Braking control system

Abstract

To suppress the large time lag between when parking braking force is generated on the first wheel and when parking braking force is generated on the second wheel. [Solution] The braking control system 60 includes a first braking ECU 70 and a redundant ECU 90 provided for each of the multiple parking actuators 31 and 32. Each of the multiple ECUs 70 and 90 performs pre-operation processing when it receives a parking braking operation request, determines whether the pre-operation processing has been completed in any of the multiple ECUs 70 and 90, and, on the condition that it has been determined that the pre-operation processing has been completed in any of the multiple ECUs 70 and 90, operates the parking actuators 31 and 32 based on the parking braking operation request.

Description

[Technical Field]

[0001] The present invention relates to a braking control system mounted on a vehicle. [Background Art]

[0002] Patent Document 1 discloses a parking brake system. The system includes two parking actuators, and two control devices provided respectively for each of the two parking actuators and configured to control the corresponding parking actuators. The two control devices are configured to be capable of communicating via a CAN bus.

[0003] Among the two control devices, when the first control device receives a parking braking request, it transmits the request to the second control device via the CAN bus. Then, the two control devices respectively actuate the parking actuators based on the request. At this time, actuation of the parking actuator controlled by the first control device generates a parking braking force at the first wheel. Further, actuation of the parking actuator controlled by the second control device generates a parking braking force at the second wheel. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2015 / 0203082 Specification [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] A large deviation between the control start timing of the parking actuator by the first control device and the control start timing of the parking actuator by the second control device means a large time lag between the timing at which parking braking force is generated at the first wheel and the timing at which parking braking force is generated at the second wheel. That is, the period during which parking braking force is generated by only one of the two wheels becomes long. [Means for solving the problem]

[0006] A braking control system for solving the above problems is applied to a vehicle comprising a first wheel and a second wheel, and a plurality of parking actuators provided for each of the first wheel and the second wheel, configured to generate parking braking force in the corresponding wheel. The braking control system comprises a plurality of control devices provided for each of the plurality of parking actuators, which operate the corresponding parking actuator. The plurality of control devices are configured to communicate with each other via an in-vehicle network. When each of the plurality of control devices receives a parking braking action request, which is a request to operate the parking actuator, it performs a pre-operation process, which is a process to be performed before the operation of the parking actuator, determines whether the pre-operation process has been completed in any of the plurality of control devices, and, on the condition that the pre-operation process has been determined to be completed in any of the plurality of control devices, operates the parking actuator based on the parking braking action request. [Effects of the Invention]

[0007] The above braking control system has the effect of suppressing a large time lag between when parking braking force is generated on the first wheel and when parking braking force is generated on the second wheel. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram showing a vehicle equipped with one embodiment of a braking control system. [Figure 2] Figure 2 is a configuration diagram showing the braking control system of Figure 1 and the electric parking device controlled by the braking control system. [Figure 3] Figure 3 is a flowchart showing a series of processes performed by the control device included in the braking control system of Figure 1. [Figure 4]Figures 4(a) to 4(h) are timing charts showing the transitions of various states in the braking control system of Figure 1, from the occurrence of an apply request to the execution of the apply process. [Figure 5] Figure 5 is a flowchart showing a series of processes performed by the control unit of the modified braking control system. [Modes for carrying out the invention]

[0009] One embodiment of the braking control system will be described with reference to Figures 1 to 4. <Vehicle Configuration> Figure 1 shows a vehicle 10 to which the braking control system 60 is applied. Figure 2 shows the braking control system 60. As shown in Figures 1 and 2, the vehicle 10 further comprises a plurality of wheels, the same number of friction brakes 20 as the wheels, a hydraulic braking device 25, and an electric parking device 30. The plurality of wheels include first wheels 11 and second wheels 12. An example of the first wheels 11 and second wheels 12 is the rear wheels.

[0010] Each of the multiple friction brakes 20 includes a rotating body 21 that rotates integrally with the corresponding wheels 11, 12, a friction material 22, and a wheel cylinder 23. The friction brake 20 is configured to generate braking force on the corresponding wheel by pressing the friction material 22 against the rotating body 21. The higher the hydraulic pressure of the wheel cylinder 23, the greater the force pressing the friction material 22 against the rotating body 21, resulting in a greater braking force being generated on the wheel.

[0011] The hydraulic braking system 25 includes a first hydraulic braking system 26 and a second hydraulic braking system 27. Each of the first hydraulic braking system 26 and the second hydraulic braking system 27 is configured to adjust the hydraulic pressure of a plurality of wheel cylinders 23. The first hydraulic braking system 26 is configured to adjust the hydraulic pressure of a plurality of wheel cylinders 23 individually. The second hydraulic braking system 27 is configured to generate hydraulic pressure in a plurality of wheel cylinders 23 corresponding to the required braking force, which is the required value of the braking force for the vehicle 10. An example of the configuration of the first hydraulic braking system 26 and the second hydraulic braking system 27 is disclosed in "Japanese Patent Application Publication No. 2024-76857".

[0012] The electric parking device 30 includes a first parking actuator 31 and a second parking actuator 32. The first parking actuator 31 is configured to generate parking braking force at the first wheel 11. The second parking actuator 32 is configured to generate parking braking force at the second wheel 12. Each of the multiple parking actuators 31, 32 has an electric motor. The multiple parking actuators 31, 32 can generate parking braking force at the wheels in accordance with the drive of the electric motors. For example, when the electric motor is driven, the friction material 22 of the friction brake 20 is pressed against the rotating body 21, so that parking braking force is generated at the wheels 11, 12. An example of the configuration of the parking actuators 31, 32 is disclosed in "Japanese Patent Application Publication No. 2022-85637".

[0013] <In-car network> The in-vehicle network of vehicle 10 will be described with reference to Figures 1 and 2. Vehicle 10 is equipped with multiple electronic control units. Hereafter, these electronic control units will be referred to as "ECUs." ECU is an abbreviation for "Electronic Control Unit." Vehicle 10 is equipped with an in-vehicle network for communication between the multiple ECUs. The in-vehicle network has multiple global communication lines. An example of a global communication line is a CAN bus. "CAN" is an abbreviation for "Control Area Network." The multiple global communication lines include a first global communication line 201 and a second global communication line 202.

[0014] <ECUs other than the ECU that make up the braking control system> Vehicle 10 is equipped with an integrated ECU 51 and a shift ECU 52 as ECUs other than those that constitute the braking control system 60. The integrated ECU 51 transmits various information, requests, and commands to other ECUs via the in-vehicle network. For example, when an occupant of vehicle 10 operates the parking brake operation switch 41, the integrated ECU 51 transmits a parking brake operation request, which is a request related to parking braking, to the first global communication line 201, as shown by arrow X1 in Figure 2. The parking brake operation switch 41 is an operating unit that the occupant operates to activate the electric parking device 30. For example, the parking brake operation switch 41 is installed inside the vehicle.

[0015] A parking brake action request includes an apply request and a release request. The apply request is a request to generate parking brake force. The release request is a request to release the state in which parking brake force is being generated.

[0016] The shift ECU 52 controls the shift device installed in the vehicle 10. The shift ECU 52 transmits range information, which is information corresponding to the shift range selected by the shift device, to the second global communication line 202.

[0017] <Braking control system> As shown in FIG. 1 and FIG. 2, the braking control system 60 includes a plurality of ECUs related to vehicle braking. The plurality of ECUs include a first braking ECU 70, a second braking ECU 80, and a redundant ECU 90.

[0018] The first braking ECU 70 actuates the first hydraulic braking device 26. The first braking ECU 70 actuates only the first parking actuator 31 among the plurality of parking actuators 31, 32. The first braking ECU 70 that actuates the first parking actuator 31 may also be referred to as a "first control device".

[0019] The first braking ECU 70 includes a processing circuit 71 and a drive circuit 73. The processing circuit 71 includes a CPU 71a and a memory 71b that stores a control program executed by the CPU 71a. The control programs include a control program for actuating the first hydraulic braking device 26 and a control program for actuating the first parking actuator 31. The processing circuit 71 can actuate the first hydraulic braking device 26 and the first parking actuator 31 by causing the CPU 71a to execute the control program stored in the memory 71b.

[0020] The drive circuit 73 is a circuit for driving the electric motor of the first parking actuator 31. When the drive circuit 73 operates based on a command from the processing circuit 71, the drive circuit 73 outputs a drive signal. The first parking actuator 31 is actuated when the electric motor is driven based on the drive signal.

[0021] The second braking ECU 80 actuates the second hydraulic braking device 27. On the other hand, the second braking ECU 80 does not set the electric parking device 30 as a control target. The second braking ECU 80 includes a processing circuit 81. The processing circuit 81 includes a CPU and a memory. The memory stores a control program for actuating the second hydraulic braking device 27. The processing circuit 81 can actuate the second hydraulic braking device 27 by causing the CPU to execute such a control program.

[0022] The redundant ECU 90 does not control the hydraulic braking device 25. On the other hand, the redundant ECU 90 operates only the second parking actuator 32 among the multiple parking actuators 31 and 32. The redundant ECU 90 that operates the second parking actuator 32 is sometimes referred to as the "second control device".

[0023] The redundant ECU 90 has a processing circuit 91 and a drive circuit 93. The processing circuit 91 has a CPU 91a and a memory 91b. The memory stores a control program that the CPU 91a executes to operate the second parking actuator 32. By executing this control program, the CPU 91a can operate the second parking actuator 32.

[0024] The drive circuit 93 is a circuit for driving the electric motor of the second parking actuator 32. When the drive circuit 93 operates based on a command from the processing circuit 91, the drive circuit 93 outputs a drive signal. The electric motor is driven based on this drive signal, thereby operating the second parking actuator 32.

[0025] The braking control system 60 has a braking communication line 61 as an in-vehicle network for communication between multiple ECUs involved in vehicle braking. An example of the braking communication line 61 is a CAN bus. The first braking ECU 70, the second braking ECU 80, and the redundant ECU 90 can communicate with each other via the braking communication line 61. On the other hand, the braking communication line 61 cannot be used for communication with ECUs other than those that make up the braking control system 60. In other words, the braking communication line 61 corresponds to an "in-vehicle network" that enables communication between the first braking ECU 70 and the redundant ECU 90.

[0026] In the braking control system 60, the first braking ECU 70 and the second braking ECU 80 acquire various requests and information from the integrated ECU 51 via the first global communication line 201. The redundant ECU 90 acquires various requests and information from the integrated ECU 51 via the second global communication line 202. For example, when the first braking ECU 70 receives a parking brake operation request via the first global communication line 201, it transmits the parking brake operation request to the redundant ECU 90 via the braking communication line 61, as shown by arrow X2 in Figure 2.

[0027] <Processing flow in the first braking ECU and redundant ECU> Referring to Figure 3, a series of processes performed by each of the multiple ECUs 70 and 90 when a parking brake operation request is received by the first braking ECU 70 and the redundant ECU 90 will be described. The processing circuit 71 of the first braking ECU 70 repeatedly executes this series of processes. The processing circuit 91 of the redundant ECU 90 repeatedly executes this series of processes.

[0028] In step S11, processing circuits 71 and 91 determine whether ECUs 70 and 90 have received a parking brake activation request. If ECUs 70 and 90 have received a parking brake activation request (S11: YES), processing circuits 71 and 91 proceed to step S13. On the other hand, if ECUs 70 and 90 have not received a parking brake activation request (S11: NO), processing circuits 71 and 91 terminate the series of processes shown in Figure 3.

[0029] In step S13, the processing circuits 71 and 91 start pre-operation processing, which is performed before the corresponding parking actuators 31 and 32 are activated. An example of pre-operation processing is the process in which the CPUs 71a and 91a write the state of the parking actuators 31 and 32 before activation to the memories 71b and 91b. Hereafter, such processing will be referred to as "writing processing".

[0030] The time required for the write operation in the first braking ECU 70 may not necessarily be the same as the time required for the write operation in the redundant ECU 90. The length of time required for the write operation varies depending on the capacity of the memory being written to and the performance of the CPU, among other factors.

[0031] In the following step S15, the processing circuits 71 and 91 transmit status signals, which are signals indicating the execution status of their own pre-operation processing, to the other ECU via the braking communication line 61. The "other ECU" as seen by processing circuit 71 is the redundant ECU 90. The "other ECU" as seen by processing circuit 91 is the first braking ECU 70.

[0032] In this embodiment, the status signal is a signal that identifies whether pre-operation processing is being performed or whether pre-operation processing has been completed. The value indicated by the signal level of the status signal when pre-operation processing has been completed is the first value. The value indicated by the signal level of the status signal when pre-operation processing is being performed is the second value. The second value is different from the first value. During the period from the time the ECU receives the parking brake operation request until immediately before the execution of pre-operation processing begins, the value indicated by the signal level of the status signal is the first value. In other words, the status signal can also be said to be a signal that identifies whether pre-operation processing is being performed or not.

[0033] In the next step S17, the processing circuits 71 and 91 determine whether the elapsed time since receiving the parking brake operation request has reached a predetermined waiting time TMmk. The length of the waiting time TMmk is set to a time corresponding to the communication cycle between the first braking ECU 70 and the redundant ECU 90 via the braking communication line 61. For example, the waiting time TMmk is set to be slightly longer than the expected communication delay between the first braking ECU 70 and the redundant ECU 90.

[0034] If the elapsed time has not reached the waiting time TMmk (S17: NO), the processing circuits 71 and 91 proceed to step S15. That is, if the elapsed time has not reached the waiting time TMmk, the processing circuits 71 and 91 continue to transmit a status signal to the other ECU at predetermined communication cycles. On the other hand, if the elapsed time has reached the waiting time TMmk (S17: YES), the processing circuits 71 and 91 proceed to step S19.

[0035] In step S19, processing circuits 71 and 91 determine whether the value indicated by the status signal they transmit to the other ECU matches the value indicated by the status signal they receive from the other ECU. That is, processing circuits 71 and 91 determine whether the execution state of their own pre-operation processing is the same as the execution state of the pre-operation processing indicated by the status signal they receive from another ECU, which is one of the multiple ECUs 70 and 90 other than themselves. If the value indicated by the status signal they transmit to the other ECU matches the value indicated by the status signal they receive from the other ECU (S19: YES), processing circuits 71 and 91 proceed to step S21. On the other hand, if the value indicated by the status signal they transmit to the other ECU does not match the value indicated by the status signal they receive from the other ECU (S19: NO), processing circuits 71 and 91 proceed to step S15.

[0036] In step S21, processing circuits 71 and 91 determine whether pre-operation processing has been completed for any of the multiple ECUs 70 and 90. If both the value indicated by the status signal that it transmits to the other ECU and the value indicated by the status signal received from the other ECU are first values, processing circuits 71 and 91 can determine that pre-operation processing has been completed for any of the multiple ECUs 70 and 90 (S21: YES). In this case, processing circuits 71 and 91 proceed to step S23. On the other hand, if both the value indicated by the status signal that it transmits to the other ECU and the value indicated by the status signal received from the other ECU are second values, processing circuits 71 and 91 can determine that pre-operation processing has not been completed for any of the multiple ECUs 70 and 90 (S21: NO). In this case, processing circuits 71 and 91 proceed to step S15.

[0037] In step S23, processing circuits 71 and 91 operate their respective parking actuators 31 and 32 based on the parking brake operation request. If the parking brake operation request is an apply request, processing circuit 71 operates the first parking actuator 31 to generate parking brake force. Processing circuit 91 operates the second parking actuator 32 to generate parking brake force. On the other hand, if the parking brake operation request is a release request, processing circuit 71 operates the first parking actuator 31 to release the state in which parking brake force is generated. Processing circuit 91 operates the second parking actuator 32 to release the state in which parking brake force is generated. Once processing circuits 71 and 91 have completed the operation of the parking actuators 31 and 32 based on the parking brake operation request, they temporarily terminate the series of processes shown in Figure 3.

[0038] <Operation and Effects of This Embodiment> Referring to Figure 4, the operation and effects of this embodiment will be explained. Figure 4 illustrates an example of a parking brake operation request when an apply request occurs. Figures 4(a) to (d) show the transitions of various states as perceived by the first braking ECU 70. Figures 4(e) to (h) show the transitions of various states as perceived by the redundant ECU 90. Hereafter, the status signal indicating the execution status of the write process in the first braking ECU 70 will be referred to as the "first status signal," and the status signal indicating the execution status of the write process in the redundant ECU 90 will be referred to as the "second status signal."

[0039] As shown in Figure 4(a), when the first braking ECU 70 receives an apply request at timing t11, the first braking ECU 70 starts the write process. Then, as shown in Figure 4(b), at timing t11, the value indicated by the first status signal transmitted by the first braking ECU 70 to the redundant ECU 90 switches from the first value to the second value. Subsequently, at timing t13, the write process in the first braking ECU 70 ends, and the value indicated by the first status signal transmitted by the first braking ECU 70 to the redundant ECU 90 switches from the second value to the first value.

[0040] In the example shown in Figure 4, as shown in Figure 4(c), the value indicated by the second status signal received by the first braking ECU 70 from the redundant ECU 90 switches from the first value to the second value at timing t14. Subsequently, at timing t17, the value indicated by the second status signal received by the first braking ECU 70 from the redundant ECU 90 switches from the second value to the first value.

[0041] In this embodiment, a waiting time TMmk is set. Therefore, in the first braking ECU 70, the operation of the first parking actuator 31 is prohibited during the period from the timing t11 when the apply request is received until the timing t15 when the waiting time TMmk has elapsed.

[0042] In the first braking ECU 70, as shown in Figures 4(b) and 4(c), at timing t17, both the value indicated by the first status signal transmitted by the first braking ECU 70 to the redundant ECU 90 and the value indicated by the second status signal received by the first braking ECU 70 from the redundant ECU 90 become the first value. In other words, the first braking ECU 70 can determine that the writing process is complete in both the first braking ECU 70 and the redundant ECU 90. As a result, as shown in Figure 4(d), at timing t17, the apply process is started in the first braking ECU 70, and the first parking actuator 31 begins to operate. In other words, parking braking force is generated at the first wheel 11.

[0043] On the other hand, the redundant ECU 90 receives the apply request at timing t13, as shown in Figure 4(e). As a result, the redundant ECU 90 starts the write process, and as shown in Figure 4(f), at timing t13, the value indicated by the second status signal that the redundant ECU 90 transmits to the first braking ECU 70 changes from the first value to the second value.

[0044] Furthermore, as shown in Figure 4(g), in the redundant ECU 90, at timing t12 between timing t11 and timing t13, the value indicated by the first status signal received by the redundant ECU 90 from the first braking ECU 70 switches from the first value to the second value. Then, at the subsequent timing t14, the value indicated by the first status signal received by the redundant ECU 90 from the first braking ECU 70 switches from the second value back to the first value.

[0045] In this embodiment, a waiting time TMmk is set. Therefore, in the redundant ECU 90, the operation of the second parking actuator 32 is prohibited during the period from the timing t13 when the apply request is received until the timing t18 when the waiting time TMmk has elapsed.

[0046] In the redundant ECU 90, as shown in Figures 4(f) and 4(g), at timing t16, both the value indicated by the second status signal transmitted by the redundant ECU 90 to the first braking ECU 70 and the value indicated by the first status signal received by the redundant ECU 90 from the first braking ECU 70 become the first value. In other words, the redundant ECU 90 can determine that the write process is complete in both the first braking ECU 70 and the redundant ECU 90. Therefore, as shown in Figure 4(h), at timing t18, after the waiting time TMmk has elapsed from timing t13, the redundant ECU 90 starts the apply process, and the second parking actuator 32 begins to operate. In other words, parking braking force is generated at the second wheel 12.

[0047] Here, we consider the first comparative example in which no waiting time TMmk is set. In the first braking ECU of this first comparative example, at timing t13, both the value indicated by the first status signal transmitted by the first braking ECU 70 to the redundant ECU 90 and the value indicated by the second status signal received by the first braking ECU 70 from the redundant ECU 90 become the first value. Therefore, as shown by the dashed line in Figure 4(d), the operation of the first parking actuator 31 based on the apply request starts at timing t13. Parking braking force is generated at the first wheel 11 even though the write process has not yet been executed in the redundant ECU 90.

[0048] In the redundant ECU of the first comparative example, at timing t16, both the value indicated by the second status signal transmitted by the redundant ECU 90 to the first braking ECU 70 and the value indicated by the first status signal received by the redundant ECU 90 from the first braking ECU 70 become the first value. Therefore, as shown by the dashed line in Figure 4(h), the operation of the second parking actuator 32 based on the apply request is started at timing t16. In this case, the time difference between the time when parking braking force is generated at the first wheel 11 and the time when parking braking force is generated at the second wheel 12 is the first time difference TD1.

[0049] In contrast, in this embodiment where a waiting time TMmk is set, as shown in Figures 4(d) and 4(h), the second time difference TD2 is the time difference between when parking braking force is generated at the first wheel 11 and when parking braking force is generated at the second wheel 12. The second time difference TD2 is shorter than the first time difference TD1. Therefore, the braking control system 60 of this embodiment can suppress a large time lag between when parking braking force is generated at the first wheel 11 and when parking braking force is generated at the second wheel 12.

[0050] The processing flow when a release request is received by multiple ECUs 70 and 90 as a parking brake operation request is generally the same as when multiple ECUs 70 and 90 receive an apply request. Therefore, the explanation of the processing flow when a release request occurs will be omitted.

[0051] In this embodiment, the following effects can be further obtained. (1) Consider a second comparative example in which the operation of the parking actuator is started without checking whether the writing process in the other ECU has finished. In the first braking ECU of this second comparative example, the operation of the first parking actuator 31 in response to the parking brake operation request is started at timing t13, which is the timing when its own writing process has finished. On the other hand, in the redundant ECU of the second comparative example, the operation of the second parking actuator 32 in response to the parking brake operation request is started at timing t16, which is the timing when its own writing process has finished. In this case, the time difference between when parking brake force is generated at the first wheel 11 and when parking brake force is generated at the second wheel 12 is the first time difference TD1.

[0052] In contrast, in this embodiment, the operation of the parking actuators 31 and 32 based on the parking brake operation request is initiated only if the writing process has been completed in any of the multiple ECUs 70 and 90. As a result, the braking control system 60 of this embodiment can shorten the time lag between the timing when parking brake force is generated at the first wheel 11 and the timing when parking brake force is generated at the second wheel 12, compared to the second comparative example described above.

[0053] (2) The status signal is a signal that identifies whether the write process is in progress or has been completed. In other words, the value indicated by the status signal alone does not allow for determination of whether the write process has actually been completed or has not yet been completed. Therefore, if the waiting time TMmk is not set, there is a risk that the parking actuator may be activated in accordance with the parking brake operation request in one of the ECUs, while the write process has been completed in the first braking ECU 70 and the redundant ECU, but the write process has not yet been started in the other ECU.

[0054] In this regard, the braking control system 60 of this embodiment has a waiting time TMmk set. Therefore, the braking control system 60 can prevent the operation of the parking actuator in accordance with the parking brake operation request from starting in one of the ECUs, while the writing process has been completed in the first braking ECU 70 and the redundant ECU, but the writing process has not yet started in the other ECU.

[0055] <Example of changes> The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0056] The integrated ECU 51 may transmit a parking brake operation request to the first braking ECU 70 via the first global communication line 201, and also transmit a parking brake operation request to the redundant ECU 90 via the second global communication line 202. In this case, the redundant ECU 90 may start the write process upon receiving a parking brake operation request via the second global communication line 202.

[0057] The status signal may be a signal that can identify whether the write operation is about to be executed, is in progress, or has been completed. In this case, the waiting time TMmk does not need to be set.

[0058] Each of the multiple ECUs 70 and 90 may use a method different from the method described in the above embodiment, as long as it can determine whether or not the writing process has been completed in any of the multiple ECUs 70 and 90. For example, each of the multiple ECUs 70 and 90 may determine that the writing process has been completed in any of the multiple ECUs 70 and 90 when a predetermined determination time TMj has elapsed since the time the parking brake operation request was received. It is preferable that the determination time TMj be set to a time that takes into account the time lag due to communication between the multiple ECUs 70 and 90, and the design value of the length of time required for the writing process of the multiple ECUs 70 and 90.

[0059] Figure 5 shows a flowchart illustrating an example of a series of processes performed by each of the multiple ECUs 70 and 90 in the braking control system of these modified examples. If the ECUs 70 and 90 receive a parking brake activation request in step S51 (S51: YES), the processing circuits 71 and 91 proceed to step S53. On the other hand, if the ECUs 70 and 90 do not receive a parking brake activation request (S51: NO), the processing circuits 71 and 91 terminate the series of processes shown in Figure 5.

[0060] In step S53, the processing circuits 71 and 91 start the write process described above, which is an example of pre-operation processing. In the following step S55, the processing circuits 71 and 91 determine whether the write process is complete or not. If the write process is not complete (S55: NO), the processing circuits 71 and 91 repeatedly perform the determination in step S55 until the write process is complete. On the other hand, if the write process is complete (S55: YES), the processing circuits 71 and 91 proceed to step S57.

[0061] In step S57, processing circuits 71 and 91 determine whether a determination time TMj has elapsed since the time of receiving the parking brake operation request. If the determination time TMj has elapsed since the time of reception, it is assumed that the write process has been completed in all of the ECUs 70 and 90. On the other hand, if the determination time TMj has not yet elapsed since the time of reception, it is assumed that the write process may not have been completed in one of the ECUs 70 and 90. If the determination time TMj has not yet elapsed since the time of reception (S57: NO), processing circuits 71 and 91 repeatedly perform the determination in step S57 until the determination time TMj has elapsed since the time of reception. On the other hand, if the determination time TMj has elapsed since the time of reception (S57: YES), processing circuits 71 and 91 proceed to step S59.

[0062] In step S59, the processing circuits 71 and 91 activate their respective parking actuators 31 and 32 based on the parking brake operation request, similar to step S23. Once the processing circuits 71 and 91 have completed the operation of the parking actuators 31 and 32 based on the parking brake operation request, they terminate the series of processes shown in Figure 5.

[0063] In this modified braking control system 60, it is possible to suppress a large time lag between when parking braking force is generated at the first wheel 11 and when parking braking force is generated at the second wheel 12. Furthermore, in this braking control system 60, it is not necessary to send and receive status signals between multiple ECUs 70 and 90.

[0064] In the braking control system, the second braking ECU 80 may have the function of operating the second parking actuator 32. In this case, the braking control system may be configured without a redundant ECU 90.

[0065] In the braking control system, the second braking ECU 80 may have the function of operating the first parking actuator 31. In this case, the second braking ECU 80 corresponds to the "first braking device".

[0066] The processing circuits 71, 81, and 91 are not limited to those that include a CPU and ROM and execute software processing. In other words, the processing circuits 71, 81, and 91 may have any of the following configurations: (a), (b), and (c).

[0067] (a) The processing circuits 71, 81, and 91 each include one or more processors that perform various processes according to a computer program. The processors include a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to perform the processes. The memory, i.e., computer-readable media, includes any available media that can be accessed by a general-purpose or dedicated computer.

[0068] (b) The processing circuits 71, 81, and 91 each include 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," and FPGA is an abbreviation for "Field Programmable Gate Array."

[0069] (c) Each processing circuit 71, 81, 91 comprises one or more processors that execute a portion of the various processes according to a computer program, and one or more dedicated hardware circuits that execute the remaining processes of the various processes.

[0070] <Other technological ideas> The technical concepts that can be understood from the above embodiments and modified examples are described below. [Note 1] The aforementioned plurality of control devices have a CPU and memory, It is preferable that the plurality of control devices perform a process in which the CPU writes the state of the parking actuator corresponding to itself to the memory as a pre-operation process. [Explanation of Symbols]

[0071] 10... Vehicles 11...1st wheel 12…Second wheel 30…Electric parking system 31, 32… Parking Actuators 60… Braking control system 61… Brake communication line (an example of an in-vehicle network) 70, 80, 90... ECU (Control Unit) 71, 81, 91… Processing circuits 71a, 91a…CPU 71b, 91b…memory

Claims

1. This invention is applied to a vehicle comprising a first wheel and a second wheel, and a plurality of parking actuators provided for each of the first wheel and the second wheel, configured to generate parking braking force on the corresponding wheel. Each of the plurality of parking actuators is provided with a plurality of control devices for operating the corresponding parking actuator, The aforementioned plurality of control devices are configured to communicate with each other via an in-vehicle network. Each of the aforementioned plurality of control devices is When a parking brake operation request is received, which is a request to activate the parking actuator, the pre-operation processing, which is a process to be performed before the parking actuator is activated, is executed. In any of the above-mentioned control devices, it is determined whether or not the pre-operation processing has been completed. The parking actuator is activated based on the parking brake operation request, provided that all of the above control devices have determined that the pre-operation processing has been completed. Braking control system.

2. Each of the aforementioned plurality of control devices is A status signal, which is a signal indicating the execution status of the pre-operation processing, is transmitted via the in-vehicle network to another control device, which is one of the plurality of control devices other than itself. Based on the execution status of its own pre-operation processing and the execution status of the pre-operation processing indicated by the status signal received from the other control devices, the control device determines whether or not the pre-operation processing has been completed in any of the multiple control devices. The braking control system according to claim 1.

3. The plurality of control devices prohibit the operation of the parking actuator based on the parking brake operation request during the period from the time the parking brake operation request is received until a predetermined waiting time has elapsed. The braking control system according to claim 2.

4. The status signal is a signal that identifies whether the pre-operation processing is in progress or whether the pre-operation processing has been completed. The braking control system according to claim 3.

5. Each of the plurality of control devices determines that the pre-operation processing is complete in any of the plurality of control devices if a predetermined determination time has elapsed since the time the parking brake operation request was received. The braking control system according to claim 1.

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