Vehicle control device

Abstract

To provide a vehicular control device that can suppress a state from being unintentionally transited when a vehicle power supply is turned on during execution of power latch control.SOLUTION: A vehicular control device includes a plurality of control circuits (41A, 42A, 51A and 52A). The control circuits are activated at a time when a vehicle power supply is turned on, so as to control an object to be controlled in cooperation or in collaboration. The control circuits execute synchronous processing for making operation modes of the object to be controlled which are determined in accordance with mutual operation states synchronize with each other, and power latch control by which the vehicle power supply is held only in a predetermined period of time, at the time when the vehicle power supply is turned off. The control circuits hold operation modes determined just before the vehicle power source is turned off, in a period of time during which the power latch control is executed. When the vehicle power supply is turned on, the control circuits do not execute the synchronous processing, in a period of time during which the control circuits recognize that the vehicle power supply is turned on and then all of the control circuits are activated normally, so that control of the object to be controlled can be executed.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] Conventionally, a so-called steer-by-wire steering device that separates the power transmission between the steering wheel and the steered wheels is known. For example, the steer-by-wire system of Patent Document 1 has 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 for steering the steered wheels.

[0003] The reaction force actuator and the steering actuator each have two control arithmetic units provided redundantly and two motor drive units provided redundantly. The control arithmetic unit performs arithmetic operations related to the drive control of the motor. The motor drive unit generates torque based on a drive signal generated by the corresponding control arithmetic unit.

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

[0005] The control arithmetic unit of the first system of the reaction force actuator and the control arithmetic unit of the first system of the steering actuator can communicate with each other. The control arithmetic unit of the second system of the reaction force actuator and the control arithmetic unit of the second system of the steering actuator can communicate with each other. The two control arithmetic units of the first system and the two control arithmetic units of the second system use the information exchanged between the systems in common to generate torque in the motor drive unit.

[0006] Conventionally, there has been an electric power steering device that assists in the operation of a steering wheel. The control device of the electric power steering device generates an assist force for an assist motor according to the steering state of the steering wheel. For example, the control device of Patent Document 2 executes power latch control that continues the control until a predetermined time has elapsed since the ignition key is turned off. When the steering wheel is operated during the execution of the power latch control, steering assistance by the motor is performed.

[0007] Also, the control device of the electric power steering device described in Patent Document 3 executes power latch control for continuing temperature estimation calculation of elements on the substrate or the like after stopping the motor drive current when the vehicle switch is turned off. The control device holds the power supply until a predetermined time has elapsed after stopping the motor drive current or until the temperature of the elements on the substrate drops below a predetermined value.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0009] It has been considered to execute power latch control as in Patent Document 2 or Patent Document 3 in a steer-by-wire system having a plurality of systems as in Patent Document 1. In this case, when the vehicle power supply is turned off through an operation such as an ignition key, each control arithmetic unit individually executes power latch control. When the vehicle power supply is turned on during the execution of the power latch control, each control arithmetic unit executes an on determination of the vehicle power supply and restarts after the on determination is established.

[0010] However, when the vehicle power supply is turned on during execution of the power latch control, 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 the concern that there may be a difference in the timing at which each control calculation unit restarts. As a result, the control calculation unit that restarts first may perform an unintended state transition by receiving pre-initialization information from other control calculation units that are still executing the power latch control. [Means for solving the problem]

[0011] A vehicle control device that can solve the above problem has a plurality of control circuits that start when the vehicle power supply is turned on and control the controlled objects in a cooperative or linked manner. The plurality of control circuits execute a synchronization process that synchronizes the operation modes of the controlled objects, which are determined according to the operating states of the control objects, with each other, and a power latch control that holds the power supply for a set period of time when the vehicle power supply is turned off, and holds the operation mode immediately before the vehicle power supply is turned off during the period during which the power latch control is being executed. When the vehicle power supply is turned on, each of the plurality of control circuits does not execute the synchronization process during the period from when it recognizes that the vehicle power supply is on until all of the control circuits, including itself, start normally and are able to control the controlled objects.

[0012] When the vehicle power supply is turned on, the timing at which each control circuit recognizes that the vehicle power supply is on, and therefore the timing at which each control circuit starts up, may differ due to differences in wiring resistance, etc. For this reason, for example, when the vehicle power supply is turned on while the power latch control is being executed, the control circuit that started up first may perform an unintended state transition by synchronizing the operation mode it holds with the operation mode before initialization held by another control circuit that is still executing the power latch control.

[0013] In this regard, according to the above configuration, when the vehicle power supply is turned on, the plurality of control circuits do not perform synchronization processing during the period from when each recognizes the turning on of the vehicle power supply until all the control circuits including itself are normally started and reach a state where they can execute control of the control target. Therefore, when the vehicle power supply is turned on during the execution of the power latch control, the control circuit that starts first does not synchronize the operation mode of the control target it holds with the operation mode held by other control circuits. Accordingly, it is possible to suppress the control circuit that starts first from performing an unintended state transition.

[0014] In the above vehicle control device, the operation mode may include an operation mode when all of the plurality of control circuits are normal and an operation mode when any one of the plurality of control circuits is abnormal.

[0015] For example, when the vehicle power supply is turned on again during the execution period of the power latch control after the vehicle power supply is turned off in a state where an abnormality of a specific control circuit among the plurality of control circuits has been confirmed, the state of the specific control circuit may be a state in which it can return to normal operation. Further, it is also conceivable that the specific control circuit starts up before other control circuits. In this case, if the specific control circuit synchronizes the operation mode of the control target it holds with the operation mode for abnormal times held by other control circuits, a situation occurs where the specific control circuit controls the control target based on the operation mode for abnormal times even though it is in a state where it can return to normal operation.

[0016] In this regard, according to the above configuration, the specific control circuit does not synchronize the operation mode of the control target it holds with the operation mode for abnormal times held by other control circuits during the period from when it recognizes the turning on of the vehicle power supply until all the control circuits including itself are normally started and reach a state where they can execute control of the control target. Therefore, it is possible to suppress the control circuit that starts first from performing an unintended state transition.

[0017] In the above vehicle control device, the control target may include a reaction force motor that generates a steering reaction force applied to a steering wheel having two sets of winding groups and with power transmission to the steered wheels separated, and a steering motor that generates a steering force for steering the steered wheels. In this case, the plurality of control circuits may include a first reaction force control circuit that controls power supply to the first set of winding groups of the reaction force motor, a second reaction force control circuit that controls power supply to the second set of winding groups of the reaction force motor, a first steering control circuit that controls power supply to the first set of winding groups of the steering motor, and a second steering control circuit that controls power supply to the second set of winding groups of the steering motor.

[0018] According to the above configuration, when the vehicle power supply is turned on, for example, the first reaction force control circuit does not execute synchronization processing during the period until all of itself, the second reaction force control circuit, the first steering control circuit, and the second steering control circuit are normally started and reach a state where they can execute control of the reaction force motor or the steering motor. The same applies to the second reaction force control circuit, the first steering control circuit, and the second steering control circuit as the first reaction force control circuit. Therefore, when the vehicle power supply is turned on during the execution of power latch control, the first reaction force control circuit, the second reaction force control circuit, the first steering control circuit, or the second steering control circuit that starts first does not synchronize the operation mode of the reaction force motor or the steering motor it holds with the operation mode held by other control circuits. Thus, it is possible to suppress the first reaction force control circuit, the second reaction force control circuit, the first steering control circuit, or the second steering control circuit that starts first from performing an unintended state transition.

[0019] In the above vehicle control device, the synchronization processing may be executed between the first reaction force control circuit and the second reaction force control circuit, between the first steering control circuit and the second steering control circuit, between the first reaction force control circuit and the first steering control circuit, and between the second reaction force control circuit and the second steering control circuit.

[0020] According to this configuration, compared with a configuration in which the first reaction force control circuit, the second reaction force control circuit, the first steering control circuit, and the second steering control circuit perform synchronization processing with all control circuits other than themselves, it is possible to simplify the signal path. For example, there is no need to provide a communication line between the first reaction force control circuit and the second steering control circuit, and a communication line between the second reaction force control circuit and the first steering control circuit.

[0021] In the above vehicle control device, the control target may include a reaction force motor that is a source of a steering reaction force applied to a steering wheel whose power transmission to a steered wheel is separated, and a steering motor that is a source of a steering force for steering the steered wheel. In this case, the plurality of control circuits may include a reaction force control circuit that controls the reaction force motor and a steering control circuit that controls the steering motor.

[0022] According to the above configuration, when the vehicle power supply is turned on during the execution of the power latch control, for example, when the reaction force control circuit starts up first, the reaction force control circuit that starts up first does not synchronize the operation mode of the control target it holds with the operation mode held by the steering control circuit. Therefore, it is possible to suppress the unintentional state transition of the reaction force control circuit that starts up first. The same applies to the steering control circuit as to the reaction force control circuit.

[0023] In the above vehicle control device, the control target may include an assist motor that generates an assist force for assisting the operation of the steering wheel. The assist motor may have a first winding group and a second winding group. 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.

[0024] According to the above configuration, when the vehicle power supply is turned on during the execution of the power latch control, for example, when the first assist control circuit starts up first, the first assist control circuit that starts up first does not synchronize the operation mode of the assist motor it holds with the operation mode held by the second assist control circuit. Therefore, it is possible to suppress the first assist control circuit that starts up first from performing an unintended state transition. The same applies to the second assist control circuit as to the first assist control circuit.

Effect of the Invention

[0025] According to the vehicle control device of the present invention, it is possible to suppress an unintended state transition when the vehicle power supply is turned on during the execution of the power latch control.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0027] <First Embodiment> Hereinafter, a first embodiment in which the vehicle control device is embodied in a steer-by-wire type steering device will be described.

[0028] As shown in FIG. 1, a steering device 10 of a vehicle has a steering shaft 12 connected to a steering wheel 11. The steering device 10 also has a steering shaft 13 extending along the vehicle width direction (the left - right direction in FIG. 1). At both ends of the steering shaft 13, steering wheels 15 are connected via tie rods 14 respectively. When the steering shaft 13 moves linearly, the steering angle θw of the steering wheels 15 is changed. The steering shaft 12 and the steering shaft 13 constitute a steering mechanism of the vehicle. Note that in FIG. 1, only the steering wheel 15 on one side is illustrated.

[0029] The steering device 10 has a reaction force motor 21 and a speed reduction mechanism 22. The reaction force motor 21 is a source of a steering reaction force. The steering reaction force refers to a force acting in a direction opposite to the operation direction of the steering wheel 11 by the driver. The rotating shaft of the reaction force motor 21 is connected to the steering shaft 12 via the speed reduction mechanism 22. The torque of the reaction force 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 feedback.

[0030] The reaction force motor 21 is, for example, a three - phase brushless motor. The reaction force motor 21 has a first - system winding group N11 and a second - system winding group N12. The first - system winding group N11 and the second - system winding group N12 are wound around a common stator (not shown). The electrical characteristics of the first - system winding group N11 and the second - system winding group N12 are equivalent.

[0031] The steering device 10 has a steering motor 31 and a speed reduction mechanism 32. The steering motor 31 is a source of a steering force. The steering force refers to the power for steering the steering wheels 15. The rotating shaft of the steering motor 31 is connected to a pinion shaft 33 via the speed reduction mechanism 32. The pinion teeth 33a of the pinion shaft 33 are meshed with the rack teeth 13b of the steering shaft 13. The torque of the steering motor 31 is applied to the steering shaft 13 as a steering force via the pinion shaft 33. In response to the rotation of the steering motor 31, the steering shaft 13 moves along the vehicle width direction.

[0032] The steering motor 31 is, for example, a three-phase brushless motor. The steering motor 31 has a first system winding group N21 and a second system winding group N22. The first system winding group N21 and the second system winding group N22 are wound around a common stator (not shown). The electrical characteristics of the first system winding group N21 and the second system winding group N22 are equivalent.

[0033] 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 control target. The reaction force control device 40 executes reaction force control for generating a steering reaction force corresponding to the steering torque Th in the reaction force motor 21. The reaction force control device 40 calculates a target steering reaction force based on the steering torque Th detected through the torque sensor 23. The torque sensor 23 is provided on the steering shaft 12. The reaction force control device 40 controls the power supply to the reaction force motor 21 so as to match the actual steering reaction force applied to the steering shaft 12 with the target steering reaction force. The reaction force control device 40 independently controls the power supply to the two system winding groups in the reaction force motor 21 for each system.

[0034] The reaction force control device 40 has a first system circuit 41 and a second system circuit 42. The first system circuit 41 controls the power supply to the first system winding group N11 in the reaction force motor 21 according to the steering torque Th detected through the torque sensor 23. The second system circuit 42 controls the power supply to the second system winding group N12 in the reaction force motor 21 according to the steering torque Th detected through the torque sensor 23.

[0035] The steering device 10 has a steering control device 50. The steering control device 50 controls the drive of the steering motor 31 which is the control target. The steering control device 50 executes steering control to generate a steering force for steering the steering wheel 15 according to the steering state in the steering motor 31. The steering control device 50 takes in the steering angle θs detected through the steering angle sensor 24 and the stroke Xw of the steering shaft 13 detected through the stroke sensor 34. The stroke Xw is a displacement amount based on the neutral position of the steering shaft 13 and is a state variable in which the steering angle θw is reflected. The steering angle sensor 24 is provided between the torque sensor 23 of the steering shaft 12 and the speed reduction mechanism 22. The stroke sensor 34 is provided in the vicinity of the steering shaft 13.

[0036] The steering control device 50 calculates the target steering angle of the steering wheel 15 based on the steering angle θs detected through the steering angle sensor 24. The steering control device 50 calculates the steering angle θw based on the stroke Xw of the steering shaft 13 detected through the stroke sensor 34. The steering control device 50 controls the power supply to the steering motor 31 so that the steering angle θw calculated based on the stroke Xw matches the target steering angle. The steering control device 50 independently controls the power supply to the two winding groups in the steering motor 31 for each system.

[0037] The steering control device 50 has a first system circuit 51 and a second system circuit 52. The first system circuit 51 controls the power supply to the winding group N21 of the first system in the steering motor 31 based on the steering angle θs detected through the steering angle sensor 24 and the stroke Xw of the steering shaft 13 detected through the stroke sensor 34. The second system circuit 52 controls the power supply to the winding group N22 of the second system in the steering motor 31 based on the steering angle θs detected through the steering angle sensor 24 and the stroke Xw of the steering shaft 13 detected through the stroke sensor 34.

[0038] Note that a so-called mechatronic reaction force actuator may be configured by integrally providing the reaction force control device 40 and the reaction force motor 21. Further, a so-called mechatronic steering actuator may be configured by integrally providing the steering control device 50 and the steering motor 31.

[0039] <Power supply path> Next, the power supply paths for the reaction force control device 40 and the steering control device 50 will be described. Power is supplied to various in-vehicle control devices including the reaction force control device 40 and the steering control device 50 from a DC power supply 60 mounted on the vehicle. The DC power supply 60 is, for example, a battery. Power is also supplied to various sensors including the torque sensor 23, the steering angle sensor 24, and the stroke sensor 34 from the DC power supply 60 respectively.

[0040] The first system circuit 41 and the second system circuit 42 of the reaction force control device 40, and the first system circuit 51 and the second system circuit 52 of the steering control device 50 are each connected to the DC power supply 60 via the 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 when starting or stopping a driving 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 to the first system circuit 41 and the second system circuit 42 of the reaction force control device 40, and the first system circuit 51 and the second system circuit 52 of the steering control device 50 via the start switch SW respectively. Turning on the start switch SW means turning on the vehicle power supply. Turning off the start switch SW means turning off the vehicle power supply.

[0041] The first system circuit 41 and the second system circuit 42 of the reaction force control device 40, and the first system circuit 51 and the second system circuit 52 of the steering control device 50 are connected to the DC power supply 60 via the power relays 61, 62, 63, 64. When the power relays 61, 62, 63, 64 are turned on, the power from the DC power supply 60 is supplied to the first system circuit 41 and the second system circuit 42 of the reaction force control device 40, and the first system circuit 51 and the second system circuit 52 of the steering control device 50 via the power relays 61, 62, 63, 64.

[0042] The first system circuit 41 of the reaction force control device 40 controls the on / off of the power 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 relay 61 on for a predetermined period. Therefore, even after the start switch SW is turned off, the first system circuit 41 can operate. When a predetermined period has elapsed, the first system circuit 41 can cut off the power supply to itself by switching the power relay 61 from on to off.

[0043] The first system circuit 41 detects the on / off of the start switch SW by monitoring the voltage across the start switch SW, for example. The first system circuit 41 detects that the start switch SW is turned 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 turned off when the voltage across the start switch SW is equal to or higher than the predetermined voltage threshold.

[0044] The second system circuit 42 of the reaction force control device 40 controls the on / off of the power relay 62. Similar to the first system circuit 41, the second system circuit 42 executes power latch control. When the start switch SW is switched from on to off, the second system circuit 42 keeps the power relay 62 on for a predetermined period.

[0045] The first system circuit 51 of the steering control device 50 controls the on / off of the power relay 63. Similar to the first system circuit 41 of the reaction force control device 40, the first system circuit 51 executes power latch control. When the start switch SW is switched from on to off, the first system circuit 51 maintains the power relay 63 in the on state for a predetermined period.

[0046] The second system circuit 52 of the steering control device 50 controls the on / off of the power relay 64. Similar to the first system circuit 41 of the reaction force control device 40, the second system circuit 52 executes power latch control. When the start switch SW is switched from on to off, the second system circuit 52 maintains the power relay 64 in the on state for a predetermined period.

[0047] Among the components of the steering device 10, such as the torque sensor 23, the steering angle sensor 24, and the stroke sensor 34, the components that are required to operate even after the start switch SW is turned off are connected to the DC power supply 60 via at least one of the power relays 61, 62, 63, and 64. Therefore, even when the start switch SW is off, when at least one of the power relays 61, 62, 63, and 64 is on, power supply to each component such as the torque sensor 23, the steering angle sensor 24, and the stroke sensor 34 continues.

[0048] <Reaction force control device> Next, the configuration of the reaction force control device will be described in detail. As shown in FIG. 2, the reaction force control device 40 has a first system circuit 41 and a second system circuit 42. The first system circuit 41 has a first reaction force control circuit 41A and a motor drive circuit 41B. The second system circuit 42 has a second reaction force control circuit 42A and a motor drive circuit 42B.

[0049] The first reaction force control circuit 41A is composed of a processing circuit including: 1) one or more processors that operate according to a computer program (software); 2) one or more dedicated hardware circuits such as an application specific integrated circuit (ASIC) that executes at least some of various processes; and 3) a combination thereof. The processor includes a CPU (central processing unit). The processor also includes memories such as a RAM (random-access memory) and a ROM (read-only memory). The memory stores program codes or instructions configured to cause the CPU to execute processes. The memory, that is, the non-transitory computer-readable medium, includes any available medium accessible by a general-purpose or dedicated computer.

[0050] 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 through the torque sensor 23, and calculates a first current command value for the first winding group N11 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 to generate the target steering reaction force in the reaction force motor 21. The first reaction force control circuit 41A generates a drive signal (PWM signal) for the motor drive circuit 41B by performing current feedback control to make the value of the actual current supplied to the first winding group N11 follow the first current command value.

[0051] The motor drive circuit 41B is a PWM inverter in which three legs corresponding to each of the three phases (U, V, W) are connected in parallel, with a switching element such as two field-effect transistors (FETs) connected in series as a leg that is the basic unit. The motor drive circuit 41B converts the DC power supplied from the DC power supply 60 into three-phase AC power by switching the switching elements of each phase based on the drive signal 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 winding group N11 of the first system of the reaction force motor 21 via the power supply path of each phase composed of a bus bar or a cable or the like. Thereby, the winding group N11 of the first system generates a torque corresponding to the first current command value.

[0052] The second reaction force control circuit 42A basically has the same configuration as the first reaction force control circuit 41A. The second reaction force control circuit 42A calculates the target steering reaction force to be generated in the reaction force motor 21 based on the steering torque Th detected through the torque sensor 23, and calculates the 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 half the value of the amount of current required to generate the target steering reaction force in the reaction force motor 21. The second reaction force control circuit 42A generates a drive signal for the motor drive circuit 42B by executing 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.

[0053] The motor drive circuit 42B basically has the same configuration as the motor drive circuit 41B. The motor drive circuit 42B converts the DC power supplied from the DC power source 60 into three-phase AC power based on the 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 the power supply path for each phase consisting of a bus bar or a cable or the like. Thereby, the second winding group N12 generates a torque corresponding to the second current command value. The reaction force motor 21 generates a total torque of the torque generated by the first winding group N11 and the torque generated by the second winding group N12.

[0054] Depending on the product specifications, there may be a master-slave relationship between the first system circuit 41 and the second system circuit 42 of the reaction force control device 40. In this case, for example, the first system circuit 41 may function as a master and the second system circuit 42 may function as a slave. Also, depending on the product specifications, the first system circuit 41 and the second system circuit 42 may have an equal relationship.

[0055] <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 system circuit 51 and a second system circuit 52. The first system circuit 51 has a first steering control circuit 51A and a motor drive circuit 51B. The second system circuit 52 has a second steering control circuit 52A and a motor drive circuit 52B.

[0056] The first steering control circuit 51A basically has the same configuration as the first reaction force control circuit 41A. The first steering control circuit 51A calculates the target steering angle of the steering wheel 15 based on the steering angle θs detected through the steering angle sensor 24. The steering control device 50 calculates the steering angle θw based on the stroke Xw of the steering shaft 13 detected through the stroke sensor 34. The first steering control circuit 51A calculates the target steering force to be generated in the steering motor 31 by executing angle feedback control that causes the steering angle θw calculated based on the stroke Xw to follow the target steering angle, and calculates a third current command value for the first winding group N21 of the steering motor 31 according to the value of the 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 to generate the target steering force in the steering motor 31. The first steering control circuit 51A generates a drive signal for the motor drive circuit 51B by executing current feedback control that causes the value of the actual current supplied to the first winding group N21 to follow the third current command value.

[0057] The motor drive circuit 51B basically has the same configuration as the motor drive circuit 41B. The motor drive circuit 51B converts the DC power supplied from the DC power source 60 into three-phase AC power based on the drive signal generated by the first steering control circuit 51A. The three-phase AC power generated by the motor drive circuit 42B is supplied to the first winding group N21 of the steering motor 31 through the power supply path of each phase consisting of a bus bar or a cable or the like. Thereby, the first winding group N21 generates torque corresponding to the third current command value.

[0058] The second steering control circuit 52A basically has the same configuration as the first reaction force control circuit 41A. The second steering control circuit 52A calculates the target steering angle of the steering wheel 15 based on the steering angle θs detected through the steering angle sensor 24. The steering control device 50 calculates the steering angle θw based on the stroke Xw of the steering shaft 13 detected through the stroke sensor 34. The second steering control circuit 52A calculates the target steering force to be generated in the steering motor 31 through the execution of angle feedback control that causes the steering angle θw calculated based on the stroke Xw to follow the target steering angle, and calculates a fourth current command value for the second winding group N22 of the steering motor 31 according to the value of the calculated target steering force. However, the fourth current command value is set to a value that is half (50%) of the amount of current required to generate the target steering force in the steering motor 31. The second steering control circuit 52A generates a drive signal for the motor drive circuit 52B by executing current feedback control that causes the value of the actual current supplied to the second winding group N22 to follow the fourth current command value.

[0059] The motor drive circuit 52B basically has the same configuration as the motor drive circuit 41B. The motor drive circuit 51B converts the DC power supplied from the DC power source 60 into three-phase AC power based on the drive signal generated by the second steering control circuit 52A. The three-phase AC power generated by the motor drive circuit 52B is supplied to the second winding group N22 of the steering motor 31 through the power supply path of each phase composed of a bus bar or a cable or the like. Thereby, the second winding group N22 generates torque corresponding to the fourth current command value. The steering motor 31 generates a total torque of the torque generated by the first winding group N21 and the torque generated by the second winding group N22.

[0060] Note that depending on the product specifications, there may be a master-slave relationship between the first system circuit 51 and the second system circuit 52 of the steering control device 50. In this case, for example, the first system circuit 51 may function as the master and the second system circuit 52 may function as the slave. Also, depending on the product specifications, the first system circuit 51 and the second system circuit 52 may have an equal relationship.

[0061] <Communication path> Next, the communication paths inside the reaction force control device 40 and the steering control device 50, as well as the communication path between the reaction force control device 40 and the steering control device 50, will be described.

[0062] 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 the communication line L1. The information includes the abnormality information of the first reaction force control circuit 41A, the second reaction force control circuit 42A, or the motor drive circuits 41B and 42B. Further, the information includes the values of flags indicating various states. 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 with each other.

[0063] The first steering control circuit 51A and the second steering control circuit 52A exchange information with each other via the communication line L2. The information includes the abnormality information of the first steering control circuit 51A, the second steering control circuit 52A, or the motor drive circuits 51B and 52B. Further, the information includes the values of flags indicating various states. 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 with each other.

[0064] The first reaction force control circuit 41A and the first steering control circuit 51A exchange information with each other via the communication line L3. The information includes the abnormality information of the first reaction force control circuit 41A, the first steering control circuit 51A, and the motor drive circuits 41B and 51B. Further, the information includes the values of flags indicating various states. The first reaction force control circuit 41A and the first steering control circuit 51A operate in cooperation based on the information exchanged with each other.

[0065] The second reaction force control circuit 42A and the second steering control circuit 52A exchange information with each other via the communication line L4. The information includes abnormality information of the second reaction force control circuit 42A, the second steering control circuit 52A, or the motor drive circuits 42B and 52B. Further, the information includes the values of flags indicating various states. The second reaction force control circuit 42A and the second steering control circuit 52A operate in cooperation based on the information exchanged with each other.

[0066] <Drive mode of the motor> Next, the drive modes of the reaction force motor 21 and the steering motor 31 will be described. The drive modes include a cooperative drive mode, an independent drive mode, and a single-system drive mode.

[0067] The cooperative drive mode is the drive mode when the first-system circuits 41 and 51 and the second-system circuits 42 and 52 are operating normally. The first-system circuit 41 and the second-system circuit 42 share information such as command values and limit values with each other, and generate equal torque on both the first-system winding group N11 and the second-system winding group N12 of the reaction force motor 21. The first-system circuit 51 and the second-system circuit 52 share information such as command values and limit values with each other, and generate equal torque on both the first-system winding group N21 and the second-system winding group N22 of the steering motor 31.

[0068] The independent drive mode is the drive mode when an abnormality has not been confirmed although the operation of any one of the four control circuits (41A, 42A, 51A, 52A) has stopped instantaneously, and there is a possibility of returning to normal operation. In the independent drive mode, for example, when there is a possibility of a control circuit whose operation has stopped returning to normal operation, the remaining three control circuits generate torque on the winding group corresponding to themselves based on their own calculation results without using information by inter-system communication.

[0069] The chip system drive mode is a drive mode when any one of the four control circuits (41A, 42A, 51A, 52A) has a confirmed abnormality and there is no possibility of returning to normal operation without performing a reset process such as when the vehicle power is turned on again. For example, when an abnormality in the first reaction force control circuit 41A or the first steering control circuit 51A is confirmed, the drive control of the reaction force motor 21 and the steering motor 31 by the first reaction force control circuit 41A and the first steering control circuit 51A is stopped, and torque is generated in the reaction force motor 21 and the steering motor 31 only by the second system circuits 42 and 52. Similarly, when an abnormality in the second reaction force control circuit 42A or the second steering control circuit 52A is confirmed, the drive control of the reaction force motor 21 and the steering motor 31 by the second reaction force control circuit 42A and the second steering control circuit 52A is stopped, and torque is generated in the reaction force motor 21 and the steering motor 31 only by the first system circuits 41 and 51.

[0070] <State Transition of Control Circuit> Next, the state transition of each control circuit (41A, 42A, 51A, 52A) will be described. When the start switch SW is turned on, each control circuit executes a startup process and an initial check. The startup process and the initial check are a series of processes required for the steering system to operate. The startup process and the initial check include, for example, checking of hardware, initialization of the CPU (Central Processing Unit), and initialization of variables or flags. During the execution of the startup process and the initial check, the control status of each control circuit is in an unassisted state. The unassisted state is a state where the control of the reaction force motor 21 and the steering motor 31 has not yet started. The control status is the operating state of each control circuit.

[0071] After the execution of the initial check is completed normally, the control status of each control circuit transitions from the unassisted state to the assist start waiting state. The assist start waiting state is a state where it is waiting for the execution of the initial check to be completed normally in all control circuits.

[0072] When the execution of the initial check is completed normally in all control circuits, each control device becomes capable of controlling the reaction force motor 21 or the steering motor 31. The control status of each control circuit transitions from the assist start waiting state to the normal control state. Each control circuit starts executing normal control to generate a steering reaction force and a steering force according to the steering state of the steering wheel 11. In the normal control state, the drive modes of the reaction force motor 21 and the steering motor 31 are the cooperative drive mode. That is, in the normal control state, each control circuit generates torque in both the first winding group N11 and the second winding group N12 of the reaction force motor 21, and also generates torque in both the first winding group N21 and the second winding group N22 of the steering motor 31.

[0073] When the control status of each control circuit is in the assist start waiting state or the normal control state, when the defined abnormality determination condition is satisfied, the control status of each control circuit transitions from the assist start waiting state to the independent drive mode state or the single-system drive mode state. Also, when the control status of each control circuit is in the independent drive mode state, when the defined return condition is satisfied, the control status of each control circuit returns from the independent drive mode state to the normal control state. Further, when the control status of each control circuit is in the independent drive mode state, when the defined abnormality confirmation condition is satisfied, the control status of each control circuit transitions from the independent drive mode state to the single-system drive mode state.

[0074] Among the control circuits, the control circuit that is executing motor drive control executes power latch control when the start switch SW is turned off. When the start switch SW is turned off, the vehicle is stopped.

[0075] For example, in the normal control state, after the start switch SW is turned off, each control circuit (41A, 42A, 51A, 52A) executes power latch control and continues temperature estimation calculation of elements on the substrate, etc.

[0076] Also, for example, when an abnormality in the first reaction force control circuit 41A or the first steering control circuit 51A is confirmed and the single-system drive mode state is in which the drive control of the reaction force motor 21 and the steering motor 31 is executed only by the second system circuits 42 and 52, the control circuit (42A, 52A) that is executing the motor drive control among the respective control circuits executes power latch control after the start switch SW is turned off, and continues temperature estimation calculation of elements on the substrate, for example.

[0077] The elements are, for example, switching elements of each motor drive circuit (41B, 42B, 51B, 52B). Each control circuit holds the power supply until a predetermined time elapses after the start switch SW is turned off, or until the temperature of elements on the substrate or the like becomes equal to or lower than a predetermined temperature. The predetermined temperature is a sufficiently low temperature.

[0078] When the temperature of elements on the substrate or the like reaches a temperature equal to or lower than the predetermined temperature, each control circuit stores the temperature of elements on the substrate or the like at that time in a non-volatile memory and ends the execution of the power latch control. By executing such power latch control, each control circuit can accurately grasp the initial temperature of elements on the substrate or the like at the start stage of the next normal control execution, and thus can appropriately execute overheat protection control. The overheat protection control refers to control that suppresses overheating of elements on the substrate or the like by restricting the reaction force control or the steering control according to the amount of temperature rise based on the initial temperature of elements on the substrate or the like.

[0079] 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 timing at which each control circuit recognizes the turning on of the start switch SW does not match. For this reason, it is also feared that a deviation will occur in the timing at which each control circuit restarts. As a result, the control circuit that restarted first may perform an unintended state transition by receiving information before initialization from other control circuits that are still continuing the execution of the power latch control.

[0080] <Comparative Example of State Transition> Next, a comparative example of the state transition of each control circuit (41A, 42A, 51A, 52A) will be described. However, here, as an example, the following situation is assumed.

[0081] That is, it is assumed that an abnormality in the first reaction force control circuit 41A is confirmed, the motor drive by the first system circuits 41 and 51 stops, and the reaction force motor 21 and the steering motor 31 are driven in a single-system drive mode by the second system circuits 42 and 52, and then the vehicle power supply is turned off. When the vehicle power supply is turned off, the first reaction force control circuit 41A and the first steering control circuit 51A, which are components of the first system that is the abnormal system, stop operating without executing the power latch control, as indicated by the horizontal line "-" in FIG. 3. The second reaction force control circuit 42A and the second steering control circuit 52A, which are components of the second system that is the normal system, start executing the power latch control. The second reaction force control circuit 42A and the second steering control circuit 52A hold the operation modes of the reaction force motor 21 and the steering motor 31 immediately before the vehicle power supply is turned off. Here, the operation modes of the reaction force motor 21 and the steering motor 31 immediately before the vehicle power supply is turned off are the system 1 failure mode. The system 1 failure mode is the operation mode in a state where the first system has failed. The state where the first system has failed includes a state in which an abnormality has occurred in the first reaction force control circuit 41A or the first steering control circuit 51A.

[0082] Incidentally, the operation mode in the state where the second system has failed is the system 2 failure mode. The state where the second system has failed includes a state in which an abnormality has occurred in the second reaction force control circuit 42A or the second steering control circuit 52A.

[0083] Now, as shown in the time chart of FIG. 3, when the vehicle power supply is turned on again (time T1) during the execution period of the power latch control after the vehicle power supply is turned off, the first reaction force control circuit 41A may be in a state where it can return to normal operation. The state where the first reaction force control circuit 41A can return to normal operation means a state where it can return to the cooperative drive mode, which is the drive mode when the first system circuits 41, 51 and the second system circuits 42, 52 are operating normally. For example, when an element of the first reaction force control circuit 41A has temporarily overheated and an abnormality of the first reaction force control circuit 41A has been confirmed, but the temperature of the element of the first reaction force control circuit 41A has sufficiently decreased between the confirmation of the abnormality of the first reaction force control circuit 41A and the vehicle power supply being turned on again.

[0084] In this case, it is also conceivable that the first reaction force control circuit 41A recognizes that the vehicle power supply has been turned on prior to the other three control circuits (42A, 51A, 52A). The other three control circuits do not recognize that the vehicle power supply has been turned on, and among them, the second reaction force control circuit 42A and the second steering control circuit 52A continue to execute the power latch control, which is one mode of the stop control ST5. In the time chart of FIG. 3, the state where each control circuit recognizes the turning on of the vehicle power supply is represented as "ON", and the state where it does not recognize is represented as "OFF".

[0085] When it is determined that the vehicle power supply has been turned on, the first reaction force control circuit 41A executes the startup process ST1 and the initial check ST2, and then becomes the assist start waiting ST3. The control status of the first reaction force control circuit 41A transitions from the unassisted state CS1 through the assist start waiting state CS2 to the independent drive mode state CS3. This is because the operation modes of the reaction force motor 21 and the steering motor 31 are synchronized between the first reaction force control circuit 41A and the second reaction force control circuit 42A.

[0086] That is, as shown by arrow D1 in FIG. 3, when transitioning to the assist start waiting state, the first reaction force control circuit 41A recognizes the operation modes of the reaction force motor 21 and the steering motor 31 recognized by the second reaction force control circuit 42A. When the first reaction force control circuit 41A recognizes that the first system has failed, it starts executing the stop control ST4 to stop its own operation, and at the same time, transitions its own control status from the independent drive mode state CS3 to the non-assist state CS4. The non-assist state CS4 is a state where the control of the reaction force motor 21 and the steering motor 31 is not executed. The first reaction force control circuit 41A eventually reaches a sleep state where it waits in a power-saving state.

[0087] When it is determined that, for example, the vehicle power supply has been turned on (time T2), the other three control circuits (42A, 51A, 52A) start executing the startup process ST1. As shown by arrow D2 in FIG. 3, when transitioning to the assist start waiting state ST3, the second reaction force control circuit 42A recognizes the operation modes of the reaction force motor 21 and the steering motor 31 recognized by the first reaction force control circuit 41A. When the second reaction force control circuit 42A recognizes that the first system has failed, it transitions its own control status to the single-system drive mode state CS5 by the second system. The second reaction force control circuit 42A controls the drive of the reaction force motor 21 in the single-system drive mode (motor control ST6).

[0088] As shown by arrow D3 in FIG. 3, for example, at the timing when the startup process ST1 is completed, the first steering control circuit 51A recognizes the operation modes of the reaction force motor 21 and the steering motor 31 recognized by the first reaction force control circuit 41A. When the first steering control circuit 51A recognizes that the first system has failed, it starts executing the stop control ST4 to stop its own operation, and at the same time, transitions its own control status from the non-assist state CS1 to the non-assist state CS4. The first steering control circuit 51A eventually reaches a sleep state.

[0089] As shown by arrow D4 in FIG. 3, when the second steering control circuit 52A transitions to the assist start waiting state CS2, it recognizes the operation modes of the reaction force motor 21 and the steering motor 31 recognized by the first steering control circuit 51A. When the second steering control circuit 52A recognizes that the first system has failed, it transitions its own control status to the single-system drive mode state CS5 by the second system. The second steering control circuit 52A controls the drive of the steering motor 31 in the single-system drive mode (motor control ST6).

[0090] In this way, when the vehicle power supply is turned on again during the execution period of the power latch control after the vehicle power supply is turned off, the operation modes of the reaction force motor 21 and the steering motor 31 (here, the system 1 failure mode) are synchronized among the control circuits (41A, 42A, 51A, 52A). For this reason, although the first reaction force control circuit 41A can return to normal operation, the control statuses of the second reaction force control circuit 42A and the second steering control circuit 52A unintentionally transition to the single-system drive mode state by the second system.

[0091] <Transition Conditions of Control Status> Therefore, in the present embodiment, the transition conditions of the control statuses of the control circuits (41A, 42A, 51A, 52A) are set as follows. That is, when the vehicle power supply is turned on, each control circuit does not execute the operation mode synchronization process during the period from when each control circuit recognizes the turning on of the vehicle power supply until all the control circuits including itself start up normally and can execute the control of the reaction force motor 21 and the steering motor 31. When the vehicle power supply is turned on, it includes, for example, the case where the vehicle power supply is first turned on in a parked state and the case where the vehicle power supply is turned on again during the execution period of the power latch control. When the vehicle power supply is turned on again during the execution period of the power latch control, each control circuit does not execute the operation mode synchronization process when the operation mode of the motor (21, 31) recognized by itself is different from the operation mode of the motor recognized by other control circuits until all the control devices can execute the control of the motor.

[0092] <Examples of State Transitions> Next, the state transitions of the respective control circuits (41A, 42A, 51A, 52A) in the present embodiment will be described. However, the assumed situation is the same as that in the previous comparative example.

[0093] As shown in the time chart of FIG. 4, when the vehicle power supply is turned on again (time T1) during the execution period of the power latch control after the vehicle power supply is turned off, the first reaction force control circuit 41A is in a state where it can return to normal operation. Further, the first reaction force control circuit 41A recognizes that the vehicle power supply has been turned on prior to the other three control circuits (42A, 51A, 52A). The other three control circuits do not recognize that the vehicle power supply has been turned on, and among them, the second reaction force control circuit 42A and the second steering control circuit 52A continue to execute the power latch control which is one mode of the stop control ST5.

[0094] When it is determined that the vehicle power supply has been turned on, the first reaction force control circuit 41A executes the startup process ST1 and the initial check ST2, and eventually enters the assist start waiting state ST3. The control status of the first reaction force control circuit 41A transitions from the unassisted state CS1 to the assist start waiting state CS2. At this time, the operation mode of the motors (21, 31) recognized by the first reaction force control circuit 41A is the normal mode. The normal mode is an operation mode in which both the first system and the second system are normal. On the other hand, the operation mode of the motors (21, 31) recognized by the second reaction force control circuit 42A is the system 1 failure mode. Thus, the operation modes of the motors recognized by the first reaction force control circuit 41A and the second reaction force control circuit 42A are different from each other. However, the first reaction force control circuit 41A does not execute a process of synchronizing the operation mode of the motors it recognizes with the operation mode of the motors recognized by the second reaction force control circuit 42A during the assist start waiting state CS2. For this reason, the control status of the first reaction force control circuit 41A is maintained in the assist start waiting state CS2.

[0095] When it is determined that the vehicle power supply is turned on, for example, at time T2, the other three control circuits (42A, 51A, 52A) start executing the startup process ST1 and the initial check ST2. At the timing when the initial check ST2 executed in these three control circuits is completed normally, each control circuit (41A, 42A, 51A, 52A) transitions the control status to the normal control state CS6. The driving modes of the motors (21, 31) recognized by each control circuit (41A, 42A, 51A, 52A) are maintained in a state synchronized with the correct driving mode, here the normal control state CS6. The first reaction force control circuit 41A and the second reaction force control circuit 42A control the driving of the reaction force motor 21 in the cooperative driving mode which is the normal driving mode (motor control ST6). The first steering control circuit 51A and the second steering control circuit 52A control the driving of the steering motor 31 in the cooperative driving mode (motor control ST6).

[0096] In this way, when the vehicle power supply is turned on again during the execution period of the power latch control, when the first reaction force control circuit 41A, which is in a state where it can return to normal operation, recognizes that the vehicle power supply has been turned on prior to the other three control circuits (42A, 51A, 52A), each control circuit (41A, 42A, 51A, 52A) starts operating normally as intended. Different from the previous comparative example, even though the first reaction force control circuit 41A is in a state where it can return to normal operation, the operating modes of the reaction force motor 21 and the steering motor 31 do not unintentionally transition to the single-system mode by the second system.

[0097] Note that when the vehicle power supply is turned on during the execution period of the power latch control after the vehicle power supply has been turned off in a state where an abnormality in a specific control circuit among the other three control circuits (42A, 51A, 52A) has been confirmed, that specific control circuit operates in the same manner as the first reaction force control circuit 41A described above.

[0098] <Effects of the First Embodiment> Therefore, according to this embodiment, the following effects can be obtained. (1-1) When the vehicle power supply is turned on again during the execution period of the power latch control after the vehicle power supply is turned off, each control circuit (41A, 42A, 51A, 52A) does not execute the process of synchronizing the operation mode if the operation mode of the motor (21, 31) it recognizes is different from the operation mode of the motor (21, 31) recognized by other control circuits. For example, when the vehicle power supply is turned on during the execution period of the power latch control after the vehicle power supply is turned off with an abnormality in a specific control circuit (41A) among the control circuits determined, the specific control circuit may be in a state where it can return to normal operation, and moreover, it may recognize that the vehicle power supply has been turned on prior to other control circuits (42A, 51A, 52A). In this case, the specific control circuit (41A) does not execute the process of synchronizing the operation mode of the motor (21, 31) during the period when it is in the assist start waiting state waiting for the initial check execution of other control circuits (42A, 51A, 52A) to complete normally. Therefore, the operation mode of the motor recognized by the specific control circuit (41A) does not unintentionally transition to the operation mode of the motor recognized by other control circuits (42A, 51A, 52A) (for example, the single-system drive mode). Thus, each control circuit (41A, 42A, 51A, 52A) starts operating normally. Therefore, the driving of the reaction force motor 21 and the steering motor 31 can be appropriately controlled.

[0099] (1-2) The synchronization process is executed between the first reaction force control circuit 41A and the second reaction force control circuit 42A, between the first steering control circuit 51A and the second steering control circuit 52A, between the first reaction force control circuit 41A and the first steering control circuit 51A, and between the second reaction force control circuit 42A and the second steering control circuit 52A. Therefore, compared with a configuration in which each control circuit (41A, 42A, 51A, 52A) executes the synchronization process with all control circuits except itself, it is possible to simplify the signal path. For example, there is no need to provide communication lines between the first reaction force control circuit 41A and the second steering control circuit 52A, and between the second reaction force control circuit 42A and the first steering control circuit 51A.

[0100] <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 members similar to those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0101] The electric power steering device has the steering wheel 11 and the steered wheels 15 mechanically connected therebetween as shown in FIG. 1 above. That is, the steering shaft 12, the pinion shaft 33, and the steering shaft 13 function as a power transmission path between the steering wheel 11 and the steered wheels 15. As the steering shaft 13 moves linearly as the steering wheel 11 is steered, the steering angle θw of the steered wheels 15 is changed.

[0102] The electric power steering device has an assist motor and an assist control device. The assist motor is provided at the same position as the reaction force motor 21 or the steering motor 31 shown in FIG. 1 above. The assist motor generates an assist force for assisting the operation of the steering wheel 11. The assist force is a torque in the same direction as the steering direction of the steering wheel 11. The assist control device controls the driving of the assist motor which is the control target.

[0103] As shown in FIG. 5, the assist motor 70 has a first system winding group N31 and a second system 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 first system winding group N31. The first assist control circuit 81A generates a drive signal for the motor drive circuit 81B based on the steering torque Th detected through the torque sensor 23.

[0104] The motor drive circuit 81B converts the DC power supplied from the DC power source 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 winding group N31 of the assist motor 70 via the power supply path for each phase consisting of a bus bar or a cable.

[0105] 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 second winding group N32. The second assist control circuit 82A generates a drive signal for the motor drive circuit 82B based on the steering torque Th detected through the torque sensor 23.

[0106] The motor drive circuit 82B converts the DC power supplied from the DC power source 60 into three-phase AC power based on the 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 winding group N32 of the assist motor 70 via the power supply path for each phase consisting of a bus bar or a cable.

[0107] 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 the abnormality information of the first assist control circuit 81A, the second assist control circuit 82A, or the motor drive circuits 81B and 82B. Also, the information 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 with each other.

[0108] The first assist control circuit 81A and the second assist control circuit 82A control the drive of the assist motor in any one of the cooperative drive mode, the independent drive mode, and the single-line drive mode, similar to each control circuit (41A, 42A, 51A, 52A) in the first embodiment. The control status of the first assist control circuit 81A and the second assist control circuit 82A transitions in the same manner as the control status of each control circuit (41A, 42A, 51A, 52A) in the first embodiment. Also, the states of the first assist control circuit 81A and the second assist control circuit 82A transition in the same manner as the states of each control circuit (41A, 42A, 51A, 52A) in the first embodiment.

[0109] When the start switch SW, that is, the vehicle power supply, is turned off while the first assist control circuit 81A and the second assist control circuit 82A are executing normal control to control the assist motor in the cooperative drive mode, they execute power latch control to self-hold the power supply. When the first assist control circuit 81A and the second assist control circuit 82A are executing power latch control, they operate in the same manner as each control circuit (41A, 42A, 51A, 52A) in the first embodiment.

[0110] That is, when the vehicle power supply is turned on, the first assist control circuit 81A and the second assist control circuit 82A do not execute synchronization processing of the operation mode during the period from when each recognizes the turn-on of the vehicle power supply until all control circuits including itself are normally started and the control of the assist motor can be executed.

[0111] When the vehicle power supply is turned on again during the execution period of the power latch control, the first assist control circuit 81A does not execute the operation mode synchronization process if the operation mode of the assist motor recognized by itself is different from the operation mode of the assist motor recognized by the second assist control circuit 82A. When the vehicle power supply is turned on again during the execution period of the power latch control, the second assist control circuit 82A does not execute the operation mode synchronization process if the operation mode of the assist motor recognized by itself is different from the operation mode of the assist motor recognized by the first assist control circuit 81A.

[0112] For example, when the vehicle power supply is turned on during the execution period of the power latch control after the vehicle power supply is turned off with the abnormality of the first assist control circuit 81A being confirmed, the first assist control circuit 81A may be in a state where it can return to normal operation, and moreover, it may recognize that the vehicle power supply has been turned on prior to the second assist control circuit 82A. In this case, the first assist control circuit 81A does not execute the process of synchronizing the operation mode of the assist motor during the period when it is in the assist start waiting state waiting for the normal completion of the execution of the initial check of the second assist control circuit 82A. Therefore, the operation mode of the assist motor recognized by the first assist control circuit 81A does not unintentionally transition to the operation mode of the assist motor recognized by the second assist control circuit 82A (for example, the single-system drive mode). Accordingly, the first assist control circuit 81A and the second assist control circuit 82A start operating normally.

[0113] When the vehicle power supply is turned on during the execution period of the power latch control after the vehicle power supply is turned off with the abnormality of the second assist control circuit 82A being confirmed, the second assist control circuit 82A operates in the same manner as the first assist control circuit 81A described above.

[0114] <Effects of the Second Embodiment> Therefore, according to the second embodiment, the following effects can be obtained. (2-1) When the vehicle power supply is turned on again during the execution period of the power latch control after the vehicle power supply is turned off, the first assist control circuit 81A and the second assist control circuit 82A do not execute the process of synchronizing their own recognized operation mode of the assist motor with the operation mode of the assist motor recognized by other control circuits if they are different. Therefore, the operation mode of the motor recognized by the first assist control circuit 81A does not unintentionally transition to the operation mode of the motor recognized by the second assist control circuit 82A. Also, the operation mode of the motor recognized by the second assist control circuit 82A does not unintentionally transition to the operation mode of the motor recognized by the first assist control circuit 81A. For this reason, the first assist control circuit 81A and the second assist control circuit 82A start operating normally. Therefore, the drive of the assist motor can be appropriately controlled.

[0115] <Other Embodiments> Note that the first and second embodiments may be implemented with the following modifications. · In the first embodiment, the reaction force motor 21 and the steering motor 31 had two sets of winding groups, but they may have one set of winding groups. In this case, the reaction force control device 40 may have only one of the first system circuit 41 and the second system circuit 42. Also, in this case, the steering control device 50 may have only one of the first system circuit 51 and the second system circuit 52. Note that the first reaction force control circuit 41A or the second reaction force control circuit 42A corresponds to the reaction force control circuit. The first steering control circuit 51A or the second steering control circuit 52A corresponds to the steering control circuit.

[0116] · In the first embodiment, the vehicle control device was embodied in a steer-by-wire type steering device, and in the second embodiment, the vehicle control device was embodied in an electric power steering device. However, for example, it may be embodied in an electric door mirror device that opens and closes in conjunction with the door lock. It is possible to embody it in all motor control devices having redundant control circuits and motor drive circuits.

Description of Symbols

[0117] 11…Steering wheel 15…Steering wheel 21…Reaction motor 31…Steering motor 41A…First reaction control circuit 42A…Second reaction control circuit 51A…First steering control circuit 52A…Second steering control circuit 70…Assist motor 81A…First assist control circuit 82A…Second assist control circuit N11…First winding group of reaction motor N12…Second winding group of reaction motor N21…First winding group of steering motor N22…Second winding group of steering motor N31…First winding group of assist motor N32…Second winding group of assist motor

Claims

1. A vehicle control device having a plurality of control circuits that are activated upon activation of a vehicle power source and control a control target in cooperation or in coordination, wherein the plurality of control circuits perform a synchronization process of synchronizing the operation modes of the control target determined according to each other's operation states, and a power latch control of holding the power for a period defined upon turning off of the vehicle power source, and during the period of performing the power latch control, holds the operation mode immediately before the vehicle power source is turned off. When the vehicle power source is turned on, the plurality of control circuits do not perform the synchronization process during the period from when each of them recognizes the turning on of the vehicle power source until all the control circuits including itself are normally activated and reach a state where the control of the control target can be executed.

2. The vehicle control device according to claim 1, wherein the operation mode includes an operation mode when all of the plurality of control circuits are normal and an operation mode when any one of the plurality of control circuits is abnormal.

3. The control target includes a reaction force motor that generates a steering reaction force applied to a steering wheel having two sets of winding groups and with power transmission to the steered wheels separated, and 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 the first set of winding groups of the reaction force motor, a second reaction force control circuit that controls power supply to the second set of winding groups of the reaction force motor, a first steering control circuit that controls power supply to the first set of winding groups of the steering motor, and a second steering control circuit that controls power supply to the second set of winding groups of the steering motor. The vehicle control device according to claim 1 or claim 2.

4. The synchronization process is performed between the first reaction force control circuit and the second reaction force control circuit, between the first steering control circuit and the second steering control circuit, between the first reaction force control circuit and the first steering control circuit, and between the second reaction force control circuit and the second steering control circuit. The vehicle control device according to claim 3.

5. The control target includes a reaction force motor that is a source of the steering reaction force applied to a steering wheel with power transmission to the steered wheels separated, and a steering motor that is a source of the steering force for steering the steered wheels. The plurality of the control circuits includes a reaction force control circuit that controls the reaction force motor and a steering control circuit that controls the steering motor, in the vehicle control device according to claim 1 or claim 2.

6. The control target includes an assist motor that generates an assist force for assisting an operation of a steering wheel. The assist motor has a first winding group and a second winding group. The plurality of the control circuits includes 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, in the vehicle control device according to claim 1 or claim 2.

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