Steering control device and steering control method

Abstract

To provide a steering control device and a steering control method capable of inhibiting a period until enabling control for steering vehicle travel from being long after a vehicular steering system is powered on.SOLUTION: A steering control device is applied to a vehicular steering system for steering vehicle travel. A reaction force control part provided in the steering control device executes control information setting processing to set a reference value for reaction force. The reaction force control part includes each CPU of two systems. Each CPU of the reaction force control part can execute normal reaction force processing with the completion of setting of the reference value for reaction force in CPUs in the whole systems as a condition while respectively executing the control information setting processing. The control information setting processing of a reaction force side includes information adjustment processing (step 208) for performing adjustment so that setting of the reference value of reaction force in the CPUs of the whole systems in the case that there is a CPU of a system in which the setting is not completed while there is a CPU of a system in which the setting of the reference value for reaction force is completed.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a steering control device and a steering control method. [Background technology]

[0002] For example, Patent Document 1 describes a steer-by-wire steering device mounted on a vehicle. The steer-by-wire steering device has a structure in which a power transmission path between the steering wheel of the vehicle and the steered wheels of the vehicle is separated. The vehicle includes a reaction force control unit and a steering control unit for controlling the steer-by-wire steering device. The reaction force control unit is configured to execute a process for setting a steering angle midpoint to obtain a neutral position of the steering wheel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-195084 A Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned process for setting the steering angle midpoint is a process for enabling control of the steering device, etc., when the vehicle is traveling. For example, if there is a circumstance in which the process for setting the steering angle midpoint cannot be completed in the reaction force control unit, it becomes impossible to enable control of the steering device, etc., when the vehicle is traveling. [Means for solving the problem]

[0005] A steering control device capable of solving the above-mentioned problems is applied to a vehicle steering system that steers the traveling of a vehicle. The steering control device includes a steering angle control unit that executes control by referring to a steering angle variable obtained in relation to the steering, and the steering angle control unit is configured to execute a control information setting process for setting control information that indicates that the vehicle travels straight and is a reference for the steering angle variable, the control information setting process is a process for enabling control of steering the traveling of the vehicle by completing the setting of the control information after the vehicle steering system is powered on, the steering angle control unit includes a plurality of control circuits that control the steering angle variable in relation to each other, and the plurality of control circuits are configured to enable control of steering the traveling of the vehicle on the condition that the setting of the control information is completed in all of the control circuits while executing the control information setting process respectively, and the control information setting process includes an adjustment process for making an adjustment so that the setting of the control information in all of the control circuits can be completed when there is a control circuit that has completed the setting of the control information among the control circuits that have completed the setting of the control information and there is a control circuit that has not completed the setting of the control information.

[0006] According to the above configuration, even if there is a control circuit in which the setting of the control information is not completed, the control circuits of the multiple systems can complete the setting of the control information in all the control circuits by the adjustment process. This makes it possible to suppress the occurrence of a situation in which the setting of the control information cannot be completed in all the control circuits and such a situation is repeated endlessly. Therefore, it is possible to suppress the length of time until the vehicle steering system is powered on and the control of steering the vehicle is enabled.

[0007] In the above-mentioned steering control device, it is preferable that the adjustment process includes a state adjustment process that adjusts the state of the control circuit that has completed setting the control information so as to transition the control circuit to a state in which the control information setting process can be executed again, and that the multiple control circuits are each able to execute the control information setting process again after the adjustment by the state adjustment process.

[0008] According to the above configuration, the adjustment process can cause the control circuit that has completed the setting of the control information to execute the control information setting process again by the state adjustment process. This allows the control information setting process to be executed again for each of the control circuits, regardless of whether the setting of the control information has been completed or not. Such a state adjustment process is a particularly effective method when the control circuits of multiple systems each set the control information by, for example, rotating the steering wheel of the vehicle.

[0009] For example, the above-mentioned vehicle steering system has a structure in which the power transmission paths between a steering unit steered by the steering wheel of the vehicle and a steering unit that operates to steer the steered wheels of the vehicle are separated, the steering angle control unit includes a reaction force control unit having the multiple control circuits, the reaction force control unit controls the operation of the steering unit to apply a steering reaction force to the steering wheel by referring to steering variables obtained from the steering unit in connection with the steering, the multiple control circuits of the reaction force control unit each execute the control information setting process based on values ​​obtained respectively while rotating the steering wheel to a limit position in a first direction or a second direction, and the multiple control circuits of the reaction force control unit are capable of executing the state adjustment process while each executes the control information setting process.

[0010] In the above configuration, the state adjustment process is made to complete the setting of control information in all control circuits of the reaction force control unit. As a result, even if the control circuits of the multiple systems of the reaction force control unit each set control information by rotating the steering wheel of the vehicle, all control circuits can execute the control information setting process again. In other words, it is possible to prevent the occurrence of a situation in which the steering wheel of the vehicle cannot be rotated due to differences in internal states between the control circuits of the multiple systems of the reaction force control unit.

[0011] In the above-mentioned steering control device, the adjustment process includes a control information adjustment process that adjusts the control circuits that have not completed setting the control information so as to complete the setting of the control information by setting the control information using the control information that has been set in the control circuits that have completed setting the control information, and it is preferable that the multiple systems of control circuits can complete the setting of the control information in all of the control circuits after the adjustment by the control information adjustment process.

[0012] According to the above configuration, the adjustment process can use the control information that has been set in the control circuit that has completed the setting of the control information to complete the setting of the control information for the control circuit that has not completed the setting of the control information by the control information adjustment process. As a result, if there is a control circuit that has completed the setting of the control information, the setting of the control information can be completed for all the control circuits. Such a control information adjustment process is a particularly effective method when multiple control circuits set their own control information by, for example, correcting the steering angle variable.

[0013] For example, the above-mentioned vehicle steering system has a structure in which power transmission paths are separated between a steering unit steered by the steering wheel of the vehicle and a steering unit that operates to steer the steered wheels of the vehicle, the steering angle control unit includes a steering control unit having the multiple control circuits, the steering control unit controls the operation of the steering unit so as to apply a steering force to the steered wheels by referring to steering variables obtained from the steering unit in relation to the steering, the multiple control circuits of the steering control unit each execute the control information setting process based on correcting the steering variables using correction variables each obtained from the steering unit in addition to the steering variables, and the multiple control circuits of the steering control unit are capable of executing the control information adjustment process while each executing the control information setting process.

[0014] In the above configuration, the control information adjustment process makes it possible to complete the setting of control information in all control circuits of the steering control section. This allows all control circuits to complete the setting of control information even when multiple control circuits of the steering control section set control information individually by correcting the steering variable using correction information obtained in addition to the steering variable. In other words, even if there is a control circuit in the multiple control circuits of the steering control section that fails to acquire the steering variable or correction variable, it is possible to quickly deal with the problem.

[0015] Further, for example, the vehicle steering system has a structure in which a power transmission path between a steering unit steered by a steering wheel of the vehicle and a steering unit operating to steer the steered wheels of the vehicle is separated, the steering angle control unit includes a reaction force control unit having the control circuits of the multiple systems, and a steering control unit having the control circuits of the multiple systems, the reaction force control unit controls the operation of the steering unit so as to apply a steering reaction force to the steering wheel by referring to a steering variable related to the steering obtained from the steering unit, the steering control unit controls the operation of the steering unit so as to apply a steering force to the steered wheels by referring to a steering variable related to the steering obtained from the steering unit, and the adjustment process is a state adjustment process for adjusting a state of the control circuit that has completed setting of the control information so as to transition to a state in which the control information setting process can be executed again. and a control information adjustment process for adjusting, for the control circuits that have not completed setting of the control information, to complete setting of the control information by setting the control information using the control information that has been set in the control circuits that have completed setting of the control information, wherein the multiple systems of control circuits of the reaction force control unit are capable of executing the state adjustment process while respectively executing the control information setting process, and when executing the state adjustment process, can each execute the control information setting process again after the adjustment by the state adjustment process, and the multiple systems of control circuits of the steering control unit are capable of executing the control information adjustment process while respectively executing the control information setting process, and when executing the control information adjustment process, can complete setting of the control information in all of the control circuits after the adjustment by the control information adjustment process.

[0016] A steering control method that can solve the above problem is a method applied to a vehicle steering system that steers the traveling of a vehicle. The steering control method includes a steering angle control process that executes control referring to a steering angle variable obtained in relation to the steering, the steering angle control process includes setting control information that is a value indicating that the vehicle travels straight and is a reference for the steering angle variable, the setting of the control information is a process for enabling control of steering the traveling of the vehicle by completing the setting of the control information after the vehicle steering system is powered on, the steering angle control process includes a process executed by a plurality of control circuits that control the steering angle variable in relation to each other, the process executed by the control circuits of the plurality of systems is configured to enable control of steering the traveling of the vehicle on the condition that the setting of the control information is completed in all of the control circuits while the control circuits of the plurality of systems are each set, and the setting of the control information includes making an adjustment so that the setting of the control information in all of the control circuits can be completed when there is a control circuit that has completed the setting of the control information among the control circuits that have completed the setting of the control information and there is a control circuit that has not completed the setting of the control information. Effect of the Invention

[0017] According to the present invention, it is possible to suppress a lengthy period from when a vehicle steering system is powered on until control of steering the traveling of the vehicle becomes possible. [Brief description of the drawings]

[0018] [Figure 1] 1 is a diagram showing a configuration of a steer-by-wire steering device according to an embodiment; [Diagram 2] FIG. 2 is a block diagram showing the electrical configuration of the steering control device in FIG. [Diagram 3] 4 is a flowchart showing the procedure of processing executed by the steering CPU of FIG. 1 when in a start-up state. [Figure 4] 4 is a flowchart showing a processing procedure on the reaction force side in the steering angle correction processing in FIG. 3. [Diagram 5]4 is a flowchart showing a processing procedure on the steering side of the steering angle correction processing in FIG. 3. [Figure 6] 13 is a diagram showing a manner in which a state adjustment process is executed in a reaction CPU; FIG. [Figure 7] FIG. 13 is a diagram showing a manner in which a control information adjustment process is executed in a steering CPU. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] A steering control device according to one embodiment will be described. As shown in FIG. 1, the vehicle steering system 2 includes a steering control device 1. The vehicle steering system 2 includes a steering unit 4 and a turning unit 6. The steering unit 4 is steered by a driver via a steering wheel 3 of the vehicle, which is a steering member. The turning unit 6 steers the left and right steered wheels 5 of the vehicle in response to the steering input to the steering unit 4 by the driver. The vehicle steering system 2 of this embodiment has a structure in which, for example, the power transmission path between the steering unit 4 and the turning unit 6 is mechanically separated at all times. The power transmission path between a steering actuator 12 described later and a turning actuator 31 described later is mechanically separated at all times. That is, the vehicle steering system 2 includes a steer-by-wire type steering device.

[0020] The steering unit 4 includes a steering shaft 11 and a steering actuator 12. The steering shaft 11 is connected to the steering wheel 3. An end 11a of the steering shaft 11 opposite to the end connected to the steering wheel 3 has a stopper mechanism 11b. The stopper mechanism 11b defines the rotation range of the steering shaft 11. As a result, the rotation range of the steering wheel 3, which rotates integrally with the steering shaft 11, is defined by the stopper mechanism 11b. For example, the steering wheel 3 is rotatable within a rotation range between a right limit position 3a and a left limit position 3b.

[0021] The steering actuator 12 has a reaction motor 13 and a steering-side reduction gear mechanism 14. The reaction motor 13 is a steering-side motor that applies a steering reaction force, which is a force resisting steering, to the steering wheel 3 via the steering shaft 11. The reaction motor 13 is connected to the steering shaft 11 via the steering-side reduction gear mechanism 14, which is made of, for example, a worm and wheel. For example, a three-phase brushless motor is used as the reaction motor 13 in this embodiment.

[0022] The steering unit 6 includes a pinion shaft 21, a rack shaft 22 as a steering shaft, and a rack housing 23. The pinion shaft 21 and the rack shaft 22 are connected with a predetermined cross angle. A rack-and-pinion mechanism 24 is formed by meshing pinion teeth 21a formed on the pinion shaft 21 with rack teeth 22a formed on the rack shaft 22. The pinion shaft 21 corresponds to a rotation axis that can be converted into a steering angle θi, which is the steering position of the steered wheels 5. The rack housing 23 accommodates the rack-and-pinion mechanism 24.

[0023] One end of the pinion shaft 21 opposite to the end connected to the rack shaft 22 protrudes from a rack housing 23. Both ends of the rack shaft 22 protrude from both axial ends of the rack housing 23. Tie rods 26 are connected to both ends of the rack shaft 22 via rack ends 25 made of ball joints. The ends of the tie rods 26 are connected to knuckles (not shown) to which the left and right steered wheels 5 are respectively attached.

[0024] The steering unit 6 includes a steering actuator 31. The steering actuator 31 includes a steering motor 32, a transmission mechanism 33, and a conversion mechanism 34. The steering motor 32 is a steering-side motor that applies a steering force for steering the steered wheels 5 relative to the rack shaft 22 via the transmission mechanism 33 and the conversion mechanism 34. The steering motor 32 transmits rotation to the conversion mechanism 34 via the transmission mechanism 33, which is, for example, a belt transmission mechanism. The transmission mechanism 33 converts the rotation of the steering motor 32 into reciprocating motion of the rack shaft 22 via the conversion mechanism 34, which is, for example, a ball screw mechanism. For the steering motor 32 of this embodiment, for example, a three-phase brushless motor is used.

[0025] In vehicle steering system 2, the steering angle θi of steered wheels 5 is changed by applying a motor torque as a steering force from steering actuator 31 to rack shaft 22 in response to steering by the driver. At this time, a steering reaction force resisting the steering by the driver is applied to steering wheel 3 from steering actuator 12. As a result, in vehicle steering system 2, the steering torque Th required for steering steering wheel 3 is changed by the steering reaction force, which is the motor torque applied from steering actuator 12.

[0026] The pinion shaft 21 is provided in order to support the rack shaft 22 together with the pinion shaft 21 inside the rack housing 23. The rack shaft 22 is supported movably along its axial direction and is pressed toward the pinion shaft 21 by a support mechanism (not shown) provided in the vehicle steering system 2. As a result, the rack shaft 22 is supported inside the rack housing 23. However, another support mechanism for supporting the rack shaft 22 in the rack housing 23 may be provided without using the pinion shaft 21.

[0027] <Electrical configuration of the steering system> 1, the reaction force motor 13 and the steering motor 32 are connected to the steering control device 1. The steering control device 1 controls the operation of each of the motors 13, 32.

[0028] Detection results of various sensors are input to the steering control device 1. The various sensors include, for example, a torque sensor 41, a steering side rotation angle sensor 42, a turning side rotation angle sensor 43, a vehicle speed sensor 44, and a pinion absolute angle sensor 45.

[0029] The torque sensor 41 is provided on the steering shaft 11 between the steering wheel 3 and the steering side reduction mechanism 14. The torque sensor 41 detects the steering torque Th, which is a value indicating the torque applied to the steering shaft 11 by the driver's steering. The steering torque Th is detected in relation to the twist of a torsion bar 41a provided on the steering shaft 11 between the steering wheel 3 and the steering side reduction mechanism 14, midway along the steering shaft 11. The steering side rotation angle sensor 42 is provided on the reaction motor 13. The steering side rotation angle sensor 42 detects the rotation angle θa, which is the rotation angle of the rotation shaft of the reaction motor 13, within a range of 360 degrees. The turning side rotation angle sensor 43 is provided on the turning motor 32. The turning side rotation angle sensor 43 detects the rotation angle θb, which is the rotation angle of the rotation shaft of the turning motor 32, within a range of 360 degrees. The vehicle speed sensor 44 detects the vehicle speed V, which is the traveling speed of the vehicle. The pinion absolute angle sensor 45 is provided on the pinion shaft 21. The pinion absolute angle sensor 45 detects the pinion absolute rotation angle θabp, which is an actual measurement value of the angle of the rotation shaft of the pinion shaft 21, in a range exceeding 360°. In this embodiment, the rotation angle θ and the rotation angle θb are examples of steering angle variables. Furthermore, the rotation angle θa is an example of a steering variable. Furthermore, the rotation angle θb is an example of a steering variable. Furthermore, the pinion absolute rotation angle θabp is an example of a correction variable.

[0030] A power supply system 46 is connected to the steering control device 1. The power supply system 46 has a battery 47. The battery 47 is a secondary battery mounted on the vehicle, and serves as a power source for supplying power to operate the reaction force motor 13 and the steering motor 32. The battery 47 also serves as a power source for supplying power to operate the steering control device 1.

[0031] A vehicle start switch 48 ("SW" in FIG. 1), such as an ignition switch, is provided between the steering control device 1 and the battery 47. The start switch 48 is provided in the middle of the power feeder L2, which is one of two power feeders L1 and L2 that connect the steering control device 1 and the battery 47 and branched from the power feeder L1. The start switch 48 is operated when starting various functions so that a driving source for running the vehicle, such as an engine, can be operated to enable the operation of the vehicle. The conduction of the power feeder L2 is turned on and off through the operation of the start switch 48. In this embodiment, the operation state of the vehicle steering system 2 is associated with the operation state of the vehicle. Note that the conduction of the power feeder L1 is basically always on, but the conduction of the power feeder L1 is indirectly turned on and off as a function of the vehicle steering system 2 depending on the operation state of the vehicle steering system 2. The operation state of the vehicle steering system 2 is associated with the on and off of the conduction of the power feeders L1 and L2, which is the state of the power supply of the battery 47. The operating state of the vehicle steering system 2 is powered on when the electrical continuity of the power feeders L1, L2 is turned on based on the operation of the start switch 48. The operating state of the vehicle steering system 2 is powered off when the electrical continuity of the power feeders L1, L2 is turned off based on the operation of the start switch 48.

[0032] <Functions of the steering control device> As shown in FIG. 2, the steering control device 1 has a reaction force control unit 50 and a turning control unit 60. The reaction force control unit 50 controls the steering wheel 3 which is the control object. The reaction force control unit 50 controls the driving of the steering actuator 12, more specifically the reaction force motor 13, in order to control the steering reaction force which is the control amount of the control object. The turning control unit 60 controls the rack shaft 22 which is the control object. The turning control unit 60 controls the driving of the turning actuator 31, more specifically the turning motor 32, in order to control the steering force which is the control amount of the control object. The reaction force control unit 50 and the turning control unit 60 transmit and receive information to each other via a local network 49 such as serial communication, for example. The reaction force control unit 50 constitutes a reaction force system RS in combination with the steering unit 4. The turning control unit 60 constitutes a steering system TS in combination with the steering unit 6. The process by which the reaction force control unit 50 controls the driving of the reaction force motor 13 is a reaction force control process. The process by which the steering control unit 60 controls the drive of the steering motor 32 is a steering control process. In this embodiment, the reaction force control unit 50 and the steering control unit 60 are an example of a steering angle control unit. The reaction force control process and the steering control process are an example of a steering angle control process.

[0033] The reaction force control unit 50 includes a central processing unit (hereinafter referred to as "CPU") 51 and a memory 52. ​​The reaction force control unit 50 executes various processes by the CPU 51 executing a program stored in the memory 52 at a predetermined calculation cycle. The steering control unit 60 includes a central processing unit (hereinafter referred to as "CPU") 61 and a memory 62. The steering control unit 60 executes various processes by the CPU 61 executing a program stored in the memory 62 at a predetermined calculation cycle. The CPUs 51, 61 and the memories 52, 62 constitute a microcomputer, which is a processing circuit. The memories 52, 62 include computer-readable media such as a RAM (Random Access Memory) and a ROM (Read Only Memory). However, it is an example that the various processes are realized by software. The processing circuits of the reaction force control unit 50 and the steering control unit 60 may be configured to realize at least a part of the processes by a hardware circuit such as a logic circuit.

[0034] The reaction force control unit 50 has a plurality of control systems that are formed by combining the CPU 51 and the memory 52 to execute various processes. The plurality of control systems are, for example, two systems including a reaction force main system RSa formed by the main CPU 51a and the main memory 52a, and a reaction force sub-system RSb formed by the sub CPU 51b and the sub memory 52b. This is the same for the steering control unit 60. That is, the steering control unit 60 has a plurality of control systems that are formed by combining the CPU 61 and the memory 62 to execute various processes. The plurality of control systems are, for example, two systems including a steering main system TSa formed by the main CPU 61a and the main memory 62a, and a steering sub-system TSb formed by the sub CPU 61b and the sub memory 62b. In this embodiment, each of the CPUs 51a, 51b and each of the CPUs 61a, 61b is an example of a control circuit. The processes executed by each of the CPUs 51a, 51b and each of the CPUs 61a, 61b is an example of a control circuit process.

[0035] Each of the CPUs 51a and 51b in the reaction force control unit 50 inputs the steering torque Th, the vehicle speed V, and the rotation angle θa. In this embodiment, the steering side rotation angle sensor 42 includes a sensor 42a for the reaction force main system RSa and a sensor 42b for the reaction force sub system RSb. The main CPU 51a inputs the rotation angle θa, which is the rotation angle θaa detected by the sensor 42a. The sub CPU 51b inputs the rotation angle θa, which is the rotation angle θab detected by the sensor 42b. In addition, each of the CPUs 51a and 51b inputs the steering information obtained from the steering control unit 60 via the local network 49. Each of the CPUs 51a and 51b calculates a control signal MSs to the reaction force inverter 53 for controlling the steering reaction force based on various information including the steering torque Th, the vehicle speed V, and the rotation angle θa. The reaction force inverter 53 is a drive circuit that converts the DC voltage of the battery 47 into an AC voltage and applies it to the reaction force motor 13. At this time, each of the CPUs 51a and 51b refers to the currents iu1, iv1, and iw1 flowing through the reaction force motor 13. The currents iu1, iv1, and iw1 are quantified as the voltage drop amounts of the shunt resistors provided in each leg of the reaction force inverter 53.

[0036] In this embodiment, the reaction force inverter 53 includes an inverter 53a for the reaction force main system RSa and an inverter 53b for the reaction force sub system RSb. The inverter 53a applies a voltage to the main winding group 13a of the reaction force motor 13. The inverter 53b applies a voltage to the sub winding group 13b of the reaction force motor 13. The main CPU 51a calculates a control signal MSsa to the inverter 53a and refers to the currents iu1a, iv1a, and iw1a in the inverter 53a. The sub CPU 51b calculates a control signal MSsb to the inverter 53b and refers to the currents iu1b, iv1b, and iw1b in the inverter 53b. In this way, each of the CPUs 51a and 51b controls the driving of the reaction force motor 13 so as to generate a motor torque that becomes a steering reaction force.

[0037] Each CPU 51a, 51b converts the rotation angle θa into an integrated rotation angle, which is an integrated value from the reaction force reference value θns stored in each memory 52a, 52b, that is, an absolute rotation angle. The absolute rotation angle is a value converted in a range exceeding 360° by counting the number of rotations of the reaction force motor 13 from the reaction force reference value θns. The reaction force reference value θns is, for example, a value indicating a straight-ahead state, which is a steering state of the steering wheel 3 when the vehicle is moving straight. In this embodiment, the reaction force reference value θns is a value indicating a steering neutral position, which is a rotation position of the steering wheel 3 in the straight-ahead state, and is an example of control information. Each CPU 51a, 51b multiplies the absolute rotation angle obtained by conversion by a conversion coefficient based on the rotation speed ratio of the steering side reduction gear mechanism 14, to calculate the steering angle θs. Each of the CPUs 51a and 51b calculates the steering angle θs as an absolute angle relative to the steering neutral position, i.e., the reaction force reference value θns. The steering angle θs thus obtained is used when calculating the control signal MSs. The steering information used by each of the CPUs 51a and 51b, such as the steering angle θs, is output to the steering control unit 60 via the local network 49.

[0038] Each of the CPUs 61a, 61b in the steering control unit 60 inputs the vehicle speed V, the rotation angle θb, and the pinion absolute rotation angle θabp. In this embodiment, the steering side rotation angle sensor 43 includes a sensor 43a for the steering main system TSa and a sensor 43b for the steering sub-system TSb. The main CPU 61a inputs the rotation angle θb, which is the rotation angle θba detected by the sensor 43a. The sub-CPU 61b inputs the rotation angle θb, which is the rotation angle θbb detected by the sensor 43b. In addition, each of the CPUs 61a, 61b inputs steering information obtained from the reaction force control unit 50 via the local network 49. Each of the CPUs 61a, 61b calculates a control signal MSt to the steering inverter 63 for controlling the steering force, based on various information including the vehicle speed V, the rotation angle θb, and the pinion absolute rotation angle θabp. The steering inverter 63 is a drive circuit that converts the DC voltage of the battery 47 into AC voltage and applies it to the steering motor 32. At that time, each CPU 61a, 61b refers to the currents iu2, iv2, iw2 that flow through the steering motor 32. The currents iu2, iv2, iw2 are quantified as the voltage drop amounts of the shunt resistors provided in each leg of the steering inverter 63.

[0039] In this embodiment, the steering inverter 63 includes an inverter 63a for the steering main system TSa and an inverter 63b for the steering sub-system TSb. The inverter 63a applies a voltage to the main winding group 32a of the steering motor 32. The inverter 63b applies a voltage to the sub-winding group 32b of the steering motor 32. The main CPU 61a calculates a control signal MSta for the inverter 63a and refers to the currents iu2a, iv2a, and iw2a in the inverter 63a. The sub-CPU 61b calculates a control signal MStb for the inverter 63b and refers to the currents iu2b, iv2b, and iw2b in the inverter 63b. As a result, each of the CPUs 61a and 61b controls the driving of the steering motor 32 so as to generate a motor torque that becomes a steering force.

[0040] Each of the CPUs 61a and 61b converts the rotation angle θb into an integrated rotation angle, which is an integrated value from the steering reference value θnt stored in each of the memories 62a and 62b, that is, into an absolute rotation angle. The absolute rotation angle is a value converted in a range exceeding 360° by counting the number of rotations of the steering motor 32 from the steering reference value θnt. The steering reference value θnt is, for example, a value indicating a straight-line state, which is a steering state of the rack shaft 22 when the vehicle is traveling straight. In this embodiment, the steering reference value θnt is a value indicating a rack neutral position, which is a position of the rack shaft 22 in the straight-line state, and is an example of control information. Each of the CPUs 61a and 61b multiplies the absolute rotation angle obtained by the conversion by a conversion coefficient based on the rotation speed ratio of the transmission mechanism 33, the lead of the conversion mechanism 34, and the rotation speed ratio of the rack and pinion mechanism 24, to calculate the pinion angle θp. Each of the CPUs 61a, 61b calculates the pinion angle θp, which is the actual rotation angle of the pinion shaft 21, as an absolute angle relative to the rack neutral position, i.e., the steering reference value θnt. The pinion angle θp thus obtained is used when calculating the control signal MSt. The steering information used by each of the CPUs 61a, 61b, such as the pinion angle θp, is output to the reaction force control unit 50 via the local network 49.

[0041] <Processing to be performed during startup> During power off, the steering control device 1 transitions to a normal control state via a startup state after the start switch 48 is turned on and the power is turned on. In this case, the CPUs 51a, 51b of the reaction force control unit 50 judge whether the power is on or off depending on the presence or absence of the input of the IG signal sg output by the start switch 48, and execute processes such as an initial check process. Similarly, the CPUs 61a, 61b of the turning control unit 60 judge whether the power is on or off, and execute processes such as an initial check process. In the following, when the CPUs 51a, 51b of the reaction force control unit 50 are collectively indicated, they are referred to as "reaction force CPUs". When the CPUs 61a, 61b of the turning control unit 60 are collectively indicated, they are referred to as "turning CPUs". When the "reaction force CPUs" and "turning CPUs" are collectively indicated, they are referred to as "steering CPUs".

[0042] As shown in Fig. 3, in the start-up state, the steering CPU executes an initial check process (step 100). The initial check process includes a check process related to whether the CPUs and memories of the steering CPUs are operating normally and the operation of the reaction force system RS and the steering system TS. The initial check process includes a check process related to communication on the local network 49. The initial check process includes a check process related to reading various information from memories corresponding to each of the steering CPUs. In the initial check process, the various information read by the steering CPUs from their corresponding memories includes the reaction force reference value θns and the steering reference value θnt.

[0043] Next, the steering CPU determines whether the steering angle correction process is complete (step 102). In step 102, the steering CPU determines that the steering angle correction process is complete when it can determine that the processes for the reaction force side and the turning side have been completed. In this case, the reaction force control unit 50 determines that the process for the reaction force side has been completed when it can determine that the processes for each of the systems RSa and RSb have been completed. Similarly, the turning control unit 60 determines that the process for the turning side has been completed when it can determine that the processes for each of the systems TSa and TSb have been completed. The steering angle correction process will be described in detail later.

[0044] Next, when the steering CPU determines that the steering angle correction process is completed (step 102: YES), it executes steering angle synchronization process (step 104). The steering angle synchronization process includes a process for synchronizing the positional relationship based on at least one of the rotation of the steering wheel 3 and the steering of the steered wheels 5. As a result of the steering angle synchronization process, the steering angle θs, which is the rotational position of the steering wheel 3, and the steering angle θi, which is the steered position of the steered wheels 5, i.e., the pinion angle θp, are synchronized so as to have a predetermined correspondence relationship.

[0045] Thereafter, the steering CPU transitions to the normal control state, regarding the processing in the startup state as being completed. The normal control state is a state in which normal reaction force processing and normal steering processing related to steering control for operating the steering unit 4 and the steering unit 6 are executed in response to the steering operation by the driver. In this case, the reaction force system RS operates the steering unit 4 so as to operate in cooperation with the steering unit 6. Also, the steering system TS operates the steering unit 6 so as to operate in cooperation with the steering unit 4.

[0046] On the other hand, in step 102, if the steering angle correction process is being executed (step 102: NO), the steering CPU determines whether or not a timeout has occurred (step 106). In step 106, the steering CPU determines whether or not the elapsed time since the start of the steering angle correction process has exceeded an upper limit time that satisfies the timeout condition. In this embodiment, the upper limit time is, for example, a value within a range in which the steering angle correction process on the steering side can be repeated multiple times.

[0047] Next, if the timeout condition is not satisfied (step 106: NO), the steering CPU continues the process of step 102, i.e., the execution of the steering angle correction process. On the other hand, if the timeout condition is satisfied (step 106: YES), the steering CPU cannot complete the process in the startup state, and therefore transitions to a function stop state in which the function of the steering control device 1 is stopped, etc.

[0048] <Reaction force side steering angle correction process> As shown in FIG. 4, in the reaction-force side steering angle correction process, the reaction force CPU judges whether or not it is necessary to execute the steering angle correction process (step 202). In step 202, if the reaction force reference value θns for reaction force could not be read in the initial check process (step 100), the reaction force CPU judges that it is necessary to execute the steering angle correction process. In the initial check process, the reaction force CPU cannot read the reaction force reference value θns for reaction force if the reaction force reference value θns is not set internally. For example, after the battery 47 is removed and replaced, the reaction force reference value θns is not set internally. Similarly, in the case of a read abnormality or a write abnormality regarding the reaction force reference value θns, the reaction force reference value θns is not set internally.

[0049] Next, if the reaction force CPU was able to read out the reaction force reference value θns in the initial check process (step 100) and therefore does not need to execute the steering angle correction process (step 202: NO), it ends the process and completes the reaction force side steering angle correction process. The completion of the reaction force side processing is notified to the steering CPU via local network 49. Note that the reaction force CPU can make a determination of step 102: YES when both the completion of the reaction force side processing and the receipt of a notification of the completion of the steering side steering angle correction processing from the steering CPU are satisfied.

[0050] On the other hand, if the reaction force CPU needs to execute a steering angle correction process (step 202: YES) because the reaction force reference value θns could not be read in the initial check process (step 100), the reaction force CPU executes a control information setting process (step 204). In step 204, the control information setting process executed by the reaction force CPU includes a process for referencing the rotation angle θa. The reaction force CPU includes an integrated rotation angle acquisition process for calculating a provisional steering angle θsi, which is an integrated value obtained using the position of the rotation angle θa at the time of power-on as a provisional reference value. The provisional steering angle θsi is an integrated rotation angle, i.e., an absolute rotation angle. The reaction force side control information setting process includes a learning process in which the reaction force CPU acquires values ​​while rotating the steering wheel 3 to each of the left and right limit positions 3a, 3b.

[0051] For example, as shown in Fig. 6, the learning process includes a process of rotating the steering wheel 3 in one of the left and right directions, i.e., rightward as a first direction. The rotation of the steering wheel 3 is performed by feedback control that makes the provisional steering angle θsi follow the steering target angle θs*. The steering target angle θs* is a value that is updated so as to gradually change from the value of the provisional steering angle θsi at the start of the learning process to exceed the rightward limit position 3a.

[0052] The learning process also includes a process of temporarily storing the right limit position θrl when the steering wheel 3 reaches the right limit position 3a. The fact that the steering wheel 3 has reached the limit position 3a is determined, for example, by monitoring the currents iu1, iv1, iw1, the steering torque Th, and the angular velocity ωs, which is the amount of change in the provisional steering angle θsi. The right limit position θrl is the provisional steering angle θsi when it is determined that the steering wheel 3 has reached the right limit position 3a.

[0053] The learning process also includes a process of rotating the steering wheel 3 to the other right side, that is, to the left, which is the second direction. This process is executed by feedback control that makes the provisional steering angle θsi follow the steering target angle θs*, similar to the process of rotating the steering wheel 3 to the right. The steering target angle θs* is a value that is updated so as to gradually change from the value of the provisional steering angle θsi when the right limit position 3a is reached to exceed the right limit position 3a.

[0054] The learning process also includes a process for temporarily storing the left limit position θll when the steering wheel 3 reaches the left limit position 3b. The fact that the steering wheel 3 has reached the limit position 3b is determined, for example, by monitoring the currents iu1, iv1, iw1, the steering torque Th, and the angular velocity ωs, which is the amount of change in the provisional steering angle θsi, in the same manner as when the steering wheel 3 has reached the right limit position 3a. The left limit position θll is the provisional steering angle θsi when it is determined that the steering wheel 3 has reached the left limit position 3b.

[0055] The learning process also includes a process of calculating a value corresponding to half the sum of the temporarily stored right limit position θrl and left limit position θll as the reaction force midpoint value θcs. The reaction force midpoint value θcs thus obtained is written into the reaction force reference value θns by the reaction force CPU, i.e., each of the CPUs 51a and 51b, and set therein.

[0056] Next, the reaction force CPU judges whether or not the setting of the reaction force reference value θns has been completed for both systems (step 206). In step 206, the reaction force CPU judges whether or not the setting of the reaction force reference value θns has been completed for each of the CPUs 51a, 51b. The reaction force CPU also judges whether or not, among the CPUs of the systems that have completed setting the reaction force reference value θns, a CPU of the system that has not completed the setting. During the learning process, the CPUs 51a, 51b notify each other by inter-microcomputer communication or the like that they have completed setting the reaction force reference value θns as a result of the learning process.

[0057] It should be noted that the reaction force CPU does not execute step 206 while neither of the CPUs 51a, 51b has completed setting the reaction force reference value θns. If neither of the CPUs 51a, 51b has completed setting the reaction force reference value θns, the timeout condition will eventually be satisfied (step 106: YES), and the steering CPU will transition to a function-stopped state.

[0058] Next, when the reaction force reference value θns has been set for both systems by each of the CPUs 51a, 51b (step 206: YES), the reaction force CPU ends the process and completes the reaction force side steering angle correction process. After that, the completion of the reaction force side process is notified to the steering CPU via the local network 49.

[0059] On the other hand, when there is a CPU of a system in which the reaction force reference value θns has been set by each of the CPUs 51a and 51b and there is a CPU of a system in which the setting has not been completed (step 206: NO), the reaction force CPU executes a state adjustment process (step 208). The state adjustment process is an adjustment process for making adjustments so that the reaction force CPUs, i.e., the CPUs 51a and 51b, can each execute the control information setting process (step 204) including the learning process again. For example, the state adjustment process includes a process for making the CPU of the reaction force CPU of the system in which the reaction force reference value θns has been set execute the learning process again together with the CPUs of the other systems while maintaining the state in which the setting has been completed. In addition, the state adjustment process may include a process for erasing the reaction force reference value θns that has been set for the reaction force CPU of the system in which the reaction force reference value θns has been set. In this case, among the reaction force CPUs, the CPU of the system that has completed setting the reaction force reference value θns is put into a state in which setting of the reaction force reference value θns is not completed, so that it can execute the learning process again together with the CPUs of the other systems. After that, the reaction force CPU repeatedly executes the control information setting process, i.e., the process after step 204. Even in this case, the reaction force CPU can only repeat the process after step 204 until the timeout condition is satisfied (step 106: YES).

[0060] <Regarding steering angle correction processing on the turning side> As shown in FIG. 5, in the steering angle correction process on the steering side, the steering CPU judges whether or not it is necessary to execute the steering angle correction process (step 302). In step 302, if the steering reference value θnt for steering could not be read in the initial check process (step 100), the steering CPU judges that it is necessary to execute the steering angle correction process. In the initial check process, the steering CPU cannot read the steering reference value θnt for steering if the steering reference value θnt is not set internally. For example, after the battery 47 is removed and replaced, the steering reference value θnt is not set internally. Similarly, in the case of a read abnormality or a write abnormality regarding the steering reference value θnt, the steering reference value θnt is not set internally.

[0061] Next, if the steering CPU was able to read out the steering reference value θnt in the initial check process (step 100) and therefore does not need to execute the steering angle correction process (step 302: NO), it ends the process and completes the steering angle correction process on the steering side. The completion of the steering side processing is notified to the reaction force CPU via local network 49. Note that the steering CPU can make a determination of step 102: YES when both the completion of the steering side processing and the receipt of a notification of the completion of the reaction force side steering angle correction processing from the reaction force CPU are satisfied.

[0062] On the other hand, if the steering CPU needs to execute steering angle correction processing (step 302: YES) because the steering reference value θnt could not be read out in the initial check processing (step 100), the steering CPU executes control information setting processing (step 304). In step 304, the control information setting processing executed by the steering CPU includes processing for referencing the rotation angle θb. The steering CPU includes processing for referencing the pinion absolute rotation angle θabp. The steering side control information setting processing includes rotation angle correction processing in which the steering CPU corrects each rotation angle θb while referring to the pinion absolute rotation angle θabp, which is correction information.

[0063] For example, as shown in Fig. 7, the rotation angle correction process includes a process of calculating the number of rotations corresponding to the pinion absolute rotation angle θabp. The rotation angle correction process includes a process of calculating a corrected pinion angle θpc obtained by correcting the rotation angle θb to an absolute rotation angle, which is an integrated rotation angle, based on the number of rotations. The rotation angle correction process includes a process of calculating a value corresponding to the rack neutral position for the corrected pinion angle θpc as a steering midpoint value θct. The steering midpoint value θct obtained in this manner is written into the steering reference value θnt by the steering CPU, i.e., each of the CPUs 61a, 61b, and set therein.

[0064] Next, the steering CPU judges whether the setting of the steering reference value θnt has been completed for both systems (step 306). In step 306, the steering CPU judges whether the setting of the steering reference value θnt has been completed for each of the CPUs 61a, 61b. The steering CPU also judges whether, among the CPUs of the systems that have completed setting the steering reference value θnt, there is a CPU of the system that has not completed the setting. During the rotation angle correction process, the CPUs 61a, 61b notify each other by inter-microcomputer communication or the like that they have completed setting the steering reference value θnt as a result of the rotation angle correction process.

[0065] The steering CPU does not execute step 306 while each of the CPUs 61a, 61b has not completed setting the steering reference value θnt. If each of the CPUs 61a, 61b has not completed setting the steering reference value θnt, the timeout condition will eventually be satisfied (step 106: YES), and the steering CPU will transition to a function-stopped state.

[0066] Next, when the setting of the steering reference value θnt for both systems is completed by each of the CPUs 61a, 61b completing the setting of the steering reference value θnt for both systems (step 306: YES), the steering CPU ends the process and completes the steering angle correction process on the steering side. After that, the completion of the processing on the steering side is notified to the reaction force CPU via the local network 49.

[0067] On the other hand, when there is a CPU of a system that has not completed setting the steering reference value θnt among the CPUs of the system that have completed setting by each of the CPUs 61a, 61b (step 306: NO), the steering CPU executes a control information adjustment process (step 308). The control information adjustment process is an adjustment process that adjusts the steering reference value θnt of the system that has not completed setting among the steering CPUs so that the steering reference value θnt that has been set in the system that has completed setting can be set. For example, the control information adjustment process includes a process of transmitting the set steering reference value θnt of the system that has completed setting the steering reference value θnt among the steering CPUs to the CPU of the system that has not completed setting the steering reference value θnt by communication between microcomputers or the like. The control information adjustment process includes a process for completing the setting of the steering reference value θnt for a CPU of a system that has not yet completed the setting of the steering reference value θnt by setting the steering reference value θnt using the steering reference value θnt received by communication between microcomputers, etc. After that, the steering CPU terminates the process and completes the steering angle correction process on the steering side, regarding each of the CPUs 61a, 61b as having completed the setting of the steering reference value θnt.

[0068] <Action of this embodiment> For example, as shown in Fig. 6, the reaction force CPUs may reach a situation where, while there are CPUs in a system that have completed setting the reaction force reference value θns by the CPUs 51a and 51b, there are CPUs in a system that have not completed the setting. Fig. 6(a) shows the state of the main CPU 51a among the reaction force CPUs. Fig. 6(b) shows the state of the sub-CPU 51b among the reaction force CPUs. The example shown here is a case where only the sub-CPU 51b among the reaction force CPUs performs a reset operation due to a temporary power drop or the like during the learning process.

[0069] The CPUs 51a and 51b both start the learning process, thereby rotating the steering wheel 3 to the right (step 402). Thereafter, while the main CPU 51a continues the learning process normally, only the sub-CPU 51b performs a reset operation.

[0070] As a result of continuing the learning process, the main CPU 51a temporarily stores the right limit position θrl because the steering wheel 3 has reached the right limit position 3a (step 404a). In response to this, the sub CPU 51b performs a reset operation (step 404b) to halt the learning process. Even if the sub CPU 51b subsequently returns from the reset operation to a state in which the control information setting process can be executed (step 406b), it cannot return to the learning process because it has halted the learning process. In other words, the sub CPU 51b determines that the learning process, i.e., the control information setting process, cannot be completed, and notifies the main CPU 51a of this fact by inter-microcomputer communication or the like.

[0071] The main CPU 51a continues the learning process, and as a result, rotates the steering wheel 3 to the left (step 406a). Furthermore, the main CPU 51a temporarily stores the left limit position θll as the steering wheel 3 reaches the left limit position 3b (step 408a), and calculates the reaction force midpoint value θcs (step 410a).

[0072] Thereafter, the main CPU 51a completes setting the reaction force reference value θns (step 412a). In contrast, the sub CPU 51b does not complete setting the reaction force reference value θns (step 412b). As a result, the reaction force CPU makes a determination of NO in step 206 (step 414) because, while there exists a main CPU 51a that has completed setting the reaction force reference value θns, there exists a sub CPU 51b that has not completed said setting. Thereafter, the reaction force CPU performs a state adjustment process to make adjustments so that each of the control information setting processes including the learning process can be executed again.

[0073] In this way, even if there is a CPU in a system in which setting of the reaction force reference value θns has not been completed, the reaction force CPU is able to complete setting of the reaction force reference value θns in the CPUs of all systems through the state adjustment process.

[0074] Similarly, as shown in Fig. 7, for example, the steering CPU may reach a situation where, while there is a CPU in a system that has completed setting the steering reference value θnt by each of CPUs 61a, 61b, there is a CPU in a system that has not completed the setting. Fig. 7(a) shows the state of main CPU 61a among the steering CPUs. Fig. 7(b) shows the state of sub-CPU 61b among the steering CPUs. The example shown here is a case where, during the rotation angle correction process, only sub-CPU 61b among the steering CPUs is unable to continue the rotation angle correction process due to a failure to refer to the rotation angle θb or pinion absolute rotation angle θabp.

[0075] Each of the CPUs 61a and 61b starts the rotation angle correction process to refer to the pinion absolute rotation angle θabp (step 502a). After that, the main CPU 61a continues the rotation angle correction process to calculate the corrected pinion angle θpc obtained by correcting the rotation angle θb based on the number of rotations corresponding to the pinion absolute rotation angle θabp (step 504a).

[0076] In response to this, the sub CPU 61b terminates the rotation angle correction process by failing to refer to the rotation angle θb or the pinion absolute rotation angle θabp (step 502b). After that, the sub CPU 61b notifies the main CPU 61a that the rotation angle correction process, i.e., the control information setting process, cannot be completed by inter-microcomputer communication or the like.

[0077] As a result of further continuing the rotation angle correction process, the main CPU 61a calculates the steering midpoint value θct (step 506a) and completes setting of the steering reference value θnt (step 508a). In contrast, the sub-CPU 61b does not complete setting of the steering reference value θnt (step 508b). As a result, the steering CPU determines step 306: NO (step 510) because there exists a sub-CPU 61b that has not completed setting the steering reference value θnt while there exists a main CPU 61a that has completed setting the steering reference value θnt. Thereafter, the steering CPU performs control information adjustment process to make adjustments so that the steering reference value θnt that has been set in the main CPU 61a can be set for the sub-CPU 61b.

[0078] In this way, even if there is a CPU in a system in which setting of the steering reference value θnt has not been completed, the steering CPU is able to complete setting of the steering reference value θnt in the CPUs of all systems through the control information adjustment process.

[0079] <Effects of the embodiment> (1-1) The reaction force CPU is adapted to complete the setting of the reaction force reference value θns in the CPUs of all systems through the state adjustment process even if there is a CPU in a system in which the setting of the reaction force reference value θns has not been completed. This is the same for the steering CPU. In other words, the steering CPU is adapted to complete the setting of the steering reference value θnt in the CPUs of all systems through the control information adjustment process. This makes it possible to prevent the reaction force CPU and the steering CPU from being unable to determine whether the setting of each reference value θns, θnt has been completed in both systems, and to prevent such a situation from occurring repeatedly. This makes it possible to prevent the period from being prolonged until the vehicle steering system 2 is powered on and control of steering the vehicle's travel becoming possible.

[0080] (1-2) The reaction force CPU can cause the CPU of the system that has completed setting of the reaction force reference value θns to execute the control information setting process including the learning process again by the state adjustment process. This allows the CPUs 51a, 51b of all systems to execute the control information setting process again, regardless of whether the setting of the reaction force reference value θns has been completed or not.

[0081] (1-3) The reaction force CPU allows all the CPUs to execute the control information setting process again even when each of the CPUs 51a, 51b of the reaction force control unit 50 sets the reaction force reference value θns for itself by rotating the steering wheel 3. In other words, it is possible to prevent the occurrence of a situation in which the steering wheel 3 cannot be rotated due to differences in internal states between the CPUs 51a, 51b.

[0082] (1-4) The steering CPU can use the steering reference value θnt that has been set in the CPU of the system that has completed setting the steering reference value θnt through the control information adjustment process to complete the setting of the steering reference value θnt for the CPU of the system that has not completed the setting. As a result, if there is a CPU of a system that has completed setting the steering reference value θnt, it is possible to complete the setting of the steering reference value θnt for the CPU of all systems.

[0083] (1-5) The steering CPU is made capable of completing the setting of the steering reference value θnt in each of the CPUs 61a, 61b of the steering control unit 60 by the control information adjustment process. This allows the CPUs of all systems to complete the setting of the steering reference value θnt even when each of the CPUs 61a, 61b sets the steering reference value θnt individually by correcting the rotation angle θb using the pinion absolute rotation angle θabp. In other words, even if there is a CPU of a system in the CPUs 61a, 61b that fails to acquire the rotation angle θb or the pinion absolute rotation angle θabp, it is possible to quickly deal with the situation.

[0084] <Other embodiments> The above embodiment may be modified as follows: In addition, the following other embodiments may be combined with each other to the extent that there is no technical contradiction.

[0085] In the reaction side control information setting process, instead of the state adjustment process, the control information adjustment process in the steering side control information setting process may be executed. In addition, the reaction side control information setting process may be configured to execute the control information adjustment process when the execution of the state adjustment process is repeated.

[0086] In the steering side control information setting process, instead of the control information adjustment process, the state adjustment process in the reaction side control information setting process may be executed. In this case, the steering side control information setting process may execute the control information adjustment process when the execution of the state adjustment process is repeated.

[0087] In the control information setting process, it is sufficient that the reaction force side control information setting process is configured to execute at least the state adjustment process. In other words, the turning side control information setting process may be configured not to execute the control information adjustment process. In the case of the other embodiments described herein, the turning control unit 60 may be configured as a single system.

[0088] In the control information setting process, it is sufficient that the control information setting process on the steering side is configured to execute at least the control information adjustment process. In other words, the control information setting process on the reaction force side may be configured not to execute the state adjustment process. In the case of the other embodiments described herein, the reaction force control unit 50 may be configured as a single system.

[0089] The method of internally setting the reaction force reference value θns is not limited to a learning operation, and may be changed as appropriate, for example, by having the operator manually set it. The learning process may be a process in which the steering wheel 3 is first turned left and then turned right.

[0090] The learning process may include a process for temporarily storing one of the limit positions θrl, θll. In other words, the process related to the learning operation may not include a process for temporarily storing one of the limit positions θrl, θll. For example, if the process for temporarily storing the right limit position θrl is included, the reaction force CPU may calculate, as the reaction force midpoint value θcs, a value obtained by subtracting half the value of the rotation range between the right limit position 3a and the left limit position 3b from the right limit position θrl.

[0091] The learning process may include a process for determining the validity of the reaction force midpoint value θcs. In the learning process, the fact that the steering wheel 3 has reached each limit position 3a, 3b may be determined by at least monitoring the currents iu1, iv1, and iw1. In addition to the above embodiment, the fact that the steering wheel 3 has reached each limit position 3a, 3b may be determined by taking into account other parameters. For example, the other parameters may be the amount of change in the currents iu1, iv1, and iw1, the amount of change in the angular velocity ωs, and the time since the steering wheel 3 started to rotate.

[0092] The amount of displacement of the steering wheel 3 is not limited to an amount calculated based on an integration process of the rotation angle θa. For example, it may be a detection value of a steering angle sensor that directly detects the rotation angle of the steering shaft 11. Note that the steering angle sensor may be provided, for example, between the steering wheel 3 and the torque sensor 41 on the steering shaft 11.

[0093] When the above-mentioned steering angle sensor is used in addition to the steering angle θs, the reaction force side control information setting process may be configured to execute a rotation angle correction process in which the reaction force CPU corrects each rotation angle θa while referring to the detection result of the steering angle sensor instead of the learning process. In the case of the other embodiments described herein, the reaction force side control information setting process may be configured to execute a control information adjustment process in the steering side control information setting process instead of the state adjustment process.

[0094] The steering side control information setting process may be configured to execute a learning process in which the steering CPU acquires values ​​while moving the rack shaft 22, i.e., the steered wheels 5, to the left and right rack ends 25, respectively, instead of the rotation angle correction process. In the case of the other embodiments described herein, the steering side control information setting process may be configured to execute a state adjustment process in the reaction side control information setting process, instead of the control information adjustment process.

[0095] The number of systems of the reaction force control unit 50 may be three or more. Even in this case, the above embodiment can be applied. The same applies to the number of systems of the steering control unit 60.

[0096] The steering actuator 12 does not necessarily need to include the steering side reduction mechanism 14. The reaction motor 13 is not limited to a three-phase brushless motor. For example, it may be a DC motor with brushes. The other embodiments described herein can be similarly applied to the steering motor 32.

[0097] The pinion angle θp may be obtained by converting a detection value of the movement amount of the rack shaft 22. In this case, the control amount and the like related to the pinion angle θp are converted by the detection value of the movement amount of the rack shaft 22.

[0098] The operating member operated by the driver to steer the vehicle is not limited to the steering wheel 3. For example, it may be a joystick. While steering unit 6 transmits the rotation of steering motor 32 to conversion mechanism 34 via transmission mechanism 33, the present invention is not limited to this. For example, steering unit 6 may be configured so that the rotation of steering motor 32 is transmitted to conversion mechanism 34 via a gear mechanism. Also, steering unit 6 may be configured so that steering motor 32 directly rotates conversion mechanism 34. Furthermore, steering unit 6 may be configured to include a second rack-and-pinion mechanism, and the rotation of steering motor 32 is converted into reciprocating motion of rack shaft 22 by the second rack-and-pinion mechanism.

[0099] The steering unit 6 is not limited to a configuration in which the right steered wheels 5 and the left steered wheels 5 are linked together. In other words, the right steered wheels 5 and the left steered wheels 5 may be independently controlled.

[0100] In the above embodiment, the vehicle steering system 2 has a linkless structure in which the steering unit 4 and the steered unit 6 are mechanically separated at all times, but the present invention is not limited to this, and may have a structure in which the steering unit 4 and the steered unit 6 can be mechanically separated by a clutch, for example. Also, the vehicle steering system 2 is not limited to a steer-by-wire type steering device, and may be one equipped with an electric power steering device that applies motor torque to the steering shaft 11 or the rack shaft 22. [Explanation of symbols]

[0101] 1...Steering control device 2...Vehicle steering system 3. Steering wheel 4…Steering unit 5…Steering wheel 6...Steering unit 50...Reaction force control unit (steering angle control unit) 51a…Main CPU (control circuit) 51b...Sub-CPU (control circuit) 60...Steering control unit (steering angle control unit) 61a…Main CPU (control circuit) 61b...Sub-CPU (control circuit) RSa…Main lineage RSb…Sub-lineage TSa…Main lineage TSb: Sub-strain

Claims

1. A steering control device applied to a vehicle steering system that steers a vehicle, a steering angle control unit that executes control by referring to a steering angle variable obtained in relation to the steering, the steering angle control unit is configured to execute a control information setting process for setting control information that is a value indicating that the vehicle is traveling straight and that serves as a reference for the steering angle variable, The control information setting process is a process for enabling control of steering the traveling of the vehicle by completing setting of the control information after the vehicle steering system is powered on, The steering angle control unit includes a plurality of control circuits that control the steering angle variables in a mutually related manner, the control circuits of the plurality of systems are configured to be able to control steering of the vehicle on the condition that the setting of the control information is completed in all of the control circuits while executing the control information setting process respectively, The control information setting process is a steering control device that includes an adjustment process that makes adjustments so that the setting of the control information in all of the control circuits can be completed when there are control circuits in which the setting of the control information has been completed and there are control circuits in which the setting of the control information has not been completed.

2. the adjustment process includes a state adjustment process of adjusting a state of the control circuit that has completed setting the control information so as to transition the state to a state in which the control information setting process can be executed again, The steering control device according to claim 1 , wherein the control circuits of the plurality of systems are capable of executing the control information setting process again for each of the plurality of systems after the adjustment by the state adjustment process.

3. The vehicle steering system has a structure in which a power transmission path between a steering unit steered by a steering wheel of the vehicle and a steering unit that operates to steer steered wheels of the vehicle is separated, The steering angle control unit includes a reaction force control unit having the control circuits of the plurality of systems, the reaction force control unit controls an operation of the steering unit so as to apply a steering reaction force to the steering wheel by referring to a steering variable, which is the steering angle variable obtained from the steering unit in relation to the steering; the plurality of control circuits of the reaction force control unit each executes the control information setting process based on a value acquired while rotating the steering wheel to a limit position in a first direction or a second direction, The steering control device according to claim 2 , wherein the control circuits of the plurality of systems of the reaction force control section are capable of executing the state adjustment process while respectively executing the control information setting process.

4. the adjustment process includes a control information adjustment process for adjusting the control circuit that has not yet completed the setting of the control information so as to complete the setting of the control information by setting the control information using the control information that has been set in the control circuit that has completed the setting of the control information; The steering control device according to claim 1 , wherein the control circuits of the plurality of systems are capable of completing setting of the control information in all of the control circuits after the adjustment by the control information adjustment process.

5. The vehicle steering system has a structure in which a power transmission path between a steering unit steered by a steering wheel of the vehicle and a steering unit that operates to steer steered wheels of the vehicle is separated, The steering angle control unit includes a steering control unit having the control circuits of the plurality of systems, the steering control unit controls the operation of the steering unit so as to apply a steering force to the steered wheels by referring to a steering variable that is the steering angle variable obtained from the steering unit in relation to the steering; The control circuits of the plurality of systems of the steering control unit execute the control information setting process on the basis of correcting the steering variables using correction variables acquired from the respective steering units in addition to the steering variables, The steering control device according to claim 4 , wherein the control circuits of the plurality of systems of the steering control section are capable of executing the control information adjustment process while respectively executing the control information setting process.

6. The vehicle steering system has a structure in which a power transmission path between a steering unit steered by a steering wheel of the vehicle and a steering unit that operates to steer steered wheels of the vehicle is separated, The steering angle control unit includes a reaction force control unit having the control circuits of the plurality of systems, and a steering control unit having the control circuits of the plurality of systems, the reaction force control unit controls an operation of the steering unit so as to apply a steering reaction force to the steering wheel by referring to a steering variable related to the steering and obtained from the steering unit; the steering control unit controls the operation of the steering unit so as to apply a steering force to the steered wheels by referring to a steering variable obtained from the steering unit in relation to the steering; The adjustment process includes: a state adjustment process for adjusting a state of the control circuit that has completed the setting of the control information so as to transition the state to a state in which the control information setting process can be executed again; a control information adjustment process for adjusting the control circuit that has not yet completed the setting of the control information, by using the control information that has been set in the control circuit that has completed the setting of the control information, so as to complete the setting of the control information; The plurality of control circuits of the reaction force control unit are capable of executing the state adjustment process while executing the control information setting process for each of them, and when executing the state adjustment process, the control information setting process can be executed again for each of them after the adjustment by the state adjustment process; 2. A steering control device as described in claim 1, wherein the control circuits of the multiple systems of the steering control unit are capable of executing the control information adjustment process while respectively executing the control information setting process, and when the control information adjustment process is executed, the setting of the control information in all of the control circuits can be completed after the adjustment by the control information adjustment process.

7. A steering control method applied to a vehicle steering system that steers a vehicle, comprising: The steering control method includes a steering angle control process for executing control by referring to a steering angle variable obtained in relation to the steering, the steering angle control process includes setting control information that is a value indicating that the vehicle is traveling straight and that serves as a reference for the steering angle variable; Setting the control information is a process for enabling control of steering the traveling of the vehicle by completing setting of the control information after the vehicle steering system is powered on, the steering angle control process includes processes executed by a plurality of control circuits that control the steering angle variables in a mutually related manner, The process executed by the control circuits of the plurality of systems is configured to enable control of steering the vehicle on condition that the setting of the control information in all of the control circuits is completed while the control information is set in each of the plurality of control circuits, A steering control method in which setting the control information includes, when some control circuits have completed setting the control information while other control circuits have not completed setting the control information, making adjustments so that setting of the control information can be completed in all of the control circuits.

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