Vehicle control devices

Abstract

To provide a vehicle control device which can properly stop the generation of steering force according to the state of a vehicle.SOLUTION: A drive control device 50 is supplied with power through a first power line L1 with turn-on of a start switch 91A of a vehicle as a trigger. The drive control device 50 executes first processing for generating driving force for travel in a vehicle. A steering control device 40 is supplied with power through a second power line L2 with turn-on of the start switch 91A as a trigger. The steering control device 40 executes second processing for generating the steering force for steering in the vehicle. The steering control device 40 permits execution stop of the second processing when it is determined that the drive control device 50 is not in the state where the first processing can be executed in a case where it is determined that power supply through the second power line L2 is stopped during travel of the vehicle. The steering control device 40 does not permit execution stop of the second processing when it is determined that the drive control device 50 is in the state where the first processing can be executed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, there is a control device that controls the motor, which is the source of the steering force applied to the vehicle's steering mechanism. The control device controls the power supply to the motor according to the steering torque and vehicle speed detected through on-board sensors. The steering force is the steering torque generated by the motor when changing the direction of travel of the vehicle.

[0003] For example, the control device described in Patent Document 1 is capable of switching the power supply path between a first power supply path and a second power supply path. The first power supply path is a power supply path that includes an ignition switch. The second power supply path is a power supply path that includes a power line drawn directly from the vehicle's battery. The ignition switch is the vehicle's start switch.

[0004] The control device maintains the power supply path as the first power supply path while the vehicle is in motion. When the power supply via the first power supply path is interrupted while the vehicle is in motion, for example, by turning off the ignition switch, the control device switches the power supply path from the first power supply path to the second power supply path. After a predetermined period of time has elapsed since the power supply via the first power supply path was interrupted, the control device interrupts the power supply via the second power supply path.

[0005] Therefore, when the power supply via the first power supply path is interrupted while the vehicle is in motion, it is possible to prevent the immediate cessation of steering force generation. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2015-1143048 [Overview of the project] [Problems that the invention aims to solve]

[0007] The control device described in Patent Document 1 cuts off the power supply via the second power supply path, regardless of the vehicle's condition, after a predetermined period of time has elapsed since the power supply via the first power supply path was cut off. Depending on the vehicle's condition, there may be situations where it is undesirable to stop the generation of steering force.

[0008] For example, even after the ignition switch is turned off and the generation of driving force is stopped, the vehicle may continue to move due to inertia. In such a situation, it is undesirable to stop the generation of steering force. [Means for solving the problem]

[0009] A vehicle control device that can solve the above problems includes a drive control device that is powered through a first power line when the vehicle's start switch is turned on, and is configured to perform a first process for generating driving force for the vehicle, and a steering control device that is powered through a second power line when the start switch is turned on, and is configured to perform a second process for generating steering force for the vehicle. The steering control device is configured to perform power latch control, which maintains power supply from the onboard DC power supply to the steering control device for a predetermined period of time when the start switch is turned off. The steering control device is Assuming that the aforementioned DC power supply has not failed, If it is determined that power supply through the second power line has stopped while the vehicle is in motion, and the drive control device is determined not to be in a state where it can perform the first process, the system is configured to allow the execution of the second process to be stopped. On the other hand, if the drive control device is determined to be in a state where it can perform the first process, the system is configured not to allow the execution of the second process to be stopped.

[0010] According to this configuration, when it is determined that power supply through the second power line has stopped during the running of the vehicle, even though the vehicle is in a state where it can generate driving force for running, the execution of the second process for generating steering force for the vehicle is prevented from stopping. That is, it becomes possible to appropriately stop the generation of steering force according to the state of the vehicle. Also, it becomes possible to appropriately maintain the steering function according to the state of the vehicle.

[0011] In the above vehicle control device, the steering control device If it is determined that power supply through the second power line has stopped while the vehicle is in motion, it is determined that the drive control device is not in a state to perform the first process, and further, When it is determined that the running of the vehicle has stopped and the steering wheel of the vehicle is not being steered, it may be configured to stop the execution of the second process.

[0012] According to this configuration, during the running of the vehicle or when the steering wheel is being steered, the execution of the second process for generating steering force for the vehicle is prevented from stopping.

[0013] In the above vehicle control device, the steering control device may be configured to determine whether the drive control device can execute the first process based on the voltage level of the first power line.

[0014] According to this configuration, based on the voltage level of the first power line, it is possible to determine whether the drive control device can execute the first process 。

[0015] above In the above vehicle control device, the second process is Steering wheel and Power transmission during which is separated The vehicle Steering for steering the steered wheels Power Process for generating Even if is good.

[0016] In the above vehicle control device, the second process may be a process for generating an assist force for assisting the steering of a steering wheel that is connected to be able to transmit power to a steered wheel of the vehicle.

Effect of the Invention

[0017] According to the vehicle control device of the present invention, the generation of steering force can be appropriately stopped according to the state of the vehicle.

Brief Description of the Drawings

[0018] [Figure 1] It is a configuration diagram of a steer-by-wire type steering device on which an embodiment of the vehicle control device is mounted. [Figure 2] It is a block diagram showing the configuration of a vehicle control system according to an embodiment. [Figure 3] (a), (b), (c), and (d) are schematic diagrams showing comparative examples of vehicle state transitions. [Figure 4] (a), (b), (c), (d), and (e) are schematic diagrams showing the state transitions of a vehicle according to an embodiment. [Figure 5] It is a configuration diagram of an electric power steering device on which a vehicle control device according to another embodiment is mounted.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, an embodiment in which the steering control device is embodied in a steer-by-wire type steering device will be described. As shown in FIG. 1, the steering device 10 of the vehicle has a steering shaft 12 connected to the steering wheel 11. Further, the steering device 10 has a steering shaft 13 extending along the vehicle width direction (the left-right direction in FIG. 1). At both ends of the steering shaft 13, steering wheels 15 are connected via tie rods 14, respectively. When the steering shaft 13 moves linearly, the steering angle θw of the steering wheels 15 is changed. The steering shaft 12 and the steering shaft 13 constitute a steering mechanism of the vehicle. In FIG. 1, only the steering wheel 15 on one side is shown.

[0020] The steering system 10 includes a reaction motor 21 and a reduction mechanism 22. The reaction motor 21 is, for example, a three-phase brushless motor. The reaction motor 21 is the source of the steering reaction force. The steering reaction force is the force that acts in the opposite direction to the direction of operation of the steering wheel 11 by the driver. The steering reaction force is the steering force generated by the reaction motor 21 when changing the direction of travel of the vehicle.

[0021] The rotation axis of the reaction motor 21 is connected to the steering shaft 12 via a reduction mechanism 22. The torque of the reaction motor 21 is applied to the steering shaft 12 as a steering reaction force. By applying this steering reaction force to the steering wheel 11, it is possible to provide the driver with a suitable level of feedback.

[0022] The steering system 10 includes a steering motor 31 and a reduction mechanism 32. The steering motor 31 is, for example, a three-phase brushless motor. The steering motor 31 is the source of the steering force. The steering force refers to the power required to steer the steering wheels 15. The steering force is the steering force generated by the steering motor 31 when changing the direction of travel of the vehicle.

[0023] The rotating shaft of the steering motor 31 is connected to the pinion shaft 33 via a reduction mechanism 32. The pinion teeth 33a of the pinion shaft 33 mesh with the rack teeth 13a of the steering shaft 13. The torque of the steering motor 31 is applied to the steering shaft 13 as a steering force via the pinion shaft 33. In response to the rotation of the steering motor 31, the steering shaft 13 moves along the vehicle width direction.

[0024] The steering system 10 has a steering control device 40. The steering control device 40 constitutes a vehicle control device. The steering control device 40 has a processing circuit that includes one of the following three configurations A1, A2, and A3.

[0025] A1. One or more processors that operate according to a computer program, which is software. A processor includes a CPU (Central Processing Unit) and memory. A2. One or more dedicated hardware circuits, such as application-specific integrated circuits (ASICs), that perform at least some of the various processes. An ASIC includes a CPU and memory.

[0026] A3. Hardware circuit combining configurations A1 and A2. Memory is a medium readable by a computer that stores programs describing processes or instructions for the computer. In this embodiment, the computer is the CPU. Memory includes RAM (Random Access Memory) and ROM (Read Only Memory). The CPU performs various controls by executing the programs stored in memory at predetermined calculation cycles.

[0027] The steering control device 40 includes a reaction force control device 40A and a steering control device 40B. The reaction force control device 40A controls the drive of the reaction force motor 21, which is the object of control. The reaction force control device 40A performs reaction force control to generate a steering reaction force in the reaction force motor 21 in accordance with the steering torque Th. The reaction force control device 40A calculates the target steering reaction force based on the steering torque Th detected through the torque sensor 23. The torque sensor 23 is provided on the steering shaft 12. The reaction force control device 40A controls the power supply to the reaction force motor 21 in order to match the actual steering reaction force applied to the steering shaft 12 with the target steering reaction force.

[0028] Furthermore, by integrally providing the reaction force control device 40A and the reaction force motor 21, a so-called electromechanically integrated reaction force actuator may be constructed. The steering control device 40B controls the drive of the steering motor 31, which is the object of control. The steering control device 40B performs steering control to generate a steering force in the steering motor 31 to steer the steering wheels 15 according to the steering state. The steering control device 40B takes in the steering angle θs detected through the steering angle sensor 24 and the stroke Xw of the steering shaft 13 detected through the stroke sensor 34. The stroke Xw is the amount of displacement of the steering shaft 13 relative to the neutral position and is a state variable that reflects the steering angle θw. The steering angle sensor 24 is provided between the torque sensor 23 and the reduction mechanism 22 of the steering shaft 12. The stroke sensor 34 is provided in the vicinity of the steering shaft 13.

[0029] The steering control device 40B calculates the target steering angle of the steering wheel 15 based on the steering angle θs detected through the steering angle sensor 24. The steering control device 40B calculates the steering angle θw based on the stroke Xw of the steering shaft 13 detected through the stroke sensor 34. The steering control device 40B controls the power supply to the steering motor 31 to match the steering angle θw calculated based on the stroke Xw to the target steering angle.

[0030] Furthermore, by integrally providing the steering control device 40B and the steering motor 31, a so-called electromechanically integrated steering actuator may be configured. In addition, the steering control device 40B and the reaction force control device 40A can communicate with each other. The steering control device 40B and the reaction force control device 40A can exchange information with each other through communication.

[0031] The vehicle has a drive control device 50. The drive control device 50 constitutes a vehicle control system. The drive control device 50 basically has the same configuration as the steering control device 40. The reaction force control device 40A and the on-board drive control device 50 are interconnected via an on-board network 51. The on-board network 51 is, for example, a CAN (Controller Area Network). The reaction force control device 40A and the drive control device 50 exchange information with each other via the on-board network 51.

[0032] The drive control device 50 controls the movement of the vehicle. Specifically, the drive control device 50 controls, for example, the vehicle's powertrain. The powertrain includes a drive source and a power transmission mechanism for driving the vehicle. The drive source generates the driving force necessary to move the vehicle. The drive source includes, for example, an engine or a motor. If the drive source is an engine, the drive control device 50 includes a fuel injection device. The power transmission mechanism is a mechanism for transmitting the driving force generated by the drive source to the drive wheels. The reaction force control device 40A controls the driving of the reaction force motor 21 based on information exchanged with the drive control device 50.

[0033] The powertrain control of the vehicle performed by the drive control device 50 corresponds to a first process for generating driving force for the vehicle. The reaction force control and steering control performed by the steering control device 40 corresponds to a second process for generating steering force for the vehicle.

[0034] <Configuration of the vehicle's control system> Next, we will explain the configuration of the vehicle's control system. As shown in Figure 2, the vehicle's control system includes various control devices or systems in addition to the steering control device 40 and drive control device 50. The control system includes, for example, a body control device 60, a power distribution control device 70, and other systems 80. These other systems 80 include various systems required to operate when generating driving force for the vehicle's powertrain.

[0035] Various control devices, including the steering control device 40, the drive control device 50, the body control device 60, and other systems 80, are powered by an onboard DC power supply 90. The DC power supply 90 is, for example, a battery. Various sensors, including the torque sensor 23, the steering angle sensor 24, and the stroke sensor 34, are also powered by the DC power supply 90.

[0036] The steering control device 40, the drive control device 50, the body control device 60, and other systems 80 are interconnected via an in-vehicle network 51. The body control device 60 and the power distribution control device 70 are communicated with each other via a board-to-board connector 61. The communication standard between the body control device 60 and the power distribution control device 70 is, for example, CXPI (Clock Extension Peripheral Interface).

[0037] The drive control device 50, body control device 60, power distribution control device 70, and other systems 80 are connected to the DC power supply 90 via a first power line L1. The steering control device 40 is connected to the DC power supply 90 via a second power line L2 and the power distribution control device 70.

[0038] The first power line L1 includes a start switch 91A and a first relay 91B. The start switch 91A is positioned closer to the DC power supply 90 than the first relay 91B.

[0039] The start switch 91A is, for example, an ignition switch or a power switch. The start switch 91A is operated to start or stop the vehicle's drive source, such as the engine. When the start switch 91A is turned on, power from the DC power supply 90 becomes available to each control device (40, 50, 60, 70) and other systems 80. Turning the start switch 91A on means turning on the vehicle power supply. Turning the start switch 91A off means turning off the vehicle power supply.

[0040] The first relay 91B opens and closes the first power line L1. The first relay 91B has a coil and contacts. When the coil is energized, the contacts close. When the coil is not energized, the contacts open.

[0041] The body control device 60 is connected to a first connection point P1 of the first power line L1. The first connection point P1 is located between the start switch 91A and the first relay 91B on the first power line L1.

[0042] The power distribution control device 70 is connected to a second connection point P2 of the first power line L1. The second connection point P2 is located between the first connection point P1 and the first relay 91B on the first power line L1.

[0043] The drive control device 50 is connected to the third connection point P3 of the first power line L1. The third connection point P3 is located on the opposite side of the second connection point P2 from the first relay 91B.

[0044] The other system 80 is connected to the fourth connection point P4 of the first power line L1. The fourth connection point P4 is located on the opposite side of the first relay 91B from the third connection point P3.

[0045] In the first power line L1, the start switch 91A, the first connection point P1, the second connection point P2, the first relay 91B, the third connection point P3, and the fourth connection point P4 are located away from the DC power supply 90 in this order.

[0046] The body control device 60 has a control circuit 60A. The control circuit 60A is a CPU. The control circuit 60A controls the overall functions of the vehicle body. For example, the control circuit 60A centrally controls the air conditioning inside the vehicle, the lighting inside and outside the vehicle, the doors, windows, mirrors, and wipers.

[0047] The power distribution control device 70 has a control circuit 70A and a second relay 70B. The control circuit 70A is the CPU. The control circuit 70A controls the distribution of power supplied from the DC power supply 90. The control circuit 70A can communicate with the control circuit 60A.

[0048] The second relay 70B has the same configuration as the first relay 91B. The input terminal of the second relay 70B is connected to the second connection point P2 of the first power supply line L1 via a connecting wire LC. The output terminal of the second relay 70B is connected to the second power supply line L2. The connecting wire LC has a diode 70C for preventing reverse current. The anode of diode 70C is connected to the second connection point P2. The cathode of diode 70C is connected to the input terminal of the second relay 70B.

[0049] The steering control device 40 is connected to the fifth connection point P5 of the second power line L2. The drive control device 50 is connected not only to the first power line L1 but also to the sixth connection point P6 of the second power line L2.

[0050] The control circuit 70A controls the opening and closing of the first relay 91B and the second relay 70B. When the first relay 91B is turned on, the portion of the first power line L1 between the second connection point P2 and the third connection point P3 becomes conductive. When the first relay 91B is turned off, the conductivity of the portion of the first power line L1 between the second connection point P2 and the third connection point P3 is interrupted. Also, when the second relay 70B is turned on, the connection line LC and the second power line L2 become conductive. When the second relay 70B is turned off, the conductivity between the connection line LC and the second power line L2 is interrupted.

[0051] The control circuit 70A has a first input terminal 70D and a second input terminal 70E. The first input terminal 70D is connected to the seventh connection point P7 of the connecting wire LC via the first service drop LW1. The seventh connection point P7 is located between the second connection point P2 of the connecting wire LC and the diode 70C. The first input terminal 70D and the first service drop LW1 are connected, for example, by a connector.

[0052] The second input terminal 70E is connected to the eighth connection point P8 of the connecting wire LC via the second lead wire LW2. The eighth connection point P8 is located between the diode 70C and the second relay 70B of the connecting wire LC. The second input terminal 70E and the second lead wire LW2 are connected, for example, by a connector.

[0053] The control circuit 70A receives power supplied to the first relay 91B via the connecting line LC and the first service drop line LW1. The control circuit 70A also receives power supplied to the second relay 70B via the connecting line LC and the second service drop line LW2. The control circuit 70A monitors the voltage level of the first input terminal 70D and the voltage level of the second input terminal 70E.

[0054] The control circuit 70A turns on the first relay 91B when the voltage level at the first input terminal 70D is equal to or greater than a first voltage threshold. That is, the control circuit 70A supplies an electrical signal to the first relay 91B to energize its coil. When the coil of the first relay 91B is energized, the contacts of the first relay 91B close. When the first relay 91B is turned on, power from the DC power supply 90 is supplied to the drive control device 50 and the other systems 80 via the first power line L1.

[0055] The first voltage threshold is set based on the voltage applied to the first input terminal 70D when the start switch 91A is turned on. The voltage level of the first input terminal 70D corresponds to the voltage level of the first power line L1.

[0056] The control circuit 70A sets the value of the first flag according to the voltage level of the first input terminal 70D. When the voltage level of the first input terminal 70D is equal to or greater than the first voltage threshold, the control circuit 70A sets the value of the first flag to "1 (=Hi)". When the voltage level of the first input terminal 70D is less than the first voltage threshold, the control circuit 70A sets the value of the first flag to "0 (=Lo)". The first flag also indicates the on / off state of the start switch 91A.

[0057] The control circuit 70A turns on the second relay 70B when the voltage level at the second input terminal 70E is equal to or greater than the second voltage threshold. That is, the control circuit 70A supplies an electrical signal to the second relay 70B to energize its coil. When the coil of the second relay 70B is energized, the contacts of the second relay 70B close. When the second relay 70B is turned on, power from the DC power supply 90 is supplied to the steering control device 40 and the drive control device 50 via the second power line L2.

[0058] The second voltage threshold is set based on the voltage applied to the second input terminal 70E when the start switch 91A is turned on. The voltage level of the second input terminal 70E corresponds to the voltage level of the second power line L2.

[0059] The control circuit 70A sets the value of the second flag according to the voltage level of the second input terminal 70E. When the voltage level of the second input terminal 70E is equal to or greater than the second voltage threshold, the control circuit 70A sets the value of the second flag to "1 (=Hi)". When the voltage level of the second input terminal 70E is less than the second voltage threshold, the control circuit 70A sets the value of the second flag to "0 (=Lo)". The second flag also indicates the on / off state of the start switch 91A.

[0060] The body control device 60 receives the values ​​of a first flag and a second flag. The values ​​of the first flag and the second flag are shared with various control devices or systems via the in-vehicle network 51. The control devices include the steering control device 40, the drive control device 50, the body control device 60, and the control devices of other systems 80.

[0061] The steering control device 40 is connected to the DC power supply 90 via a power relay (not shown). When the power relay is turned on, power from the DC power supply 90 is supplied to the steering control device 40 via the power relay. When the power relay is turned off, the power supply via the power relay is cut off. The steering control device 40 controls the on / off state of the power relay. The steering control device 40 turns on the power relay when the start switch 91A is turned on. The steering control device 40 turns off the power relay when the start switch 91A is turned off.

[0062] Incidentally, the steering control device 40 may be configured to perform power latch control, which keeps the power relay ON for a predetermined period of time when the start switch 91A is turned OFF. In this way, the steering control device 40 can operate even after the start switch 91A has been turned OFF. The steering control device 40 cuts off its power supply by turning off the power relay after the predetermined period has elapsed.

[0063] When the power supply to the steering control device 40 via the power relay is cut off, the steering control device 40 stops performing reaction force control and steering control. <Regarding turning off the starter switch while driving> In the case of a vehicle, the following concerns arise. Specifically, it is anticipated that the start switch 91A may be turned off while the vehicle is in motion. However, since the vehicle is in motion, it is undesirable for the steering control device 40 to immediately stop performing reaction force control and steering control due to the interruption of power supply to the steering control device 40 via the power relay.

[0064] Therefore, in order to deal with the off operation of the start switch 91A while driving, the steering control device 40 may be configured as follows. The steering control device 40 determines, for example, that the start switch 91A has been turned off while the vehicle is in motion when all three of the following conditions B1 to B3 are met. When the steering control device 40 determines that the start switch 91A has been turned off while the vehicle is in motion, it continues to perform reaction force control and steering control.

[0065] B1. "V2 < V " However, "V2" is the voltage level of the second power line L2. "V 2th " is the voltage threshold. The voltage threshold is a criterion for determining whether the start switch 91A is turned off. For example, it is set based on the voltage level of the second power line L2 when the start switch 91A is turned off.

[0066] B2. "V > V th1 " However, "V" is the value of the vehicle speed obtained via the in-vehicle network 51. "V th1 " is the first vehicle speed threshold. The first vehicle speed threshold V th1 is a criterion for determining whether the vehicle is running. For example, it is set based on a very low speed of several Km / h.

[0067] B3. "FG2 = 0" However, "FG2" is the value of the second flag set by the power distribution control device 70. The fact that the value of the second flag FG2 is "0" indicates that the voltage level of the second input terminal 70E is less than the second voltage threshold. The steering control device 40 acquires the value of the second flag FG2 via the in-vehicle network 51.

[0068] When it is determined that the start switch 91A has been turned off during the running of the vehicle, the steering control device 40 permits the execution stop of the reaction force control and the steering control. However, when it is determined that the start switch 91A has been turned off during the running of the vehicle, the steering control device 40 stops the execution of the reaction force control and the steering control when both of the following two conditions C1 and C2 are satisfied.

[0069] C1. "V ≤ V th2 " and "T1 ≥ T1 th " However, "V th2 " is the second vehicle speed threshold. The second vehicle speed threshold V th2 is the first vehicle speed threshold Vth1 It may be the same as the second vehicle speed threshold V. "T1" is when the vehicle speed V is the second vehicle speed threshold V th2 This is the elapsed time since the value decreased to the following level: "T1 th This is the first time threshold. The first time threshold is the criterion for determining whether the vehicle is stopped or not.

[0070] C2. "Th≦Th" th " and "T2 ≥ T2 th " However, "Th" is steering torque. th " is the torque threshold. The torque threshold is the criterion for determining whether the steering wheel 11 is not being steered. "T2" is the elapsed time since the steering torque Th fell to a value below the torque threshold. th This is the second time threshold. The second time threshold is the criterion for determining whether or not steering is being performed on the steering wheel 11.

[0071] Furthermore, the following condition may be adopted as condition C1. C1. "T3≧T3" th " However, "T3" is the elapsed time since the start switch 91A was turned off while the vehicle was in motion. th This is the third time threshold. Third time threshold T3 th The first time threshold T1 th It is set to a value that is sufficiently large compared to the third time threshold T3. th This is the criterion for determining whether a vehicle is stopped or not.

[0072] In this way, even if the start switch 91A is turned off while the vehicle is in motion, the reaction force control and steering control performed by the steering control device 40 will not be immediately stopped. When the vehicle stops moving and steering of the steering wheel 11 is no longer performed, the reaction force control and steering control performed by the steering control device 40 will stop.

[0073] However, the following issues may occur in vehicles. As shown in Figure 3(a), it is conceivable that the connector 100 connecting the second input terminal 70E of the power distribution control device 70 and the second service drop LW2 may become disconnected while the vehicle is in motion. In this case, even though the start switch 91A is not turned off, the steering control device 40 may stop performing the reaction force control and steering control.

[0074] In other words, when connector 100 is disconnected, the voltage level of the second input terminal 70E drops to a value below the second voltage threshold. Therefore, the power distribution control device 70 sets the value of the second flag FG2 to "0". Also, because the voltage level of the second input terminal 70E drops to a value below the second voltage threshold, the power distribution control device 70 turns off the second relay 70B. As a result, power is stopped from the DC power supply 90 to the second power line L2.

[0075] Therefore, when the vehicle is in motion, the value of the vehicle speed V is equal to the first vehicle speed threshold V. th1 If the value is greater than this, the steering control device 40 will incorrectly determine that the start switch 91A was turned off while the vehicle was in motion, assuming that all three conditions B1 to B3 above are met.

[0076] As shown in Figures 3(b) and 3(c), when the vehicle stops moving, thus fulfilling condition C1, and when the steering wheel 11 ceases to steer, thus fulfilling condition C2, the steering control device 40 stops executing the reaction force control and steering control.

[0077] As shown in Figure 3(d), even if the steering control device 40 stops performing reaction force control and steering control, the drive control device 50 continues to operate normally. In other words, even though the vehicle is in a drivable state, there is a risk of losing steering functionality. The steering function is the function of steering the steering wheels 15 according to the amount of movement of the steering wheel 11.

[0078] Furthermore, if a break or ground fault occurs in the second service drop line LW2 or the second power line L2 while the vehicle is in motion, the same events as when connector 100 is disconnected may occur.

[0079] <Processing to determine the state of the start switch while driving> Therefore, in this embodiment, the steering control device 40 is configured as follows. Specifically, the steering control device 40 has the following condition B4 in addition to the three conditions B1 to B3 mentioned above as conditions for determining the state of the start switch 91A while the vehicle is running.

[0080] B4. "FG1=0" However, "FG1" is the value of a first flag set by the power distribution control device 70. A value of "0" for the first flag FG1 indicates that the voltage level of the first input terminal 70D is less than the first voltage threshold. The steering control device 40 obtains the value of the first flag FG1 via the in-vehicle network 51.

[0081] The steering control device 40 determines that the start switch 91A was turned off while the vehicle was in motion when all four conditions B1 to B4 above are met. When the steering control device 40 determines that the start switch 91A was turned off while the vehicle was in motion, it permits the cessation of reaction force control and steering control. However, if the steering control device 40 determines that the start switch 91A was turned off while the vehicle was in motion, it cessates the execution of reaction force control and steering control when all two conditions C1 and C2 above are met.

[0082] <Operation of the Embodiment> Next, the operation of this embodiment will be explained. As shown in Figure 4(a), it is assumed that the connector 100 connecting the second input terminal 70E of the power distribution control device 70 and the second service drop line LW2 will become disconnected while the vehicle is in motion. In this case, the voltage level of the second input terminal 70E will drop to a value below the second voltage threshold. Therefore, the power distribution control device 70 will set the value of the second flag FG2 to "0". Also, the power distribution control device 70 will turn off the second relay 70B because the voltage level of the second input terminal 70E has dropped to a value below the second voltage threshold. As a result, the power supply from the DC power supply 90 to the second power line L2 will stop. Therefore, when the vehicle is in motion and the value of the vehicle speed V is below the first vehicle speed threshold V th1 If it is greater than this, then the three conditions B1 to B3 mentioned above are met.

[0083] However, if the start switch 91A is not actually turned off, the voltage level of the first input terminal 70D is maintained at a value equal to or greater than the first voltage threshold. That is, the value of the first flag FG1 is maintained at "1". Since the above condition B4 is not met, the steering control device 40 does not determine that the start switch 91A has been turned off while the vehicle is running.

[0084] Therefore, the steering control device 40 will not stop performing reaction force control and steering control, even if both of the above two conditions C1 and C2 are met. Consequently, the continued operation of the drive control device 50 prevents the vehicle from losing steering function even though it is in a drivable state. The steering function is maintained by the steering control device 40 continuing to perform reaction force control and steering control.

[0085] Furthermore, if a break or ground fault occurs in the second service drop LW2 or the second power line L2 while the vehicle is in motion, the same procedure as when the connector 100 is disconnected will be performed. As shown in Figure 4(b), if the start switch 91A is actually turned off while the vehicle is in motion, the voltage level at the first input terminal 70D drops to a value below the first voltage threshold. Therefore, the power distribution control device 70 sets the value of the first flag FG1 to "0". Also, the power distribution control device 70 turns off the first relay 91B because the voltage level at the first input terminal 70D drops to a value below the first voltage threshold. As a result, the power supply from the DC power supply 90 to the first power line L1 is stopped. Consequently, the operation of the drive control device 50 and the other systems 80 stops, and the vehicle's powertrain does not generate any driving force. However, if the start switch 91A is turned off while the vehicle is in motion, the vehicle can continue to move due to inertia.

[0086] Furthermore, if the start switch 91A is actually turned off while the vehicle is in motion, the voltage level at the second input terminal 70E drops to a value below the second voltage threshold. Therefore, the power distribution control device 70 sets the value of the second flag FG2 to "0". Also, the power distribution control device 70 turns off the second relay 70B because the voltage level at the second input terminal 70E drops to a value below the second voltage threshold. This stops the power supply from the DC power supply 90 to the second power line L2. Therefore, if the vehicle is in motion and the vehicle speed V is below the first vehicle speed threshold V th1 If it is greater than this, then all four conditions B1 to B4 above are satisfied.

[0087] The steering control device 40 determines that the start switch 91A was turned off while the vehicle was in motion when all four conditions B1 to B4 are met. As shown in Figures 4(c), (d), and (e), when the vehicle stops moving, thus fulfilling condition C1, and when steering of the steering wheel 11 ceases, thus fulfilling condition C2, the steering control device 40 stops performing reaction force control and steering control. The drive control device 50, other systems 80, and the vehicle's powertrain are kept in a stopped state.

[0088] <Effects of the Embodiment> According to this embodiment, the following effects can be obtained. (1) When the steering control device 40 determines that the power supply through the second power line L2 has stopped while the vehicle is in motion, and determines that the drive control device 50 is not in a state to perform the process of generating driving force for the vehicle, it permits the suspension of reaction force control and steering control. Conversely, when the steering control device 40 determines that the power supply through the second power line L2 has stopped while the vehicle is in motion, and determines that the drive control device 50 is in a state to perform the process of generating driving force for the vehicle, it does not permit the suspension of reaction force control and steering control.

[0089] Therefore, if it is determined that power supply through the second power line L2 has stopped while the vehicle is in motion, the execution of reaction force control and steering control will not be stopped even though the vehicle is in a state where it can generate driving force for propulsion. In other words, by stopping the execution of reaction force control and steering control according to the state of the vehicle, it is possible to appropriately stop the steering function. Conversely, by continuing the execution of reaction force control and steering control according to the state of the vehicle, it is possible to appropriately maintain the steering function.

[0090] (2) For example, it is assumed that the power supply through the second power line L2 will be stopped if the connector 100 is disconnected. If the connector 100 is disconnected, the power supply through the first power line L1 will continue, while only the power supply through the second power line L2 will be stopped. In contrast, if the start switch 91A is turned off, both the power supply through the first power line L1 and the power supply through the second power line L2 will be stopped.

[0091] From this perspective, if the steering control device 40 determines that power supply through the second power line L2 has stopped while the vehicle is in motion, and determines that the drive control device 50 is in a state where it can perform the process of generating driving force for driving, it will not permit the stopping of reaction force control and steering control. In other words, even if the above conditions B1 to B3 are met, the steering control device 40 will not permit the stopping of reaction force control and steering control unless condition B4 is met. Therefore, it is possible to more accurately determine whether the start switch 91A has been turned off. Accordingly, it is possible to prevent the steering control device 40 from mistakenly stopping the execution of reaction force control and steering control due to the disconnection of the connector 100.

[0092] The same applies if a break or ground fault occurs in the second service drop line LW2 or the second power line L2. (3) When the steering control device 40 permits the stopping of the reaction force control and steering control, it stops the execution of the reaction force control and steering control when both of the above two conditions C1, C1 are met, and it is determined that the vehicle has stopped moving and the steering wheel 11 is not being steered. In this way, the stopping of the execution of the reaction force control and steering control is avoided when the vehicle is moving or when the steering wheel 11 is being steered.

[0093] (4) The steering control device 40 can easily determine whether the drive control device 50 is in a state where it can perform the process of generating driving force for driving based on the voltage level of the first power line L1. The voltage level of the first power line L1 can be recognized based on the value of the first flag FG1 set by the power distribution control device 70.

[0094] (5) In a steer-by-wire steering system 10, power transmission between the steering wheel 11 and the steering wheels 15 is separated. Therefore, the steering system 10 is required to appropriately maintain or appropriately stop the steering function depending on the state of the vehicle. In this regard, the steering control device 40 does not stop the execution of reaction force control and steering control while the vehicle is in motion or when the steering wheel 11 is being steered, even if it is determined that the start switch 91A has been turned off while the vehicle is running. For this reason, this embodiment is suitable for a steer-by-wire steering system 10.

[0095] <Other Embodiments> This embodiment may be implemented with the following modifications. The reaction motor 21 may have a first winding group and a second winding group. The first and second winding groups are wound around a common stator. The electrical characteristics of the first and second winding groups are equivalent. The reaction force control device 40A independently controls the power supply to the two winding groups in the reaction motor 21 for each system.

[0096] In this case, the reaction force control device 40A may have a first system circuit and a second system circuit. The first system circuit controls the power supply to the first system winding group in the reaction force motor 21 according to the steering torque Th detected through the torque sensor 23. The second system circuit controls the power supply to the second system winding group in the reaction force motor 21 according to the steering torque Th detected through the torque sensor 23.

[0097] The steering motor 31 may have a first winding group and a second winding group. The first and second winding groups are wound around a common stator. The electrical characteristics of the first and second winding groups are equivalent. The steering control device 40B independently controls the power supply to the two winding groups in the steering motor 31 for each system.

[0098] In this case, the steering control device 40B may have a first system circuit and a second system circuit. The first system circuit controls the power supply to the first system winding group in the steering motor 31 based on the steering angle θs detected through the rudder angle sensor 24 and the stroke Xw of the steering shaft 13 detected through the stroke sensor 34. The second system circuit controls the power supply to the second system winding group in the steering motor 31 based on the steering angle θs detected through the rudder angle sensor 24 and the stroke Xw of the steering shaft 13 detected through the stroke sensor 34.

[0099] The drive control device 50 starts executing the predetermined startup preparations when the start switch 91A is turned on, that is, when the vehicle power is turned on. After the startup preparations are complete, the drive control device 50 starts the vehicle's powertrain. When the powertrain startup process is complete, the drive control device 50 turns on the ready signal. The ready signal is information indicating that the vehicle's powertrain is in a state where it can generate driving force for propulsion. The ready signal may also be a third flag. When the vehicle's powertrain is in a state where it can generate driving force for propulsion, the drive control device 50 sets the value of the third flag to "1". When the vehicle's powertrain is not in a state where it can generate driving force for propulsion, the drive control device 50 sets the value of the third flag to "0".

[0100] Based on this, the steering control device 40 may adopt the following condition B5 instead of the above condition B4 as a condition for determining the state of the start switch 91A while the vehicle is in motion.

[0101] B5. "FG3=0" However, "FG3" is the value of a third flag set by the drive control device 50. The steering control device 40 obtains the value of the third flag FG3 via the in-vehicle network 51.

[0102] In this way, the steering control device 40 can determine whether the drive control device 50 is ready to start up, and whether the drive control device 50 is in a state where it can perform the process of generating driving force for driving. The steering control device 40 can also determine whether the start switch 91A was turned off while the vehicle was running, based on whether all of the above four conditions B1 to B3 and B5 are met. When the steering control device 40 determines that the start switch 91A was turned off while the vehicle was running, it permits the stopping of the reaction force control and steering control. The steering control device 40 stops the execution of the reaction force control and steering control when all of the above two conditions (C1) and (C2) are met.

[0103] The steering control device 40 may be implemented as an electric power steering system. In the electric power steering system 200, the steering wheel 11 and the steering wheels 15 shown in Figure 1 are mechanically connected. That is, the steering shaft 12, pinion shaft 33, and steering shaft 13 function as power transmission paths between the steering wheel 11 and the steering wheels 15. As the steering wheel 11 is turned, the steering shaft 13 moves in a straight line, changing the steering angle θw of the steering wheels 15.

[0104] The electric power steering system 200 includes an assist motor 201 and an assist control device 202. The assist motor 201 is located in the same position as the reaction motor 21 or steering motor 31 shown in Figure 1. In Figure 5, as an example, the assist motor 201 is located in the same position as the reaction motor 21 shown in Figure 1. The assist control device 202 corresponds to a steering control device. The assist control device 202 controls the drive of the assist motor 201, which is the object of control. The assist control device 202 performs assist control to generate an assist force in the assist motor 201. The assist force is a torque to assist the operation of the steering wheel 11, and is a torque in the same direction as the steering direction of the steering wheel 11. The assist force is also the steering force generated by the assist motor 201 when changing the direction of travel of the vehicle.

[0105] The assist control device 202 determines whether the start switch 91A was turned off while the vehicle was running, based on whether all of the above four conditions B1 to B4 are met. The assist control device 202 determines that the start switch 91A was turned off while the vehicle was running if all of the above four conditions B1 to B4 are met. If the assist control device 202 determines that the start switch 91A was turned off while the vehicle was running, and if all of the above two conditions C1 and C2 are met, it stops the execution of the assist control.

[0106] If connector 100 is disconnected while the vehicle is in motion, condition B4 above will not be met. Therefore, if connector 100 is disconnected while the vehicle is in motion, the assist control device 202 will not mistakenly determine that the start switch 91A was turned off while the vehicle was in motion. The assist control device 202 will continue to perform assist control even if both of the above two conditions C1 and C2 are met. Thus, loss of steering function is avoided even though the vehicle is in a drivable state. [Explanation of Symbols]

[0107] 11… Steering wheel 15… Steering wheel 40... Steering control system, which is part of a vehicle control system. 50…Drive control device that constitutes a vehicle control system 91A...Start switch L1…First power line L2…Second power line

Claims

1. A drive control device that is powered through a first power line when the vehicle's start switch is turned on, and is configured to perform a first process for generating driving force for the vehicle, A steering control device that is powered through a second power line when the aforementioned start switch is turned on, and is configured to perform a second process for generating steering force for steering the vehicle, The steering control device is configured to perform power latch control, which, when the start switch is turned off, maintains power supply from the onboard DC power supply to the steering control device for a predetermined period of time. The steering control device is configured to, assuming that the DC power supply has not failed, permit the cessation of the execution of the second process when it is determined that the power supply through the second power line has stopped while the vehicle is in motion, and when it is determined that the drive control device is not in a state to execute the first process, to permit the cessation of the execution of the second process, while when it is determined that the drive control device is in a state to execute the first process, it does not permit the cessation of the execution of the second process.

2. The vehicle control device according to claim 1, wherein the steering control device is configured to stop executing the second process when it is determined that power supply through the second power line has stopped while the vehicle is in motion, and further determined that the vehicle has stopped moving and the vehicle's steering wheel is not being steered.

3. The vehicle control device according to claim 1 or 2, wherein the steering control device is configured to determine whether the drive control device is in a state where it can perform the first process based on the voltage level of the first power line.

4. The vehicle control device according to claim 1 or 2, wherein the second process includes a process for generating a steering force to steer a vehicle's steering wheel, from which power transmission has been separated.

5. The vehicle control device according to claim 1 or 2, wherein the second process is a process for generating an assist force to assist in steering a steering wheel that is power-transmitted to the steering wheels of a vehicle.

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