Steering control system

Abstract

To provide a steering control device capable of maintaining traveling stability of a vehicle during stopping processing by a vehicle control device.SOLUTION: A steering control device includes a control unit constituted to control a turning motor for generating torque for turning a turning wheel of a vehicle in which power transmission to a steering wheel is separated. The control unit is constituted to request execution of specified stopping processing for a vehicle control device for controlling traveling of the vehicle when an abnormality occurs at a section for driving the turning motor. The control unit is constituted to execute processing (S105) for suppressing the rotation of the turning motor when it is possible to continue power supply control of the turning motor in the even that the execution of the stopping processing is requested.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Conventionally, steering systems exist that assist the operation of the steering wheel by applying motor torque as an assist force to the steering shaft. The control unit of the steering system calculates a current command value for the motor based on the steering torque detected through a torque sensor. The control unit controls the power supply to the motor based on the current command value. As a result, the motor generates torque corresponding to the steering torque.

[0003] For example, the steering system described in Patent Document 1 stops the motor-assisted steering when it detects an abnormality in itself. However, the steering system includes a differential gear. When an abnormality in the steering system is detected, the differential gear control device provides alternative steering assistance by controlling the differential gear based on the vehicle state. Therefore, even if an abnormality occurs in the steering system, steering assistance can be continued. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2009-166763 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, Patent Document 1 raises the following concerns. Specifically, if a malfunction occurs in the steering system, the steering assistance provided by the motor is stopped. As a result, when alternative steering assistance is performed to adjust the rotational speed difference between the left and right wheels via the differential gear, there is a risk that the steering angle of the steering wheels may change inappropriately as the vehicle moves. Therefore, there is a concern that the vehicle's driving stability may not be maintained while alternative steering assistance is being performed. [Means for solving the problem]

[0006] A steering control device capable of solving the above problems includes a control unit configured to control a steering motor that generates torque for steering the steering wheels of a vehicle, with power transmission separated from the steering wheel. The control unit is configured to request a vehicle control device, which controls the vehicle's movement, to perform a predetermined stopping procedure when an abnormality occurs in the part that drives the steering motor. When the control unit requests the execution of the stopping procedure, and it is possible to continue power supply control of the steering motor, it is configured to perform a procedure to suppress the rotation of the steering motor.

[0007] With this configuration, if an abnormality occurs in the part that drives the steering motor, the rotation of the steering motor is suppressed as long as power supply control to the steering motor can be continued. Therefore, while the vehicle control device is performing a stopping process, the steering position of the steering wheels is prevented from changing inappropriately as the vehicle moves. Consequently, the vehicle's driving stability can be maintained while the stopping process is being performed.

[0008] In the steering control device described above, the stopping process may include a process to change the direction of travel of the vehicle by controlling the distribution of driving force between the left and right wheels through the vehicle's braking device. In this case, the control unit may be configured to wait for the vehicle to be determined to be in a straight-ahead state before executing a process to suppress the rotation of the steering motor when it requests the execution of the stopping process.

[0009] With this configuration, if an abnormality occurs in the part that drives the steering motor, the steering position of the steering wheel is fixed to the neutral steering position as long as power supply control to the steering motor can be continued. Therefore, while the vehicle control device is performing a stopping process, inappropriate changes in the steering position of the steering wheel due to the vehicle's movement are suppressed. In particular, if the stopping process includes a process of changing the direction of travel of the vehicle by controlling the distribution of driving force between the left and right wheels through the vehicle's braking system, changes in yaw moment due to unintended changes in the position of the steering wheel are suppressed. Therefore, the direction of travel of the vehicle can be changed stably through the execution of the stopping process by the vehicle control device.

[0010] In the steering control device described above, the control unit may be configured to set the rotation angle of the steering motor immediately after it is determined that the vehicle is in a straight-ahead state as the target rotation angle of the steering motor when it requests the execution of the stopping process, and to control the drive of the steering motor so as to eliminate the difference between the target rotation angle and the actual rotation angle of the steering motor.

[0011] With this configuration, the rotation angle of the steering motor is maintained at an angle corresponding to the vehicle's straight-ahead state. Therefore, the steering position of the steering wheels can be fixed in the neutral steering position. In the steering control device described above, the control unit may be configured to control the drive of the steering motor using the rotation angle of the steering motor. In this case, when the control unit requests the execution of the stopping process, and the rotation angle of the steering motor cannot be detected, it may calculate an estimated rotation angle of the steering motor based on the induced voltage generated by the steering motor, set the estimated rotation angle immediately after it is determined that the vehicle is in a straight-ahead state as the target rotation angle of the steering motor, and drive the steering motor to eliminate the difference between the target rotation angle and the estimated rotation angle.

[0012] In this configuration, when the rotation angle of the steering motor cannot be detected, the estimated rotation angle of the steering motor, calculated based on the induced voltage generated by the steering motor, is maintained at an angle corresponding to the vehicle's straight-ahead state. Therefore, the steering position of the steering wheels can be fixed to the steering neutral position.

[0013] In the steering control device described above, the control unit may be configured to perform a process to operate the steering motor as a generator if it is unable to continue power supply control to the steering motor when it requests the execution of the stopping process.

[0014] In this configuration, the steering motor acts as a generator, generating a braking force on it. This braking force suppresses the rotation of the steering motor. In the steering control device described above, the steering motor has a first winding group and a second winding group, and the control unit may include a first control unit that independently controls the power supply to the first winding group and a second control unit that independently controls the power supply to the second winding group. In this case, the first control unit and the second control unit may be configured to request the vehicle control device to perform the stopping process when an abnormality occurs in both the first system corresponding to the first winding group and the second system corresponding to the second winding group.

[0015] With this configuration, when it is possible to continue power supply control of the steering motor by at least one of the first system and the second system, a process to suppress the rotation of the steering motor can be executed. [Effects of the Invention]

[0016] According to the steering control device of the present invention, the vehicle's driving stability can be maintained while the vehicle control device is performing a stopping process. [Brief explanation of the drawing]

[0017] [Figure 1] This is a diagram showing the configuration of a steering system on which the first embodiment of the steering control device is installed. [Figure 2] This is a block diagram of the reaction force control device and steering control device according to the first embodiment. [Figure 3] This is a flowchart showing the procedure for motor lock processing according to the first embodiment. [Figure 4] This is a circuit diagram of a brake circuit according to the second embodiment. [Modes for carrying out the invention]

[0018] <First Embodiment> The following describes a first embodiment of the steering control device. <Overall Structure> As shown in Figure 1, the steering control device 1 controls a steer-by-wire type steering system 2. The steering system 2 has a steering mechanism 3 and a steering mechanism 4. The steering mechanism 3 is the part of the mechanism that is steered by the driver via the steering wheel 5. The steering mechanism 4 is the part of the mechanism that steers the steering wheels 6 of the vehicle in response to the steering of the steering wheel 5. The steering control device 1 includes a reaction force control device 1A and a steering control device 1B. The reaction force control device 1A controls the steering mechanism 3. The reaction force control device 1A performs reaction force control. The steering control device 1B controls the steering mechanism 4. The steering control device 1B performs steering control.

[0019] The steering mechanism 3 includes a steering shaft 11, a reaction motor 12, and a reduction gear 13. The steering wheel 5 is rotatably connected to the steering shaft 11. The reaction motor 12 is the source of the steering reaction force applied to the steering shaft 11. The steering reaction force is a force in the opposite direction to the steering direction of the steering wheel 5. The reaction motor 12 is, for example, a three-phase brushless motor. The reduction gear 13 reduces the rotation of the reaction motor 12 and transmits the reduced rotation to the steering shaft 11.

[0020] The steering mechanism 4 includes a pinion shaft 21, a steering shaft 22, and a housing 23. The housing 23 rotatably supports the pinion shaft 21. The housing 23 also reciprocates the steering shaft 22. Power transmission between the steering shaft 22 and the steering wheel 5 is isolated. The pinion shaft 21 is positioned to intersect the steering shaft 22. The pinion teeth 21a of the pinion shaft 21 mesh with the rack teeth 22a of the steering shaft 22. Tie rods 25 are connected to both ends of the steering shaft 22 via rack ends 24, which are ball joints. The ends of the tie rods 25 are connected to knuckles (not shown) to which the steering wheel 6 is assembled.

[0021] The steering mechanism 4 comprises a steering motor 31, a transmission mechanism 32, and a conversion mechanism 33. The steering motor 31 is the source of the steering force applied to the steering shaft 22. The steering force is the force that causes the steering wheel 6 to turn. The steering motor 31 is, for example, a three-phase brushless motor. The transmission mechanism 32 is, for example, a belt drive mechanism. The transmission mechanism 32 transmits the rotation of the steering motor 31 to the conversion mechanism 33. The conversion mechanism 33 is, for example, a ball screw mechanism. The conversion mechanism 33 converts the rotation transmitted via the transmission mechanism 32 into axial motion of the steering shaft 22.

[0022] As the steering shaft 22 moves axially, the steering angle θ of the steering wheel 6 changes. w The pinion teeth 21a of the pinion shaft 21 mesh with the rack teeth 22a of the steering shaft 22, and therefore rotate in conjunction with the movement of the steering shaft 22. The pinion shaft 21 is a shaft or rotating body that rotates in conjunction with the steering action of the steering wheel 6.

[0023] The reaction force control device 1A controls the operation of the reaction force motor 12. The reaction force control device 1A has a processing circuit that includes one of the following three configurations A1, A2, and A3. A1. One or more processors that operate according to a computer program, which is software. A processor includes a CPU (Central Processing Unit) and memory.

[0024] A2. One or more dedicated hardware circuits, such as application-specific integrated circuits (ASICs), that perform at least some of the various processes. An ASIC includes a CPU and memory.

[0025] A3. Hardware circuit combining configurations A1 and A2. Memory is a medium readable by a computer that stores programs describing processes or instructions for the computer. In this embodiment, the computer is the CPU. Memory includes RAM (Random Access Memory) and ROM (Read Only Memory). The CPU performs various controls by executing the programs stored in memory at predetermined calculation cycles.

[0026] The reaction force control device 1A acquires detection results from on-board sensors. The sensors include a vehicle speed sensor 41, a torque sensor 42, and a rotation angle sensor 43. The vehicle speed sensor 41 detects the vehicle speed V. The vehicle speed V is a state variable that reflects the vehicle's driving state. The torque sensor 42 is installed on the steering shaft 11. The torque sensor 42 is located on the steering wheel 5 side of the steering shaft 11 relative to the connection portion of the reduction gear 13. The torque sensor 42 detects the steering torque Th applied to the steering shaft 11. The steering torque Th is calculated based on the amount of twist of the torsion bar 42a installed on the steering shaft 11. The rotation angle sensor 43 is installed on the reaction motor 12. The rotation angle sensor 43 detects the rotation angle θ of the reaction motor 12. a Detects.

[0027] Steering torque Th, and the rotation angle θ of the reaction force motor 12. aFor example, a positive value occurs when steering wheel 5 to the right, and a negative value occurs when steering wheel 5 to the left.

[0028] The reaction force control device 1A controls the operation of the reaction force motor 12 using the detection results of the vehicle speed sensor 41, the torque sensor 42, and the rotation angle sensor 43. The reaction force control device 1A controls the power supply to the reaction force motor 12 so that it generates a steering reaction force corresponding to the steering torque Th.

[0029] The reaction force control device 1A controls the rotation angle θ of the reaction force motor 12 detected through the rotation angle sensor 43. a Based on this, the steering angle θ of the steering wheel 5 s The reaction force control device 1A calculates the reaction force command value based on the steering torque Th and vehicle speed V. The reaction force command value is the target value of the steering reaction force that should be generated by the reaction force motor 12. The steering reaction force is the torque in the opposite direction to the steering direction of the steering wheel 5. The larger the absolute value of the steering torque Th and the slower the vehicle speed V, the larger the absolute value of the reaction force command value becomes.

[0030] The reaction force control device 1A supplies power to the reaction force motor 12 according to the reaction force torque command value. Based on the reaction force torque command value, the reaction force control device 1A calculates the current command value for the reaction force motor 12. The reaction force control device 1A detects the current supplied to the reaction force motor 12 through a current sensor installed in the power supply path to the reaction force motor 12. The reaction force control device 1A determines the deviation between the current command value and the current value of the reaction force motor 12, and controls the power supply to the reaction force motor 12 to eliminate this deviation. As a result, the reaction force motor 12 generates torque according to the reaction force torque command value.

[0031] The steering control device 1B controls the operation of the steering motor 31. Similar to the reaction force control device 1A, the steering control device 1B has a processing circuit that includes one of the three configurations A1, A2, and A3 mentioned above.

[0032] The steering control device 1B acquires detection results from on-board sensors. The sensors include a vehicle speed sensor 41 and a rotation angle sensor 44. The rotation angle sensor 44 is located on the steering motor 31. The rotation angle sensor 44 detects the rotation angle θ of the steering motor 31. b The rotation angle θ of the steering motor 31 is detected. b For example, a positive value occurs when steering wheel 5 to the right, and a negative value occurs when steering wheel 5 to the left.

[0033] The steering control device 1B controls the operation of the steering motor 31 using the detection results of the vehicle speed sensor 41 and the rotation angle sensor 44. The steering control device 1B controls the power supply to the steering motor 31 so that the steering wheels 6 are steered according to the steering state of the steering wheel 5.

[0034] The steering control device 1B can communicate with the on-board vehicle control device 50. The steering control device 1B and the vehicle control device 50 are interconnected via an on-board network 51. The on-board network 51 is, for example, a CAN (Controller Area Network). The steering control device 1B and the vehicle control device 50 exchange information with each other via the on-board network 51. Incidentally, the reaction force control device 1A can also communicate with the vehicle control device 50 via the on-board network 51, similar to the steering control device 1B.

[0035] The vehicle control device 50 controls the vehicle's braking system 52. The braking system 52 generates a braking force to decelerate or stop the vehicle in accordance with the amount the brake pedal is pressed. The braking system 52 includes an electric parking brake (EPB). The electric parking brake is used to lock the wheels when the vehicle is parked or stopped. The electric parking brake is operated by a built-in motor. The braking system 52 is provided on each wheel of the vehicle. The vehicle is, for example, a four-wheeled automobile.

[0036] Furthermore, the vehicle control device 50 controls the movement of the vehicle. The vehicle control device 50 also controls the vehicle's powertrain. The powertrain includes a drive source for the vehicle and a power transmission mechanism. The drive source is, for example, an engine or a motor. The power transmission mechanism is a mechanism for transmitting the power generated by the drive source to the drive wheels.

[0037] The steering control device 1B generates a stop request signal to the vehicle control device 50 when an abnormality occurs, for example, that makes it difficult to steer the steering wheels 6. The stop request signal is an electrical signal that requests the vehicle control device 50 to perform a predetermined stopping process to safely stop the vehicle. The stopping process includes a process to automatically stop the vehicle within the lane. The stopping process also includes an automatic evacuation process that pulls the vehicle over to a safe place such as the shoulder of the road and stops it automatically, regardless of the driver's driving state. The vehicle control device 50 can recognize the surrounding environment of the vehicle through on-board cameras and sensors.

[0038] When a stop request signal is received, the vehicle control device 50 performs a predetermined stopping process. For example, the vehicle control device 50 moves the vehicle to a safe place such as the shoulder of the road by performing torque vectoring control. Torque vectoring control is a control that changes the direction of travel of the vehicle by controlling the distribution of driving force to the left and right wheels through the braking device 52. Through the control of the braking device 52, the vehicle control device 50 applies different amounts of driving force to the left and right wheels, generating a force that turns the vehicle due to the difference in driving force between the left and right sides. The vehicle control device 50 controls the braking device 52 so that the vehicle gradually decelerates and stops in a safe place such as the shoulder of the road. Through the execution of the stopping process, the vehicle comes to a safe stop.

[0039] <Configuration of steering motor 31 and steering control device 1B> Next, the configuration of the steering motor 31 and the steering control device 1B will be described in detail. As shown in FIG. 2, the steering motor 31 has a rotor 31A, a first winding group 31B wound around a stator (not shown), and a second winding group 31C. The first winding group 31B has a U-phase coil, a V-phase coil, and a W-phase coil. The second winding group 31C also has a U-phase coil, a V-phase coil, and a W-phase coil. The rotation angle sensor 44 includes a first rotation angle sensor 44A and a second rotation angle sensor 44B. The first rotation angle sensor 44A detects the first rotation angle θ b1 of the steering motor 31. The second rotation angle sensor 44B detects the second rotation angle θ b2 of the steering motor 31. The first rotation angle θ b1 , and the second rotation angle θ b2 are also the rotation angles of the rotor 31A.

[0040] The steering control device 1B controls the power supply to the first winding group 31B and the second winding group 31C for each system. The steering control device 1B has a first control unit 60 and a second control unit 70. The first control unit 60 controls the power supply to the first winding group 31B. The second control unit 70 controls the power supply to the second winding group 31C.

[0041] The first control unit 60 has a first drive circuit 61 and a first control circuit 63. Power is supplied to the first drive circuit 61 from a DC power source 81 such as a vehicle-mounted battery. The plus terminal of the first drive circuit 61 and the DC power source 81 is connected by a first power supply line 82. The minus terminal of the DC power source 81 is connected to the ground. A power switch 83 is provided in the first power supply line 82. The power switch 83 is an ignition switch or a power switch. The power switch 83 is operated when starting the driving source for vehicle running. The driving source for vehicle running is an engine or a driving motor for running. When the power switch 83 is turned on, the power of the DC power source 81 is supplied to the first drive circuit 61 via the first power supply line 82. A voltage sensor 65 is provided in the first power supply line 82. The voltage sensor 65 detects the voltage V b1 of the DC power source 81.

[0042] Furthermore, when the power switch 83 is turned on, the first control circuit 63 and the first rotation angle sensor 44A are supplied with power from a DC power supply 81 via a power supply line (not shown). The first drive circuit 61 is a PWM (Pulse Width Modulation) inverter. The first drive circuit 61 has three legs corresponding to each of the three phases (U, V, W). Each leg has two switching elements connected in series. The switching elements are, for example, FETs (Field Effect Transistors). The three legs are connected in parallel. The first drive circuit 61 receives a command signal S generated by the first control circuit 63. c1 Based on this, the switching elements of each phase of the three-phase system perform switching operations, converting the DC power supplied from the DC power supply 81 into three-phase AC power. The three-phase AC power generated by the first drive circuit 61 is supplied to the first winding group 31B via the power supply paths 84 for each phase of the three-phase system, which consist of busbars or cables.

[0043] The power supply path 84 is provided with a first current sensor 66, a first voltage sensor 67, and a first motor relay group 68. The first current sensor 66 measures the current I of each three phase supplied from the first drive circuit 61 to the first winding group 31B. m1 The first voltage sensor 67 detects the output terminal voltage of each phase of the three-phase in the first drive circuit 61, in other words, the terminal voltage V of each phase of the three-phase in the first winding group 31B. m1 The first motor relay group 68 includes a U-phase relay, a V-phase relay, and a W-phase relay. Each relay is normally kept in the ON state. If an abnormality such as an open circuit fault or a short circuit occurs in the first drive circuit 61, each relay is switched from the ON state to the OFF state. When each relay is turned OFF, the power supply path 84 between the first drive circuit 61 and the first winding group 31B is interrupted, thereby interrupting the power supply from the first drive circuit 61 to the first winding group 31B. Note that the U-phase relay, V-phase relay, and W-phase relay may be FETs.

[0044] The first control circuit 63 detects the first rotation angle θ of the steering motor 31 through the first rotation angle sensor 44A. b1 Based on this, the pinion angle θ p The calculation is performed. Pinion angle θ p This is the rotation angle of the pinion shaft 21, and corresponds to the actual angle of the pinion shaft 21. The steering motor 31 and the pinion shaft 21 are linked via the transmission mechanism 32, the conversion mechanism 33, and the steering shaft 22. Therefore, the first rotation angle θ of the steering motor 31 b1 and pinion angle θ p There is a correlation between the two. This correlation is used to determine the first rotation angle θ of the steering motor 31. b1 From the pinion angle θ p The pinion shaft 21 is meshed with the steering shaft 22. Therefore, the pinion angle θ can be determined. p There is also a correlation between this and the amount of movement of the steering shaft 22. That is, the pinion angle θ p The steering angle θ of the steering wheel 6. w This value reflects the situation.

[0045] The first control circuit 63 controls the steering angle θ calculated by the reaction force control device 1A. s The first control circuit 63 takes in the steering angle θ. s The target pinion angle is calculated based on the following: The target pinion angle is the pinion angle θ. p This is the target angle. The first control circuit 63 calculates the target pinion angle so that the steering angle ratio set according to the product specifications is achieved. The steering angle ratio is the steering angle θ s The steering angle θ relative to this angle w It is the ratio of .

[0046] The first control circuit 63 sets the steering angle ratio according to the vehicle's driving conditions, such as the vehicle speed V, and calculates the target pinion angle according to this set steering angle ratio. The first control circuit 63 adjusts the steering angle θ as the vehicle speed V increases. s The steering angle θ relative to this angle w The target pinion angle is calculated so that the value becomes small. The first control circuit 63 calculates the steering angle θ in order to achieve the steering angle ratio set according to the vehicle's driving state.s The correction angle is calculated for the steering angle θ, and this calculated correction angle is used as the steering angle θ. s By adding this to the rudder angle ratio, the target pinion angle corresponding to the rudder angle ratio is calculated.

[0047] The first control circuit 63 controls the pinion angle θ p The pinion angle θ is set so that it follows the target pinion angle. p The steering torque command value is calculated through feedback control. The steering torque command value is the target value of the torque generated by the steering motor 31. The first control circuit 63 calculates a first current command value for the steering motor 31 based on the steering torque command value. However, the absolute value of the first current command value is set to half (50%) of the amount of current (100%) required to generate the torque in the steering motor 31 according to the steering torque command value.

[0048] The first control circuit 63 supplies current I to the first winding group 31B through the first current sensor 66. m1 The value of is detected. The first control circuit 63 supplies current I to the first winding group 31B. m1 By performing current feedback control to make the value of follow the first current command value, the command signal S to the first drive circuit 61 is transmitted. c1 Generates command signal S. c1 This is a PWM signal. Command signal S c1 This specifies the duty cycle of each switching element in the first drive circuit 61. The duty cycle is the ratio of the on-time of the switching element to the pulse period.

[0049] The first control circuit 63 detects the first rotation angle θ of the steering motor 31 through the first rotation angle sensor 44A. b1 The power supply to the first winding group 31B is controlled using the command signal S via the first drive circuit 61. c1 When a current corresponding to the first winding group 31B is supplied to the first winding group 31B, the first winding group 31B generates a torque corresponding to the first current command value. The torque is equal to half of the steering torque command value.

[0050] The second control unit 70 has basically the same configuration as the first control unit 60. That is, the second control unit 70 has a second drive circuit 71 and a second control circuit 73. The second drive circuit 71 is also supplied with power from the DC power supply 81. In the first power supply line 82, there is a connection point P between the power switch 83 and the first control unit 60. b A connection point P is provided. b The second drive circuit 71 is connected to the DC power supply 81 by a second power supply line 85. When the power switch 83 is turned on, power from the DC power supply 81 is supplied to the second drive circuit 71 via the second power supply line 85. A voltage sensor 75 is provided on the second power supply line 85. The voltage sensor 75 detects the voltage V of the DC power supply 81. b2 Detects.

[0051] Furthermore, when the power switch 83 is turned on, the second control circuit 73 and the second rotation angle sensor 44B are supplied with power from a DC power supply 81 via a power supply line (not shown). The second drive circuit 71 is a PWM inverter having the same configuration as the first drive circuit 61. The second drive circuit 71 receives the command signal S generated by the second control circuit 73. c2 Based on this, the switching elements of each phase of the three-phase system perform switching operations, converting the DC power supplied from the DC power supply 81 into three-phase AC power. The three-phase AC power generated by the second drive circuit 71 is supplied to the second winding group 31C via the power supply paths 86 for each phase, which consist of busbars or cables.

[0052] The power supply path 86 is provided with a second current sensor 76, a second voltage sensor 77, and a second motor relay group 78. The second current sensor 76 receives the current I supplied from the second drive circuit 71 to the second winding group 31C. m2 The second voltage sensor 77 detects the output terminal voltage of each phase of the three-phase in the second drive circuit 71, in other words, the terminal voltage V of each phase of the three-phase in the second winding group 31C. m2The second motor relay group 78 includes a U-phase relay, a V-phase relay, and a W-phase relay. Each relay is normally kept in the ON state. If an abnormality such as an open circuit fault or a short circuit occurs in the second drive circuit 71, each relay is switched from the ON state to the OFF state. When each relay is turned OFF, the power supply path 86 between the second drive circuit 71 and the second winding group 31C is interrupted, thereby interrupting the power supply from the second drive circuit 71 to the second winding group 31C. Note that the U-phase relay, V-phase relay, and W-phase relay may be FETs.

[0053] The second control circuit 73 basically has the same calculation function as the first control circuit 63. The second control circuit 73 detects the second rotation angle θ of the steering motor 31 through the second rotation angle sensor 44B. b2 Based on this, the pinion angle θ p The second control circuit 73 calculates the steering angle θ calculated by the reaction force control device 1A. s The second control circuit 73 takes in the steering angle θ. s The target pinion angle is calculated based on this.

[0054] The second control circuit 73 sets the steering angle ratio according to the vehicle's driving conditions, such as the vehicle speed V, and calculates the target pinion angle according to this set steering angle ratio. The second control circuit 73 adjusts the steering angle θ as the vehicle speed V increases. s The steering angle θ relative to this angle w The target pinion angle is calculated so that the value becomes small. The second control circuit 73 controls the steering angle θ in order to achieve the steering angle ratio set according to the vehicle's driving state. s The correction angle is calculated for the steering angle θ, and this calculated correction angle is used as the steering angle θ. s By adding this to the rudder angle ratio, the target pinion angle corresponding to the rudder angle ratio is calculated.

[0055] The second control circuit 73 controls the pinion angle θ p The pinion angle θ is set so that it follows the target pinion angle. pThe steering torque command value is calculated through feedback control. The second control circuit 73 calculates a second current command value for the steering motor 31 based on the steering torque command value. However, the absolute value of the second current command value is set to half (50%) of the amount of current (100%) required to generate torque in the steering motor 31 according to the steering torque command value.

[0056] The second control circuit 73 supplies current I to the second winding group 31C through the second current sensor 76. m2 The value of is detected. The second control circuit 73 supplies current I to the second winding group 31C. m2 By performing current feedback control to make the value of follow the second current command value, the command signal S to the second drive circuit 71 is controlled. c2 Generates command signal S. c2 This is a PWM signal. Command signal S c2 This specifies the duty cycle of each switching element in the second drive circuit 71.

[0057] The second control circuit 73 controls the second rotation angle θ of the steering motor 31, which is detected through the second rotation angle sensor 44B. b2 The power supply to the second winding group 31C is controlled using the command signal S via the second drive circuit 71. c2 A current corresponding to the second winding group 31C is supplied to the second winding group 31C, causing the second winding group 31C to generate a torque corresponding to the second current command value. The torque is equal to half of the steering torque command value.

[0058] The sum of the torque generated by the first winding group 31B and the torque generated by the second winding group 31C equals the torque corresponding to the steering torque command value. In other words, the steering motor 31 generates torque corresponding to the steering torque command value.

[0059] <Anomaly detection function> The first control circuit 63 and the second control circuit 73 have the function of detecting abnormalities in themselves and the systems to which they belong. Furthermore, the first control circuit 63 and the second control circuit 73 can exchange information with each other via a communication line. This information includes the calculation results of the first control circuit 63, the calculation results of the second control circuit 73, and the abnormality detection results.

[0060] The first control circuit 63 receives a first status signal S indicating the state of the first system to which it belongs. d1 A first state signal S is generated. d1 This is transmitted to the second control circuit 73. First status signal S d1 This includes information indicating the abnormal condition of the first system and the steering control status. The first system is the system corresponding to the first winding group 31B.

[0061] An abnormal condition includes whether or not there is an abnormality in the components for driving the steering motor 31 in the first system. The components for driving the steering motor 31 include, for example, whether or not there is an abnormality in the first winding group 31B, the first control circuit 63, the first drive circuit 61, the first motor relay group 68, and the first rotation angle sensor 44A.

[0062] The steering control state includes a first control state and a second control state. The first control state is a state in which the first control circuit 63 can perform steering control. The first control state includes two states: during steering control and waiting for the start of steering control. The second control state is a state in which the first control circuit 63 cannot perform steering control, for example, due to a drop in power supply voltage.

[0063] The second control circuit 73, like the first control circuit 63, provides a second status signal S indicating the state of the second system to which it belongs. d2 This generates a second state signal S. d2 The second status signal S is supplied to the first control circuit 63. d2 This includes information indicating the abnormal condition of the second system and the steering control status. The second system is the system corresponding to the second winding group 31C.

[0064] An abnormal condition includes whether or not there is an abnormality in the components for driving the steering motor 31 in the second system. The components for driving the steering motor 31 include, for example, whether or not there is an abnormality in the first winding group 31B, the second control circuit 73, the second drive circuit 71, the second motor relay group 78, and the second rotation angle sensor 44B.

[0065] The steering control state includes a first control state and a second control state. The first control state is a state in which the second control circuit 73 can perform steering control. The first control state includes two states: during steering control and waiting for steering control to start. The second control state is a state in which the second control circuit 73 cannot perform steering control, for example, due to a drop in power supply voltage.

[0066] The first control circuit 63 receives a first status signal S, which includes information indicating that the first system is functioning normally and capable of performing steering control by the first system. d1 A first state signal S is generated. d1 This is transmitted to the second control circuit 73. The second control circuit 73 receives a second status signal S, which includes information indicating that the second system is functioning correctly and is in a state where steering control can be performed by the second system. d2 This generates a second state signal S. d2 This is transmitted to the first control circuit 63.

[0067] The first control circuit 63 and the second control circuit 73 receive the first status signal S d1 and the second status signal S d2 Through the exchange of signals, they recognize each other as being in a normal state. The first control circuit 63 controls the power supply to the first winding group 31B, and the second control circuit 73 controls the power supply to the second winding group 31C. In other words, the method of driving the steering motor 31 by the steering control device 1B is a two-system drive that performs power supply control for two winding groups.

[0068] The first control circuit 63 performs a predetermined fail-safe control when the first system is abnormal and steering control cannot be performed by the first system. As a fail-safe control, the first control circuit 63 stops the execution of steering control by the first system, i.e., power supply control to the first winding group 31B. The first control circuit 63 also receives a first status signal S which contains information indicating that an abnormality has been detected in the first system. d1 A first state signal S is generated. d1 This is sent to the second control circuit 73.

[0069] The second control circuit 73 receives the first state signal S d1 If the steering control device 1B detects that steering control by the first system cannot be performed, and the second system is functioning correctly, it will perform steering control by the second system. In this case, power is supplied only to the second winding group 31C, which is the functioning system. That is, the driving method of the steering motor 31 by the steering control device 1B switches from a two-system drive that performs power supply control to two winding groups to a one-system drive that performs power supply control to only one winding group.

[0070] The second control circuit 73 performs a predetermined fail-safe control when the second system is abnormal and steering control cannot be performed by the second system. As a fail-safe control, the second control circuit 73 stops the execution of steering control by the second system, i.e., power supply control to the second winding group 31C. The second control circuit 73 also receives a second status signal S which contains information indicating that an abnormality has been detected in the second system. d2 This generates a second state signal S. d2 This is transmitted to the first control circuit 63.

[0071] The first control circuit 63 receives the second state signal S d2If the steering control device 1B detects that steering control by the second system cannot be performed, and the first system is functioning normally, it will perform steering control by the first system. In this case, power is supplied only to the first winding group 31B, which is the normal system. That is, the driving method of the steering motor 31 by the steering control device 1B switches from a two-system drive that performs power supply control to two winding groups to a one-system drive that performs power supply control to only one winding group.

[0072] In this way, by independently controlling the power supply to the two winding groups in the steering motor 31, even if a malfunction occurs in one system, the steering motor 31 can be driven by the power supply to the winding group of the other system.

[0073] <If a malfunction occurs in two systems> However, if one system is performing single-system drive, it is possible that an abnormality may occur in the other system, which is functioning normally. In this case, the control circuit of the other system will, as a fail-safe measure, stop the steering control by the other system, that is, the power supply control to the winding group of the other system. As a result, it will become impossible to drive the steering motor 31, and consequently, to steer the steering wheels 6.

[0074] The first control circuit 63 and the second control circuit 73 receive the first status signal S d1 and the second status signal S d2 Through the exchange of signals, it is recognized that both the first and second systems are abnormal. At this time, the first control circuit 63 or the second control circuit 73 sends a stop request signal S to the vehicle control device 50. stp This generates a stop request signal S. In this embodiment, the first control circuit 63 generates a stop request signal S. stp Generates.

[0075] The vehicle control device 50 receives a stop request signal S stp When the signal is received, the predetermined stopping procedure is executed. The vehicle control device 50 controls the braking device 52, for example, so that the vehicle gradually decelerates and comes to a safe place such as the shoulder of the road.

[0076] However, during the execution of the parking process by the vehicle control device 50, there are the following concerns. That is, when an abnormality occurs in both the first system and the second system, the drive of the steering motor 31 stops. Since the torque of the steering motor 31 is not applied to the steering shaft 22, the steering angle θ w of the steering wheel 6 may change inappropriately as the vehicle travels. Therefore, during the execution of the parking process, there is a concern that the running stability of the vehicle cannot be maintained.

[0077] Therefore, in the present embodiment, the steering control device 1B is configured to execute the following process. The process is executed契机 when the vehicle power supply is turned on. <Motor Locking Process> As shown in the flowchart of FIG. 3, when the first control circuit 63 detects that an abnormality has occurred in both the first system and the second system (step S101), a parking request signal S stp is generated for the vehicle control device 50. Further, when the first control circuit 63 detects that an abnormality has occurred in both the first system and the second system, the process of step S102 is executed. The first control circuit 63 detects an abnormality in the second system based on the second state signal S d2 generated by the second control circuit 73.

[0078] In step S102, the first control circuit 63 determines whether it is possible to lock the steering motor 31 based on the content of the abnormalities that have occurred in the first system and the second system. Locking the steering motor 31 means controlling the steering motor 31 so that its rotational position does not change from the current position.

[0079] The first control circuit 63 determines that it is possible to lock the steering motor 31 when it is possible to continue the power supply control of the steering motor 31 by the first system. When the first control circuit 63 determines, for example, that the voltage applied to the first drive circuit 61 and the first winding group 31B is normal, it can determine that the power supply control of the steering motor 31 can be continued by the first system. The first control circuit 63 determines, for example, that the voltage applied to the first drive circuit 61 is normal when the value of the voltage V b1 of the DC power supply 81 detected through the voltage sensor 65 is greater than the power supply voltage threshold value. The first control circuit 63 determines that the voltage applied to the first winding group 31B is normal when the value of the terminal voltage V m1 of the first winding group 31B detected through the first voltage sensor 67 is greater than the terminal voltage threshold value.

[0080] When the first control circuit 63 determines that it is possible to lock the steering motor 31 (YES in step S102), the process proceeds to step S103. In step S103, the first control circuit 63 determines whether the pinion angle θ p can be detected.

[0081] The first control circuit 63 detects abnormalities in the first rotation angle sensor 44A and the second rotation angle sensor 44B based on, for example, the first rotation angle θ b1 detected through the first rotation angle sensor 44A and the second rotation angle θ b2 detected through the second rotation angle sensor 44B. The first control circuit 63 determines that the first rotation angle sensor 44A is abnormal, for example, when the absolute value of the difference between the current value and the previous value of the first rotation angle θ b1 deviates from the determined allowable range. The first control circuit 63 determines that the second rotation angle sensor 44B is abnormal, for example, when the absolute value of the difference between the current value and the previous value of the second rotation angle θ b2 deviates from the determined allowable range. The allowable range is set in consideration of the operation cycle of the first control circuit 63 or the detection tolerance of the first rotation angle sensor 44A and the second rotation angle sensor 44B.

[0082] The first control circuit 63, when at least one of the first rotation angle sensor 44A and the second rotation angle sensor 44B is functioning normally, determines the pinion angle θ p It is determined that it is detectable. The first control circuit 63 controls the pinion angle θ p When it is determined that the vehicle is detectable (YES in S103), the process proceeds to step S104. In step S104, the first control circuit 63 determines whether the vehicle is moving straight.

[0083] The first control circuit 63 determines, for example, that the vehicle is moving straight when the following equation (1) is true. θ p <θ pth …(1) However, "θ" p " is the first rotation angle θ of the steering motor 31 b1 The pinion angle θ is calculated based on this. p , and the second rotation angle θ of the steering motor 31 b2 The pinion angle θ is calculated based on this. p It is at least one of the following: "θ pth " is the pinion angle threshold θ pth The pinion angle threshold θ is... pth This is the pinion angle θ when the vehicle is traveling in a straight line. p It is set based on the pinion angle threshold θ. pth This is the criterion for determining whether a vehicle is moving straight.

[0084] The first control circuit 63 waits for it to determine that the vehicle is moving straight (NO in step S104). When the first control circuit 63 determines that the vehicle is moving straight (YES in step S104), it proceeds to step S105. In step S105, the first control circuit 63 performs a motor lock process. The motor lock process is a process to suppress the rotation of the steering motor 31.

[0085] The first control circuit 63 controls, for example, the rotation angle θ of the steering motor 31 immediately after it is determined in step S104 that the vehicle is moving straight.b This is set as the target rotation angle of the steering motor 31. Rotation angle θ of the steering motor 31 b This is the first rotation angle θ of the steering motor 31 detected through the first rotation angle sensor 44A. b1 , or the second rotation angle θ of the steering motor 31 detected through the second rotation angle sensor 44B b2 That is the case.

[0086] In step S103, when the first rotation angle sensor 44A is determined to be normal, the first control circuit 63 determines the first rotation angle θ b1 The first control circuit 63 uses the second rotation angle θ when, in the previous step S103, it is determined that the first rotation angle sensor 44A is abnormal, while the second rotation angle sensor 44B of the second system is normal. b2 The second rotation angle θ that is incorporated is then taken into account. b2 Use this.

[0087] The first control circuit 63 calculates the difference between the target rotation angle and the actual rotation angle of the steering motor 31, and drives the steering motor 31 so that the calculated difference becomes 0 (zero). In other words, when the rotation position of the steering motor 31 changes due to the steering action of the steering wheel 6 caused by an external force, the first control circuit 63 controls the steering motor 31 so that the actual rotation angle of the steering motor 31 returns to the target rotation angle. The target rotation angle is the angle corresponding to the straight-ahead state of the vehicle. Therefore, by fixing the rotation position of the steering motor 31 to the target rotation angle, the steering position of the steering wheel 6 is fixed to the steering neutral position or near the steering neutral position. The steering neutral position is the steering position of the steering wheel 6 corresponding to the straight-ahead state of the vehicle.

[0088] Furthermore, the first control circuit 63 is determined to be unable to lock the steering motor 31 in step S102 (NO in step S102), and in step S103, the pinion angle θ p If it is determined that the steering motor cannot be detected (NO in S103), the steering motor 31 is stopped. The stopping process is a process to stop the power supply to the steering motor 31.

[0089] The second control circuit 73 executes each process in the flowchart of Figure 3, similar to the first control circuit 63. The second control circuit 73 executes the motor lock process when all three of the following conditions C1 to C3 are met.

[0090] C1. The steering motor 31 can be locked (YES in step S102). C2. Pinion angle θ p It must be detectable (YES in S103). C3. The vehicle is moving straight ahead (YES in step S104).

[0091] The second control circuit 73 determines that the steering motor 31 can be locked when it is possible to continue power supply control of the steering motor 31 by the second system. The first control circuit 63 determines that it is possible to continue power supply control of the steering motor 31 by the second system when, for example, the voltage applied to the second drive circuit 71 and the second winding group 31C is normal. The second control circuit 73 determines, for example, the voltage V of the DC power supply 81 detected through the voltage sensor 75. b2 When the value of is greater than the power supply voltage threshold, it is determined that the voltage applied to the second drive circuit 71 is normal. The second control circuit 73 detects the terminal voltage V of the second winding group 31C through the second voltage sensor 77. m2 When the value of is greater than the terminal voltage threshold, it is determined that the voltage applied to the second winding group 31C is normal.

[0092] The second control circuit 73 executes a stop process for the steering motor 31 when neither of the above conditions C1 or C2 is met. Therefore, even while the vehicle control device 50 is performing a stopping process, if it is possible to continue power supply control of the steering motor 31 by at least one of the first system and the second system, the steering position of the steering wheel 6 is fixed to the steering neutral position or near the steering neutral position through the drive control of the steering motor 31.

[0093] <Effects of the First Embodiment> The first embodiment provides the following effects: (1-1) If an abnormality occurs simultaneously in the first and second systems, and power supply control of the steering motor 31 can be continued, the steering position of the steering wheel 6 is fixed at the neutral steering position or near the neutral steering position. Therefore, while the vehicle control device 50 is performing the stopping process, the steering angle θ of the steering wheel 6 changes as the vehicle moves. w This prevents inappropriate changes from occurring. Therefore, the vehicle's driving stability can be maintained while the stopping process is being executed.

[0094] For example, when the vehicle control device 50 generates a yaw moment in the vehicle to move it to a safe place such as the shoulder of the road through the execution of torque vectoring control, an unintended steering angle θ may occur. w The change in yaw moment caused by this change is suppressed. As a result, the vehicle can be appropriately moved to a safe place such as the shoulder of the road.

[0095] (1-2) If an abnormality occurs simultaneously in the first and second systems, and power supply control of the steering motor 31 can be continued, the rotation angle θ of the steering motor 31 immediately after it is determined that the vehicle is moving straight. b This is set as the target rotation angle of the steering motor 31. The target rotation angle and the actual rotation angle θ of the steering motor 31 b The steering motor 31 is controlled to eliminate the difference. Therefore, the rotation angle θ of the steering motor 31 b However, it is maintained at an angle corresponding to the vehicle's straight-ahead state. Therefore, the steering position of the steering wheel 6 can be fixed to the steering neutral position. Rotation angle θ b is the first rotation angle θ b1 and the second rotation angle θ b2 Includes.

[0096] (1-3) The steering motor 31 has a first winding group 31B and a second winding group 31C. The steering control device 1B includes a first control unit 60 that independently controls the power supply to the first winding group 31B and a second control unit 70 that independently controls the power supply to the second winding group 31C. When an abnormality occurs in both the first system corresponding to the first winding group 31B and the second system corresponding to the second winding group 31C, the first control unit 60 and the second control unit 70 request the vehicle control device 50 to perform a stop process. Therefore, when it is possible to continue power supply control of the steering motor 31 by at least one of the first system and the second system, a process to suppress the rotation of the steering motor 31 can be performed.

[0097] <Second Embodiment> Next, a second embodiment of the steering control device will be described. This embodiment basically has the same configuration as the first embodiment shown in Figures 1 and 2. For this reason, the same reference numerals are used for the same components and components as in the first embodiment, and their detailed descriptions are omitted. This embodiment differs from the first embodiment in terms of the configuration of the steering control device 1B and the procedure for motor lock processing.

[0098] The steering control device 1B has a so-called electric braking function. The electric braking function is a braking function that operates the steering motor 31 as a generator. That is, the steering motor 31 is braked by converting the kinetic energy of the steering motor 31 into electrical energy and consuming the converted electrical energy. The electrical energy is consumed, for example, by releasing it to the ground.

[0099] As shown in Figure 4, the first control unit 60 has a first brake circuit 90A. The first brake circuit 90A is provided, for example, downstream of the first motor relay group 68 in the power supply path 84 for each of the three phases. The first brake circuit 90A has a first FET 91U, a second FET 91V, a third FET 91W, and a diode 92 for preventing reverse current.

[0100] The drain terminal of the first FET91U is connected to the power supply path of the U-phase among the power supply paths 84 for each of the three phases. The source terminal of the first FET91U is connected to ground GND. The gate terminal of the first FET91U is connected to the cathode of diode 92. The anode of diode 92 is connected to the first control circuit 63.

[0101] The drain terminal of the second FET 91V is connected to the V-phase power supply path of the three-phase power supply path 84. The source terminal of the second FET 91V is connected to ground GND. The gate terminal of the second FET 91V is connected to the cathode of diode 92.

[0102] The drain terminal of the third FET 91W is connected to the power supply path of the W phase among the power supply paths 84 for each phase of the three phases. The source terminal of the third FET 91W is connected to ground GND. The gate terminal of the third FET 91W is connected to the cathode of diode 92.

[0103] When the first control circuit 63 performs the electric braking function, it first stops the power supply to the steering motor 31. The first control circuit 63 stops the power supply to the steering motor 31 by, for example, turning off each switching element of the first drive circuit 61 or turning off the first motor relay group 68. If the steering motor 31 is rotating, it will continue to rotate due to inertia even if the power supply to the steering motor 31 is stopped. The U-phase coil, V-phase coil, and W-phase coil do not stop immediately because there is still generated charge remaining in them.

[0104] Subsequently, the first control circuit 63 applies voltage to the gate terminals of the first FET 91U, the second FET 91V, and the third FET 91W. When the first FET 91U, the second FET 91V, and the third FET 91W are turned on, the coil terminals of each phase of the three-phase system are short-circuited to ground (GND). As a result, any remaining charge in the coils of each phase of the three-phase system is discharged to ground (GND). With the remaining charge in the coils of each phase of the three-phase system gone, a braking force is generated in the steering motor 31. This braking force suppresses the rotation of the steering motor 31.

[0105] As indicated by the reference numerals in parentheses in Figure 3, the second control unit 70 has a second brake circuit 90B. The second brake circuit 90B is provided, for example, downstream of the second motor relay group 78 in the power supply path 86 for each phase of the three-phase system. The second brake circuit 90B has the same configuration as the first brake circuit 90A. The second control circuit 73 performs the electric brake function in the same procedure as the first control circuit 63.

[0106] <Motor locking process> Next, we will explain the procedure for motor lock processing. The first control circuit 63 basically executes each process shown in the flowchart of Figure 3. However, if the first control circuit 63 determines in step S102 that it cannot lock the steering motor 31 (NO in S102), it proceeds to step S103 instead of step S106.

[0107] In step S103, the first control circuit 63 controls the pinion angle θ p When it is determined that the vehicle is detectable (YES in step S103), the process proceeds to step S104. In step S104, the first control circuit 63 determines that the vehicle is moving straight (YES in step S104), and proceeds to step S105. In step S105, the first control circuit 63 performs motor lock processing.

[0108] The first control circuit 63 performs the aforementioned electric braking function as a motor lock process. Specifically, the first control circuit 63 first stops the power supply to the steering motor 31. After this, the first control circuit 63 turns on the first FET 91U, the second FET 91V, and the third FET 91W. By short-circuiting the coil terminals of each of the three phases to ground GND, a braking force is generated in the steering motor 31. This braking force suppresses the rotation of the steering motor 31, and consequently, the steering operation of the steering wheels 6.

[0109] The second control circuit 73 performs motor lock processing in the same procedure as the first control circuit 63. <Effects of the second embodiment> The second embodiment provides the following effects.

[0110] (2-1) If an abnormality occurs simultaneously in the first and second systems, and it is not possible to continue power supply control of the steering motor 31, an electric brake function is executed to generate braking force on the steering motor 31. The steering position of the steering wheels 6 is less likely to change from the neutral steering position or near the neutral steering position, so the steering angle θ of the steering wheels 6 changes as the vehicle moves while the vehicle control device 50 is performing the stopping process. w This prevents inappropriate changes from occurring. Therefore, the vehicle's driving stability can be maintained while the stopping process is being executed.

[0111] <Third Embodiment> Next, a third embodiment of the steering control device will be described. This embodiment basically has the same configuration as the first embodiment shown in Figures 1 and 2. For this reason, the same reference numerals are used for the same components and components as in the first embodiment, and their detailed descriptions are omitted. This embodiment differs from the first embodiment in terms of the motor lock processing procedure.

[0112] The first control circuit 63 basically executes each process shown in the flowchart of Figure 3. When the first control circuit 63 determines in step S102 that the steering motor 31 can be locked (YES in S102), it proceeds to step S103, and the pinion angle θ p Determine whether it is detectable.

[0113] In step S103, the first control circuit 63 checks if at least one of the first rotation angle sensor 44A and the second rotation angle sensor 44B is normal, and the pinion angle θ p When it is determined that the motor can be detected (YES in step S103), the process proceeds to step S104. In step S104, if the first control circuit 63 determines that the vehicle is moving straight (YES in step S104), the process proceeds to step S105 and executes the motor lock process described above.

[0114] However, in step S103, the first control circuit 63 checks if both the first rotation angle sensor 44A and the second rotation angle sensor 44B are abnormal, and the first rotation angle θ b1 or the second rotation angle θ b2 Based on the pinion angle θ p If it is determined that it cannot be detected (NO in S103), the process proceeds to step S104 instead of step S106.

[0115] In step S104, the first control circuit 63 switches the control method of the steering motor 31 to so-called rotation angle sensorless control. Rotation angle sensorless control is controlled by the first rotation angle θ detected through the first rotation angle sensor 44A. b1 , and the second rotation angle θ detected through the second rotation angle sensor 44B b2 Instead, this method controls the steering motor 31 using an estimated rotation angle calculated based on the induced voltage generated by the steering motor 31.

[0116] The first control circuit 63 calculates an added angle based on the induced voltage of the steering motor 31 and calculates the estimated rotation angle of the steering motor 31 by integrating the calculated added angles. The added angle is, for example, the angle by which the steering motor 31 rotates during one calculation cycle of the first control circuit 63. The sign of the added angle is determined, for example, by the direction of rotation of the steering motor 31 estimated based on the sign of the steering torque Th detected through the torque sensor 42.

[0117] The first control circuit 63 controls the pinion angle θ based on the estimated rotation angle of the steering motor 31. p The calculation is performed, and the calculated pinion angle θ p Based on this, it is determined whether the vehicle is moving straight. The first control circuit 63 determines that the vehicle is moving straight when equation (1) above is true. When the first control circuit 63 determines that the vehicle is moving straight (YES in step S104), it proceeds to step S105 and executes the motor lock process.

[0118] The first control circuit 63 sets the estimated rotation angle of the steering motor 31 immediately after it is determined in step S104 that the vehicle is moving straight, as the target rotation angle of the steering motor 31. The estimated rotation angle is the rotation angle of the steering motor 31 estimated based on the induced voltage of the steering motor 31, and corresponds to the actual rotation angle of the steering motor 31.

[0119] The first control circuit 63 calculates the difference between the target rotation angle and the estimated rotation angle of the steering motor 31, and drives the steering motor 31 so that the calculated difference becomes 0 (zero). In other words, when the rotation position of the steering motor 31 changes due to the steering action of the steering wheel 6 caused by an external force, the first control circuit 63 controls the steering motor 31 so that the estimated rotation angle of the steering motor 31 returns to the target rotation angle. The target rotation angle is the angle corresponding to the straight-ahead state of the vehicle. Therefore, by fixing the rotation position of the steering motor 31 to the target rotation angle, the steering position of the steering wheel 6 is fixed to the steering neutral position.

[0120] The second control circuit 73 performs motor lock processing in the same procedure as the first control circuit 63. The third embodiment provides the following effects.

[0121] (3-1) If abnormalities occur simultaneously in the first and second systems, power supply control of the steering motor 31 can be continued. However, if both the first rotation angle sensor 44A and the second rotation angle sensor 44B are abnormal, the control method of the steering motor 31 is switched to rotation angle sensorless control. Through the execution of this rotation angle sensorless control, the steering position of the steering wheel 6 is fixed at the steering neutral position or near the steering neutral position. Therefore, while the vehicle control device 50 is performing the stopping process, the steering angle θ of the steering wheel 6 changes as the vehicle moves. w This prevents inappropriate changes from occurring. Therefore, the vehicle's driving stability can be maintained while the stopping process is being executed.

[0122] <Other Embodiments> Furthermore, each embodiment may be implemented with the following modifications. The first control circuit 63 determines the pinion angle θ immediately after determining that the vehicle is moving straight. p You may also set the target pinion angle as follows: The target pinion angle is the pinion angle θ. p This is the target rotation angle. The first control circuit 63 controls the target pinion angle and the first rotation angle θ. b1 or the second rotation angle θ b2 The actual pinion angle θ is calculated based on this. p The difference between this and the calculated value is calculated, and the steering motor 31 is driven so that the calculated difference becomes 0 (zero). p However, by fixing the steering wheel 6 to a target rotation angle corresponding to the vehicle's straight-ahead state, the steering position of the steering wheel 6 is fixed to the neutral steering position.

[0123] In each embodiment, the steering control device 1B had a redundant configuration of two systems, but a non-redundant configuration of one system may also be adopted. That is, the steering control device 1B may have a configuration having only the first control unit 60, or a configuration having only the second control unit 70. In this case, the steering motor 31 may have a configuration having only the first winding group 31B, or a configuration having only the second winding group 31C. When an abnormality is detected in the system corresponding to itself (step S101), the first control circuit 63 or the second control circuit 73 executes the processes related to motor lock processing (steps S102 to S106). [Explanation of Symbols]

[0124] 1... Steering control device 5… Steering wheel 6… Steering wheel 31... Steering motor 31B...First winding group 31C...Second winding group 50... Vehicle control device 52...braking device 60...First control unit 70...Second control unit

Claims

1. A steering control device having a control unit configured to control a steering motor that generates torque for steering the steering wheels of a vehicle, from which power transmission is separated to the steering wheel, wherein the control unit is configured to request a vehicle control device that controls the movement of the vehicle to perform a predetermined stopping procedure when an abnormality occurs in the part that drives the steering motor, The control unit is configured to perform a process to suppress the rotation of the steering motor when it requests the execution of the stopping process and it is possible to continue the power supply control of the steering motor.

2. The aforementioned stopping process includes a process of changing the direction of travel of the vehicle by controlling the distribution of driving force between the left and right wheels through the vehicle's braking system. The steering control device according to claim 1, wherein the control unit is configured to wait for the vehicle to be determined to be in a straight-ahead state when it requests the execution of the stopping process, and then execute a process to suppress the rotation of the steering motor.

3. The steering control device according to claim 2, wherein, when the control unit requests the execution of the stopping process, it sets the rotation angle of the steering motor immediately after it is determined that the vehicle is in a straight-ahead state as the target rotation angle of the steering motor, and controls the drive of the steering motor so as to eliminate the difference between the target rotation angle and the actual rotation angle of the steering motor.

4. The control unit is configured to control the drive of the steering motor using the rotation angle of the steering motor, The steering control device according to claim 2, wherein when the control unit requests the execution of the stopping process, and the rotation angle of the steering motor cannot be detected, it calculates an estimated rotation angle of the steering motor based on the induced voltage generated by the steering motor, sets the estimated rotation angle immediately after it is determined that the vehicle is in a straight-ahead state as the target rotation angle of the steering motor, and drives the steering motor to eliminate the difference between the target rotation angle and the estimated rotation angle.

5. The steering control device according to any one of claims 1 to 4, wherein the control unit is configured to perform a process to operate the steering motor as a generator when it is unable to continue power supply control of the steering motor when it requests the execution of the stopping process.

6. The steering motor has a first winding group and a second winding group, The control unit includes a first control unit that independently controls the power supply to the first winding group, and a second control unit that independently controls the power supply to the second winding group. The steering control device according to any one of claims 1 to 4, wherein the first control unit and the second control unit are configured to request the vehicle control device to execute the stopping process when an abnormality occurs in both the first system corresponding to the first winding group and the second system corresponding to the second winding group.

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