Braking control device and braking control method

Abstract

A braking control device (70) comprises: a selection unit (82) configured so that, when braking force is imparted to a vehicle (10) to stop the vehicle (10), the selection unit (82) selects a stop control from a stop control group having a first stop control that includes a braking force reduction process and a braking force increase process and a second stop control that includes a braking force reduction process but does not include a braking force increase process, the selection unit (82) selecting the stop control in accordance with the time allowed to stop the vehicle (10); and a control unit (81) configured to execute the stop control selected by the selection unit (82) when braking force is imparted to the vehicle (10) to stop the vehicle (10).

Description

Braking control device and braking control method

[0001] The present disclosure relates to a braking control device and a braking control method.

[0002] Conventionally, braking control devices are known that perform stopping control to suppress changes in the vehicle's posture when the vehicle is about to stop by adjusting the braking force applied to the vehicle immediately before the vehicle stops. For example, a braking control device described in Patent Document 1 suppresses changes in the vehicle's posture by performing a braking force reduction process to reduce the braking force applied to the vehicle before the vehicle stops. Also, a braking control device described in Patent Document 2 suppresses changes in the vehicle's posture while suppressing an increase in the braking distance by performing a braking force increase process to increase the braking force applied to the vehicle before performing the braking force reduction process.

[0003] JP 2016-28913 A JP 2021-112950 A

[0004] Depending on the vehicle conditions, there are cases where it is better to execute only the braking force reduction process, and there are cases where it is better to execute both the braking force increase process and the braking force reduction process.

[0005] According to one aspect of the present disclosure, there is provided a brake control device configured to execute a stop control when applying a braking force to a vehicle to stop it. The stop control includes a first stop control including a braking force reduction process that reduces the braking force applied to the vehicle to be less than a required braking force and stops the vehicle, and a braking force increase process that is executed prior to execution of the braking force reduction process and increases the braking force applied to the vehicle to be more than the required braking force, and a second stop control that includes the braking force reduction process but does not include the braking force increase process. The brake control device includes a selection unit configured to select the stop control from a stop control group including the first stop control and the second stop control according to a time allowed for stopping the vehicle when applying a braking force to the vehicle to stop it, and a control unit configured to execute the stop control selected by the selection unit when applying a braking force to the vehicle to stop it.

[0006] According to another aspect of the present disclosure, there is provided a braking control method for executing a stop control when applying a braking force to a vehicle to stop it. The stop control includes a first stop control including a braking force reduction process for reducing the braking force applied to the vehicle below a required braking force and stopping the vehicle, and a braking force increase process executed prior to execution of the braking force reduction process for increasing the braking force applied to the vehicle above the required braking force, and a second stop control including the braking force reduction process but not the braking force increase process. The braking control method includes, when applying a braking force to the vehicle to stop it, selecting the stop control from a stop control group including the first stop control and the second stop control in accordance with an allowed time for stopping the vehicle, and executing the selected stop control when applying a braking force to the vehicle to stop it.

[0007] Fig. 1 is a schematic diagram of a vehicle equipped with a brake control device. Fig. 2 is a timing chart showing changes in vehicle body speed, longitudinal acceleration, and braking force when the brake control device of Fig. 1 executes first brake control. Fig. 3 is a timing chart showing changes in vehicle body speed, longitudinal acceleration, and braking force when the brake control device of Fig. 1 executes second brake control. Fig. 4 is a flowchart showing the flow of processing executed by the brake control device of Fig. 1 to select first brake control or second brake control.

[0008] The present invention relates to a vehicle having a brake control device and a brake control method, and is described in detail below. As shown in FIG. 1, a vehicle 10 includes a plurality of wheels 20, a brake operating member 30, a plurality of friction brakes 40, a brake actuator 50, a detection system 60, and a brake control device 70.

[0009] The plurality of wheels 20 includes two front wheels 21 and two rear wheels 22. The brake operating member 30 is a member that is operated by the driver when applying a braking force to the vehicle 10. An example of the brake operating member 30 is a brake pedal.

[0010] <Friction Brake> The plurality of friction brakes 40 each apply a braking force to the corresponding wheel 20. The friction brake 40 has a wheel cylinder 41, a rotating body 42, and a friction portion 43. The rotating body 42 rotates integrally with the wheel 20. Therefore, braking force is applied to the wheel 20 by pressing the friction portion 43 against the rotating body 42. The force pressing the friction portion 43 against the rotating body 42 increases as the wheel hydraulic pressure, which is the hydraulic pressure inside the wheel cylinder 41, increases. Therefore, the friction brake 40 can apply a greater braking force to the wheel 20 as the wheel hydraulic pressure increases.

[0011] <Brake Actuator> The brake actuator 50 controls the wheel hydraulic pressure in the plurality of wheel cylinders 41 to control the braking force applied to the wheels 20. For example, the brake actuator 50 has a pressure source that supplies brake fluid to the plurality of wheel cylinders 41. The pressure source is, for example, an electric pump and an electric cylinder. The brake actuator 50 can individually adjust the wheel hydraulic pressure in the wheel cylinder 41 for the front wheels 21 and the wheel hydraulic pressure in the wheel cylinder 41 for the rear wheels 22.

[0012] <Detection System> The detection system 60 has a brake sensor 61, a plurality of wheel speed sensors 62, and a distance sensor 63. The brake sensor 61, the plurality of wheel speed sensors 62, and the distance sensor 63 output detection signals to the braking control device 70.

[0013] The brake sensor 61 detects information related to the driver's operation of the brake operating member 30. An example of the brake sensor 61 is a stroke sensor that detects the amount of operation of the brake operating member 30 by the driver. The detection system 60 may also include a sensor that detects the operating force of the brake operating member 30 by the driver.

[0014] A wheel speed sensor 62 is provided for each of the plurality of wheels 20. The plurality of wheel speed sensors 62 respectively detect the rotational speed of the corresponding wheel 20. The rotational speed of the wheel 20 based on the detection signal of the wheel speed sensor 62 is referred to as the wheel speed.

[0015] The distance sensor 63 is, for example, a sensor that measures the distance to an obstacle present ahead of the vehicle 10. The distance sensor 63 may be a millimeter-wave radar, a camera, or any other sensor. For example, the distance sensor 63 measures the inter-vehicle distance DC to a preceding vehicle located ahead of the vehicle 10 while the vehicle 10 is traveling.

[0016] <Brake Control Device> As shown in Fig. 1, the brake control device 70 includes a processing circuit 71. An example of the processing circuit 71 is an electronic control device. In this case, the processing circuit 71 includes a CPU 72 and a memory 73. The memory 73 stores a control program executed by the CPU 72. When the CPU 72 executes the control program stored in the memory 73, the CPU 72 functions as a functional unit including a brake control unit 81 and a selection unit 82.

[0017] <Brake Control Unit> When the driver operates the brake operating member 30, the brake control unit 81 calculates a required braking force BPR based on the detection result of the brake sensor 61. The required braking force BPR is a required value of braking force. The brake control unit 81 calculates the required braking force BPR so that the greater the amount of operation of the brake operating member 30, the greater the value of the required braking force BPR. Next, the brake control unit 81 sets a command braking force BPT, which is a command value of braking force for the brake actuator 50. Depending on the braking control performed by the brake control unit 81, the command braking force BPT and the required braking force BPR may be equal or different. Then, the brake control unit 81 controls the brake actuator 50 based on the command braking force BPT. That is, the brake control unit 81 adjusts the braking force by activating the multiple friction brakes 40.

[0018] The braking control unit 81 executes stopping control when the driver is operating the brake operating member 30, i.e., when applying a braking force to the vehicle 10 to stop the vehicle 10. The stopping control is braking control for suppressing a change in the attitude of the vehicle 10 that accompanies stopping. In this embodiment, the stopping control includes a first stopping control and a second stopping control.

[0019] <First Stop Control> The first stop control will be described with reference to (a) to (c) of Figure 2. (a) to (c) of Figure 2 show the transitions of the vehicle speed VB, the longitudinal acceleration, and the braking force when the driver stops the vehicle 10 by operating the brake operating member 30. The longitudinal acceleration takes a positive value when the vehicle 10 accelerates, and takes a negative value when the vehicle 10 decelerates.

[0020] When the driver starts operating the brake operating member 30 at timing t11 while the vehicle 10 is traveling, the required braking force BPR begins to increase. If the vehicle body speed VB of the vehicle 10 is higher than the first increase start speed VIth1, as was the case before timing t12, the brake control unit 81 sets the command braking force BPT to the required braking force BPR. The brake control unit 81 then controls the brake actuator 50 so that the braking force becomes the command braking force BPT. Note that the vehicle body speed VB is the traveling speed of the vehicle 10 derived based on the wheel speed. When braking force is applied to the vehicle 10 in this manner, the vehicle body speed VB decreases. Furthermore, the absolute value of the longitudinal acceleration increases as the braking force increases.

[0021] When the vehicle speed VB reaches the first increase start speed VIth1 at timing t12, the braking control unit 81 starts the first stopping control. The first increase start speed VIth1 is a threshold value for setting the start timing of the first stopping control. From timing t12, the braking control unit 81 starts the braking force increase process of the first stopping control. In the braking force increase process, the braking control unit 81 sets the command braking force BPT to a braking force greater than the required braking force BPR. For example, the braking control unit 81 sets the command braking force BPT to the sum of the required braking force BPR and an offset value. Then, the braking control unit 81 controls the brake actuator 50 so that the braking force becomes the command braking force BPT. As a result, even if the required braking force BPR remains the same, the absolute value of the longitudinal acceleration of the vehicle 10 becomes greater by the amount of the offset value than before timing t12.

[0022] At timing t13, the vehicle speed VB becomes a first decrease start speed VDth1. The first decrease start speed VDth1 is set to a vehicle speed VB that is smaller than the first increase start speed VIth1. When the vehicle speed VB is equal to or smaller than the first decrease start speed VDth1, it is assumed that the vehicle 10 is approaching a stop position. The stop position is a position where the vehicle 10 is predicted to stop. The braking control unit 81 shifts the first stop control process from a braking force increase process to a braking force decrease process. In the braking force decrease process, the braking control unit 81 decreases the command braking force BPT at a constant rate. Then, the braking control unit 81 controls the brake actuator 50 so that the braking force becomes the command braking force BPT. By the braking control unit 81 executing the braking force decrease process in this manner, the braking force becomes smaller than the required braking force BPR. As a result, even if the required braking force BPR remains the same, the absolute value of the longitudinal acceleration of the vehicle 10 gradually decreases.

[0023] At timing t14, the command braking force BPT becomes equal to the stop-maintenance braking force. The stop-maintenance braking force is set to the minimum braking force necessary to maintain the stop of the vehicle 10 on the current road surface on which the vehicle 10 is traveling, or to a braking force slightly greater than that braking force. From timing t14, in the braking force reduction process, the braking control unit 81 maintains the command braking force BPT at the stop-maintenance braking force.

[0024] At timing t15, the braking control unit 81 determines that the vehicle 10 has stopped, and therefore transitions the processing of the first stop control from braking force reduction processing to degeneration processing. In the degeneration processing, the braking control unit 81 increases the commanded braking force BPT. For example, the braking control unit 81 increases the commanded braking force BPT to the required braking force BPR. The braking control unit 81 controls the brake actuator 50 based on the commanded braking force BPT, thereby increasing the braking force. When the commanded braking force BPT becomes equal to the required braking force BPR at timing t16, the braking control unit 81 ends the first stop control.

[0025] The second stop control will be described with reference to (a) to (c) of Figure 3. As in the case shown in Figure 2, when the driver starts to operate the brake operating member 30 at timing t21 while the vehicle 10 is traveling, the required braking force BPR begins to increase. Therefore, from timing t21, the vehicle body speed VB decreases and the absolute value of the longitudinal acceleration increases.

[0026] When the vehicle speed VB reaches the second decrease start speed VDth2 at timing t22, the braking control unit 81 starts the second stopping control. The second decrease start speed VDth2 is a threshold value for setting the start timing of the second stopping control. From timing t22, the braking control unit 81 starts the braking force reduction process of the second stopping control. In the braking force reduction process, the braking control unit 81 reduces the command braking force BPT at a constant rate. Then, the braking control unit 81 controls the brake actuator 50 so that the braking force becomes the command braking force BPT. By the braking control unit 81 performing the braking force reduction process in this manner, the braking force becomes smaller than the required braking force BPR. As a result, even if the required braking force BPR remains the same, the absolute value of the longitudinal acceleration of the vehicle 10 gradually decreases.

[0027] At timing t23, the command braking force BPT becomes equal to the vehicle stop maintenance braking force. From timing t23, in the braking force reduction process, the braking control unit 81 maintains the command braking force BPT at the vehicle stop maintenance braking force.

[0028] At timing t24, the braking control unit 81 determines that the vehicle 10 has stopped, and therefore transitions the processing of the second stop control from braking force reduction processing to degeneration processing. In the degeneration processing, the braking control unit 81 increases the command braking force BPT. The braking control unit 81 controls the brake actuator 50 based on the command braking force BPT, thereby increasing the braking force. When the command braking force BPT becomes equal to the required braking force BPR at timing t25, the braking control unit 81 ends the second stop control.

[0029] The braking control unit 81 executes the stopping control selected by the selection unit 82, which will be described next, from the first stopping control and the second stopping control. For example, when the first stopping control is selected, the braking control unit 81 starts the first stopping control from the timing when the vehicle body speed VB becomes less than the first increase start speed VIth1. On the other hand, when the second stopping control is selected, the braking control unit 81 starts the second stopping control from the timing when the vehicle body speed VB becomes less than the second decrease start speed VDth2. Note that when neither the first stopping control nor the second stopping control is selected, the braking control unit 81 maintains the command braking force BPT at a value equal to the required braking force BPR.

[0030] <Selection Unit> As shown in FIG. 2 , the first stopping control is executed over a period from timing t12 to timing t16. Meanwhile, as shown in FIG. 3 , the second stopping control is executed over a period from timing t22 to timing t25. Because the first stopping control includes a braking force increase process in addition to a braking force decrease process, the time required to execute the first stopping control is longer than the time required to execute the second stopping control when stopping the vehicle 10 under the same conditions. Furthermore, the braking distance is defined as the distance traveled by the vehicle 10 from when the driver starts operating the brake operating member 30 until the vehicle 10 stops. While the first stopping control includes a braking force increase process, the second stopping control does not include a braking force increase process. Therefore, when stopping the vehicle 10 under the same conditions, the braking distance when the first stopping control is executed is shorter than the braking distance when the second stopping control is executed.

[0031] In the second stopping control, the braking distance can be shortened by delaying the start of the braking force reduction process and increasing the absolute value of the reduction rate of the command braking force BPT in the braking force reduction process. However, in this case, the change in longitudinal acceleration per unit time becomes larger, resulting in greater fluctuation in the vehicle attitude when the vehicle 10 is stopped. In other words, there is a risk of the ride comfort of the occupants of the vehicle 10 becoming worse. On the other hand, by reducing the absolute value of the reduction rate of the command braking force BPT in the braking force reduction process of the first stopping control, the braking distance when the first stopping control is executed can be made equal to the braking distance when the second stopping control is executed. In this case, fluctuations in the vehicle attitude are further reduced when the first stopping control is executed.

[0032] Taking these points into consideration, the selection unit 82 selects the stopping control to be executed by the braking control unit 81 from a stopping control group including the first stopping control and the second stopping control in accordance with the allowable time allowed for stopping the vehicle 10 based on the situation of the vehicle 10. In detail, the selection unit 82 selects the first braking control when the allowable time is predicted to be long, and selects the second braking control when the allowable time is predicted to be short. In other words, the selection unit 82 selects the first stopping control when the allowable time is relatively long, and selects the second stopping control when the allowable time is relatively short.

[0033] If the vehicle body speed VB is low when the driver starts operating the brake operating member 30, i.e., if the vehicle body speed VB at the beginning of braking of the vehicle 10 is low, the allowable time is predicted to be short. In other words, even if time to execute the second braking control is secured, there is a possibility that time to execute the first braking control is not secured. Therefore, the selection unit 82 selects the first braking control when the vehicle body speed VB at the beginning of braking of the vehicle 10 is equal to or greater than the first increase start speed VIth1, and selects the second braking control when the vehicle body speed VB at the beginning of braking of the vehicle 10 is less than the first increase start speed VIth1. In the following description, the vehicle body speed VB at the beginning of braking of the vehicle 10 is referred to as the "initial speed VB0." The initial speed VB0 is the vehicle body speed VB at the timing when the driver starts operating the brake operating member 30. It is preferable that the selection unit 82 stores the initial speed VB0 in the memory 73 at the timing when the driver starts operating the brake operating member 30.

[0034] When the driver strongly operates the brake operating member 30, i.e., when the required braking force BPR is high, it is highly likely that the driver wants to quickly stop the vehicle 10. In other words, when the required braking force BPR is high, it is predicted that the allowable time is short. Therefore, the selection unit 82 selects the first braking control when the current required braking force BPR is less than a predetermined braking force determination value BPth, and selects the second braking control when the current required braking force BPR is equal to or greater than the braking force determination value BPth.

[0035] When braking the vehicle 10, if the inter-vehicle distance DC to the preceding vehicle is short, the allowable time is assumed to be short. Therefore, the selection unit 82 acquires the inter-vehicle distance DC to the preceding vehicle based on the detection result of the distance sensor 63. Then, the selection unit 82 selects the first braking control when the inter-vehicle distance DC to the preceding vehicle is equal to or greater than a predetermined distance determination value DCth, and selects the second braking control when the inter-vehicle distance DC to the preceding vehicle is less than the distance determination value DCth. The preceding vehicle may be a preceding vehicle that is already stopped, or may be a preceding vehicle that is decelerating in order to stop. The distance to the preceding vehicle corresponds to the "external environment of the vehicle 10."

[0036] If the initial speed VB0 is less than the second decrease start speed VDth2, there is a possibility that the time to execute the second braking control may not be sufficient. In this case, it is preferable that the selection unit 82 does not select the first braking control or the second braking control. In other words, it is preferable that the braking control unit 81 sets the command braking force BPT to the required braking force BPR. The same applies to the case where the required braking force BPR is much greater than the braking force determination value BPth and the case where the inter-vehicle distance DC to the preceding vehicle is much smaller than the distance determination value DCth.

[0037] <Processing flow executed by the brake control device> The processing flow executed by the brake control device 70 to select the first stop control or the second stop control will be described with reference to the flowchart shown in Figure 4. This processing is executed at each predetermined control cycle while the driver is operating the brake operating member 30 when neither the first stop control nor the second stop control is being executed.

[0038] As shown in FIG. 4 , the brake control device 70 determines whether the current vehicle speed VB is equal to or greater than a first increase start speed VIth1 (S11). If the vehicle speed VB is less than the first increase start speed VIth1 (S11: NO), i.e., if the vehicle speed VB has decreased to the extent that the first stopping control cannot be executed, the brake control device 70 determines whether the current vehicle speed VB is equal to or greater than a second decrease start speed VDth2 (S12). If the current vehicle speed VB is less than the second decrease start speed VDth2 (S12: NO), i.e., if the vehicle speed VB has decreased to the extent that the second stopping control cannot be executed, the brake control device 70 terminates this process. In this case, the brake control device 70 does not execute the first braking control or the second braking control. In other words, the brake control device 70 sets the command braking force BPT to the required braking force BPR.

[0039] In step S12, if the current vehicle speed VB is equal to or greater than the second decrease start speed VDth2 (S12: YES), the brake control device 70 selects the second stop control as the stop control (S13). After that, the brake control device 70 ends this process.

[0040] In step S11, if the current vehicle speed VB is equal to or greater than the first increase start speed VIth1 (S11: YES), the brake control device 70 determines whether the initial speed VB0 is equal to or greater than the first increase start speed VIth1 (S14). If the initial speed VB0 is less than the first increase start speed VIth1 (S14: NO), i.e., if the allowable time is predicted to be short, the brake control device 70 proceeds to step S12. On the other hand, if the initial speed VB0 is equal to or greater than the first increase start speed VIth1 (S14: YES), i.e., if the allowable time is predicted to be long, the brake control device 70 determines whether the current inter-vehicle distance DC is equal to or greater than the distance determination value DCth (S15). If the current inter-vehicle distance DC is less than the distance determination value DCth (S15: NO), i.e., if the allowable time is predicted to be short, the brake control device 70 proceeds to step S13. On the other hand, if the current inter-vehicle distance DC is greater than or equal to the distance judgment value DCth (S15: YES), i.e., if the allowable time is predicted to be long, the brake control device 70 determines whether the required braking force BPR is greater than or equal to the braking force judgment value BPth (S16).

[0041] If the required braking force BPR is equal to or greater than the braking force determination value BPth (S16: YES), i.e., if the allowable time is predicted to be short, the brake control device 70 proceeds to step S13. On the other hand, if the required braking force BPR is less than the braking force determination value BPth (S16: NO), i.e., if the allowable time is predicted to be long, the brake control device 70 selects the first stopping control as the stopping control (S17). Thereafter, the brake control device 70 ends this process.

[0042] Then, when the first braking control is selected and the vehicle body speed VB is less than the first increase start speed VIth1, the braking control device 70 starts the first braking control. On the other hand, when the second braking control is selected and the vehicle body speed VB is less than the second decrease start speed VDth2, the braking control device 70 starts the second braking control.

[0043] <Actions and Effects of the Present Embodiment> In a situation where the driver operates the brake operating member 30 to stop the vehicle 10, if it is predicted that the allowable time until the vehicle 10 is stopped is short, the second braking control is executed. That is, in the period immediately before the vehicle 10 is stopped, a braking force reduction process is executed to reduce the braking force applied to the vehicle 10 to be less than the required braking force BPR. As a result, the brake control device 70 can suppress fluctuations in the vehicle attitude immediately before the vehicle 10 is stopped.

[0044] On the other hand, in a situation where the driver operates the brake operating member 30 to stop the vehicle 10, if the allowable time until the vehicle 10 is stopped is predicted to be long, the first braking control is executed. In other words, if there is sufficient allowable time, a braking force increase process is executed to increase the braking force applied to the vehicle 10 beyond the required braking force BPR before executing the braking force reduction process. As a result, the brake control device 70 can suppress fluctuations in vehicle attitude as well as an increase in braking distance. Furthermore, the brake control device 70 can further suppress fluctuations in vehicle attitude by making the decrease gradient of the command braking force BPT in the braking force reduction process gentler.

[0045] The braking control unit 81 predicts the length of the allowable time based on the vehicle speed VB, the initial speed VB0, the required braking force BPR, the inter-vehicle distance DC, etc. Therefore, the braking control unit 81 can appropriately select the first braking control or the second braking control.

[0046] <Modifications> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0047] The selection unit 82 may predict the length of the permissible time based on at least one of the initial speed VB0, the required braking force BPR, and the following distance DC. The absolute value of the reduction rate of the command braking force BPT in the braking force reduction process of the first braking control may be smaller or larger than the absolute value of the reduction rate of the command braking force BPT in the braking force reduction process of the second braking control.

[0048] When the road surface is wet or icy, the coefficient of friction between the wheels 20 and the road surface is lower than when the road surface is dry. The selection unit 82 may select the stopping control based on such an external environment of the vehicle 10.

[0049] In the first braking control and the second braking control, the braking force reduction process may be a process that does not set a period for maintaining the braking force. In the above embodiment, the braking control unit 81 determines the start timing of the braking force increase process and the start timing of the braking force decrease process in accordance with changes in the vehicle body speed VB. However, the braking control unit 81 may determine the start timing of each process using a parameter other than the vehicle body speed VB, as long as the parameter value decreases as the vehicle 10 approaches the stopping position. Examples of the other parameters include a stopping distance and a predicted stopping time. The stopping distance is the distance from the current position of the vehicle 10 to the stopping position. The predicted stopping time is the time required for the vehicle 10 to stop. An example of a predicted stopping time is TTC. TTC is an abbreviation for "Time To Collision."

[0050] When executing the stop control, the brake control device 70 may control not only the frictional braking force but also the regenerative braking force. In this case, the braking force applied to the vehicle 10 is the sum of the total frictional braking force applied to the vehicle 10 and the total regenerative braking force applied to the vehicle 10.

[0051] The braking control device 70 is not limited to the processing circuit 71 that includes a CPU 72 and a memory 73 and executes software processing. For example, the braking control device 70 may include a dedicated hardware circuit that executes at least some of the various processes executed 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 70 may have any of the following configurations (a) to (c):

[0052] (a) A processing circuit comprising a processing device that executes all of the above processes according to a program and a program storage device such as a ROM that stores the program. (b) A processing circuit comprising a processing device and program storage device that executes part of the above processes according to a program, and a dedicated hardware circuit that executes the remaining processes.

[0053] (c) A processing circuit comprising dedicated hardware circuits for executing all of the above processes, wherein the software execution device comprising a processing device and a program storage device, and the dedicated hardware circuits may be plural.

Claims

1. A braking control device configured to execute a stopping control when applying a braking force to a vehicle to stop it, the stopping control including: a first stopping control including a braking force reduction process that reduces the braking force applied to the vehicle to be less than a required braking force and stops the vehicle, and a braking force increase process that is executed prior to execution of the braking force reduction process and increases the braking force applied to the vehicle to be more than the required braking force; and a second stopping control that includes the braking force reduction process but does not include the braking force increase process; the braking control device comprising: a selection unit configured to select the stopping control from a stopping control group having the first stopping control and the second stopping control in accordance with a time allowed for stopping the vehicle when applying a braking force to the vehicle to stop it; and a control unit configured to execute the stopping control selected by the selection unit when applying a braking force to the vehicle to stop it.

2. The brake control device according to claim 1, wherein the selection unit is further configured to select the stopping control according to the time allowed for stopping the vehicle based on at least one of the initial braking speed of the vehicle and the required braking force.

3. A brake control device according to claim 1 or 2, wherein the selection unit is further configured to select the stopping control according to a time allowed for stopping the vehicle based on an external environment of the vehicle.

4. A braking control method for executing stopping control when applying braking force to a vehicle to stop the vehicle, the stopping control including: a first stopping control including a braking force reduction process for reducing the braking force applied to the vehicle to be less than a required braking force and stopping the vehicle, and a braking force increase process that is executed prior to execution of the braking force reduction process and increases the braking force applied to the vehicle to be more than the required braking force; and a second stopping control that includes the braking force reduction process but does not include the braking force increase process; the braking control method including: when applying braking force to the vehicle to stop the vehicle, selecting the stopping control from a stopping control group having the first stopping control and the second stopping control in accordance with a time allowed for stopping the vehicle; and when applying braking force to the vehicle to stop the vehicle, executing the selected stopping control.

Images