Vehicle control device

Abstract

To provide a vehicular control device that enables timings when control circuits are activated to coincide with each other even when a vehicle power supply is turned on during execution of power latch control.SOLUTION: A vehicular control device includes a first reaction force control circuit 41A, a second reaction force control circuit 42A, a first turning control circuit 51A and a second turning control circuit 52A. The control circuits are activated at a time when a vehicle power supply is turned on. Further the control circuits execute power latch control by which the vehicle power supply is held only in a predetermined period of time, at the time (a time T1) when the vehicle power supply is turned off. When the vehicle power supply is turned on during execution of the power latch control after the vehicle power supply is turned off, the control circuits are activated after all of the control circuits recognize that the vehicle power supply is turned on (a time T7).SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Conventionally, so-called steer-by-wire steering devices have been known in which power transmission between the steering wheel and the steered wheels is separated. For example, the steer-by-wire system disclosed in Patent Document 1 includes a reaction force actuator and a steering actuator. The reaction force actuator generates a steering reaction force applied to the steering shaft. The steering actuator generates a steering force that steers the steered wheels.

[0003] The reaction force actuator and the steering actuator each have two redundant control calculation units and two redundant motor drive units. The control calculation units perform calculations related to motor drive control. The motor drive units generate torque based on drive signals generated by their corresponding control calculation units.

[0004] The two control calculation units of the first and second systems of the reaction force actuator can communicate with each other and can operate in cooperation based on information exchanged between them.The two control calculation units of the first and second systems of the steering actuator can communicate with each other and can operate in cooperation based on information exchanged between them.

[0005] The control calculation unit of the first system of the reaction force actuator and the control calculation unit of the first system of the steering actuator are capable of communicating with each other. The control calculation unit of the second system of the reaction force actuator and the control calculation unit of the second system of the steering actuator are capable of communicating with each other. The two control calculation units of the first system and the two control calculation units of the second system commonly use information exchanged between them through inter-system communication to generate torque in the motor drive unit.

[0006] Conventionally, there are electric power steering devices that assist steering wheel operation. A control device of an electric power steering device causes an assist motor to generate an assist force according to the steering state of the steering wheel. For example, the control device disclosed in Patent Document 2 executes power latch control, which continues control until a predetermined time has elapsed since the ignition key was turned off. When the steering wheel is operated while the power latch control is being executed, steering assistance is provided by the motor.

[0007] Furthermore, the control device of the electric power steering device described in Patent Document 3 stops the motor drive current when the vehicle switch is turned off, and then executes power latch control to continue temperature estimation calculations for the elements on the board, etc. The control device maintains power until a predetermined time has elapsed since the motor drive current was stopped, or until the temperature of the elements on the board drops below a predetermined value. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication No. 2021-075182 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-248850 [Patent Document 3] Japanese Patent Publication No. 2020-108327 Summary of the Invention [Problem to be solved by the invention]

[0009] It is being considered to have a steer-by-wire system having multiple systems such as that described in Patent Document 1 execute power latch control as described in Patent Document 2 or Patent Document 3. In this case, when the vehicle power supply is turned off by operating an ignition key or the like, each control calculation unit executes power latch control individually. If the vehicle power supply is turned on while the power latch control is being executed, each control calculation unit executes a vehicle power on determination, and restarts after the on determination is established.

[0010] However, if the vehicle power supply is turned on while the power latch control is being executed, there is a risk that the timing at which each control calculation unit recognizes that the vehicle power supply is turned on may not coincide due to differences in wiring resistance, etc. This raises concerns that there may also be a difference in the timing at which each control calculation unit restarts. As a result, the control calculation unit that restarts first may receive pre-initialization information calculated by other control calculation units that are still executing the power latch control, which may result in the output of an unintended calculation result or an unintended state transition.

[0011] In particular, when the vehicle power supply is turned on during power latch control, unlike when the vehicle power supply is turned on for the first time, each control and calculation unit operates until just before it recognizes that the vehicle power supply is on. Therefore, there is a high probability that each control and calculation unit will output an unintended calculation result or perform an unintended state transition. Furthermore, in a steer-by-wire steering device in which power transmission between the steering wheel and the steered wheels is separated, if the above-mentioned unintended calculation result is output or a state transition occurs, the reaction force actuator and the steering actuator may not be controlled appropriately, causing a sense of discomfort to the driver. [Means for solving the problem]

[0012] A vehicle control device that can solve the above problem has a plurality of control circuits that start up when the vehicle power supply is turned on and executes control of a control target, and that start up when the vehicle power supply is turned off and executes power latch control that maintains power for a predetermined period of time. If the vehicle power supply is turned on while the power latch control is being executed after the vehicle power supply has been turned off, the plurality of control circuits wait until all of the control circuits, including the control circuit itself, recognize that the vehicle power supply is on before starting up.

[0013] According to this configuration, when the vehicle power is turned on during execution of the power latch control after the vehicle power has been turned off, each control circuit waits until all control circuits, including the control circuit itself, recognize that the vehicle power has been turned on before starting up. Therefore, when the vehicle power is turned on during execution of the power latch control after the vehicle power has been turned off, even if the timing at which each control device recognizes that the vehicle power has been turned on differs, the timing at which each control circuit starts up can be synchronized.

[0014] In the vehicle control device, the plurality of control circuits may set flag values ​​according to a result of recognizing whether or not the vehicle power supply is on. In this case, the plurality of control circuits may determine, based on the value of the flag, whether or not all of the control circuits, including the plurality of control circuits, recognize that the vehicle power supply is on.

[0015] According to this configuration, each control circuit can easily determine whether all control circuits, including itself, have recognized that the vehicle power supply is on, based on the value of each flag. In the above vehicle control device, the controlled object may include a reaction motor having two systems of winding groups and generating a steering reaction force to be applied to a steering wheel whose power transmission between the reaction motor and the steered wheels is separated, and a turning motor that generates a steering force for turning the steered wheels. In this case, the plurality of control circuits may include a first reaction control circuit that controls power supply to a first system of winding groups of the reaction motor, a second reaction control circuit that controls power supply to a second system of winding groups of the reaction motor, a first turning control circuit that controls power supply to the first system of winding groups of the turning motor, and a second turning control circuit that controls power supply to the second system of winding groups of the turning motor.

[0016] With this configuration, when the vehicle power supply is turned on during execution of power latch control after the vehicle power supply has been turned off, even if the first reaction force control circuit and second reaction force control circuit that control the power supply to the reaction force motor and the first turning control circuit and second turning control circuit that control the power supply to the turning motor recognize that the vehicle power supply is on at different times, the timing at which each control circuit starts activation can be synchronized, thereby making it possible to appropriately control the drive of the reaction force motor and the turning motor.

[0017] In the above-described vehicle control device, the first reaction force control circuit and the second reaction force control circuit may perform a first mutual confirmation to mutually confirm whether they have recognized that the vehicle power supply is on. The first turning control circuit and the second turning control circuit may perform a second mutual confirmation to mutually confirm whether they have recognized that the vehicle power supply is on. The first reaction force control circuit and the first turning control circuit may perform a third mutual confirmation to mutually confirm whether the first mutual confirmation and the second mutual confirmation are successful, and when the first mutual confirmation and the second mutual confirmation are successful, it may be determined that all of the control circuits have recognized that the vehicle power supply is on. The second reaction force control circuit and the second turning control circuit may perform a fourth mutual confirmation to mutually confirm whether the first mutual confirmation and the second mutual confirmation are successful, and when the first mutual confirmation and the second mutual confirmation are successful, it may be determined that all of the control circuits have recognized that the vehicle power supply is on.

[0018] This configuration simplifies the signal paths compared to a configuration in which the first reaction force control circuit and the second reaction force control circuit, and the first turning control circuit and the second turning control circuit, mutually confirm the recognition results of the vehicle power-on with all control circuits other than themselves. For example, there is no need to provide a communication line between the first reaction force control circuit and the second turning control circuit, and a communication line between the second reaction force control circuit and the first turning control circuit.

[0019] In the above vehicle control device, the controlled object may include a reaction motor that is a source of a steering reaction force applied to a steering wheel whose power transmission is separated from that of the steered wheels, and a turning motor that is a source of a steering force that steers the steered wheels. In this case, the plurality of control circuits may include a reaction force control circuit that controls the reaction motor, and a turning control circuit that controls the turning motor. The reaction force control circuit and the turning control circuit may confirm with each other whether they have recognized that the vehicle power supply is on.

[0020] With this configuration, when the vehicle power supply is turned on during execution of power latch control after the vehicle power supply has been turned off, even if the reaction force control circuit and the steering control circuit recognize that the vehicle power supply has been turned on at different times, the reaction force control circuit and the steering control circuit can start to start up at the same time, thereby making it possible to appropriately control the drive of the reaction force motor and the steering motor.

[0021] In the above vehicle control device, the controlled object may include an assist motor that generates an assist force to assist steering wheel operation. The assist motor may have a first winding group and a second winding group. In this case, the plurality of control circuits may include a first assist control circuit that controls power supply to the first winding group and a second assist control circuit that controls power supply to the second winding group. The first assist control circuit and the second assist control circuit may confirm with each other whether they have recognized that the vehicle power source is on.

[0022] According to this configuration, if the vehicle power is turned on while the power latch control is being executed after the vehicle power is turned off, the first assist control circuit and the second assist control circuit wait until both the first assist control circuit and the second assist control circuit recognize that the vehicle power is on before starting their activation. Therefore, if the vehicle power is turned on while the power latch control is being executed after the vehicle power is turned off, even if the first assist control circuit and the second assist control circuit recognize that the vehicle power is on at different times, the timing at which the first assist control circuit and the second assist control circuit start their activation can be synchronized. This allows for appropriate control of the drive of the assist motor.

[0023] In the vehicle control device, the control circuit may be configured to be able to communicate with an in-vehicle system that executes processing to transition the vehicle to a drivable state. In this case, when the vehicle power is turned on during execution of power latch control after the vehicle power has been turned off, the control circuit may be configured to wait until all the control circuits, including the control circuit itself, recognize that the vehicle power is on before allowing communication with the in-vehicle system.

[0024] With this configuration, each control circuit cannot communicate with the in-vehicle system unless all of the control circuits recognize that the vehicle power is on. This prevents a control circuit that recognizes that the vehicle power is on from starting communication with the in-vehicle system before all of the control circuits recognize that the vehicle power is on.

[0025] In the above-described vehicle control device, the control circuit may be configured to communicate with an in-vehicle system that executes a process for transitioning the vehicle to a drivable state, and may be configured to permit communication with the in-vehicle system when the vehicle power is turned on. The control circuit may also have information indicating whether the in-vehicle system is permitted to execute the process. In this case, the control circuit may be configured to, when the vehicle power is turned off during execution of control of the control target, initialize the information by changing the content of the information from a content that permits the in-vehicle system to execute the process to a content that requests the in-vehicle system to prohibit execution of the process, and to transmit the information to the in-vehicle system when the vehicle power is turned on during execution of power latch control after the vehicle power was turned off.

[0026] If the vehicle power is turned on during power latch control after the vehicle power is turned off, there is a risk that the control circuit that first recognized the vehicle power being on will start communicating with the in-vehicle system before all control circuits recognize that the vehicle power is on. In this case, there is a concern that the control circuit that first recognized the vehicle power being on will send information to the in-vehicle system indicating whether or not to permit the in-vehicle system to execute a process to transition the vehicle to a drivable state. However, the content of the information sent to the in-vehicle system is changed to request that the in-vehicle system prohibit the execution of the process to transition the vehicle to a drivable state. This prevents the in-vehicle system from starting the process to transition the vehicle to a drivable state before all control circuits recognize that the vehicle power is on.

[0027] In the above-described vehicle control device, the control circuit may be configured to communicate with an in-vehicle system that executes a process for transitioning the vehicle to a drivable state, and may be configured to permit communication with the in-vehicle system when the vehicle power is turned on. The control circuit may also have information indicating whether to permit the in-vehicle system to execute the process. In this case, the control circuit may be configured to, when the vehicle power is turned off during execution of control of the control target, retain the content of the information as the content that permits the in-vehicle system to execute the process, which is the content at the time of execution of control of the control target, and to transmit the information to the in-vehicle system when the vehicle power is turned on during execution of power latch control after the vehicle power was turned off. In this case, the control circuit may be configured to, when the vehicle power is turned on during execution of power latch control after the vehicle power was turned off, execute processing to request the in-vehicle system to ignore the information if not all the control circuits, including the control circuit itself, recognize that the vehicle power is on.

[0028] If the vehicle power is turned on during execution of power latch control after the vehicle power is turned off, there is a risk that the control circuit that first recognized the vehicle power being on may start communicating with the in-vehicle system before all control circuits recognize that the vehicle power is on. In this case, there is a concern that the control circuit that first recognized the vehicle power being on may send to the in-vehicle system information indicating whether or not to allow the in-vehicle system to execute processing to transition the vehicle to a drivable state.

[0029] During execution of power latch control, the content of the information indicating whether to permit the in-vehicle system to execute a process to transition the vehicle to a drivable state is maintained as the content at the time of execution of control of the controlled object, i.e., the content permitting the in-vehicle system to execute a process to transition the vehicle to a drivable state. Therefore, there is a risk that the in-vehicle system will start executing a process to transition the vehicle to a drivable state before all control circuits recognize that the vehicle power is on.

[0030] In this regard, with the above configuration, if the vehicle power is turned on during execution of power latch control after the vehicle power is turned off, the control circuit that first recognized the vehicle power is turned on executes processing to request the in-vehicle system to ignore the destination information transmitted to it if all control circuits, including the control circuit itself, have not yet recognized that the vehicle power is on. Therefore, it is possible to prevent the in-vehicle system from starting processing to transition the vehicle to a drivable state before all control circuits recognize that the vehicle power is on. [Effects of the Invention]

[0031] According to the vehicle control device of the present invention, even if the vehicle power supply is turned on while the power latch control is being executed, the start timings of the control circuits can be synchronized. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a configuration diagram of a steer-by-wire steering device in which a first embodiment of a vehicle control device is mounted. [Figure 2] FIG. 2 is a block diagram of a reaction force control device and a steering control device according to the first embodiment. [Figure 3] 4 is a time chart showing state transitions of each control circuit in the first embodiment. [Figure 4] FIG. 2 is a configuration diagram of a second embodiment of a vehicle control device. [Figure 5] 10 is a time chart showing a first comparative example of state transitions of each control circuit. [Figure 6] 10 is a time chart showing a second comparative example of state transitions of each control circuit. [Figure 7] 10 is a time chart showing a first mode of state transition of each control circuit in the third embodiment. [Figure 8] 13 is a time chart showing a second mode of state transition of each control circuit in the third embodiment. [Figure 9]13 is a time chart showing a first mode of state transition of each control circuit in the fourth embodiment. [Figure 10] 13 is a time chart showing a second mode of state transition of each control circuit in the fourth embodiment. [Figure 11] 13 is a time chart showing a first mode of state transition of each control circuit in the fifth embodiment. [Figure 12] 13 is a time chart showing a second mode of state transition of each control circuit in the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0033] First Embodiment A first embodiment in which the vehicle control device is embodied in a steer-by-wire type steering device will be described below.

[0034] As shown in FIG. 1, vehicle steering device 10 has steering shaft 12 connected to steering wheel 11. Steering device 10 also has steered shaft 13 extending in the vehicle width direction (left-right direction in FIG. 1). Steered wheels 15 are connected to both ends of steered shaft 13 via tie rods 14. The linear movement of steered shaft 13 changes the steering angle θw of steered wheels 15. Steering shaft 12 and steered shaft 13 constitute the steering mechanism of the vehicle. Note that FIG. 1 shows only steered wheels 15 on one side.

[0035] The steering device 10 has a reaction motor 21 and a reduction mechanism 22. The reaction motor 21 is a source of a steering reaction force. The steering reaction force is a force that acts in the opposite direction to the direction of operation of the steering wheel 11 by the driver. The rotation shaft of the reaction motor 21 is connected to the steering shaft 12 via the reduction mechanism 22. The torque of the reaction motor 21 is applied to the steering shaft 12 as a steering reaction force. By applying the steering reaction force to the steering wheel 11, it is possible to give the driver an appropriate sense of response.

[0036] The reaction motor 21 is, for example, a three-phase brushless motor. The reaction motor 21 has a first winding group N11 and a second winding group N12. The first winding group N11 and the second winding group N12 are wound around a common stator (not shown). The first winding group N11 and the second winding group N12 have equivalent electrical characteristics.

[0037] Steering device 10 has a steering motor 31 and a reduction mechanism 32. Steering motor 31 is a source of steering force. The steering force refers to the power for steering steered wheels 15. The rotating shaft of steering motor 31 is connected to pinion shaft 33 via reduction mechanism 32. Pinion teeth 33a of pinion shaft 33 mesh with rack teeth 13a of steering shaft 13. The torque of steering motor 31 is applied to steering shaft 13 via pinion shaft 33 as a steering force. In response to the rotation of steering motor 31, steering shaft 13 moves in the vehicle width direction.

[0038] The steering motor 31 is, for example, a three-phase brushless motor. The steering motor 31 has a first winding group N21 and a second winding group N22. The first winding group N21 and the second winding group N22 are wound around a common stator (not shown). The first winding group N21 and the second winding group N22 have equivalent electrical characteristics.

[0039] The steering device 10 has a reaction force control device 40. The reaction force control device 40 controls the drive of the reaction force motor 21, which is the object to be controlled. The reaction force control device 40 executes reaction force control in which the reaction force motor 21 generates a steering reaction force corresponding to the steering torque Th. The reaction force control device 40 calculates a target steering reaction force based on the steering torque Th detected through a torque sensor 23. The torque sensor 23 is provided on the steering shaft 12. The reaction force control device 40 controls the power supply to the reaction force motor 21 so that the actual steering reaction force applied to the steering shaft 12 matches the target steering reaction force. The reaction force control device 40 controls the power supply to each of the two systems of winding groups in the reaction force motor 21 independently.

[0040] The reaction force control device 40 has a first circuit system 41 and a second circuit system 42. The first circuit system 41 controls the power supply to the winding group N11 of the first system in the reaction force motor 21 in accordance with the steering torque Th detected by the torque sensor 23. The second circuit system 42 controls the power supply to the winding group N12 of the second system in the reaction force motor 21 in accordance with the steering torque Th detected by the torque sensor 23.

[0041] Steering device 10 has steering control device 50. Steering control device 50 controls the drive of steering motor 31, which is the object to be controlled. Steering control device 50 executes steering control in which steering motor 31 generates a steering force for turning steered wheels 15 in accordance with the steering state. Steering control device 50 takes in steering angle θs detected via steering angle sensor 24 and stroke Xw of steered shaft 13 detected via stroke sensor 34. Stroke Xw is the amount of displacement of steered shaft 13 relative to the neutral position, and is a state variable that reflects steering angle θw. Steering angle sensor 24 is provided between torque sensor 23 of steering shaft 12 and reduction mechanism 22. Stroke sensor 34 is provided in the vicinity of steered shaft 13.

[0042] Steering control device 50 calculates a target steering angle of steered wheels 15 based on steering angle θs detected by steering angle sensor 24. The target steering angle can be obtained, for example, by multiplying the detected steering angle θs by a steering angle ratio. The steering angle ratio is the ratio of steering angle θw to steering angle θs. The steering angle ratio is a value that is set in advance according to product specifications, etc. Steering control device 50 calculates steering angle θw based on stroke Xw of steered shaft 13 detected by stroke sensor 34. Steering control device 50 controls the power supply to steering motor 31 so that steering angle θw calculated based on stroke Xw matches the target steering angle. Steering control device 50 controls the power supply to two systems of winding groups in steering motor 31 independently for each system.

[0043] Steering control device 50 has first circuit system 51 and second circuit system 52. First circuit system 51 controls the power supply to winding group N21 of the first system in steering motor 31, based on steering angle θs detected via steering angle sensor 24 and stroke Xw of steering shaft 13 detected via stroke sensor 34. Second circuit system 52 controls the power supply to winding group N22 of the second system in steering motor 31, based on steering angle θs detected via steering angle sensor 24 and stroke Xw of steering shaft 13 detected via stroke sensor 34.

[0044] Note that a so-called electromechanical integrated type reaction force actuator may be configured by integrally providing reaction force control device 40 and reaction force motor 21. Also, a so-called electromechanical integrated type steering actuator may be configured by integrally providing steering control device 50 and steering motor 31.

[0045] <Power supply path> Next, the power supply paths to the reaction force control device 40 and the steering control device 50 will be described. The various on-board control devices including the reaction force control device 40 and the steering control device 50 are each supplied with power from a DC power supply 60 mounted on the vehicle. The DC power supply 60 is, for example, a battery. The various sensors including the torque sensor 23, the steering angle sensor 24, and the stroke sensor 34 are also each supplied with power from the DC power supply 60.

[0046] The first and second circuit systems 41 and 42 of the reaction force control device 40 and the first and second circuit systems 51 and 52 of the turning control device 50 are each connected to a DC power supply 60 via a start switch SW of the vehicle. The start switch SW is, for example, an ignition switch or a power switch. The start switch SW is operated to start or stop a drive source for running the vehicle, such as an engine. When the start switch SW is turned on, power from the DC power supply 60 is supplied via the start switch SW to the first and second circuit systems 41 and 42 of the reaction force control device 40 and the first and second circuit systems 51 and 52 of the turning control device 50. Turning the start switch SW on means that the vehicle power supply is on. Turning the start switch SW off means that the vehicle power supply is off.

[0047] The first circuit system 41 and the second circuit system 42 of the reaction force control device 40, and the first circuit system 51 and the second circuit system 52 of the turning control device 50 are connected to a DC power supply 60 via power supply relays 61, 62, 63, and 64. When the power supply relays 61, 62, 63, and 64 are turned on, power from the DC power supply 60 is supplied to the first circuit system 41 and the second circuit system 42 of the reaction force control device 40, and the first circuit system 51 and the second circuit system 52 of the turning control device 50 via the power supply relays 61, 62, 63, and 64.

[0048] The first system circuit 41 of the reaction force control device 40 controls the on / off of the power supply relay 61. When the start switch SW is switched from on to off, the first system circuit 41 executes power latch control to keep the power supply relay 61 in the on state for a predetermined period of time. Therefore, the first system circuit 41 can operate even after the start switch SW is turned off. The first system circuit 41 can cut off the power supply to itself by switching the power supply relay 61 from on to off after the predetermined period has elapsed.

[0049] The first system circuit 41 detects whether the start switch SW is on or off by, for example, monitoring the voltage across the start switch SW. The first system circuit 41 detects that the start switch SW is on when the voltage across the start switch SW falls below a predetermined voltage threshold. The first system circuit 41 detects that the start switch SW is off when the voltage across the start switch SW is equal to or greater than the predetermined voltage threshold.

[0050] The second system circuit 42 of the reaction force control device 40 controls the on / off of the power supply relay 62. The second system circuit 42 executes power latch control in the same manner as the first system circuit 41. When the start switch SW is switched from on to off, the second system circuit 42 keeps the power supply relay 62 in an on state for a predetermined period of time.

[0051] The first system circuit 51 of the steering control device 50 controls the on / off of the power supply relay 63. The first system circuit 51 executes power latch control in the same manner as the first system circuit 41 of the reaction force control device 40. When the start switch SW is switched from on to off, the first system circuit 51 keeps the power supply relay 63 in an on state for a predetermined period of time.

[0052] The second system circuit 52 of the turning control device 50 controls the on / off of the power supply relay 64. The second system circuit 52 executes power latch control in the same manner as the first system circuit 41 of the reaction force control device 40. When the start switch SW is switched from on to off, the second system circuit 52 keeps the power supply relay 64 in an on state for a predetermined period of time.

[0053] Among the components of the steering device 10, those that are required to continue operating even after the start switch SW is turned off, such as the torque sensor 23, the steering angle sensor 24, and the stroke sensor 34, are connected to the DC power supply 60 via at least one of the power supply relays 61, 62, 63, and 64. Therefore, even if the start switch SW is turned off, power continues to be supplied to the components, such as the torque sensor 23, the steering angle sensor 24, and the stroke sensor 34, as long as at least one of the power supply relays 61, 62, 63, and 64 is turned on.

[0054] <Reaction force control device> Next, the configuration of the reaction force control device will be described in detail. 2, the reaction force control device 40 has a first circuit system 41 and a second circuit system 42. The first circuit system 41 has a first reaction force control circuit 41A and a motor drive circuit 41B. The second circuit system 42 has a second reaction force control circuit 42A and a motor drive circuit 42B.

[0055] The first reaction force control circuit 41A is configured with processing circuits including: 1) one or more processors operating according to a computer program (software); 2) one or more dedicated hardware circuits such as application-specific integrated circuits (ASICs) that perform at least some of the various processes; and 3) a combination thereof. The processor includes a central processing unit (CPU). The processor also includes memory such as random-access memory (RAM) and read-only memory (ROM). The memory stores program code or instructions configured to cause the CPU to execute processes. Memory, i.e., non-transitory computer-readable medium, includes any available medium that can be accessed by a general-purpose or special-purpose computer.

[0056] The first reaction force control circuit 41A calculates a target steering reaction force to be generated in the reaction force motor 21 based on the steering torque Th detected via the torque sensor 23, and calculates a first current command value for the winding group N11 of the first system according to the value of the calculated target steering reaction force. However, the first current command value is set to a value that is half (50%) of the amount of current (100%) required for the reaction force motor 21 to generate the target steering reaction force. The first reaction force control circuit 41A generates a drive signal (PWM signal) for the motor drive circuit 41B by executing current feedback control that causes the value of the actual current supplied to the winding group N11 of the first system to follow the first current command value.

[0057] The motor drive circuit 41B is a PWM inverter in which three legs, each corresponding to one of the three phases (U, V, and W), are connected in parallel, with each leg consisting of two switching elements such as field-effect transistors (FETs) connected in series. The motor drive circuit 41B converts DC power supplied from the DC power supply 60 into three-phase AC power by switching the switching elements of each phase based on drive signals generated by the first reaction force control circuit 41A. The three-phase AC power generated by the motor drive circuit 41B is supplied to the first winding group N11 of the reaction force motor 21 via power supply paths for each phase, such as bus bars or cables. This causes the first winding group N11 to generate torque according to a first current command value.

[0058] The second reaction force control circuit 42A has basically the same configuration as the first reaction force control circuit 41A. The second reaction force control circuit 42A calculates a target steering reaction force to be generated in the reaction force motor 21 based on the steering torque Th detected by the torque sensor 23, and calculates a second current command value for the winding group N12 of the second system according to the value of the calculated target steering reaction force. However, the second current command value is set to a value that is half the amount of current required for the reaction force motor 21 to generate the target steering reaction force. The second reaction force control circuit 42A generates a drive signal for the motor drive circuit 42B by performing current feedback control that causes the value of the actual current supplied to the winding group N12 of the second system to follow the second current command value.

[0059] The motor drive circuit 42B has basically the same configuration as the motor drive circuit 41B. The motor drive circuit 42B converts DC power supplied from a DC power supply 60 into three-phase AC power based on a drive signal generated by the second reaction force control circuit 42A. The three-phase AC power generated by the motor drive circuit 42B is supplied to the second winding group N12 of the reaction force motor 21 via power supply paths for each phase, which are formed by bus bars or cables, etc. This causes the second winding group N12 to generate torque according to the second current command value. The reaction force motor 21 generates a torque that is the sum of the torque generated by the first winding group N11 and the torque generated by the second winding group N12.

[0060] Depending on the product specifications, there may be a master-slave relationship between the first circuit system 41 and the second circuit system 42 of the reaction force control device 40. In this case, for example, the first circuit system 41 may function as the master and the second circuit system 42 may function as the slave. Also, depending on the product specifications, the first circuit system 41 and the second circuit system 42 may have an equal relationship.

[0061] <Steering control device> Next, the configuration of the steering control device 50 will be described in detail. As shown in Fig. 2, the steering control device 50 has a first circuit system 51 and a second circuit system 52. The first circuit system 51 has a first steering control circuit 51A and a motor drive circuit 51B. The second circuit system 52 has a second steering control circuit 52A and a motor drive circuit 52B.

[0062] First steering control circuit 51A has basically the same configuration as first reaction force control circuit 41A. First steering control circuit 51A calculates a target steering angle of steered wheels 15 based on steering angle θs detected by steering angle sensor 24. Steering control device 50 calculates steering angle θw based on stroke Xw of steered shaft 13 detected by stroke sensor 34. First steering control circuit 51A calculates a target steering force to be generated in steering motor 31 by executing angle feedback control that causes steering angle θw calculated based on stroke Xw to follow the target steering angle, and calculates a third current command value for first system winding group N21 of steering motor 31 according to the value of this calculated target steering force. However, the third current command value is set to a value that is half (50%) of the amount of current required for steering motor 31 to generate the target steering force. The first steering control circuit 51A generates a drive signal for the motor drive circuit 51B by performing current feedback control that causes the value of the actual current supplied to the first system winding group N21 to follow the third current command value.

[0063] Motor drive circuit 51B basically has the same configuration as motor drive circuit 41B. Motor drive circuit 51B converts DC power supplied from DC power supply 60 into three-phase AC power based on a drive signal generated by first steering control circuit 51A. The three-phase AC power generated by motor drive circuit 42B is supplied to winding group N21 of the first system of steering motor 31 via power supply paths for each phase formed by bus bars, cables or the like. This causes winding group N21 of the first system to generate torque according to the third current command value.

[0064] Second steering control circuit 52A has basically the same configuration as first reaction force control circuit 41A. Second steering control circuit 52A calculates a target steering angle of steered wheels 15 based on steering angle θs detected by steering angle sensor 24. Steering control device 50 calculates steering angle θw based on stroke Xw of steered shaft 13 detected by stroke sensor 34. Second steering control circuit 52A calculates a target steering force to be generated in steering motor 31 by executing angle feedback control that causes steering angle θw calculated based on stroke Xw to follow the target steering angle, and calculates a fourth current command value for second system winding group N22 of steering motor 31 in accordance with the value of this calculated target steering force. However, fourth current command value is set to a value that is half (50%) of the amount of current required for steering motor 31 to generate the target steering force. The second steering control circuit 52A generates a drive signal for the motor drive circuit 52B by performing current feedback control that causes the value of the actual current supplied to the second system winding group N22 to follow the fourth current command value.

[0065] Motor drive circuit 52B basically has the same configuration as motor drive circuit 41B. Motor drive circuit 51B converts DC power supplied from DC power supply 60 into three-phase AC power based on a drive signal generated by second steering control circuit 52A. The three-phase AC power generated by motor drive circuit 52B is supplied to winding group N22 of the second system of steering motor 31 via power supply paths for each phase formed by bus bars, cables, or the like. This causes winding group N22 of the second system to generate torque according to the fourth current command value. Steering motor 31 generates torque which is the sum of the torque generated by winding group N21 of the first system and the torque generated by winding group N22 of the second system.

[0066] Depending on the product specifications, there may be a master-slave relationship between the first circuit system 51 and the second circuit system 52 of the steering control device 50. In this case, for example, the first circuit system 51 may function as the master and the second circuit system 52 may function as the slave. Also, depending on the product specifications, the first circuit system 51 and the second circuit system 52 may have an equal relationship.

[0067] <Communication path> Next, the internal communication paths of the reaction force control device 40 and the steering control device 50, and the communication path between the reaction force control device 40 and the steering control device 50 will be described.

[0068] As shown in FIG. 2, the first reaction force control circuit 41A and the second reaction force control circuit 42A exchange information with each other via a communication line L1. The information includes abnormality information about the first reaction force control circuit 41A, the second reaction force control circuit 42A, or the motor drive circuits 41B and 42B. The information also includes the values ​​of various flags. The first reaction force control circuit 41A and the second reaction force control circuit 42A cooperate to control the drive of the reaction force motor 21 based on the information exchanged between them.

[0069] The first steering control circuit 51A and the second steering control circuit 52A exchange information with each other via communication line L2. The information includes abnormality information of the first steering control circuit 51A, the second steering control circuit 52A, or the motor drive circuits 51B, 52B. The information also includes the values ​​of various flags. The first steering control circuit 51A and the second steering control circuit 52A cooperate to control the drive of the steering motor 31 based on the information exchanged between them.

[0070] The first reaction force control circuit 41A and the first turning control circuit 51A exchange information with each other via communication line L3. The information includes abnormality information for the first reaction force control circuit 41A, the first turning control circuit 51A, and the motor drive circuits 41B, 51B. The information also includes the values ​​of various flags. The first reaction force control circuit 41A and the first turning control circuit 51A operate in cooperation with each other based on the information exchanged between them.

[0071] The second reaction force control circuit 42A and the second turning control circuit 52A exchange information with each other via communication line L4. The information includes abnormality information of the second reaction force control circuit 42A, the second turning control circuit 52A, or the motor drive circuits 42B, 52B. The information also includes the values ​​of various flags. The second reaction force control circuit 42A and the second turning control circuit 52A operate in cooperation with each other based on the information exchanged between them.

[0072] When an abnormality occurs in first system circuits 41, 51, which are components of the first system, reaction force motor 21 and steering motor 31 are driven by second system circuits 42, 52, which are components of the second system. When an abnormality occurs in second system circuits 42, 52, which are components of the second system, reaction force motor 21 and steering motor 31 are driven by first system circuits 41, 51, which are components of the first system.

[0073] For example, if an abnormality occurs in the first reaction force control circuit 41A, the first reaction force control circuit 41A stops operating, while the second reaction force control circuit 42A continues to control the power supply to the second winding group N12 of the reaction force motor 21. In this case, the second reaction force control circuit 42A may supply half (50%) of the current required to generate the target steering reaction force in the reaction force motor 21 to the second winding group N12. Alternatively, the second reaction force control circuit 42A may supply more than half of the current required to generate the target steering reaction force in the reaction force motor 21 to the second winding group N12. This is determined according to product specifications, etc. Only the torque generated by the second winding group N12 of the reaction force motor 21 is applied to the steering shaft 12 as steering reaction force.

[0074] Furthermore, when an abnormality occurs in first reaction force control circuit 41A, first steering control circuit 51A stops operating, while second steering control circuit 52A continues to control the power supply to second system winding group N22 of steering motor 31. In this case, second steering control circuit 52A may supply to second system winding group N22 an amount of current that is half (50%) of the amount of current required to generate the target steering force in steering motor 31. Also, second steering control circuit 52A may supply to second system winding group N22 an amount of current that exceeds half of the amount of current required to generate the target steering force in steering motor 31. This is determined according to product specifications, etc. Only the torque generated by second system winding group N22 of steering motor 31 is applied to steering shaft 13 as a steering force.

[0075] Similarly, if an abnormality occurs in second reaction force control circuit 42A, second reaction force control circuit 42A stops operating, while first reaction force control circuit 41A continues to control the power supply to winding group N11 of the first system of reaction force motor 21. Furthermore, if an abnormality occurs in second reaction force control circuit 42A, second turning control circuit 52A stops operating, while first turning control circuit 51A continues to control the power supply to winding group N21 of the first system of turning motor 31.

[0076] Even if an abnormality occurs in first turning control circuit 51A or second turning control circuit 52A, the normal system continues to control the power supply to reaction force motor 21 and turning motor 31, just as when an abnormality occurs in first reaction force control circuit 41A or second reaction force control circuit 42A. Even if an abnormality occurs in motor drive circuits 41B, 51B of the first system and motor drive circuits 42B, 52B of the second system, the normal system continues to control the power supply to reaction force motor 21 and turning motor 31.

[0077] <Control circuit state transition> Next, the state transition of each control circuit (41A, 42A, 51A, 52A) will be described. 3, first reaction force control circuit 41A executes power latch control when start switch SW is turned off (time T1) while normal control is being executed. Like first reaction force control circuit 41A, second reaction force control circuit 42A, first turning control circuit 51A and second turning control circuit 52A also execute power latch control when start switch SW is turned off.

[0078] Normal control refers to control for generating a steering reaction force and a turning force according to the steering state of steering wheel 11. In normal control, torque is generated in both the first winding group N11 and the second winding group N12 of reaction force motor 21, and torque is generated in both the first winding group N21 and the second winding group N22 of turning motor 31. When start switch SW is turned off, the vehicle is stopped.

[0079] After the start switch SW is turned off, each control circuit (41A, 42A, 51A, 52A) executes power latch control and continues temperature estimation calculations for elements on the circuit board, for example. The elements are, for example, switching elements of each motor drive circuit (41B, 42B, 51B, 52B). Each control circuit maintains power until a predetermined time has elapsed since the start switch SW was turned off, or until the temperature of the elements on the circuit board falls below a predetermined temperature. The predetermined temperature is a sufficiently low temperature.

[0080] When the temperature of the elements on the board falls below a predetermined temperature, each control circuit stores the temperature of the elements on the board at that time in a non-volatile memory and terminates execution of power latch control. By executing such power latch control, each control circuit can accurately grasp the initial temperature of the elements on the board at the start of the next normal control execution, and thereby appropriately execute overheat protection control. Overheat protection control is a control that prevents overheating of the elements on the board by limiting reaction force control or steering control in accordance with the amount of temperature rise based on the initial temperature of the elements on the board.

[0081] Here, during the execution period of the power latch control after the start switch SW is turned off, it is assumed that the start switch SW is turned on again. In this case, the following concerns arise. That is, when the start switch SW is turned on during the execution period of the power latch control, due to differences in wiring resistance, etc., there is a possibility that the timings at which the first reaction force control circuit 41A, the second reaction force control circuit 42A, the first steering control circuit 51A, and the second steering control circuit 52A recognize the turning on of the start switch SW do not match.

[0082] An example of the timing at which each control circuit (41A, 42A, 51A, 52A) recognizes the turning on of the start switch SW is as follows. That is, when the start switch SW is turned on during the execution period of the power latch control (time T2), the first reaction force control circuit 41A recognizes the turning on of the start switch SW at the timing of time T3. The second reaction force control circuit 42A recognizes the turning on of the start switch SW at the timing of time T4. The first steering control circuit 51A recognizes the turning on of the start switch SW at the timing of time T5. The second steering control circuit 52A recognizes the turning on of the start switch SW at the timing of time T6. The temporal precedence relationship of each time is as shown in the following relational expression (1).

[0083] T1 < T2 < T3 < T5 < T6 < T4 …(1) However, for example, “T1 < T2” indicates that time T2 is a timing later than time T1.

[0084] Thus, due to the different timings at which each control circuit (41A, 42A, 51A, 52A) recognizes the turning on of the start switch SW, there is a concern that the timings at which each control circuit starts up are also different. Therefore, in the present embodiment, each control circuit performs the first mutual confirmation MC1, the second mutual confirmation MC2, the third mutual confirmation MC3, and the fourth mutual confirmation in order to match the timings at which each starts up.

[0085] <The first mutual confirmation MC1> The first reaction force control circuit 41A and the second reaction force control circuit 42A perform a first mutual confirmation MC1 in which they confirm with each other whether or not they have recognized that the vehicle power supply is on. Specifically, this is as follows.

[0086] The first reaction force control circuit 41A sets the value of flag F11 according to the result of determination as to whether the start switch SW is on. When it is determined that the start switch SW is off, the first reaction force control circuit 41A sets the value of flag F11 to "0." When it is determined that the start switch SW is on during the execution period of power latch control (time T3), the first reaction force control circuit 41A sets the value of flag F11 to "1." The first reaction force control circuit 41A transmits the value of flag F11 to the second reaction force control circuit 42A.

[0087] The second reaction force control circuit 42A sets the value of flag F21 depending on the result of determination as to whether the start switch SW is on. When it is determined that the start switch SW is off, the second reaction force control circuit 42A sets the value of flag F21 to "0." When it is determined that the start switch SW is on during the execution period of power latch control (time T4), the second reaction force control circuit 42A sets the value of flag F21 to "1." The second reaction force control circuit 42A transmits the value of flag F21 to the first reaction force control circuit 41A.

[0088] The first reaction force control circuit 41A sets the value of flag F12 according to the values ​​of flags F11 and F21. The value of flag F12 indicates whether both the first reaction force control circuit 41A and the second reaction force control circuit 42A recognize that the start switch SW is on, i.e., whether the first mutual confirmation MC1 was successful. The first reaction force control circuit 41A sets the value of flag F12 to "0" when at least one of flags F11 and F21 is "0." This indicates that at least one of the first reaction force control circuit 41A and the second reaction force control circuit 42A does not recognize that the start switch SW is on. The first reaction force control circuit 41A sets the value of flag F12 to "1" when the values ​​of flags F11 and F21 are both "1." This indicates that both the first reaction force control circuit 41A and the second reaction force control circuit 42A recognize that the start switch SW is on. First reaction force control circuit 41A transmits the value of flag F12 to first turning control circuit 51A.

[0089] The second reaction force control circuit 42A sets the value of flag F22 according to the values ​​of flag F11 and flag F21. Like the previous flag F12, the value of flag F22 indicates whether both the first reaction force control circuit 41A and the second reaction force control circuit 42A recognize that the start switch SW is on, i.e., whether the first mutual confirmation MC1 was successful or not. The second reaction force control circuit 42A sets the value of flag F22 to "0" when the value of at least one of flag F11 and flag F21 is "0." The second reaction force control circuit 42A sets the value of flag F22 to "1" when the value of flag F11 and the value of flag F21 are both "1." The second reaction force control circuit 42A transmits the value of flag F22 to the second turning control circuit 52A.

[0090] <Second Mutual Confirmation MC2> First turning control circuit 51A and second turning control circuit 52A perform second mutual confirmation MC2 in which they confirm with each other whether or not they have recognized that the vehicle power supply is on. Specifically, this is as follows.

[0091] The first steering control circuit 51A sets the value of flag F31 according to the result of the determination as to whether the start switch SW is on. When the first steering control circuit 51A determines that the start switch SW is off, it sets the value of flag F31 to "0." When the first steering control circuit 51A determines that the start switch SW is on during the execution period of power latch control (time T5), it sets the value of flag F31 to "1." The first steering control circuit 51A transmits the value of flag F31 to the second steering control circuit 52A.

[0092] The second steering control circuit 52A sets the value of flag F41 according to the result of the determination as to whether the start switch SW is on. When the second steering control circuit 52A determines that the start switch SW is off, it sets the value of flag F41 to "0." When the second steering control circuit 52A determines that the start switch SW is on during the execution period of power latch control (time T6), it sets the value of flag F41 to "1." The second steering control circuit 52A transmits the value of flag F41 to the first steering control circuit 51A.

[0093] The first steering control circuit 51A sets the value of flag F32 according to the values ​​of flag F31 and flag F41. The value of flag F32 indicates whether both the first steering control circuit 51A and the second steering control circuit 52A recognize that the start switch SW is on, i.e., whether the second mutual confirmation MC2 was successful. The first steering control circuit 51A sets the value of flag F32 to "0" when the value of at least one of flag F31 and flag F41 is "0." This indicates that at least one of the first steering control circuit 51A and the second steering control circuit 52A does not recognize that the start switch SW is on. The first steering control circuit 51A sets the value of flag F32 to "1" when the value of flag F31 and the value of flag F41 are both "1." This indicates that both the first steering control circuit 51A and the second steering control circuit 52A recognize that the start switch SW is on. The first turning control circuit 51A transmits the value of the flag F32 to the first reaction force control circuit 41A.

[0094] The second steering control circuit 52A sets the value of flag F42 according to the values ​​of flag F31 and flag F41. Like the previous flag F32, the value of flag F42 indicates whether both the first steering control circuit 51A and the second steering control circuit 52A recognize that the start switch SW is on, i.e., whether the second mutual confirmation MC2 was successful. The second steering control circuit 52A sets the value of flag F42 to "0" when the value of at least one of flag F31 and flag F41 is "0." The second steering control circuit 52A sets the value of flag F42 to "1" when the value of flag F31 and the value of flag F41 are both "1." The second steering control circuit 52A transmits the value of flag F42 to the second reaction force control circuit 42A.

[0095] <Third Mutual Confirmation MC3> The first reaction force control circuit 41A and the first turning control circuit 51A perform a third mutual confirmation MC3 in which they mutually confirm the success or failure of the first mutual confirmation MC1 and the second mutual confirmation MC2. When the first mutual confirmation MC1 and the second mutual confirmation MC2 are successful, the first reaction force control circuit 41A and the first turning control circuit 51A determine that all the control circuits (41A, 42A, 51A, 52A) have recognized that the vehicle power supply is on. Specifically, this is as follows.

[0096] The first reaction force control circuit 41A sets the value of flag F13 according to the values ​​of flag F12 and flag F32. The value of flag F13 indicates whether the first reaction force control circuit 41A, the second reaction force control circuit 42A, the first turning control circuit 51A, and the second turning control circuit 52A all recognize that the start switch SW is on, i.e., whether the first mutual confirmation MC1 and the second mutual confirmation MC2 are successful or not. When at least one of flag F12 and flag F32 is set to "0," the first reaction force control circuit 41A determines that at least one of the first mutual confirmation MC1 and the second mutual confirmation MC2 is not successful, and sets the value of flag F13 to "0." When both flag F12 and flag F32 are set to "1," the first reaction force control circuit 41A determines that the first mutual confirmation MC1 and the second mutual confirmation MC2 are successful, and sets the value of flag F13 to "1." This triggers the activation of the first reaction force control circuit 41A (time T7).

[0097] First steering control circuit 51A sets the value of flag F33 according to the values ​​of flag F12 and flag F32. Like flag F13, the value of flag F33 indicates whether first reaction force control circuit 41A, second reaction force control circuit 42A, first turning control circuit 51A, and second turning control circuit 52A all recognize that start switch SW is on, i.e., whether first mutual confirmation MC1 and second mutual confirmation MC2 have been successful. When the value of at least one of flag F12 and flag F32 is "0," first steering control circuit 51A determines that at least one of first mutual confirmation MC1 and second mutual confirmation MC2 has not been successful, and sets the value of flag F33 to "0." When the value of flag F12 and the value of flag F32 are both "1," first turning control circuit 51A determines that first mutual confirmation MC1 and second mutual confirmation MC2 are established, and sets the value of flag F33 to "1." This triggers start-up of first turning control circuit 51A (time T7).

[0098] <Fourth Mutual Confirmation MC4> The second reaction force control circuit 42A and the second turning control circuit 52A perform a fourth mutual confirmation MC4 in which they mutually confirm the success or failure of the first mutual confirmation MC1 and the second mutual confirmation MC2. When the first mutual confirmation MC1 and the second mutual confirmation MC2 are successful, the second reaction force control circuit 42A and the second turning control circuit 52A determine that all the control circuits (41A, 42A, 51A, 52A) have recognized that the vehicle power supply is on. Specifically, this is as follows.

[0099] The second reaction force control circuit 42A sets the value of flag F23 according to the values ​​of flags F22 and F42. Like flag F13, the value of flag F23 indicates whether the first reaction force control circuit 41A, the second reaction force control circuit 42A, the first turning control circuit 51A, and the second turning control circuit 52A all recognize that the start switch SW is on, i.e., whether the first mutual confirmation and the second mutual confirmation have been successful. When at least one of flags F22 and F42 has a value of "0," the second reaction force control circuit 42A determines that at least one of the first mutual confirmation and the second mutual confirmation has not been successful and sets the value of flag F23 to "0." When both flags F22 and F42 have a value of "1," the second reaction force control circuit 42A determines that the first mutual confirmation and the second mutual confirmation have been successful and sets the value of flag F23 to "1." This triggers the activation of the second reaction force control circuit 42A (time T7).

[0100] The second steering control circuit 52A sets the value of flag F43 according to the values ​​of flag F22 and flag F42. Like flag F13, the value of flag F43 indicates whether the first reaction force control circuit 41A, the second reaction force control circuit 42A, the first turning control circuit 51A, and the second turning control circuit 52A all recognize that the start switch SW is on, i.e., whether the first mutual confirmation and the second mutual confirmation have been successful. When at least one of flag F22 and flag F42 has a value of "0," the second steering control circuit 52A determines that at least one of the first mutual confirmation and the second mutual confirmation has not been successful and sets the value of flag F43 to "0." When both flags F22 and F42 have a value of "1," the second steering control circuit 52A determines that the first mutual confirmation and the second mutual confirmation have been successful and sets the value of flag F43 to "1." This triggers the activation of the second steering control circuit 52A (time T7).

[0101] In this way, when the start switch SW is turned on during the power latch control period, each control circuit (41A, 42A, 51A, 52A) starts up at the same timing (time T7). Each control circuit executes an initial sequence upon startup and then transitions to a normal control execution state. The initial sequence refers to a series of processes required for the steering system to operate. The initial sequence processing includes, for example, hardware checks, CPU initialization, and variable or flag initialization.

[0102] <Advantages of the First Embodiment> Therefore, according to the first embodiment, the following effects can be obtained. (1-1) When the vehicle power supply is turned on during execution of power latch control after the vehicle power supply has been turned off, each control circuit (41A, 42A, 51A, 52A) waits for all control circuits, including itself, to recognize that the vehicle power supply is on before starting activation. Therefore, when the vehicle power supply is turned on during execution of power latch control after the vehicle power supply has been turned off, even if the timing at which each control device recognizes that the vehicle power supply is on differs, the timing at which each control circuit starts activation can be synchronized. Therefore, the drive of reaction force motor 21 and steering motor 31 can be appropriately controlled.

[0103] (1-2) Each control circuit (41A, 42A, 51A, 52A) sets the value of each flag (F11, F21, F31, F41) depending on the result of recognizing whether the vehicle power supply is on. Each control circuit can easily determine whether all control circuits, including itself, have recognized that the vehicle power supply is on based on the value of each flag.

[0104] (1-3) The first reaction force control circuit 41A and the second reaction force control circuit 42A perform a first mutual confirmation MC1 in which they mutually confirm whether they have recognized that the vehicle power supply is on by exchanging the values ​​of flags F11 and F21. The first turning control circuit 51A and the second turning control circuit 52A perform a second mutual confirmation MC2 in which they mutually confirm whether they have recognized that the vehicle power supply is on by exchanging the values ​​of flags F31 and F41. The first reaction force control circuit 41A and the first turning control circuit 51A perform a third mutual confirmation MC3 in which they mutually confirm the success or failure of the first mutual confirmation MC1 and the second mutual confirmation MC2 by exchanging the values ​​of flags F12 and F32. When the first mutual confirmation MC1 and the second mutual confirmation MC2 are successful, the first reaction force control circuit 41A and the first turning control circuit 51A determine that all control circuits have recognized that the vehicle power supply is on. The second reaction force control circuit 42A and the second turning control circuit 52A mutually confirm the success or failure of the first mutual confirmation MC1 and the second mutual confirmation MC2 by exchanging the values ​​of flags F22 and F42 (a fourth mutual confirmation MC4). When the first mutual confirmation MC1 and the second mutual confirmation MC2 are successful, the second reaction force control circuit 42A and the second turning control circuit 52A determine that all control circuits have recognized that the vehicle power is on. This simplifies the signal path compared to when each control circuit (41A, 42A, 51A, 52A) mutually confirms the values ​​of each flag (F11, F21, F31, F41). For example, there is no need to provide a communication line between the first reaction force control circuit 41A and the second turning control circuit 52A, and a communication line between the second reaction force control circuit 42A and the first turning control circuit 51A.

[0105] <Second embodiment> Next, a second embodiment in which the vehicle control device is embodied in an electric power steering device will be described. Note that the same reference numerals are used to designate the same components as those in the first embodiment, and detailed descriptions thereof will be omitted.

[0106] The electric power steering device is configured by mechanically connecting steering wheel 11 and steered wheels 15 shown in Fig. 1 above. That is, steering shaft 12, pinion shaft 33 and steered shaft 13 function as a power transmission path between steering wheel 11 and steered wheels 15. When steering wheel 11 is steered, steered shaft 13 moves linearly, thereby changing the steered angle θw of steered wheels 15.

[0107] The electric power steering device has an assist motor and an assist control device. The assist motor is provided in the same position as reaction motor 21 or steering motor 31 shown in FIG. 1 above. The assist motor generates an assist force to assist the operation of steering wheel 11. The assist force is a torque in the same direction as the steering direction of steering wheel 11. The assist control device controls the drive of the assist motor, which is the object of control.

[0108] As shown in FIG. 4, the assist motor 70 has a first winding group N31 and a second winding group N32. The assist control device 80 has a first system circuit 81. The first system circuit 81 has a first assist control circuit 81A and a motor drive circuit 81B. The first assist control circuit 81A controls the power supply to the winding group N31 of the first system. The first assist control circuit 81A generates a drive signal for the motor drive circuit 81B based on the steering torque Th detected via the torque sensor 23.

[0109] The motor drive circuit 81B converts the DC power supplied from the DC power supply 60 into three-phase AC power based on the drive signal generated by the first assist control circuit 81A. The three-phase AC power generated by the motor drive circuit 81B is supplied to the first system winding group N31 of the assist motor 70 via power supply paths for each phase, which are formed by bus bars, cables, or the like.

[0110] The assist control device 80 has a second system circuit 82. The second system circuit 82 has a second assist control circuit 82A and a motor drive circuit 82B. The second assist control circuit 82A controls the power supply to the winding group N32 of the second system. The second assist control circuit 82A generates a drive signal for the motor drive circuit 82B based on the steering torque Th detected via the torque sensor 23.

[0111] The motor drive circuit 82B converts the DC power supplied from the DC power supply 60 into three-phase AC power based on a drive signal generated by the second assist control circuit 82A. The three-phase AC power generated by the motor drive circuit 82B is supplied to the second system winding group N32 of the assist motor 70 via power supply paths for each phase, which are formed by bus bars, cables, or the like.

[0112] The first assist control circuit 81A and the second assist control circuit 82A exchange information with each other via a communication line. The information includes abnormality information about the first assist control circuit 81A, the second assist control circuit 82A, or the motor drive circuits 81B, 82B. The information also includes the values ​​of various flags. The first assist control circuit 81A and the second assist control circuit 82A cooperate to control the drive of the assist motor 70 based on the information exchanged between them.

[0113] When the start switch SW is turned off while normal control is being performed, the first assist control circuit 81A executes power latch control to self-maintain the power supply. The first assist control circuit 81A sets the value of flag F51 according to the result of determining whether the start switch SW is on. When the first assist control circuit 81A determines that the start switch SW is off, it sets the value of flag F51 to "0." When the first assist control circuit 81A determines that the start switch SW is on while power latch control is being performed, it sets the value of flag F51 to "1." The first assist control circuit 81A transmits the value of flag F51 to the second assist control circuit 82A.

[0114] When the start switch SW is turned off while normal control is being executed, the second assist control circuit 82A executes power latch control to self-hold the power supply. The second assist control circuit 82A sets the value of flag F61 according to the result of determining whether the start switch SW is on. When the second assist control circuit 82A determines that the start switch SW is off, it sets the value of flag F61 to "0." When the second assist control circuit 82A determines that the start switch SW is on while power latch control is being executed, it sets the value of flag F61 to "1." The second assist control circuit 82A transmits the value of flag F61 to the first assist control circuit 81A.

[0115] The first assist control circuit 81A and the second assist control circuit 82A determine whether or not both the first assist control circuit 81A and the second assist control circuit 82A recognize that the start switch SW is on, depending on the value of flag F51 and the value of flag F61.

[0116] When the value of at least one of flag F51 and flag F61 is "0", the first assist control circuit 81A and the second assist control circuit 82A determine that at least one of the first assist control circuit 81A and the second assist control circuit 82A does not recognize that the start switch SW is on.

[0117] When the value of flag F51 and the value of flag F61 are both 1, the first assist control circuit 81A and the second assist control circuit 82A determine that they have recognized that the start switch SW is on. This triggers the first assist control circuit 81A and the second assist control circuit 82A to begin activation.

[0118] In this way, when the start switch SW is turned on during the power latch control period, the first assist control circuit 81A and the second assist control circuit 82A start up at the same time. Upon startup, the first assist control circuit 81A and the second assist control circuit 82A execute an initial sequence and then transition to a state in which normal control is executed.

[0119] <Advantages of the second embodiment> Therefore, according to the second embodiment, the following effects can be obtained. (2-1) If the vehicle power supply is turned on while the power latch control is being executed after the vehicle power supply has been turned off, the first assist control circuit 81A and the second assist control circuit 82A wait until both the first assist control circuit 81A and the second assist control circuit 82A recognize that the vehicle power supply has been turned on before starting their activation. Therefore, if the vehicle power supply is turned on while the power latch control is being executed after the vehicle power supply has been turned off, even if the first assist control circuit 81A and the second assist control circuit 82A recognize that the vehicle power supply has been turned on at different times, the timing at which the first assist control circuit 81A and the second assist control circuit 82A start their activation can be synchronized. This allows the drive of the assist motor 70 to be appropriately controlled.

[0120] (2-2) The first assist control circuit 81A and the second assist control circuit 82A set the values ​​of flags F51 and F61 depending on the result of determining whether the vehicle power supply is on. By mutually checking the values ​​of flags F51 and F61, the first assist control circuit 81A and the second assist control circuit 82A can easily determine whether both the first assist control circuit 81A and the second assist control circuit 82A have recognized that the vehicle power supply is on.

[0121] <Third embodiment> Next, a third embodiment will be described in which the vehicle control device is embodied in a steer-by-wire steering device. This embodiment basically has the same configuration as the first embodiment shown in Figures 1 to 3. Therefore, the same members and configurations as those in the first embodiment are given the same reference numerals, and detailed description thereof will be omitted.

[0122] As shown in Fig. 1, reaction force control device 40 is mutually connected to various on-vehicle systems 72 via on-vehicle network 71. On-vehicle network 71 is, for example, a CAN (Controller Area Network). Reaction force control device 40 and on-vehicle system 72 exchange information with each other via on-vehicle network 71. Turning control device 50 is also mutually connected to various on-vehicle systems 72 via on-vehicle network 71. Turning control device 50 and on-vehicle system 72 exchange information with each other via on-vehicle network 71.

[0123] The in-vehicle system 72 includes, for example, a steering lock control device, a shift lock control device, a power train control device, and a meter control device. The steering lock control device controls the operation of the steering lock mechanism. The steering lock mechanism is a mechanism for restricting the rotation of the steering wheel 11. When the start switch SW is turned on, the steering lock control device controls the operation of the steering lock mechanism so that the steering wheel 11 is unlocked. The process for unlocking the steering wheel 11 is a process for transitioning the vehicle to a state in which it can be driven. When the start switch SW is turned off, the steering lock control device controls the operation of the steering lock mechanism so that the steering wheel 11 is locked.

[0124] The shift lock control device controls the operation of the shift lock mechanism. The shift lock mechanism is a mechanism for restricting the operation of a shift lever with a locking member. The shift lock control device controls the operation of the shift lock mechanism so that the shift lever is unlocked when the start switch SW is turned on with the shift lever in the parking position and the brake pedal depressed. The process for unlocking the shift lever is a process for transitioning the vehicle to a state in which it can be driven. The shift lock control device controls the operation of the shift lock mechanism so that the shift lever is locked when the start switch SW is turned off with the shift lever in the parking position.

[0125] The powertrain control device controls the running of a vehicle. More specifically, the powertrain control device controls the vehicle's powertrain. The powertrain includes a driving source for running the vehicle and a power transmission mechanism. The driving source for running includes, for example, an engine or a motor. The power transmission mechanism is a mechanism for transmitting power generated by the driving source for running to the drive wheels. When the start switch SW is turned on, the powertrain control device begins executing a predetermined startup preparation. The startup preparation includes an initial check including processes such as hardware checks, CPU initialization, and initialization of variables or flags, as well as processes required to start the vehicle's powertrain. After the startup preparation is complete, the powertrain control device starts the powertrain. The process for starting the powertrain is a process for transitioning the vehicle to a state where it can run.

[0126] The meter control device controls the illumination of indicator lights on the meter panel. The indicator lights include warning lights that notify of abnormalities or malfunctions related to vehicle operation, and warning lights that warn or caution the vehicle driver when they do not operate the vehicle correctly. The warning lights illuminate in different colors depending on the warning level. For example, red indicates the occurrence of an abnormality that requires immediate inspection. Yellow indicates the occurrence of an abnormality that requires immediate inspection. Green indicates that the vehicle is normal.

[0127] First reaction force control circuit 41A is capable of communicating via in-vehicle network 71 when the voltage of the power source supplied via start switch SW is within a predetermined operating voltage range. The operating voltage range is the power supply voltage required to operate each control circuit (41A, 42A, 51A, 52A) including first reaction force control circuit 41A. The operating voltage range is set, for example, based on the viewpoint of ensuring communication reliability. When the voltage of the power source supplied via start switch SW reaches a value within the operating voltage range, first reaction force control circuit 41A transmits various information to in-vehicle system 72 via in-vehicle network 71. Second reaction force control circuit 42A, first turning control circuit 51A, and second turning control circuit 52A perform the same processing as first reaction force control circuit 41A.

[0128] The information includes, for example, the following five flags (A1) to (A5). (A1) Communication permission flag F71 (A2) First unlock permission flag F72 (A3) Second unlock permission flag F73 (A4) Start permission flag F74 (A5) Meter notification flag F75 The communication permission flag F71 is information indicating whether communication through the in-vehicle network 71 is permitted. The first reaction force control circuit 41A sets the value of the communication permission flag F71 based on whether the voltage of the power source supplied via the start switch SW is within the operating voltage range. When the voltage of the power source supplied via the start switch SW is within the operating voltage range, the first reaction force control circuit 41A sets the value of the communication permission flag F71 to "permitted." Setting the value of the communication permission flag F71 to "permitted" indicates that communication through the in-vehicle network 71 of each control circuit (41A, 42A, 51A, 52A) is permitted. When the voltage of the power source supplied via the start switch SW is outside the operating voltage range, the first reaction force control circuit 41A sets the value of the communication permission flag F71 to "prohibited." Setting the value of the communication permission flag F71 to "prohibited" indicates that execution of communication through the in-vehicle network 71 of each of the control circuits (41A, 42A, 51A, 52A) is not permitted.

[0129] The first unlock permission flag F72 is information indicating whether the steering lock control device is permitted to unlock the steering wheel 11. The first reaction force control circuit 41A sets the value of the first unlock permission flag F72 based on whether the start switch SW is turned on. Here, the first reaction force control circuit 41A determines that the start switch SW is turned on when the voltage of the power source supplied via the start switch SW is within the operating voltage range. On the other hand, the first reaction force control circuit 41A determines that the start switch SW is turned off when the voltage of the power source supplied via the start switch SW is outside the operating voltage range.

[0130] When the start switch SW is turned on, the first reaction force control circuit 41A sets the value of the first unlock permission flag F72 to "permitted." Setting the value of the first unlock permission flag F72 to "permitted" indicates to the steering lock control device that unlocking of the steering wheel 11 is permitted. When the start switch SW is turned off, the first reaction force control circuit 41A sets the value of the first unlock permission flag F72 to "prohibited." Setting the value of the first unlock permission flag F72 to "prohibited" indicates to the steering lock control device that unlocking of the steering wheel 11 is not permitted.

[0131] The second unlock permission flag F73 is information indicating whether or not the shift lock control device is permitted to unlock the shift lever. The first reaction force control circuit 41A sets the value of the second unlock permission flag F73 based on whether or not charging of the DC power supply 60 is complete. For example, the first reaction force control circuit 41A determines that charging of the DC power supply 60 is complete when the charge amount of the DC power supply 60 exceeds 90% of the full charge amount. The first reaction force control circuit 41A determines that charging of the DC power supply 60 is not complete when the charge amount of the DC power supply 60 is 90% or less of the full charge amount.

[0132] When charging of the DC power supply 60 is complete, the first reaction force control circuit 41A sets the value of the second unlock permission flag F73 to "permitted." Setting the value of the second unlock permission flag F73 to "permitted" indicates to the shift lock control device that unlocking of the shift lever is permitted. When charging of the DC power supply 60 is not complete, the first reaction force control circuit 41A sets the value of the second unlock permission flag F73 to "prohibited." Setting the value of the second unlock permission flag F73 to "prohibited" indicates to the shift lock control device that unlocking of the shift lever is not permitted.

[0133] The start permission flag F74 is information indicating whether or not starting of the powertrain is permitted. The first reaction force control circuit 41A sets the value of the start permission flag F74 based on whether execution of the initial sequence has been completed. When execution of the initial sequence has been completed, the first reaction force control circuit 41A sets the value of the start permission flag F74 to "Permitted." Setting the value of the start permission flag F74 to "Permitted" indicates to the powertrain control device that starting of the powertrain is permitted. When execution of the initial sequence has not been completed, the first reaction force control circuit 41A sets the value of the start permission flag F74 to "Prohibited." Setting the value of the start permission flag F74 to "Prohibited" indicates to the powertrain control device that starting of the powertrain is not permitted.

[0134] The meter notification flag F75 is information indicating the operating status of the four control circuits (41A, 42A, 51A, 52A) as a steer-by-wire system. Each control circuit sets the value of the meter notification flag F75 to "normal" when all of the control circuits are operating normally. Each control circuit sets the value of the meter notification flag F75 to "abnormal" when at least one of the control circuits is not operating normally or is not started up. Each control circuit also sets the value of the meter notification flag F75 to "abnormal" when, for example, a break in the power supply path to a specific one of the control circuits is detected.

[0135] Second reaction force control circuit 42A, first turning control circuit 51A, and second turning control circuit 52A set the values ​​of the respective flags (F71 to F75) in the same manner as first reaction force control circuit 41A.

[0136] However, all of the four control circuits (41A, 42A, 51A, 52A) do not necessarily have the function of setting the values ​​of the permission flags (F72, F73, F74). That is, the function of setting the permission flags may be shared among the control circuits. In this case, there may be a control circuit that does not have the function of setting the permission flags.

[0137] For example, only second reaction force control circuit 42A may have the function of setting the values ​​of first unlock permission flag F72 and second unlock permission flag F73. Also, second reaction force control circuit 42A and first turning control circuit 51A may have the function of setting the value of start permission flag F74. Also, only first turning control circuit 51A may have the function of setting the value of meter notification flag F75. The function of setting the value of communication permission flag F71 may be provided by all of the control circuits.

[0138] Therefore, even if the start switch SW is turned on, the vehicle will not transition to a state in which it is possible to drive until the reaction force control device 40 and the steering control device 50 have completed execution of the initial sequence and are in a state in which it is possible to execute normal control. In other words, unlocking of the steering wheel 11 and the shift lever and starting of the powertrain are not permitted until it is possible to execute normal control. This prevents the vehicle from transitioning to a state in which it is possible to drive while it is not possible to execute normal control by the reaction force control device 40 and the steering control device 50. Furthermore, it is possible to start driving the vehicle in a state that is safer for the driver, that is, in a state in which it is possible to turn the vehicle in the direction intended by the driver.

[0139] <First Comparative Example of State Transition of Control Circuit> Next, a first comparative example of the state transition of each control circuit (41A, 42A, 51A, 52A) will be described.

[0140] As shown in the time chart of FIG. 5, when the start switch SW is turned off (time T11) while normal control is being performed, each control circuit performs power latch control. When the start switch SW is turned off, the level of the power supply voltage supplied to each control circuit (41A, 42A, 51A, 52A) via the power supply path including the start switch SW switches from "Hi" to "Lo." "Hi" indicates that the power supply voltage is above the lower limit of the operating voltage range and below the upper limit of the operating voltage range. "Lo" indicates that the power supply voltage is below the lower limit of the operating voltage range. When the power supply voltage level switches from "Hi" to "Lo," the value of the communication permission flag F71 switches from "permitted" to "prohibited."

[0141] During execution of power latch control, the value of the first unlock permission flag F72, the value of the second unlock permission flag F73, the value of the start permission flag F74, and the value of the meter notification flag F75 are maintained at the same values ​​as during execution of normal control immediately before the start switch SW is turned off. That is, the value of the first unlock permission flag F72, the value of the second unlock permission flag F73, and the value of the start permission flag F74 are each maintained at "permitted." The value of the meter notification flag F75 is maintained at "normal." The values ​​of each flag (F72, F73, F74, F75) are reset, for example, when the start of each control circuit (41A, 42A, 51A, 52A) is confirmed, that is, when all of the control circuits recognize that the start switch SW is turned on.

[0142] When the start switch SW is turned off, the steering lock control device switches the state of the steering wheel 11 from an unlocked state to a locked state via the steering lock mechanism.

[0143] When the start switch SW is turned off, the shift lock control device switches the state of the shift lever from an unlocked state to a locked state via the shift lock mechanism.

[0144] When the start switch SW is turned off, the powertrain control device switches the state of the powertrain from "READY-ON" to "READY-OFF." "READY-ON" is a state in which the powertrain is ready to start and can be started. "READY-OFF" is a state in which the operation of the powertrain is stopped.

[0145] When the start switch SW is turned off, the meter control device switches the indicator light on the meter panel that indicates the status of the steer-by-wire system from a lit state, which indicates that the steer-by-wire system is operating normally, to an unlit state, which indicates that the steer-by-wire system is stopped.

[0146] Here, it is assumed that the start switch SW is turned on again during the execution period of the power latch control after the start switch SW is turned off (time T12). In this case, due to differences in wiring resistance or the like, the timing at which each control circuit (41A, 42A, 51A, 52A) recognizes that the start switch SW is turned on may not coincide. Furthermore, it is conceivable that a situation may occur in which a specific control circuit among the control circuits (41A, 42A, 51A, 52A) is unable to recognize that the start switch SW is turned on due to a break in the power supply path to that specific control circuit. The power supply path is a power supply path that includes the start switch SW.

[0147] If such an event occurs, the following concerns arise: As an example, assume that a break occurs in the power supply path to a specific control circuit during the period from when the start switch SW is turned off until the start switch SW is turned on again during power latch control (time T11 to time T12). The power supply path is a power supply path that includes the start switch SW. In this case, the power supply voltage is not supplied to the specific control circuit via the start switch SW. Therefore, the specific control circuit cannot recognize that the start switch SW is turned on. Furthermore, the specific control circuit will not start up.

[0148] Therefore, a situation cannot occur in which all four control circuits (41A, 42A, 51A, 52A) recognize that the start switch SW is on. Furthermore, each control circuit continues to execute power latch control without starting up. After a predetermined period has elapsed from the time the start switch SW is turned off, each control circuit stops executing power latch control and transitions to a sleep state (time T13). Sleep means that each control circuit temporarily stops operation and waits in a power-saving state. When transitioning to the sleep state, each control circuit transmits information indicating the transition to the sleep state to the in-vehicle system 72 via the in-vehicle network 71.

[0149] However, when the start switch SW is turned on while the power latch control is being executed, the power supply voltage is supplied to three of the four control circuits (41A, 42A, 51A, 52A) other than the specific control circuit via a power supply path including the start switch SW. When the power supply voltage supplied in response to the start switch SW being turned on reaches a value within the operating voltage range, the three control circuits other than the specific control circuit set the value of the communication permission flag F71 to "permitted."

[0150] Furthermore, during execution of power latch control, the three control circuits other than the specific control circuit maintain the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, the start permission flag F74, and the meter notification flag F75 at the same values ​​as during execution of normal control immediately before the start switch SW is turned off. That is, the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, and the start permission flag F74 are all set to "permitted." The value of the meter notification flag F75 is set to "normal."

[0151] Therefore, when the value of the communication permission flag F71 switches from "prohibited" to "permitted" during execution of power latch control, the three control circuits other than the specific control circuit transmit the values ​​of each flag (F72, F73, F74, F75) to the in-vehicle system 72 via the in-vehicle network 71. This enables the steering lock control device to execute processing to unlock the steering wheel 11. The shift lock control device to execute processing to unlock the shift lever. The powertrain control device to execute processing to start the powertrain.

[0152] Therefore, even though the four control circuits (41A, 42A, 51A, 52A) are in a state where they cannot be activated as a steer-by-wire system, the vehicle transitions to a state where it can run. Specifically, this is as follows.

[0153] The steering lock control device switches the state of the steering wheel 11 from a locked state to an unlocked state through the steering lock mechanism based on the value of the first unlock permission flag F72 that is set to "permitted."

[0154] The shift lock control device switches the state of the shift lever from a locked state to an unlocked state through the shift lock mechanism based on the value of the second unlock permission flag F73 being set to "permitted."

[0155] When the start switch is turned on, the powertrain control device begins executing a predetermined startup preparation. The startup preparation includes processes such as an initial check required to start the powertrain. When the startup preparation is completed, the state of the powertrain switches from "READY-OFF" to "READY-ON." In other words, the powertrain transitions to a state where it can be started. The powertrain control device starts the powertrain based on the value of the start permission flag F74, which is set to "permitted."

[0156] Based on the value of the meter notification flag F75, which is set to "normal," the meter control device switches the indicator light on the meter panel that indicates the status of the steer-by-wire system from an off state, which indicates that the steer-by-wire system is stopped, to an on state, which indicates that the steer-by-wire system is operating normally.

[0157] In this way, with the four control circuits not activated as a steer-by-wire system, the steering wheel 11 and the shift lever are unlocked and the powertrain is permitted to start, thereby transitioning the vehicle to a state in which it can run.

[0158] The meter control device switches the illumination state of the indicator light when it receives information via the in-vehicle network 71 indicating that each control circuit will transition to a sleep state, or when communication with each control circuit is interrupted. For example, the meter control device switches the illumination state of the indicator light from an illuminated state indicating normal operation of the steer-by-wire system to, for example, a red illuminated state. After each control circuit has completed execution of power latch control, the driver can visually recognize an abnormality in the steer-by-wire system.

[0159] Note that even if the timing at which the four control circuits (41A, 42A, 51A, 52A) recognize that the start switch SW is turned on does not coincide, an event similar to that occurring when a break occurs in the power supply path including the start switch SW for a specific control circuit occurs. That is, the control circuit that first recognizes that the start switch SW is turned on transmits the values ​​of each flag (F72, F73, F74, F75) to the in-vehicle system 72 via the in-vehicle network 71. For this reason, there is a risk that the vehicle will transition to a state where it can run even though the four control circuits have not yet started up as a steer-by-wire system.

[0160] Even when the function of setting the values ​​of each permission flag (F72, F73, F74) is shared among the control circuits, the same phenomenon occurs as when a break occurs in the power supply path including the start switch SW for a specific control circuit.

[0161] For example, if only the second reaction force control circuit 42A has the function of setting the values ​​of the first unlock permission flag F72 and the second unlock permission flag F73, it is assumed that the second reaction force control circuit 42A will recognize that the start switch SW is on before the other three control circuits. In this case, the second reaction force control circuit 42A will transmit the values ​​of the first unlock permission flag F72 and the second unlock permission flag F73 to the in-vehicle system 72 via the in-vehicle network 71. This could result in the steering wheel 11 and the shift lever being unlocked even though the four control circuits are not activated as a steer-by-wire system. Incidentally, a similar event could occur when a break occurs in the power supply path to a specific control circuit other than the second reaction force control circuit 42A, and the power supply path is the power supply path that includes the start switch SW.

[0162] Furthermore, for example, if second reaction force control circuit 42A and first steering control circuit 51A have a function for setting the value of start permission flag F74, it is assumed that second reaction force control circuit 42A or first steering control circuit 51A will recognize that start switch SW is on before the other three control circuits. In this case, second reaction force control circuit 42A or first steering control circuit 51A will transmit the value of start permission flag F74 to on-board system 72 via on-board network 71. This could result in the vehicle powertrain being started even though the four control circuits are not activated as a steer-by-wire system. Incidentally, a similar event could occur if a break occurs in the power supply path to a specific control circuit other than second reaction force control circuit 42A or first steering control circuit 51A. The power supply path is a power supply path that includes start switch SW.

[0163] <Second Comparative Example of State Transition of Control Circuit> Next, a second comparative example of the state transition of each control circuit (41A, 42A, 51A, 52A) will be described.

[0164] As shown in the time chart of Figure 6, during execution of normal control immediately before the start switch SW is turned off, a situation may occur in which a specific control circuit is unable to recognize that the start switch SW is on due to a break in the power supply path to the specific control circuit. The power supply path is a power supply path that includes the start switch SW. Even in this case, when the start switch SW is turned on again during execution of power latch control after the start switch SW is turned off, an event similar to that in the first comparative example shown in Figure 5 occurs.

[0165] For this reason, there is a concern that the vehicle may transition to a state in which it is capable of running even though the four control circuits have not yet been activated as a steer-by-wire system. Also, if the function of setting the values ​​of the permission flags (F72, F73, F74) is shared and executed by each control circuit, for example, the following concern may arise: That is, even though each control circuit has not been activated as a steer-by-wire system, the steering wheel 11 and the shift lever may be unlocked or the powertrain may be started.

[0166] However, when a break in the power supply path to a specific control circuit is detected during normal control immediately before the start switch SW is turned off, each control circuit sets the value of the meter notification flag F75 to “abnormal.” Based on the value of the meter notification flag F75 being set to “abnormal,” the meter control device switches the illumination state of the indicator lamp, for example, to a yellow illumination state.

[0167] While the power latch control is being executed after the start switch SW is turned off, the value of the meter notification flag F75 is maintained in the state set to “abnormal.” Therefore, if the start switch SW is turned on again during the execution of the power latch control, and the value of the communication permission flag F71 is set to “permitted,” the meter control device switches the illumination state of the indicator lamp to a yellow illumination state based on the value of the meter notification flag F75 set to “abnormal.”

[0168] During the period when the start switch SW is turned off, the meter control device changes the indicator lamp from a lit state to an unlit state. It is not desirable for the vehicle to transition to a state in which it can travel, or for processing to transition the vehicle to a state in which it can travel, to be executed even though the control circuits are not activated as a steer-by-wire system, as in the first comparative example shown in Fig. 5 and the second comparative example shown in Fig. 6. This is because the reaction force control and steering control according to the steering state of the steering wheel 11 are not executed, and therefore the traveling direction of the vehicle cannot be changed to the direction intended by the driver.

[0169] Therefore, in this embodiment, the reaction force control device 40 and the steering control device 50 have the following configurations. <Communication permission conditions> Each control circuit (41A, 42A, 51A, 52A) sets the value of the communication permission flag F71 to "permitted" when all of the following five conditions B1 to B5 are met. The conditions B1 to B5 constitute communication permission conditions. The communication permission conditions are conditions for each control circuit to determine whether or not it is permissible to permit communication through the in-vehicle network 71.

[0170] B1. The value of the communication permission flag F71 is set to "prohibited." B2. The value of the vehicle power on flag F76 is set to "on." B3. The power supply voltage is above the lower limit of the operating voltage range.

[0171] B4. The power supply voltage is below the upper limit of the operating voltage range. B5. The condition in which conditions B1 to B4 are met continues for a set period of time or longer. The vehicle power on flag F76 is information indicating whether all of the control circuits recognize that the start switch SW is on. The control circuits mutually confirm whether they recognize that the start switch SW is on, i.e., that the vehicle power is on, through the first mutual confirmation MC1, second mutual confirmation MC2, third mutual confirmation MC3, and fourth mutual confirmation MC4 shown in FIG. 3 . When a control circuit determines that even one of the control circuits has not recognized that the start switch SW is on, it sets the value of the vehicle power on flag F76 to "off." When a control circuit determines that all of the control circuits recognize that the start switch SW is on, it sets the value of the vehicle power on flag F76 to "on."

[0172] Conditions B3 and B4 are conditions for determining whether the power supply voltage recognized by each control device is within the operating voltage range. Condition B5 is set to prevent the value of communication permission flag F71 from being erroneously set to "permitted" when conditions B1 to B4 are instantaneously met, for example.

[0173] Therefore, each control circuit can execute communication via the in-vehicle network 71 when it is determined that all of the four control circuits, including itself, recognize that the start switch SW is on.

[0174] <First mode of state transition of control circuit> Next, a first mode of state transition of each control circuit (41A, 42A, 51A, 52A) in this embodiment will be described.

[0175] As an example, assume that a power supply path to a specific control circuit is broken during the period from when the start switch SW is turned off until the start switch SW is turned on again during power latch control. The power supply path includes the start switch SW. Therefore, the power supply voltage is not supplied to the specific control circuit via the start switch SW. Therefore, the specific control circuit cannot recognize that the start switch SW is turned on. Furthermore, the specific control circuit is not started.

[0176] As shown in the time chart of FIG. 7, when the start switch SW is turned off while normal control is being performed (time T11), each control circuit performs power latch control. When the start switch SW is turned off, the power supply voltage level switches from "Hi" to "Lo." Therefore, when the start switch SW is turned off, each control circuit switches the value of the vehicle power on flag F76 from "on" to "off." In addition, each control circuit switches the value of the communication permission flag F71 from "permitted" to "prohibited."

[0177] During execution of power latch control, the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, the start permission flag F74, and the meter notification flag F75 are maintained at the same values ​​as during execution of normal control immediately before the start switch SW is turned off. That is, the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, and the start permission flag F74 are all maintained at "permitted." The value of the meter notification flag F75 is maintained at "normal."

[0178] When the start switch SW is turned on while power latch control is being executed (time T12), power supply voltage is supplied to three of the four control circuits (41A, 42A, 51A, 52A) except for a specific control circuit via a power supply path that includes the start switch SW. However, because the power supply via the start switch SW is cut off to the specific control circuit, it is unable to recognize that the start switch SW is on. For this reason, a situation in which all four control circuits (41A, 42A, 51A, 52A) recognize that the start switch SW is on cannot occur.

[0179] Therefore, during execution of the power latch control, each control circuit maintains the value of the vehicle power on flag F76 at "off" even if the power supply voltage level actually switches from "Lo" to "Hi" when the start switch SW is turned on. Also, each control circuit maintains the value of the communication permission flag F71 at "prohibited" because conditions B2 and B5 of the communication start determination conditions are not met.

[0180] Since communication through the in-vehicle network 71 is not permitted, the three control circuits other than the specific control circuit will not transmit the values ​​of each flag (F72, F73, F74, F75) to the in-vehicle system 72 via the in-vehicle network 71.

[0181] Therefore, the steering lock control device does not start executing a process to unlock the steering wheel 11. The steering lock control device maintains the state of the steering wheel 11 in a locked state. Furthermore, the shift lock control device does not start executing a process to unlock the shift lever. The shift lock control device maintains the state of the shift lever in a locked state. Furthermore, the powertrain control device does not start executing a process to start the powertrain. The powertrain control device maintains the state of the powertrain in a "READY-OFF" state, i.e., a state in which the operation of the powertrain is stopped.

[0182] Therefore, even though the four control circuits (41A, 42A, 51A, 52A) are in a state where they cannot be activated as a steer-by-wire system, the vehicle does not transition to a state where it can run.

[0183] When the start switch SW is turned on, the meter control device changes the indicator lamp from an off state to, for example, a red light. This is because communication with each control circuit is not possible even though the start switch SW is turned on. The driver can immediately recognize an abnormality in the steer-by-wire system visually without waiting for each control circuit to complete execution of power latch control.

[0184] The same applies if the four control circuits (41A, 42A, 51A, 52A) simply do not recognize that the start switch SW is on at the same time. That is, the control circuit that first recognizes that the start switch SW is on will not transmit the values ​​of the flags (F72, F73, F74, F75) to the in-vehicle system 72 via the in-vehicle network 71. This is because communication through the in-vehicle network 71 is not permitted until all four control circuits recognize that the start switch SW is on. For this reason, even though the four control circuits have not started up as a steer-by-wire system, the vehicle will not transition to a state where it can run.

[0185] The same applies to the case where the function of setting the values ​​of each permission flag (F72, F73, F74) is shared and executed by each control circuit. For example, if only the second reaction force control circuit 42A has the function of setting the values ​​of the first unlock permission flag F72 and the second unlock permission flag F73, it is assumed that the second reaction force control circuit 42A will recognize that the start switch SW is on before the other three control circuits. In this case, the second reaction force control circuit 42A will not transmit the values ​​of the first unlock permission flag F72 and the second unlock permission flag F73 to the in-vehicle system 72 via the in-vehicle network 71. Therefore, even if the four control circuits are not activated as a steer-by-wire system, the steering wheel 11 and the shift lever will not be unlocked. The same applies when a break occurs in the power supply path to a specific control circuit other than the second reaction force control circuit 42A. The power supply path is a power supply path that includes the start switch SW.

[0186] Furthermore, for example, if second reaction force control circuit 42A and first steering control circuit 51A have the function of setting the value of start permission flag F74, it is assumed that second reaction force control circuit 42A or first steering control circuit 51A will recognize that start switch SW is on before the other three control circuits. In this case, second reaction force control circuit 42A or first steering control circuit 51A will not transmit the value of start permission flag F74 to on-vehicle system 72 via on-vehicle network 71. Therefore, even if the four control circuits are not activated as a steer-by-wire system, the vehicle powertrain will not be started. Incidentally, the same applies when a break occurs in the power supply path to a specific control circuit other than second reaction force control circuit 42A or first steering control circuit 51A. The power supply path is a power supply path that includes start switch SW.

[0187] <Second mode of state transition of control circuit> Next, a second mode of state transition of each control circuit (41A, 42A, 51A, 52A) in this embodiment will be described.

[0188] As shown in the time chart of Fig. 8, during execution of normal control immediately before the start switch SW is turned off, a situation may occur in which a specific control circuit is unable to recognize that the start switch SW is turned on due to a break in the power supply path to the specific control circuit. The power supply path is a power supply path that includes the start switch SW. Even in this case, when the start switch SW is turned on again during execution of power latch control after the start switch SW is turned off, each control circuit performs processing similar to that of the first mode shown in Fig. 7.

[0189] Therefore, even if the four control circuits are not activated as a steer-by-wire system, the vehicle will not transition to a state in which it is possible to drive. The same applies when the function of setting the values ​​of the permission flags (F72, F73, F74) is shared among the control circuits. In other words, even if the control circuits are not activated as a steer-by-wire system, the steering wheel 11 and the shift lever will not be unlocked and the powertrain will not be started.

[0190] <Advantages of the third embodiment> Therefore, according to the third embodiment, the following effects can be obtained. (3-1) When the start switch SW is turned on, the four control circuits (41A, 42A, 51A, 52A) wait until all control circuits, including themselves, recognize that the start switch SW is turned on before starting up. Furthermore, when the start switch SW is turned on, communication through the in-vehicle network 71 is not permitted until all four control circuits recognize that the start switch SW is turned on. Therefore, if there is a control circuit that does not recognize that the start switch SW is turned on, the other control circuits that recognize that the start switch SW is turned on cannot transmit the values ​​of the flags (F72, F73, F74, F75) to the in-vehicle system 72. Therefore, it is possible to prevent the vehicle from transitioning to a state where it can run, or to prevent processing for transitioning the vehicle to a state where it can run, from being executed even though the control circuits have not started up as a steer-by-wire system.

[0191] (3-2) When the start switch SW is turned on but communication with each control circuit is not possible, the meter control device changes the indicator lamp from off to red. The red lamp indicates an abnormality in the steer-by-wire system. This allows the driver to immediately recognize the abnormality in the steer-by-wire system visually, without waiting for the completion of power latch control by each control circuit.

[0192] <Fourth embodiment> Next, a fourth embodiment will be described in which the vehicle control device is embodied in a steer-by-wire steering device. This embodiment basically has the same configuration as the first embodiment shown in Figures 1 to 3. Therefore, the same members and configurations as those in the first embodiment are given the same reference numerals, and detailed description thereof will be omitted.

[0193] This embodiment differs from the third embodiment in the content of the process that each control circuit (41A, 42A, 51A, 52A) executes when the start switch SW is turned off. When the following three conditions C1 to C3 are all satisfied, each control circuit initializes the value of a flag to be transmitted to the in-vehicle system 72. The flags transmitted to the in-vehicle system 72 include a first unlock permission flag F72, a second unlock permission flag F73, a start permission flag F74, and a meter notification flag F75.

[0194] C1. The value of the control stop flag F77 is set to "Stop." C2. The value of the vehicle power off flag F78 is set to "off." C3. The value of the communication permission flag F71 is set to "prohibited."

[0195] The control stop flag F77 is information indicating whether each control circuit has stopped the execution of the reaction force control or the steering control. When each control circuit has not stopped the execution of the reaction force control or the steering control, it sets the value of the control stop flag F77 to "not stopped." When each control circuit has stopped the execution of the reaction force control or the steering control, it sets the value of the control stop flag F77 to "stop."

[0196] The vehicle power off flag F78 is information indicating whether all of the control circuits have recognized that the start switch SW is off. The control circuits confirm with each other whether they have recognized that the start switch SW is off, i.e., that the vehicle power is off, through the first mutual confirmation MC1, second mutual confirmation MC2, third mutual confirmation MC3, and fourth mutual confirmation MC4 shown in FIG. 3 . Each control circuit sets the value of the vehicle power off flag F78 to "on" when it determines that even one of the control circuits has not recognized that the start switch SW is off. Each control circuit sets the value of the vehicle power off flag F78 to "off" when it determines that all of the control circuits have recognized that the start switch SW is off.

[0197] The communication permission flag F71 is information indicating whether communication via the in-vehicle network 71 is permitted. When all of the above five conditions B1 to B5 are met, each control circuit sets the value of the communication permission flag F71 to "permitted." When the start switch SW is turned off, each control circuit sets the value of the communication permission flag F71 to "prohibited."

[0198] As an initialization process, each control circuit sets the value of the first unlock permission flag F72, the second unlock permission flag F73, and the start permission flag F74 to "prohibited." Also, as an initialization process, each control circuit switches the value of the meter notification flag F75 to a value corresponding to the current state of the steer-by-wire system.

[0199] <First mode of state transition of control circuit> Next, a first mode of state transition of each control circuit (41A, 42A, 51A, 52A) in this embodiment will be described.

[0200] As an example, assume that a power supply path to a specific control circuit is broken during the period from when the start switch SW is turned off until the start switch SW is turned on again during power latch control. The power supply path includes the start switch SW. Therefore, the power supply voltage is not supplied to the specific control circuit via the start switch SW. Therefore, the specific control circuit cannot recognize that the start switch SW is turned on. Furthermore, the specific control circuit is not started.

[0201] As shown in the time chart of FIG. 9, when the start switch SW is turned off while normal control is being performed (time T11), each control circuit performs power latch control. When the start switch SW is turned off, the level of the power supply voltage switches from "Hi" to "Lo." As a result, each control circuit stops the execution of the reaction force control or the steering control, and switches the value of the control stop flag F77 from "non-stop" to "stop." In addition, each control circuit switches the value of the vehicle power off flag F78 from "on" to "off." In addition, each control circuit switches the value of the communication permission flag F71 from "permitted" to "prohibited."

[0202] When all of the three conditions C1 to C3 are satisfied, each control circuit initializes the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, the start permission flag F74, and the meter notification flag F75. That is, each control circuit switches the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, and the start permission flag F74 from "permitted" to "prohibited." Furthermore, each control circuit switches the value of the meter notification flag F75 to a value corresponding to the current state of the steer-by-wire system. In this case, because a break has occurred in the power supply path to a specific control circuit, the value of the meter notification flag F75 is set to "abnormal." Incidentally, the value of the meter notification flag F75 may be set to a more specific value such as "yellow illumination request" instead of "abnormal."

[0203] During the execution period of the power latch control after the start switch SW is turned off, when the start switch SW is turned on again (time T12), the power supply voltage is not supplied to the specific control circuit via the power supply path including the start switch SW. Therefore, the specific control circuit cannot recognize that the start switch SW is turned on. Furthermore, the specific control circuit is not activated.

[0204] However, the three control circuits other than the specific control circuit are supplied with power supply voltage via a power supply path including the start switch SW. When the power supply voltage supplied in response to the start switch SW being turned on reaches a value within the operating voltage range, the three control circuits other than the specific control circuit set the value of the communication permission flag F71 to "permitted." This allows the three control circuits other than the specific control circuit to communicate via the in-vehicle network 71.

[0205] When the value of the communication permission flag F71 switches from "prohibited" to "permitted," the three control circuits other than the specific control circuit transmit the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, the start permission flag F74, and the meter notification flag F75 to the in-vehicle system 72 via the in-vehicle network 71.

[0206] However, the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, and the start permission flag F74 are set to "prohibited" by initialization. Therefore, the steering lock control device does not start executing a process to unlock the steering wheel 11. The steering lock control device maintains the state of the steering wheel 11 in a locked state. Furthermore, the shift lock control device does not start executing a process to unlock the shift lever. The shift lock control device maintains the state of the shift lever in a locked state. Furthermore, the powertrain control device does not start executing a process to start the powertrain. The powertrain control device maintains the state of the powertrain in a "READY-OFF" state, i.e., a state in which the operation of the powertrain is stopped.

[0207] Therefore, even though the four control circuits (41A, 42A, 51A, 52A) are in a state where they cannot be activated as a steer-by-wire system, the vehicle does not transition to a state where it can run.

[0208] The meter control device changes the indicator lamp from off to yellow on based on the fact that the value of the meter notification flag F75 is set to "abnormal." The driver can immediately recognize the abnormality in the steer-by-wire system visually without waiting for the completion of power latch control by each control circuit.

[0209] The same applies if the four control circuits (41A, 42A, 51A, 52A) simply do not recognize the on-state of the start switch SW at the same time. That is, the control circuit that first recognizes the on-state of the start switch SW may transmit the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, the start permission flag F74, and the meter notification flag F75 to the in-vehicle system 72 via the in-vehicle network 71. However, the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, and the start permission flag F74 are set to "prohibited" by initialization. Therefore, even though the four control circuits are not activated as a steer-by-wire system, the vehicle does not transition to a state in which it can travel.

[0210] The same applies to the case where the function of setting the values ​​of each permission flag (F72, F73, F74) is shared and executed by each control circuit. For example, if only the second reaction force control circuit 42A has the function of setting the values ​​of the first unlock permission flag F72 and the second unlock permission flag F73, it is assumed that the second reaction force control circuit 42A will recognize that the start switch SW is turned on before the other three control circuits. In this case, the second reaction force control circuit 42A may transmit the values ​​of the first unlock permission flag F72 and the second unlock permission flag F73 to the in-vehicle system 72 via the in-vehicle network 71. However, the values ​​of the first unlock permission flag F72 and the second unlock permission flag F73 are set to "prohibited" by initialization. Therefore, even if the four control circuits are not activated as a steer-by-wire system, the steering wheel 11 and the shift lever will not be unlocked. Incidentally, the same applies when a disconnection occurs in the power supply path to a specific control circuit other than the second reaction force control circuit 42A. The power supply path includes the start switch SW.

[0211] Furthermore, for example, if second reaction force control circuit 42A and first steering control circuit 51A have a function for setting the value of start permission flag F74, it is possible that second reaction force control circuit 42A or first steering control circuit 51A will recognize that start switch SW is on before the other three control circuits. In this case, second reaction force control circuit 42A or first steering control circuit 51A may transmit the value of start permission flag F74 to on-board system 72 via on-board network 71. However, the value of start permission flag F74 is set to "prohibited" by initialization. Therefore, even if the four control circuits are not activated as a steer-by-wire system, the vehicle powertrain will not start. Incidentally, the same applies when a break occurs in the power supply path to a specific control circuit other than second reaction force control circuit 42A or first steering control circuit 51A. The power supply path includes the start switch SW.

[0212] <Second mode of state transition of control circuit> Next, a second mode of state transition of each control circuit (41A, 42A, 51A, 52A) in this embodiment will be described.

[0213] As shown in the time chart of Figure 10, during execution of normal control immediately before the start switch SW is turned off, it is possible that the power supply to a specific control circuit is cut off due to a break in the power supply path to the specific control circuit. The power supply path is a power supply path that includes the start switch SW. If the start switch SW is turned off in this state, and all of the above three conditions C1 to C3 are met, each control circuit initializes the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, the start permission flag F74, and the meter notification flag F75.

[0214] That is, each control circuit switches the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, and the start permission flag F74 from "permitted" to "prohibited." Also, each control circuit switches the value of the meter notification flag F75 to a value corresponding to the current state of the steer-by-wire system. In this case, because a break has occurred in the power supply path to a specific control circuit, the value of the meter notification flag F75 is set to "abnormal."

[0215] If the start switch SW is turned on again during the execution period of the power latch control after the start switch SW is turned off, each control circuit executes the same processing as the first mode shown in Fig. 9. That is, when the value of the communication permission flag F71 switches from "prohibited" to "permitted," the three control circuits other than the specific control circuit transmit the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, the start permission flag F74, and the meter notification flag F75 to the in-vehicle system 72 via the in-vehicle network 71.

[0216] However, the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, and the start permission flag F74 are set to "prohibited" by initialization. Therefore, even if the four control circuits are not activated as a steer-by-wire system, the vehicle will not transition to a state in which it is capable of running. The same applies when the function of setting the values ​​of the permission flags (F72, F73, F74) is shared among the control circuits. In other words, even if the control circuits are not activated as a steer-by-wire system, the steering wheel 11 and the shift lever will not be unlocked and the powertrain will not be started.

[0217] <Advantages of the Fourth Embodiment> Therefore, according to the fourth embodiment, the following effects can be obtained. (4-1) When the start switch SW is turned off, each control circuit (41A, 42A, 51A, 52A) initializes the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, and the start permission flag F74. That is, each control device sets the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, and the start permission flag F74 to "prohibited."

[0218] If the start switch SW is turned on again during the execution period of the power latch control after the start switch SW is turned off, and there is a control circuit that does not recognize that the start switch SW is on, the control circuits will not start up as a steer-by-wire system. However, there is a risk that other control circuits that recognize that the start switch SW is on will send the values ​​of the permission flags (F72, F73, F74) to the in-vehicle system 72.

[0219] At this time, because the values ​​of the permission flags (F72, F73, F74) are set to "prohibited," the steering wheel 11 and the shift lever are not unlocked and the powertrain is not started. Therefore, even though the control circuits have not been activated as a steer-by-wire system, it is possible to prevent the vehicle from transitioning to a state in which it is capable of running, or to prevent the execution of processing to transition the vehicle to a state in which it is capable of running.

[0220] (4-2) When the start switch SW is turned off, each control circuit (41A, 42A, 51A, 52A) initializes the value of the meter notification flag F75. That is, each control circuit switches the value of the meter notification flag F75 to a value corresponding to the current state of the steer-by-wire system. For example, when a break in the power supply path to a specific control circuit is detected at the time the start switch SW is turned off, each control circuit sets the value of the meter notification flag F75 to "abnormal." If the start switch SW is turned on again during the execution of power latch control after the start switch SW is turned off, the control circuit that recognizes that the start switch SW is turned on transmits the value of the meter notification flag F75 to the in-vehicle system 72. Based on the fact that the value of the meter notification flag F75 is set to "abnormal," the meter control device switches the illumination state of the indicator lamp from an off state to an illumination state indicating an abnormality in the steer-by-wire system. The illumination state indicating an abnormality is, for example, a yellow illumination state. Therefore, the driver can immediately recognize an abnormality in the steer-by-wire system visually without waiting for the completion of the execution of the power latch control by each control circuit.

[0221] <Fifth embodiment> Next, a fifth embodiment will be described in which the vehicle control device is embodied in a steer-by-wire steering device. This embodiment basically has the same configuration as the first embodiment shown in Figures 1 to 3. Therefore, the same members and configurations as those in the first embodiment are given the same reference numerals, and detailed description thereof will be omitted.

[0222] This embodiment differs from the third embodiment in the content of the process that each control circuit (41A, 42A, 51A, 52A) executes when start switch SW is turned on. When the start switch SW is turned on, each control circuit sets the value of the activation status flag F79. The activation status flag F79 is information indicating whether all of the control circuits recognize that the start switch SW is on. The control circuits confirm with each other whether they recognize that the start switch SW is on, i.e., that the vehicle power is on, through the first mutual confirmation MC1, second mutual confirmation MC2, third mutual confirmation MC3, and fourth mutual confirmation MC4 shown in FIG. 3. When a control circuit determines that even one of the control circuits has not recognized that the start switch SW is off, it sets the value of the activation status flag F79 to "not activated." Setting the value of the activation status flag F79 to "not activated" indicates that the control circuit cannot be activated as a steer-by-wire system. When a control circuit determines that all of the control circuits recognize that the start switch SW is on, it sets the value of the activation status flag F79 to "activated." When the value of the activation status flag F79 is set to "activation", it indicates that each control circuit is in a state where it can be activated as a steer-by-wire system.

[0223] Next, a first mode of state transition of each control circuit (41A, 42A, 51A, 52A) in this embodiment will be described. As an example, assume that a power supply path to a specific control circuit is broken during the period from when the start switch SW is turned off until the start switch SW is turned on again during power latch control. The power supply path includes the start switch SW. Therefore, the power supply voltage is not supplied to the specific control circuit via the start switch SW. Therefore, the specific control circuit cannot recognize that the start switch SW is turned on. Furthermore, the specific control circuit is not started.

[0224] As shown in the time chart of Fig. 11, when the start switch SW is turned off while normal control is being performed (time T11), each control circuit performs power latch control. When the start switch SW is turned off, the power supply voltage level switches from "Hi" to "Lo." When the power supply voltage level switches from "Hi" to "Lo," each control circuit switches the value of the communication permission flag F71 from "permitted" to "prohibited."

[0225] During execution of power latch control, the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, the start permission flag F74, and the meter notification flag F75 are maintained at the same values ​​as during execution of normal control immediately before the start switch SW is turned off. That is, the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, and the start permission flag F74 are each maintained at "permitted." The value of the meter notification flag F75 is maintained at "normal." The value of the startup status flag F79 is maintained at "started."

[0226] During the execution period of the power latch control after the start switch SW is turned off, when the start switch SW is turned on again (time T12), the power supply voltage is not supplied to the specific control circuit via the power supply path including the start switch SW. Therefore, the specific control circuit cannot recognize that the start switch SW is turned on. Therefore, the specific control circuit does not start up.

[0227] The three control circuits other than the specific control circuit are supplied with power supply voltage via a power supply path that includes the start switch SW. In this case, the specific control circuit cannot recognize that the start switch SW is on, so a situation in which all of the control circuits recognize that the start switch SW is on cannot occur. Therefore, the three control circuits other than the specific control circuit set the value of the activation status flag F79 to "not activated."

[0228] When the power supply voltage supplied by turning on the start switch SW reaches a value within the operating voltage range, the three control circuits other than the specific control circuit set the value of the communication permission flag F71 to "permitted." This enables the three control circuits other than the specific control circuit to communicate via the in-vehicle network 71.

[0229] When the value of the communication permission flag F71 switches from "prohibited" to "permitted," the three control circuits other than the specific control circuit transmit the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, the start permission flag F74, the meter notification flag F75, and the activation status flag F79 to the in-vehicle system 72 via the in-vehicle network 71. The process of transmitting the value of the activation status flag F79 set to "not activated" to the in-vehicle system 72 is a process for requesting the in-vehicle system 72 to ignore the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, and the start permission flag F74.

[0230] Therefore, when the value of the activation status flag F79 is set to "not activated," the in-vehicle system 72 ignores the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, and the start permission flag F74. That is, even if the value of the first unlock permission flag F72, the value of the second unlock permission flag F73, and the value of the start permission flag F74 are each set to "permitted," the in-vehicle system 72 does not operate.

[0231] That is, the steering lock control device does not execute a process to unlock the steering wheel 11. As a result, the steering wheel 11 remains locked. Furthermore, the shift lock control device does not execute a process to unlock the shift lever. As a result, the shift lever remains locked. Furthermore, the powertrain control device does not execute a process to start the powertrain. As a result, the powertrain remains stopped.

[0232] Therefore, even though the four control circuits (41A, 42A, 51A, 52A) are in a state where they cannot be activated as a steer-by-wire system, the vehicle does not transition to a state where it can run.

[0233] When the start switch SW is turned on, if the value of the activation status flag F79 is set to "not activated," the meter control device switches the indicator lamp from an off state to, for example, a red illuminated state. This is because the activation status flag F79 being set to "not activated" indicates that each control circuit cannot be activated as a steer-by-wire system. The driver can immediately recognize an abnormality in the steer-by-wire system visually, without waiting for each control circuit to complete execution of power latch control.

[0234] The same applies if the timings at which the four control circuits (41A, 42A, 51A, 52A) recognize that the start switch SW is turned on simply do not match. That is, the control circuit that first recognizes that the start switch SW is turned on may transmit the values ​​of the flags (F72, F73, F74, F75, F79) to the in-vehicle system 72 via the in-vehicle network 71. However, if there is a control circuit that does not recognize that the start switch SW is turned on, the value of the activation status flag F79 is set to "not activated." Therefore, even if the permission flags (F72, F73, F74) set to "enabled" are transmitted to the in-vehicle system 72, the in-vehicle system 72 will not operate. Therefore, even if the four control circuits are not activated as a steer-by-wire system, the vehicle will not transition to a state where it can run.

[0235] The same applies to the case where the function of setting the values ​​of each permission flag (F72, F73, F74) is shared and executed by each control circuit. For example, if only the second reaction force control circuit 42A has the function of setting the values ​​of the first unlock permission flag F72 and the second unlock permission flag F73, it is expected that the second reaction force control circuit 42A will recognize that the start switch SW is turned on before the other three control circuits. In this case, there is a risk that the second reaction force control circuit 42A will transmit the values ​​of the first unlock permission flag F72 and the second unlock permission flag F73 to the in-vehicle system 72 via the in-vehicle network 71.

[0236] However, if there is a control circuit that does not recognize that the start switch SW is on, the value of the activation status flag F79 is set to "Not activated." Therefore, even if the value of the first unlock permission flag F72 set to "Allowed" is transmitted to the in-vehicle system 72, the steering lock control device will not start executing the process to unlock the steering wheel 11. Similarly, even if the value of the second unlock permission flag F73 set to "Allowed" is transmitted to the in-vehicle system 72, the shift lock control device will not start executing the process to unlock the shift lever. Therefore, even if the four control circuits are not activated as a steer-by-wire system, the steering wheel 11 and the shift lever will not be unlocked. Incidentally, the same applies when a break occurs in the power supply path to a specific control circuit other than the second reaction force control circuit 42A. The power supply path is a power supply path that includes the start switch SW.

[0237] Furthermore, for example, if second reaction force control circuit 42A and first turning control circuit 51A have a function to set the value of start permission flag F74, it is conceivable that second reaction force control circuit 42A or first turning control circuit 51A will recognize that start switch SW is on before the other three control circuits. In this case, there is a risk that second reaction force control circuit 42A or first turning control circuit 51A will transmit the value of start permission flag F74 to on-vehicle system 72 via on-vehicle network 71.

[0238] However, if there is a control circuit that does not recognize that the start switch SW is on, the value of the activation status flag F79 is set to "not activated." Therefore, even if the start permission flag F74 set to "permitted" is sent to the in-vehicle system 72, the powertrain control device will not start executing processing to operate the powertrain. Therefore, even if the four control circuits are not activated as a steer-by-wire system, the powertrain will not be started. Incidentally, the same applies if a break occurs in the power supply path to a specific control circuit other than the second reaction force control circuit 42A or the first turning control circuit 51A. The power supply path is the power supply path that includes the start switch SW.

[0239] <Second mode of state transition of control circuit> Next, a second mode of state transition of each control circuit (41A, 42A, 51A, 52A) in this embodiment will be described.

[0240] As shown in the time chart of FIG. 12, during normal control immediately before the start switch SW is turned off, a situation may occur in which a specific control circuit is unable to recognize that the start switch SW is on due to a break in the power supply path to that specific control circuit. The power supply path is a power supply path that includes the start switch SW. Even in this case, when the start switch is turned off, each control circuit executes the same process as the first mode shown in FIG. 11. That is, when each control circuit determines that even one of the control circuits has not recognized that the start switch SW is off, it sets the value of the activation status flag F79 to "not activated."

[0241] Therefore, even if the four control circuits are not activated as a steer-by-wire system, the vehicle will not transition to a state in which it is possible to drive. The same applies when the function of setting the values ​​of the permission flags (F72, F73, F74) is shared among the control circuits. In other words, even if the control circuits are not activated as a steer-by-wire system, the steering wheel 11 and the shift lever will not be unlocked and the powertrain will not be started.

[0242] <Advantages of the Fifth Embodiment> Therefore, according to the fifth embodiment, the following effects can be obtained. (5-1) When the start switch SW is turned on, each of the control circuits (41A, 42A, 51A, 52A) sets the value of the activation status flag F79 to "not activated" if there is at least one control circuit that does not recognize that the start switch SW is turned on. When the value of the activation status flag F79 is set to "not activated," the in-vehicle system 72 ignores the values ​​of the first unlock permission flag F72, the second unlock permission flag F73, and the start permission flag F74. This makes it possible to prevent the vehicle from transitioning to a state where it can travel or to prevent processing for transitioning the vehicle to a state where it can travel being executed, even though each control circuit has not been activated as a steer-by-wire system.

[0243] (5-2) When the start switch SW is turned on, if the value of the activation status flag F79 is set to "not activated," the meter control device switches the illumination state of the indicator lamp from an off state to, for example, a red illumination state. This is because the activation status flag F79 being set to "not activated" indicates that each control circuit cannot be activated as a steer-by-wire system. Therefore, the driver can immediately recognize an abnormality in the steer-by-wire system visually, without waiting for each control circuit to complete execution of power latch control.

[0244] <Other embodiments> Each embodiment may be modified as follows. In the first embodiment and the third to fifth embodiments, the initial sequence executed by each control circuit (41A, 42A, 51A, 52A) at startup may include a midpoint learning process and a steering angle synchronization process.

[0245] The midpoint learning process is a process for learning the neutral steering position of the steering wheel 11. The steering device 10 has a stopper mechanism that restricts the rotation of the steering wheel 11 to set a limit on the steering angle of the steering wheel 11. The stopper mechanism, for example, restricts the steering range of the steering wheel 11 to less than 360°. The reaction force control device 40 controls the reaction force motor 21 to move the steering wheel 11 to a first operating end and then to a second operating end. After this, the reaction force control device 40 calculates the midpoint of the steering angle based on the rotation angle of the reaction force motor 21 at the start and end of the steering wheel 11's reversal movement. The midpoint of the steering angle corresponds to the motor midpoint, which is the rotational position of the reaction force motor 21 when the steering wheel 11 is located in the neutral steering position. The reaction force control device 40 stores the midpoint of the steering angle or the motor midpoint in memory as the neutral steering position of the steering wheel 11.

[0246] However, the reaction force control device 40 learns the neutral steering position of the steering wheel 11 when the information about the neutral steering position stored in the memory is lost. This applies, for example, to the first time the vehicle power is turned on after a new battery is installed in the vehicle. This is because when the battery is removed from the vehicle for battery replacement, the information about the neutral steering position stored in the memory of the reaction force control device 40 is lost due to the loss of power supply to the reaction force control device 40.

[0247] Depending on the product specifications, the reaction force control device 40 may be configured to execute the midpoint learning process each time the vehicle power is turned on, or may be configured to execute the midpoint learning process when the reliability of the information regarding the steering neutral position stored in the memory has decreased.

[0248] The steering angle synchronization process is a process for correcting the rotational position of the steering wheel 11. When the rotational position of the steering wheel 11 is different from the rotational position corresponding to the steered position of the steered wheels 15, the reaction force control device 40 drives the reaction force motor 21 so that the rotational position of the steering wheel 11 becomes the rotational position corresponding to the steered position of the steered wheels 15.

[0249] For example, when the vehicle power supply is turned off, the reaction force control device 40 stores the steering angle θs detected immediately before as a reference steering angle. The reference steering angle is a reference for determining whether or not the steering wheel 11 is rotating while the vehicle power supply is turned off. When the steering angle θs immediately after the vehicle power supply is turned on does not match the reference steering angle, the reaction force control device 40 calculates the difference between the steering angle θs immediately after the vehicle power supply is turned on and the reference steering angle, and controls the power supply to the reaction force motor 21 to eliminate the difference.

[0250] In addition, the reaction force control device 40 may calculate the difference between the value of the steering angle θs immediately after the vehicle power supply is turned on and the value obtained by multiplying the steering angle θw immediately after the vehicle power supply is turned on by the reciprocal of the steering angle ratio, and control the power supply to the reaction force motor 21 so as to eliminate this difference.

[0251] In the first embodiment, reaction force motor 21 and steering motor 31 have two systems of winding groups, but they may also have one system of winding groups. In this case, reaction force control device 40 may have only one of first system circuit 41 and second system circuit 42. Also, in this case, steering control device 50 may have only one of first system circuit 51 and second system circuit 52. Here, we will take as an example a case where reaction force control device 40 has only first system circuit 41 and steering control device 50 has only first system circuit 51. First reaction force control circuit 41A sets the value of flag F11 in accordance with the result of determining whether start switch SW is on. First turning control circuit 51A sets the value of flag F31 in accordance with the result of determining whether start switch SW is on. When the value of flag F11 and the value of flag F31 are both "1," first reaction force control circuit 41A and first turning control circuit 51A determine that both first reaction force control circuit 41A and first turning control circuit 51A recognize that start switch SW is on. This triggers activation of first reaction force control circuit 41A and first turning control circuit 51A. Therefore, if the vehicle power supply is turned on during execution of power latch control after the vehicle power supply has been turned off, even if the first reaction force control circuit 41A and the first turning control circuit 51A recognize the on of the vehicle power supply at different times, the timing at which the first reaction force control circuit 41A and the first turning control circuit 51A start activation can be synchronized. This also applies when reaction force control device 40 has only second system circuit 42 and when turning control device 50 has only second system circuit 52. Therefore, drive of the reaction force motor and the turning motor can be appropriately controlled. It should be noted that first reaction force control circuit 41A or second reaction force control circuit 42A corresponds to a reaction force control circuit. First turning control circuit 51A or second turning control circuit 52A corresponds to a turning control circuit. This configuration may be applied to the third to fifth embodiments.

[0252] In the first embodiment, the control circuits (41A, 42A, 51A, 52A) may mutually confirm the values ​​of the flags (F11, F21, F31, F41) to determine whether all the control circuits have recognized that the vehicle power supply is on. In this case, however, the first reaction force control circuit 41A and the second turning control circuit 52A are arranged to be able to exchange information with each other via a communication line. The second reaction force control circuit 42A and the first turning control circuit 51A are also arranged to be able to exchange information with each other via a communication line. This configuration may be applied to the third to fifth embodiments.

[0253] In the first embodiment, one specific control circuit among the control circuits (41A, 42A, 51A, 52A) may check the flag values ​​of the other control circuits to determine whether all the control circuits have recognized that the vehicle power supply is on. The specific control circuit notifies the other control circuits of the determination result of whether all the control circuits have recognized that the vehicle power supply is on. In this case, however, the first reaction force control circuit 41A and the second turning control circuit 52A, or the second reaction force control circuit 42A and the first turning control circuit 51A, are configured to be able to exchange information with each other via a communication line. This configuration may be applied to the third to fifth embodiments.

[0254] In the first embodiment, the vehicle control device is embodied in a steer-by-wire steering device, and in the second embodiment, the vehicle control device is embodied in an electric power steering device. However, the vehicle control device may also be embodied in, for example, a door mirror device that opens and closes in conjunction with door locks. The present invention can be embodied in all vehicle systems that require synchronized state transitions between multiple control circuits. However, the event that triggers the synchronized state transitions is not limited to turning on the vehicle power supply. As with the first and second embodiments, the third to fifth embodiments can also be embodied in all vehicle systems that require synchronized state transitions between multiple control circuits. [Explanation of symbols]

[0255] 11...Steering wheel 15...Steering wheel 21...Reaction motor 31...Steering motor 41A...First reaction force control circuit 42A...Second reaction force control circuit 51A...First steering control circuit 52A...Second steering control circuit 70...Assist motor 72...In-vehicle systems N11: Winding group of the first reaction motor N12: Second winding group of reaction motor N21: First winding group of steering motor N22: Second winding group of steering motor N31: Assist motor first system winding group N32: Second winding group of assist motor

Claims

1. The control circuit includes a plurality of control circuits that are activated when the vehicle power supply is turned on to control the control target, and that are activated when the vehicle power supply is turned off to perform power latch control to maintain power for a predetermined period of time, When the vehicle power supply is turned on while power latch control is being executed after the vehicle power supply has been turned off, the plurality of control circuits wait for all of the control circuits, including the control circuit itself, to recognize that the vehicle power supply is on before starting up.

2. The plurality of control circuits set flag values ​​according to the recognition result of whether the vehicle power supply is on or not, The vehicle control device according to claim 1 , wherein each of the plurality of control circuits determines whether or not all of the control circuits, including itself, recognize that the vehicle power supply is on, based on the value of the flag.

3. The control object is a reaction motor having two winding groups and generating a steering reaction force to be applied to a steering wheel whose power transmission between the steering wheel and the steered wheels is separated; a steering motor that generates a steering force for steering the steered wheels, The plurality of control circuits include: a first reaction force control circuit that controls power supply to a first system of windings of the reaction force motor; a second reaction force control circuit that controls power supply to a second system of windings of the reaction force motor; a first steering control circuit that controls power supply to a first system of windings of the steering motor; 3. The vehicle control device according to claim 1, further comprising: a second steering control circuit that controls power supply to a second system of windings of the steering motor.

4. the first reaction force control circuit and the second reaction force control circuit perform a first mutual confirmation in which they confirm with each other whether they have recognized that a vehicle power source is on; the first turning control circuit and the second turning control circuit perform a second mutual confirmation in which they confirm with each other whether they have recognized that the vehicle power supply is on; the first reaction force control circuit and the first steering control circuit perform a third mutual confirmation in which they mutually confirm the success or failure of the first mutual confirmation and the second mutual confirmation, and when the first mutual confirmation and the second mutual confirmation are successful, it is determined that all of the control circuits have recognized that the vehicle power supply is on; 4. The vehicle control device according to claim 3, wherein the second reaction force control circuit and the second steering control circuit perform a fourth mutual confirmation in which they mutually confirm the success or failure of the first mutual confirmation and the second mutual confirmation, and when the first mutual confirmation and the second mutual confirmation are successful, it is determined that all of the control circuits have recognized that the vehicle power supply is on.

5. the controlled object includes a reaction motor which is a source of generating a steering reaction force applied to a steering wheel whose power transmission is separated from that of the steered wheels, and a turning motor which is a source of generating a turning force for turning the steered wheels, the plurality of control circuits include a reaction force control circuit that controls the reaction force motor, and a steering control circuit that controls the steering motor, 3. The vehicle control device according to claim 1, wherein the reaction force control circuit and the steering control circuit confirm with each other whether they have recognized that the vehicle power supply is on.

6. the controlled object includes an assist motor that generates an assist force to assist the operation of a steering wheel, the assist motor has a first winding group and a second winding group, the plurality of control circuits include a first assist control circuit that controls power supply to the first system of winding groups, and a second assist control circuit that controls power supply to the second system of winding groups; 3. The vehicle control device according to claim 1, wherein the first assist control circuit and the second assist control circuit confirm with each other whether they have recognized that the vehicle power supply is turned on.

7. the control circuit is configured to be able to communicate with an in-vehicle system that executes a process for transitioning the vehicle to a drivable state; 3. The vehicle control device according to claim 1, wherein the control circuit is configured such that, when the vehicle power is turned on while power latch control is being executed after the vehicle power is turned off, the control circuit waits until all of the control circuits, including the control circuit itself, recognize that the vehicle power is on before allowing communication with the in-vehicle system to be executed.

8. the control circuit is configured to be able to communicate with an in-vehicle system that executes a process for transitioning the vehicle to a drivable state, and is configured to be allowed to communicate with the in-vehicle system when the vehicle power supply is turned on; the control circuit has information indicating whether or not the in-vehicle system is permitted to execute the process; When the vehicle power supply is turned off during execution of control of the control target, the control circuit initializes the information by changing the content of the information from a content that allows the in-vehicle system to execute the process to a content that requests the in-vehicle system to prohibit execution of the process, 3. The vehicle control device according to claim 1, wherein the information is transmitted to the in-vehicle system when the vehicle power supply is turned on during execution of power latch control after the vehicle power supply has been turned off.

9. the control circuit is configured to be able to communicate with an in-vehicle system that executes a process for transitioning the vehicle to a drivable state, and is configured to be allowed to communicate with the in-vehicle system when the vehicle power supply is turned on; the control circuit has information indicating whether or not the in-vehicle system is permitted to execute the process; the control circuit is configured to, when the vehicle power supply is turned off during execution of the control of the control object, hold the content of the information as the content at the time of execution of the control of the control object, which is the content that permits the in-vehicle system to execute the process, and to transmit the information to the in-vehicle system when the vehicle power supply is turned on during execution of the power latch control after the vehicle power supply is turned off; 3. The vehicle control device according to claim 1, wherein the control circuit is configured to execute processing to request the in-vehicle system to ignore the information when the vehicle power is turned on during execution of power latch control after the vehicle power is turned off and all of the control circuits, including the control circuit itself, are not in a state where they recognize that the vehicle power is on.

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