braking force to the vehicle corresponding to the required deceleration when the vehicle stops; and setting a target driving force, which is a target value of the driving force applied to the vehicle. Setting the target driving force includes, when it is determined that the vehicle cannot be kept stopped in a situation where the road surface is not a downhill road, executing a first setting process to set the target driving force to be smaller the greater the required deceleration; and when it is determined that the vehicle can be kept stopped, executing a second setting process to set the target driving force to be smaller than the target driving force set when the first setting process is executed.
[0007] Figure 1 is a schematic diagram showing a vehicle equipped with the vehicle control device of the first embodiment. Figure 2 is a flowchart showing the first half of a series of processes performed by the vehicle control device of Figure 1. Figure 3 is a flowchart showing the second half of a series of processes performed by the vehicle control device of Figure 1. Figure 4 is a timing chart showing the changes in various parameters when the vehicle in Figure 1 is stopped by applying braking force. Figure 5 is a timing chart showing the changes in various parameters when the vehicle equipped with the vehicle control device of the second embodiment is stopped by applying braking force.
[0008] (First Embodiment) A first embodiment of the vehicle control device and vehicle control method will be described with reference to Figures 1 to 4. <Vehicle Configuration> Figure 1 shows a vehicle 10 to which the motion control device 70 is applied. The motion control device 70 corresponds to the "vehicle control device". The vehicle 10 further includes a drive operating member 11, a brake operating member 12, a plurality of wheels 13, a drive device 20, a brake device 30, and a plurality of sensors. In Figure 1, only one of the plurality of wheels 13 is shown.
[0009] <Operating Members> The drive operating member 11 is a member operated by the driver when adjusting the acceleration of the vehicle 10. An example of a drive operating member 11 is the accelerator pedal. The brake operating member 12 is a member operated by the driver when adjusting the deceleration of the vehicle 10. An example of a brake operating member 12 is the brake pedal.
[0010] <Drive System> The drive system 20 comprises a power unit 21 and a drive control device 25. The power unit 21 has at least a motor generator 22 among an engine and a motor generator as a power source for the vehicle 10. In other words, the vehicle 10 is an electric vehicle such as a hybrid vehicle or a battery vehicle.
[0011] The motor-generator 22 functions as an electric motor, enabling the power unit 21 to provide a driving force Fd to the vehicle 10. The motor-generator 22 functions as a generator, enabling the power unit 21 to provide a regenerative braking force FbE to the vehicle 10.
[0012] The drive control device 25 includes a processing circuit 26 that controls the power unit 21. An example of the processing circuit 26 is an electronic control device. In this case, the processing circuit 26 has a CPU and a memory that stores a control program executed by the CPU. By the CPU executing the control program in the memory, the processing circuit 26 can control the power unit 21.
[0013] The drive control device 25 is capable of sending and receiving various information and commands with other onboard control devices via the in-vehicle network 60. "Other onboard control devices" here include the braking control device 45 and the motion control device 70, which will be described later. An example of the in-vehicle network 60 is a CAN bus. CAN is an abbreviation for "Controller Area Network".
[0014] <Braking System> The braking system 30 includes multiple friction brakes 31 corresponding to each of the multiple wheels 13, a braking actuator 41, and a braking control device 45. Figure 1 shows only one of the multiple friction brakes 31.
[0015] Each of the multiple friction brakes 31 has a wheel cylinder 32, a rotating body 33, and a friction part 34. The rotating body 33 rotates integrally with the wheel 13. Therefore, by pressing the friction part 34 against the rotating body 33, a frictional braking force is generated on the corresponding wheel 13. The force pressing the friction part 34 against the rotating body 33 increases as the wheel pressure, which is the hydraulic pressure inside the wheel cylinder 32, increases. Therefore, the friction brake 31 can generate a greater frictional braking force on the wheel 13 as the wheel pressure increases.
[0016] The braking actuator 41 is configured to adjust the wheel pressure of multiple wheel cylinders 32. For example, the braking actuator 41 has a pressurizing source that can supply brake fluid to multiple wheel cylinders 32. The pressurizing source is, for example, an electric pump and an electric cylinder. The brake fluid discharged from the braking actuator 41 is supplied to the wheel cylinders 32 via the supply passage 42.
[0017] Hereafter, the sum of the frictional braking forces generated by multiple wheels 13 will be referred to as "frictional braking force FbM applied to the vehicle 10". Furthermore, the sum of the frictional braking force FbM and the regenerative braking force FbE will be referred to as "braking force Fb applied to the vehicle 10".
[0018] The braking control device 45 includes a processing circuit 46 that controls the braking actuator 41. An example of the processing circuit 46 is an electronic control device. In this case, the processing circuit 46 has a CPU and a memory that stores a control program executed by the CPU. By executing the control program in the memory, the processing circuit 46 can control the braking actuator 41.
[0019] The braking control device 45 is capable of sending and receiving various information and commands with other onboard control devices via the in-vehicle network 60. The "other onboard control devices" referred to here include the drive control device 25 and the motion control device 70.
[0020] <Sensors> The multiple sensors include an accelerator sensor 51, a brake sensor 52, multiple wheel speed sensors 53, and front and rear acceleration sensors 54.
[0021] The accelerator sensor 51 detects information related to the driver's operation of the drive control member 11. An example of the accelerator sensor 51 is a stroke sensor that detects the amount of operation of the driver's drive control member 11. The detection signal from the accelerator sensor 51 is output to the drive control device 25.
[0022] The brake sensor 52 detects information related to the driver's operation of the braking control member 12. An example of the brake sensor 52 is a stroke sensor that detects the amount of operation of the driver's braking control member 12. The detection signal from the brake sensor 52 is output to the braking control device 45. The vehicle 10 may also be equipped with a sensor that detects the force of the driver's operation of the braking control member 12.
[0023] The vehicle 10 is equipped with the same number of wheel speed sensors 53 as there are wheels 13. Figure 1 shows only one of the multiple wheel speed sensors 53. The wheel speed sensor 53 detects the rotational speed of the corresponding wheel 13. The detection signal from the wheel speed sensor 53 is output to the braking control device 45.
[0024] The longitudinal acceleration sensor 54 detects the longitudinal acceleration of the vehicle 10. The detection signal from the longitudinal acceleration sensor 54 is output to the motion control device 70. Hereafter, the amount of operation of the drive operating member 11 based on the detection signal from the accelerator sensor 51 will be referred to as "drive operation amount INd". The amount of operation of the braking operating member 12 based on the detection signal from the brake sensor 52 will be referred to as "braking operation amount INb". The rotational speed of the wheel 13 based on the detection signal from the wheel speed sensor 53 will be referred to as "wheel speed VW". The longitudinal acceleration based on the detection signal from the longitudinal acceleration sensor 54 will be referred to as "longitudinal acceleration Gx".
[0025] Furthermore, various types of information detected by the sensors are shared among multiple control devices 25, 45, and 70 via the in-vehicle network 60. <Motion control device> The motion control device 70 includes a processing circuit 71 that sets a target driving force FdTr, which is a target value of the driving force Fd to be applied to the vehicle 10 when a braking request is made to the vehicle 10. An example of the processing circuit 71 is an electronic control device. In this case, the processing circuit 71 has a CPU 72, a first memory 73, and a second memory 74. The first memory 73 stores a control program executed by the CPU 72. The second memory 74 stores the calculation results of the CPU 72, etc. By the CPU 72 executing the control program in the first memory 73, the processing circuit 71 performs various processes to set the target driving force FdTr.
[0026] <Functional Configuration of Multiple Processing Circuits> The processing circuit 26 of the drive control device 25 functions as a drive control unit 101 and a regenerative control unit 102 when the CPU executes a control program in the memory.
[0027] The processing circuit 46 of the braking control device 45 functions as a braking control unit 111 when the CPU executes a control program for the memory. The processing circuit 71 of the motion control device 70 functions as a plurality of functional units when the CPU 72 executes a control program for the first memory 73. The plurality of functional units include a gradient estimation unit 121, a gradient actual value acquisition unit 122, a holding braking force acquisition unit 123, a requested deceleration acquisition unit 124, a determination unit 125, and a setting unit 126.
[0028] The braking control unit 111 adjusts the braking force Fb applied to the vehicle 10 when a braking request is received for the vehicle 10. Specifically, the braking control unit 111 derives the required deceleration DVSRq, which is the required value of the deceleration degree of the vehicle 10, based on the braking operation amount INb. For example, the braking control unit 111 derives the required deceleration DVSRq such that the value increases as the braking operation amount INb increases. The braking control unit 111 derives the value obtained by converting the required deceleration DVSRq into braking force as the required braking force FbRq. As a result, the required braking force FbRq increases as the required deceleration DVSRq increases.
[0029] The braking control unit 111 transmits the requested deceleration DVSRq to the motion control device 70's requested deceleration acquisition unit 124 at predetermined control cycles. The braking control unit 111 also transmits the requested braking force FbRq to the drive control device 25's regenerative control unit 102 at predetermined control cycles.
[0030] The regenerative braking control unit 102 derives a target regenerative braking force FbETr, which is the target value of the regenerative braking force FbE, based on the requested braking force FbRq. The regenerative braking control unit 102 sets the target regenerative braking force FbETr to the larger of the requested braking force FbRq and the limit regenerative braking force FbEL. The limit regenerative braking force FbEL is the maximum regenerative braking force that the motor generator 22 can currently apply to the vehicle 10, or a regenerative braking force slightly smaller than that maximum value. The regenerative braking control unit 102 applies the regenerative braking force FbE to the vehicle 10 by driving the motor generator 22 based on the target regenerative braking force FbETr.
[0031] The braking control unit 111 acquires the regenerative braking force FbE that the motor generator 22 applies to the vehicle 10. If the regenerative braking force FbE is greater than or equal to the required braking force FbRq, the braking control unit 111 sets the target friction braking force FbMTr, which is the target value of the friction braking force FbM, to 0 (zero). On the other hand, if the regenerative braking force FbE is less than the required braking force FbRq, the braking control unit 111 sets the target friction braking force FbMTr to the magnitude of the difference between the required braking force FbRq and the regenerative braking force FbE. Then, the braking control unit 111 applies the friction braking force FbM to the vehicle 10 by operating the braking actuator 41 based on the target friction braking force FbMTr. In this way, the braking control unit 111 can apply the braking force Fb corresponding to the required braking force FbRq, i.e., the required deceleration DVSRq, to the vehicle 10.
[0032] Furthermore, when the vehicle speed VS of the vehicle 10 falls below the low-speed determination speed VSth1, the braking control unit 111 performs substitution control to substitute the regenerative braking force FbE with the friction braking force FbM. The vehicle speed VS is the travel speed of the vehicle 10 calculated based on the wheel speeds VW of the multiple wheels 13. In substitution control, the braking control unit 111 instructs the regenerative control unit 102 to reduce the regenerative braking force FbE so that it becomes 0 (zero) before the vehicle speed VS reaches a specified speed. Then, the regenerative control unit 102 reduces the target regenerative braking force FbETr to 0 (zero) in accordance with this instruction and operates the motor generator 22 based on the target regenerative braking force FbETr. At this time, the braking control unit 111 sets the magnitude of the difference between the acquired regenerative braking force FbE and the required braking force FbRq as the target friction braking force FbMTr, and then operates the braking actuator 41 based on the target friction braking force FbMTr. As a result, the braking control unit 111 can replace the regenerative braking force FbE with the friction braking force FbM before the vehicle 10 comes to a stop.
[0033] The braking control unit 111 may perform a stop-hold control when the vehicle 10 is stopped by the application of a braking force Fb (i.e., friction braking force FbM) and predetermined holding conditions are met. The predetermined holding conditions include, for example, the vehicle 10 being stopped on an uphill road. In the stop-hold control, the braking control unit 111 operates the braking actuator 41 to maintain the braking force Fb even if the braking operation amount INb decreases, i.e., even if the required deceleration DVSRq decreases.
[0034] When the braking control unit 111 is performing a stop-hold control, it terminates the stop-hold control when a predetermined termination condition is met. That is, the braking control unit 111 operates the braking actuator 41 so that the braking force Fb (i.e., friction braking force FbM) decreases to 0 (zero). The predetermined termination condition includes, for example, the start of operation of the drive operating member 11 and the elapsed time since the release of operation of the braking operating member 12 exceeds a predetermined time.
[0035] The drive control unit 101 adjusts the driving force Fd applied to the vehicle 10. For example, when the drive operating member 11 is operated, the drive control unit 101 derives a target driving force FdTr, which is a target value of the driving force Fd, based on the drive operation amount INd. For example, the drive control unit 101 derives the target driving force FdTr such that the value increases as the drive operation amount INd increases. Also, when another onboard control device requests that the vehicle 10 be accelerated, the drive control unit 101 sets the driving force corresponding to that request to the target driving force FdTr. Then, the drive control unit 101 operates the power unit 21 based on the target driving force FdTr. In this way, the drive control unit 101 can apply the driving force Fd to the vehicle 10.
[0036] Incidentally, in the case of vehicle 10, a driving force Fd may be applied even when the drive operating member 11 is not being operated. More specifically, when vehicle 10 is traveling at a very low speed or when vehicle 10 is stopped, a driving force Fd equivalent to the creep torque in a conventional vehicle may be applied to vehicle 10. A conventional vehicle is a vehicle that is equipped with only the engine among the engine and motor generator as the power source of the vehicle, and has a torque converter arranged in the power transmission path.
[0037] Multiple functional units 121 to 126 of the motion control device 70 are functional units for setting the target driving force FdTr when the vehicle 10 is traveling at a very low speed or when the vehicle 10 is stopped.
[0038] The gradient estimation unit 121 calculates a gradient estimate θe, which is an estimated value of the gradient of the road surface on which the vehicle 10 travels. The gradient estimation unit 121 calculates the vehicle acceleration DVS by differentiating the vehicle speed VS of the vehicle 10 with respect to time. For example, the gradient estimation unit 121 calculates the difference ΔDVS using the following relational expression (D1). In this case, the gradient estimation unit 121 calculates a positive value as the difference ΔDVS when the road surface is an uphill road, and a negative value as the difference ΔDVS when the road surface is a downhill road.
[0039] ΔDVS = DVS - Gx ... (D1) The gradient estimation unit 121 calculates the gradient estimate θe by converting the calculated difference ΔDVS into a gradient.
[0040] The gradient value acquisition unit 122 acquires the gradient value θr, which is the gradient of the road surface where the vehicle 10 is located, when the vehicle 10 is stopped. When the vehicle 10 is stopped, the vehicle acceleration DVS is 0 (zero). Therefore, the gradient value acquisition unit 122 calculates the difference ΔDVS by substituting 0 (zero) into "DVS" in the above relational expression (D1). The gradient value acquisition unit 122 acquires the calculated difference ΔDVS converted into a gradient as the gradient value θr.
[0041] The holding brake force acquisition unit 123 derives the holding brake force FbH, which is the braking force required to maintain the vehicle 10's stop when the vehicle 10 has come to a halt. For example, the holding brake force acquisition unit 123 acquires the lower limit value FbL of the braking force Fb that can maintain the vehicle 10's stop on the road surface, or the sum of the lower limit value FbL and a predetermined offset value, as the holding brake force FbH. The lower limit value FbL increases as the magnitude of the gradient estimate value θe increases. Therefore, the holding brake force acquisition unit 123 acquires a holding brake force FbH that is larger as the magnitude of the gradient estimate value θe increases.
[0042] The requested deceleration acquisition unit 124 acquires the requested deceleration DVSRq. For example, the requested deceleration acquisition unit 124 acquires the requested deceleration DVSRq transmitted by the braking control unit 111. The determination unit 125 determines whether the vehicle 10 can be kept stopped by applying a braking force to the vehicle 10 corresponding to the requested deceleration DVSRq when the vehicle 10 has stopped. The determination unit 125 acquires the value obtained by converting the requested deceleration DVSRq into braking force as the requested braking force FbRq. The determination unit 125 then determines that the vehicle 10 can be kept stopped if the requested braking force FbRq is equal to or greater than the holding braking force FbH. On the other hand, the determination unit 125 determines that the vehicle 10 cannot be kept stopped if the requested braking force FbRq is less than the holding braking force FbH. As described above, the holding braking force FbH is a braking force derived based on the gradient estimation value θe. Therefore, it can be said that the determination unit 125 determines whether or not it can maintain the vehicle 10 in a stopped position based on the gradient estimate θe.
[0043] When the vehicle 10 is decelerating due to the application of the braking force Fb or the vehicle 10 has stopped due to the application of the braking force Fb, the setting unit 126 sets the target driving force FdTr. Then, the setting unit 126 transmits the set target driving force FdTr to the drive control unit 101.
[0044] The following describes the procedure for setting the target driving force FdTr. The setting unit 126 determines whether the road surface is a downhill road based on the gradient estimated value θe. For example, when the gradient estimated value θe is less than the downhill road determination value θTh1, the setting unit 126 determines that the road surface is a downhill road. On the other hand, when the gradient estimated value θe is greater than or equal to the downhill road determination value θTh1, the setting unit 126 determines that the road surface is not a downhill road, that is, determines that the road surface is a flat road or an uphill road. The criterion for determining whether the road surface is a downhill road is set to the downhill road determination value θTh1. For example, as shown in FIG. 4(a), a value slightly smaller than 0 (zero) is set as the downhill road determination value θTh1.
[0045] Further, when the setting unit 126 determines that the road surface is not a downhill road, it determines whether the road surface is an uphill road. For example, when the gradient estimated value θe is greater than or equal to the uphill road determination value θTh2, the setting unit 126 determines that the road surface is an uphill road. On the other hand, when the gradient estimated value θe is less than the uphill road determination value θTh2, the setting unit 126 determines that the road surface is not an uphill road, that is, determines that the road surface is a flat road. The criterion for determining whether the road surface is an uphill road is set to the uphill road determination value θTh2. For example, as shown in FIG. 4(a), a value slightly larger than 0 (zero) is set as the uphill road determination value θTh2.
[0046] When the setting unit 126 determines that the road surface is a downhill road, it sets the target driving force FdTr by the third setting process described later. When the setting unit 126 determines that the road surface is not a downhill road, it selects and executes the first setting process or the second setting process described later based on whether a plurality of conditions (A1), (A2), and (A3) shown below are satisfied.
[0047] (A1) Determining that the road surface is an uphill road. (A2) The magnitude of the gradient estimated value θe is equal to or greater than the steep gradient determination value θTh21. (A3) It is determined by the determination unit 125 that the stop of the vehicle 10 can be maintained.
[0048] The determination criterion for whether it is an uphill road with a relatively large gradient is set to the steep gradient determination value θTh21. Therefore, as shown in Fig. 4(a), the steep gradient determination value θTh21 is larger than the uphill road determination value θTh2.
[0049] Among the plurality of conditions (A1) to (A3), when the condition (A3) is not satisfied, regardless of whether the conditions (A1) and (A2) are satisfied, the setting unit 126 sets the target driving force FdTr by the first setting process. Among the plurality of conditions (A1) to (A3), when only the condition (A2) is not satisfied, the setting unit 126 sets the target driving force FdTr by the second setting process. When both of the conditions (A1) and (A2) are satisfied, regardless of whether the condition (A3) is satisfied, the setting unit 126 sets the target driving force FdTr by the first setting process.
[0050] In the first setting process, the setting unit 126 sets the target driving force FdTr based on the required deceleration DVSRq. The fact that the required deceleration DVSRq is small under the situation where the driver is operating the braking operation member 12 may mean that the driver has the intention to make the vehicle 10 travel slowly, that is, the intention to make the vehicle 10 perform a running like creep running. On the other hand, the fact that the required deceleration DVSRq is large may mean that the driver has the intention to stop the vehicle 10.
[0051] Therefore, in the first setting process, the setting unit 126 sets the target driving force FdTr to be smaller the larger the requested deceleration DVSRq is. Specifically, the setting unit 126 sets the driving force corresponding to the requested deceleration DVSRq to the specified driving force FdK. The specified driving force FdK is the final target value of the target driving force FdTr in the first setting process. Therefore, the setting unit 126 sets the specified driving force FdK to be smaller the larger the requested deceleration DVSRq is. Then, the setting unit 126 changes the target driving force FdTr to the specified driving force FdK at a predetermined rate of change and holds the target driving force FdTr at the specified driving force FdK. In this way, the setting unit 126 can make the target driving force FdTr smaller the larger the requested deceleration DVSRq is.
[0052] In the second setting process, the setting unit 126 sets the target driving force FdTr to be smaller than the target driving force FdTr set when the first setting process is executed. For example, the setting unit 126 sets the target driving force FdTr to 0 (zero).
[0053] In the third setting process, the setting unit 126 sets the specific driving force FdT to the target driving force FdTr. The specific driving force FdT is the final target value of the target driving force FdTr in the third setting process. For example, the specific driving force FdT is greater than 0 (zero). The setting unit 126 changes the target driving force FdTr to the specific driving force FdT at a predetermined rate of change and holds the target driving force FdTr at the specific driving force FdT.
[0054] Here, if the vehicle 10 is not stopped, noise associated with the movement of the vehicle 10 may be superimposed on the detection signals of the longitudinal acceleration sensor 54 and the wheel speed sensor 53. Therefore, the accuracy of the gradient estimate θe is not very high. On the other hand, if the vehicle 10 is stopped, such noise is less likely to be superimposed on the detection signal of the longitudinal acceleration sensor 54. Therefore, the accuracy of the actual gradient value θr is relatively high.
[0055] Therefore, if the power unit 21 is applying a driving force Fd to the vehicle 10 based on the target driving force FdTr set by the second setting process, and the vehicle 10 is stopped by the application of braking force Fb, the setting unit 126 may change the target driving force FdTr according to the actual gradient value θr. For example, if the actual gradient value θr is greater than or equal to the steep gradient determination value θTh21, the setting unit 126 increases the target driving force FdTr. For example, the setting unit 126 increases the target driving force FdTr to the specified driving force FdK. On the other hand, if the actual gradient value θr is less than the steep gradient determination value θTh21, the setting unit 126 maintains the target driving force FdTr.
[0056] Referring to Figures 2 and 3, a series of processes executed by the processing circuit 71 of the motion control device 70 when no acceleration request has been made to the vehicle 10 will be explained. The processing circuit 71 determines that no acceleration request has been made if both of the following conditions are met: the drive operating member 11 is not being operated and no acceleration request for the vehicle 10 has been made from any other on-board control device. If the processing circuit 71 has determined that no acceleration request has been made, it repeatedly executes the series of processes at predetermined control cycles.
[0057] In step S11, the processing circuit 71 determines whether or not a braking request has occurred. For example, the processing circuit 71 determines that a braking request has occurred if at least one of the following conditions is met: the braking operating member 12 is being operated, and another on-board control device has requested deceleration of the vehicle 10. If the processing circuit 71 determines that a braking request has occurred (S11: YES), the processing circuit 71 proceeds to step S13. On the other hand, if the processing circuit 71 determines that no braking request has occurred (S11: NO), the processing circuit 71 terminates the series of processes.
[0058] In step S13, the processing circuit 71 functions as a gradient estimation unit 121 to calculate the gradient estimate θe. In the subsequent step S15, the processing circuit 71 functions as a holding brake force acquisition unit 123 to acquire the holding brake force FbH.
[0059] In the next step S17, the processing circuit 71 functions as a requested deceleration acquisition unit 124 to acquire the requested deceleration DVSRq. In the following step S19, the processing circuit 71 functions as a determination unit 125 to acquire the value obtained by converting the requested deceleration DVSRq into braking force as the requested braking force FbRq.
[0060] In the next step S20, the processing circuit 71 determines whether the vehicle speed VS is less than or equal to the low-speed determination speed VSTh1. The low-speed determination speed VSTh1 is the criterion for determining whether the vehicle 10 is traveling at an extremely low speed. If the vehicle speed VS is less than or equal to the low-speed determination speed VSTh1 (S20: YES), the processing circuit 71 proceeds to step S21. On the other hand, if the vehicle speed VS is greater than the low-speed determination speed VSTh1 (S20: NO), the processing circuit 71 terminates the series of processes.
[0061] In step S21, the processing circuit 71 functions as a determination unit 125 and determines whether the road surface on which the vehicle 10 is located is a downhill road based on the gradient estimate θe calculated in step S13. If the processing circuit 71 determines that the road surface is a downhill road (S21: YES), the processing circuit 71 proceeds to step S23. On the other hand, if the processing circuit 71 determines that the road surface is not a downhill road (S21: NO), the processing circuit 71 proceeds to step S25.
[0062] In step S23, the processing circuit 71, functioning as a setting unit 126, sets the target driving force FdTr by executing a third setting process. The processing circuit 71 then transmits the target driving force FdTr to the drive control device 25. After that, the processing circuit 71 temporarily terminates the series of processes.
[0063] In this case, the processing circuit 26 of the drive control device 25 operates the power unit 21 based on the received target driving force FdTr. In step S25, the processing circuit 71 determines whether or not the vehicle is stopped. Here, "stopped" means that the vehicle 10 is stopped due to the application of braking force Fb. For example, if the duration of the state in which the vehicle speed VS is 0 (zero) is longer than or equal to the determination time, the vehicle 10 can be considered to be stopped, i.e., stationary. On the other hand, if the vehicle speed VS is greater than 0 (zero), or if the duration is less than the determination time, the vehicle can be considered not to be stopped. If the processing circuit 71 determines that the vehicle is stopped (S25: YES), the processing circuit 71 proceeds to step S41. On the other hand, if the processing circuit 71 determines that the vehicle is not stopped (S25: NO), the processing circuit 71 proceeds to step S27.
[0064] In step S27, the processing circuit 71, functioning as a determination unit 125, determines whether the requested braking force FbRq is equal to or greater than the holding braking force FbH. If the requested braking force FbRq is equal to or greater than the holding braking force FbH, it can be considered that the vehicle 10 can be kept stopped by applying a braking force Fb corresponding to the requested deceleration DVSRq to the vehicle 10 when the vehicle 10 has stopped. On the other hand, if the requested braking force FbRq is less than the holding braking force FbH, it can be considered that the vehicle 10 cannot be kept stopped even if a braking force Fb corresponding to the requested deceleration DVSRq is applied to the vehicle 10. If the requested braking force FbRq is equal to or greater than the holding braking force FbH (S27: YES), the processing circuit 71 proceeds to step S29. On the other hand, if the requested braking force FbRq is less than the holding braking force FbH (S27: NO), the processing circuit 71 proceeds to step S31.
[0065] In step S29, the processing circuit 71 functions as a determination unit 125 to determine whether the gradient estimate θe calculated in step S13 is less than the steep gradient determination value θTh21. If the gradient estimate θe is less than the steep gradient determination value θTh21, the vehicle 10 can be considered to be located on a level road or on an uphill road with a relatively gentle gradient. On the other hand, if the gradient estimate θe is greater than or equal to the steep gradient determination value θTh21, the vehicle 10 can be considered to be located on an uphill road with a relatively steep gradient. If the gradient estimate θe is less than or equal to the steep gradient determination value θTh21 (S29: YES), the processing circuit 71 proceeds to step S33. On the other hand, if the gradient estimate θe is greater than or equal to the steep gradient determination value θTh21 (S29: NO), the processing circuit 71 proceeds to step S31.
[0066] In step S31, the processing circuit 71, functioning as a setting unit 126, sets the target driving force FdTr by executing a first setting process. The processing circuit 71 then transmits the target driving force FdTr to the drive control device 25. After that, the processing circuit 71 temporarily terminates the series of processes.
[0067] In this case, the processing circuit 26 of the drive control device 25 operates the power unit 21 based on the received target driving force FdTr. In step S33, the processing circuit 71, functioning as a setting unit 126, sets the target driving force FdTr by executing a second setting process. The processing circuit 71 then transmits the target driving force FdTr to the drive control device 25. After that, the processing circuit 71 temporarily terminates the series of processes.
[0068] In this case, the processing circuit 26 of the drive control device 25 operates the power unit 21 based on the received target driving force FdTr. In step S41, the processing circuit 71 determines whether the current target driving force FdTr is equal to the specified driving force FdK. If the target driving force FdTr is equal to the specified driving force FdK, it can be considered that the power unit 21 is operating due to the target driving force FdTr set in the first setting process. If the target driving force FdTr is less than the specified driving force FdK, it can be considered that the power unit 21 is operating due to the target driving force FdTr set in the second setting process. If the processing circuit 71 determines that the target driving force FdTr is equal to the specified driving force FdK (S41: YES), the processing circuit 71 terminates the series of processes. On the other hand, if the processing circuit 71 determines that the target driving force FdTr is less than the specified driving force FdK (S41: NO), the processing circuit 71 moves the process to step S43.
[0069] In step S43, the processing circuit 71 functions as a gradient actual value acquisition unit 122 to acquire the gradient actual value θr. In the following step S45, the processing circuit 71 determines whether the magnitude of the gradient actual value θr acquired in step S43 is greater than or equal to the steep gradient determination value θTh21. If the magnitude of the gradient actual value θr is greater than or equal to the steep gradient determination value θTh21 (S45: YES), the processing circuit 71 proceeds to step S53. On the other hand, if the magnitude of the gradient actual value θr is less than the steep gradient determination value θTh21 (S45: NO), the processing circuit 71 proceeds to step S47.
[0070] In step S47, the processing circuit 71 determines whether the requested braking force FbRq obtained in step S19 is less than the holding braking force FbH. If the requested braking force FbRq is less than the holding braking force FbH, it can be assumed that the driver is reducing the braking operation amount INb with the intention of starting the vehicle 10. Therefore, if the requested braking force FbRq is less than the holding braking force FbH (S47: YES), the processing circuit 71 proceeds to step S49. On the other hand, if the requested braking force FbRq is equal to or greater than the holding braking force FbH (S47: NO), the processing circuit 71 terminates the series of processes.
[0071] In step S49, the processing circuit 71 determines whether the braking control device 45 is performing stop-hold control. If stop-hold control is being performed (S49: YES), the processing circuit 71 proceeds to step S51. On the other hand, if stop-hold control is not being performed (S49: NO), the processing circuit 71 proceeds to step S53.
[0072] In step S51, the processing circuit 71 determines whether the termination condition for the stop-holding control is met. If the processing circuit 71 determines that the termination condition is met (S51: YES), the processing circuit 71 proceeds to step S53. On the other hand, if the processing circuit 71 determines that the termination condition is not met (S51: NO), the processing circuit 71 terminates the series of processes.
[0073] In step S53, the processing circuit 71, functioning as a setting unit 126, resets the target driving force FdTr by executing a first setting process. The processing circuit 71 then transmits the set target driving force FdTr to the drive control device 25. After that, the processing circuit 71 temporarily terminates the series of processes.
[0074] In this case, the processing circuit 26 of the drive control device 25 operates the power unit 21 based on the received target driving force FdTr. <Operation and Effects of this Embodiment> Referring to Figure 4, the operation and effects of stopping the vehicle 10 by applying a braking force Fb will be explained. Figure 4 shows the changes in various parameters when stopping the vehicle 10 on an uphill road.
[0075] In the example shown in Figure 4, the following conditions are met: (B1) The road surface on which the vehicle 10 is traveling is not a downhill road. (B2) The estimated gradient value θe is greater than the uphill road determination value θTh2, and the estimated gradient value θe is less than the steep gradient determination value θTh21.
[0076] (B3) When the vehicle 10 comes to a stop, the vehicle 10 can be kept stopped by applying a braking force to the vehicle 10 corresponding to the requested deceleration DVSRq. As shown in Figures 4(a) to (f), when a braking force Fb is applied to the vehicle 10, the vehicle speed VS of the vehicle 10 gradually decreases. In the example shown in Figure 4, since no acceleration request has been made to the vehicle 10, the target driving force FdTr is set to 0 (zero), as shown in Figure 4(f). Therefore, the driving force Fd is 0 (zero).
[0077] Substitution control is initiated at timing t11 in this state. Then, as shown in Figure 4(d), the regenerative braking force FbE is reduced to 0 (zero), and the frictional braking force FbM is increased. At the end of the substitution control, the frictional braking force FbM is substantially equal to the required braking force FbRq.
[0078] At timing t12, the vehicle speed VS becomes less than or equal to the low-speed judgment speed VSth1. At the subsequent timing t13, the vehicle speed VS becomes 0 (zero). In other words, the vehicle 10 stops due to the application of braking force Fb.
[0079] Here, let's consider a comparative example in which the target driving force FdTr is set by a first setting process from timing t12. In the comparative example, as shown by the dashed line in Figure 4(f), the target driving force FdTr is increased from timing t12. In the first setting process, the target driving force FdTr is increased to a driving force corresponding to the required braking force FbRq (i.e., the required deceleration DVSRq). Then, the power unit 21 is operated based on this target driving force FdTr.
[0080] In the first setting process, the larger the requested deceleration DVSRq, the smaller the driving force set as the target driving force FdTr. In other words, if the requested deceleration DVSRq is relatively small, a relatively large driving force is set as the target driving force FdTr. Therefore, even if all of the above conditions (B1) to (B3) are met, if the requested deceleration DVSRq is not very large, a relatively large driving force Fd will be applied to the vehicle 10. As a result, the braking force Fb may be canceled out by the driving force Fd, which could cause the vehicle 10 to stop beyond the desired stopping position.
[0081] In contrast, in this embodiment, if any of the above conditions (B1) to (B3) are met, the second setting process is executed instead of the first setting process. As a result, a smaller driving force is set to the target driving force FdTr than when the first setting process is executed. Consequently, the difference between the braking force Fb and the driving force Fd becomes larger compared to when the first setting process is executed. Therefore, the motion control device 70 can suppress the discrepancy between the actual stopping position of the vehicle 10 and the desired stopping position.
[0082] From timing t14, while the vehicle 10 is stopped, the required deceleration DVSRq, i.e., the required braking force FbRq, begins to decrease. Then, at timing t15, the required braking force FbRq becomes less than or equal to the holding braking force FbH. In the example shown in Figure 4, as shown in Figures 4(c) and (d), the braking force Fb decreases in accordance with the decrease in the required braking force FbRq. In other words, the stop-hold control is not being performed. Therefore, the first setting process is executed from timing t15, and as shown in Figure 4(f), the target driving force FdTr is increased to the specified driving force FdK. As a result, the driving force Fd also increases. Therefore, the motion control device 70 can suppress a delay in the increase of the driving force Fd when the vehicle 10 is subsequently requested to start, and thus can suppress a delay in the vehicle 10's start.
[0083] In this embodiment, the following effects can be obtained: (1-1) In the second setting process, 0 (zero) is set as the target driving force FdTr. Therefore, when the second setting process is executed, the driving force Fd is not applied to the vehicle 10 just before it stops and when the vehicle 10 has stopped. Thus, the motion control device 70 can further enhance the effect of suppressing the discrepancy between the actual stopping position of the vehicle 10 and the desired stopping position.
[0084] (1-2) When the road surface on which the vehicle 10 is stopped is an uphill road, the driving force Fd acts on the vehicle 10 as a force that suppresses the vehicle 10 from sliding downhill. When stopping the vehicle 10 on an uphill road with a relatively steep gradient, if the driving force Fd is small, the vehicle 10, which has been stopped by the application of the braking force Fb, may then slide downhill.
[0085] Therefore, when the road surface is an uphill road, the motion control device 70 sets a larger driving force to the target driving force FdTr than when the second setting process is executed, if the magnitude of the estimated gradient θe is greater than or equal to the steep gradient determination value θTh21. As a result, even when the above conditions (B1) and (B3) are met, the motion control device 70 can apply a relatively large driving force Fd to the vehicle 10. Consequently, the motion control device 70 can suppress the vehicle 10 from sliding downhill due to reducing the driving force Fd applied to the stationary vehicle 10.
[0086] (1-3) While the vehicle 10 is in motion, noise caused by the vehicle's movement is superimposed on the detection signals of the longitudinal acceleration sensor 54 and the wheel speed sensor 53. Therefore, the accuracy of the gradient estimate θe calculated based on the detection signals of the longitudinal acceleration sensor 54 and the wheel speed sensor 53 is not high. On the other hand, while the vehicle 10 is stopped, the detection signals of the longitudinal acceleration sensor 54 are less susceptible to the aforementioned noise compared to before the vehicle 10 stopped. Therefore, the accuracy of the actual gradient value θr based on the detection signals of the longitudinal acceleration sensor 54 is higher than the accuracy of the gradient estimate θe calculated while the vehicle 10 is in motion.
[0087] Therefore, the motion control device 70 increases the target driving force FdTr when the magnitude of the actual gradient value θr obtained under the condition that a driving force Fd is applied to the vehicle 10 based on the target driving force FdTr set by the second setting process is greater than or equal to the steep gradient determination value θTh21. In this way, the motion control device 70 can increase the driving force Fd. In other words, the motion control device 70 can apply a driving force Fd to the vehicle 10 that has been stopped by the application of braking force Fb, with a magnitude corresponding to the gradient of the road surface on which the vehicle 10 has stopped. Thus, the motion control device 70 can suppress the occurrence of the vehicle 10 sliding down due to insufficient driving force Fd.
[0088] (1-4) The braking control device 45 may perform stop-hold control when the vehicle 10 is stopped by the application of braking force Fb. When stop-hold control is performed, the application of braking force Fb continues even without a braking request. In other words, the state in which the vehicle 10 is stopped continues. For this reason, when stop-hold control is performed, the motion control device 70 maintains the target driving force FdTr with the driving force set in the second setting process if the termination condition for stop-hold control has not been met. Subsequently, when the termination condition is met, the motion control device 70 increases the target driving force FdTr.
[0089] As a result, the driving force Fd increases in accordance with the decrease in the braking force Fb of the vehicle 10 as the stop-holding control ends. Consequently, the motion control device 70 can suppress the delay in the vehicle 10's departure when a departure request is issued.
[0090] (Second Embodiment) A second embodiment of the motion control device will be described with reference to Figure 5. The second embodiment differs from the first embodiment in that a smooth stop process is performed by the braking control device just before the vehicle comes to a complete stop. In the following description, the differences from the first embodiment will be mainly described, and the same reference numerals will be used for components identical to those in the first embodiment to avoid redundant explanations.
[0091] <Smooth Stop Processing> Referring to Figure 5, the smooth stop processing performed by the braking control unit 111 of the braking control device 45 will be explained. Note that in the example shown in Figure 5, the road surface on which the vehicle 10 is traveling is not an incline.
[0092] As shown in Figures 5(a) to (f), at timing t21 while the vehicle 10 is decelerating due to the application of braking force Fb, the vehicle speed VS becomes less than or equal to the start determination speed VSTh2, and the braking control unit 111 starts the smooth stop process. The start determination speed VSTh2 is the criterion for determining whether the vehicle 10 is about to stop or not. The start determination speed VSTh2 may be the same as the low-speed determination speed VSTh1 described above, or it may be a different value from the low-speed determination speed VSTh1.
[0093] The smooth stop process includes both attenuation correction control and degraded control. At timing t21, the attenuation correction control of the smooth stop process begins. When the vehicle 10 stops at the subsequent timing t23, the control switches from attenuation correction control to degraded control.
[0094] As shown in Figure 5(d), in reduction correction control, the braking force Fb is made smaller than the required braking force FbRq. For example, the target braking force FbTr, which is the target value of the braking force, is reduced to the holding braking force FbH at a predetermined speed. As a result, the braking force Fb is reduced to the holding braking force FbH. When the target braking force FbTr reaches the holding braking force FbH at timing t22, the target braking force FbTr is held at the holding braking force FbH. That is, from timing t22 onwards, the braking force Fb is held. In the example shown in Figure 5, at timing t23, while the braking force Fb is being held, the vehicle speed VS becomes 0 (zero). In other words, the vehicle 10 comes to a stop.
[0095] Then, the reduction correction control ends and the degenerate control begins. In the degenerate control, the braking force Fb is increased to the required braking force FbRq. For example, the target braking force FbTr is increased to the required braking force FbRq at a predetermined speed. As a result, the braking force Fb is increased to the required braking force FbRq. When the target braking force FbTr reaches the required braking force FbRq at timing t24, the smooth stop process ends.
[0096] When vehicle 10 is stopped, this smooth stop process is executed, resulting in a smaller change in the vehicle body acceleration DVS associated with the stopping of vehicle 10, as shown in Figure 5(e). This suppresses changes in the vehicle's attitude when vehicle 10 is stopped.
[0097] <Operation and Effects of this Embodiment> In this embodiment, in addition to the operations and effects equivalent to those of the first embodiment described above, the following effects can be obtained.
[0098] (2-1) When the smooth stop process is performed just before the vehicle 10 comes to a complete stop, the braking force Fb is relatively small. Therefore, if the driving force Fd is large, the vehicle 10 is likely to stop after passing the desired stopping position.
[0099] In this embodiment, as shown in the example in Figure 5, when all of the above conditions (B1) to (B3) are met, the motion control device 70 sets the target braking force FbTr by the second setting process instead of the first setting process. This makes it possible to reduce the driving force Fd just before the vehicle 10 comes to a stop compared to when the target braking force FbTr is set in the first setting process. Therefore, when the smooth stop process is executed, the motion control device 70 can suppress the actual stopping position of the vehicle 10 from deviating from the desired stopping position.
[0100] (Examples of modifications) The above multiple embodiments can be implemented with the following modifications. The above multiple embodiments and the following examples of modifications can be combined with each other to the extent that they do not contradict each other technically.
[0101] - The processing circuit 71 of the motion control device 70, i.e., the setting unit 126, may perform a second setting process when the vehicle 10 stops on a downhill road. - The processing circuit 71, i.e., the setting unit 126, does not need to change the target driving force FdTr based on the actual gradient value θr when the vehicle 10 stops while the power unit 21 is operating based on the target driving force FdTr set by the second setting process. In this case, the processing circuit 71 does not need to function as the actual gradient value acquisition unit 122.
[0102] - The processing circuit 71, i.e., the setting unit 126, may set the target driving force FdTr by a process different from the first setting process if, under conditions where the road surface is an uphill road, the magnitude of the gradient estimate θe is greater than or equal to the steep gradient determination value θTh21, and if this allows for a larger target driving force FdTr than when the second setting process is executed. For example, the processing circuit 71 may set the target driving force FdTr to be the driving force obtained by adding a predetermined offset value to the target driving force FdTr set in the second setting process.
[0103] - The processing circuit 71, i.e., the setting unit 126, may set the target driving force FdTr to a driving force greater than 0 (zero) in the second setting process if it can set a driving force smaller than that when the first setting process is executed. In this case, it is preferable that the processing circuit 71 increases the target driving force FdTr at a slower rate than when the first setting process is executed in the second setting process.
[0104] In the above-described embodiments, a motion control device 70, distinct from the drive control device 25 and the brake control device 45, functions as a "vehicle control device," but this is not limited to this. For example, the drive control device 25 may also have the function of a motion control device. In this case, the drive control device 25 would correspond to the "vehicle control device."
[0105] Furthermore, the braking control device 45 may also have the function of a motion control device. In this case, the braking control device 45 will correspond to the "vehicle control device". The motion control device 70 may be configured to have multiple processing circuits. Of the multiple processing circuits, the first processing circuit may function as some of the multiple functional units 121 to 126. When the functional unit on which the first processing circuit functions is designated as the first functional unit, the second processing circuit may function as at least one of the functional units other than the first functional unit among the multiple functional units 121 to 126.
[0106] - The vehicle control device is not limited to one that includes a CPU and ROM and performs software processing. In other words, the vehicle control device may have any of the following configurations: (a), (b), and (c).
[0107] (a) The vehicle control system comprises one or more processors that perform various processes according to a computer program. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to perform processes. The memory, i.e., computer-readable media, includes any available media that can be accessed by a general-purpose or dedicated computer.
[0108] (b) The vehicle control device includes one or more dedicated hardware circuits that perform various processes. Examples of dedicated hardware circuits include application-specific integrated circuits, i.e., ASICs or FPGAs. ASIC is an abbreviation for "Application Specific Integrated Circuit". FPGA is an abbreviation for "Field Programmable Gate Array".
[0109] (c) The vehicle control device comprises one or more processors that execute a portion of various processes according to a computer program, and one or more dedicated hardware circuits that execute the remaining processes of the various processes.
[0110] In this specification, the expression "at least one" means "one or more" of the desired options. For example, if there are two options, the expression "at least one" means "only one option" or "both of the two options." As another example, if there are three or more options, the expression "at least one" means "only one option" or "a combination of two or more arbitrary options."
Claims
1. A vehicle control device comprising: a gradient estimation unit configured to calculate a gradient estimation value which is an estimated value of the gradient of the road surface on which a vehicle is traveling; a required deceleration acquisition unit configured to acquire a required deceleration value which is a required value of the degree of deceleration of the vehicle; a determination unit configured to determine whether the vehicle can be kept stopped by applying a braking force to the vehicle corresponding to the required deceleration when the vehicle stops, based on the gradient estimation value; and a setting unit configured to set a target driving force which is a target value of the driving force applied to the vehicle, wherein the setting unit is further configured to execute a first setting process which sets the target driving force to be smaller the greater the required deceleration when the determination unit determines that the vehicle cannot be kept stopped when the road surface is not a downhill road, and executes a second setting process which sets the target driving force to be smaller than the target driving force set when the first setting process is executed when the determination unit determines that the vehicle can be kept stopped.
2. The vehicle control device according to claim 1, wherein the setting unit is further configured to set the target driving force to be greater than when the second setting process is executed, when the magnitude of the estimated gradient is greater than or equal to the determination value, under the condition that the road surface is an uphill road.
3. The vehicle control device according to claim 1, further comprising a gradient value acquisition unit configured to acquire a gradient value which is the gradient of the road surface when the vehicle is stopped, wherein the setting unit is further configured to increase the target driving force when the magnitude of the gradient value acquired by the gradient value acquisition unit is equal to or greater than a determination value, in a situation where the vehicle is stopped and driving force is applied to the vehicle based on the target driving force set by the second setting process.
4. The vehicle control device according to any one of claims 1 to 3, wherein the setting unit is further configured to set 0 (zero) to the target driving force in the second setting process.
5. The vehicle control device according to any one of claims 1 to 3, wherein the setting unit is further configured to execute the first setting process when the magnitude of the estimated gradient is equal to or greater than a determination value under the condition that the road surface is an uphill road.
6. The vehicle control device according to any one of claims 1 to 3, further comprising a holding brake force acquisition unit configured to acquire as a holding brake force a lower limit of the braking force that can maintain the vehicle's stop on the road surface in which the vehicle is located, or the sum of the lower limit and a predetermined offset value.
7. The vehicle control device according to claim 6, wherein the vehicle includes a power unit configured to impart driving force to the vehicle by driving based on the target driving force, and the setting unit is further configured to increase the target driving force when the braking force corresponding to the required deceleration falls below the holding braking force when the power unit is driving based on the target driving force set in the second setting process while the vehicle is stopped.
8. The vehicle includes a braking control unit configured to control the braking force applied to the vehicle, the braking control unit is further configured to perform a stop-hold control that maintains the vehicle in a stopped state by holding the braking force applied to the vehicle when the vehicle is stopped, and the setting unit is further configured to hold the target driving force set in the second setting process when the stop-hold control is being performed and the termination condition for the stop-hold control has not been met, and to increase the target driving force when the termination condition is met, the vehicle control device according to any one of claims 1 to 3.
9. The vehicle is equipped with a braking control unit configured to control the braking force applied to the vehicle, the braking control unit is further configured to perform: a reduction correction control that stops the vehicle by applying braking force, with the braking force applied to the vehicle being less than the braking force corresponding to the required deceleration; and a degenerate control that, when it is determined that the vehicle has stopped, increases the braking force applied to the vehicle toward the braking force corresponding to the required deceleration; the setting unit is further configured to perform the second setting process when the determination unit determines that the vehicle can be kept stopped, given that the road surface is not a downhill road and the reduction correction control is being performed, the vehicle control device according to any one of claims 1 to 3.
10. A vehicle control method comprising: calculating a gradient estimate, which is an estimated value of the gradient of the road surface on which the vehicle is traveling; obtaining a required deceleration, which is a required value of the degree of deceleration of the vehicle; determining, based on the gradient estimate, whether or not the vehicle can be kept stopped by applying a braking force to the vehicle corresponding to the required deceleration when the vehicle stops; and setting a target driving force, which is a target value of the driving force applied to the vehicle, wherein setting the target driving force includes, in situations where the road surface is not a downhill road, executing a first setting process to set the target driving force to be smaller the greater the required deceleration when it is determined that the vehicle cannot be kept stopped, and executing a second setting process to set the target driving force to be smaller than the target driving force set when the first setting process is executed when it is determined that the vehicle can be kept stopped.