Vehicle steering device and vehicle system

Abstract

A vehicle steering device (1) is provided with a steering control unit (60) for controlling a steering motor unit (4) that includes: a steering motor (13) connected to a steering shaft (11); and a steering motor angle sensor (42) that detects a steering motor angle (θa). The vehicle steering device is provided with a rotation angle processing unit (52) that includes: a non-volatile memory (52b) that stores a reference value (N) serving as a reference for an integrated angle (θg) integrated in accordance with the rotation of the steering shaft; and an absolute angle calculation unit (52a) that calculates an absolute angle (θabs) on the basis of the integrated angle and the reference value. The steering control unit executes processing for calculating a steering control angle (θs) in the course of controlling the operation of the steering motor. The processing for calculating the steering control angle includes processing for calculating the steering control angle on the basis of the reference value and the absolute angle obtained from the rotation angle processing unit, and the steering motor angle obtained from the steering motor angle sensor.

Description

Vehicle steering device and vehicle system

[0001] The present disclosure relates to a vehicle steering device and a vehicle system.

[0002] For example, Patent Document 1 (JP-A-2003-134999) describes a steering device including a steering wheel connected to a steering shaft, a reaction motor that generates a steering reaction force on the steering shaft, and a reaction control unit that controls the operation of the reaction motor. The reaction control unit stores a steering angle midpoint used to control the behavior of the steering device in a memory. The memory may lose the steering angle midpoint due to a power outage caused by, for example, removing or attaching a battery. After the steering angle midpoint is lost, the steering angle midpoint is re-stored in the memory. In this case, the reaction control unit calculates the steering angle midpoint by controlling the reaction motor to move the steering wheel to a first operating end and then reverse the movement to a second operating end (hereinafter referred to as "lock-to-lock operation"). The reaction control unit stores the calculated steering angle midpoint in the memory.

[0003] Japanese Patent Application Laid-Open No. 2021-195084

[0004] In the above-mentioned Patent Document 1, if the steering angle midpoint stored in the memory of the reaction force control unit disappears, it becomes difficult to perform smooth control of the steering device.

[0005] A vehicle control device according to one aspect of the present disclosure includes a steering control unit configured to control a steering motor unit including a steering motor connected to a steering shaft to generate a steering force on the steering shaft to which a steering wheel is connected and a steering motor angle sensor that detects a steering motor angle, which is the angle of a rotation shaft of the steering motor, as a relative angle, and a rotation angle processing unit including a non-volatile memory configured to store a reference value that serves as a reference for an integrated angle that is integrated in accordance with the rotation of the steering shaft, and an absolute angle calculation unit configured to calculate an absolute angle based on the integrated angle and the reference value. The steering control unit is configured to execute a process of calculating a steering control angle used to control steering of the vehicle while controlling the operation of the steering motor. The process of calculating the steering control angle includes a process of calculating the steering control angle based on the reference value and the absolute angle obtained from the rotation angle processing unit and the steering motor angle obtained from the steering motor angle sensor.

[0006] According to another aspect of the present disclosure, there is provided a vehicle system including a vehicle steering device, a vehicle control device separate from the vehicle steering device, and a vehicle network connecting the vehicle steering device and the vehicle control device so as to enable communication between them. The vehicle steering device is configured to execute a process of controlling a steering motor unit including a steering motor connected to a steering shaft to generate a steering force on the steering shaft to which a steering wheel is connected and a steering motor angle sensor that detects a steering motor angle, which is the rotation angle of the steering motor, as a relative angle, and a process of calculating an absolute angle based on an integrated angle integrated in accordance with the rotation of the steering shaft and a reference value serving as a reference for the integrated angle. The vehicle control device includes a non-volatile memory that stores the reference value. The process of controlling the steering motor unit includes a process of calculating a steering control angle used to control the steering of the vehicle while controlling the operation of the steering motor. The process of calculating the absolute angle includes a process of obtaining the reference value from the vehicle control device by communication via the vehicle network. The process of calculating the steering control angle includes a process of calculating the steering control angle based on the reference value obtained from the vehicle control device by communication via the vehicle network, the absolute angle obtained in the process of calculating the absolute angle, and the steering motor angle obtained from the steering motor angle sensor.

[0007] FIG. 1 is a diagram showing the configuration of a steering device applied to a vehicle steering device and a vehicle system according to a first embodiment. FIG. 2 is a diagram showing the configuration of the vehicle system of FIG. 1. FIG. 3 is a diagram explaining a method of calculating a steering control angle for the vehicle steering device of FIG. 2. FIG. 4 is a diagram explaining a vehicle assembly process for the steering device of FIG. 1. FIG. 5 is a diagram explaining the flow of a start-up sequence process for the vehicle steering device of FIG. 2. FIG. 6 is a diagram explaining a method of calculating an absolute angle for a vehicle steering device according to a second embodiment. FIG. 7 is a diagram explaining a method of calculating a steering angle for a vehicle steering device according to a third embodiment. FIG. 8 is a diagram showing the configuration of a vehicle system according to a fourth embodiment.

[0008] <First Embodiment> A first embodiment will now be described with reference to the drawings. As shown in FIG. 1 , a vehicle steering device 1 controls a steering device 2. The steering device 2 is, for example, a steer-by-wire type vehicle steering device. The steering device 2 includes a steering unit 4 and a steering unit 6. The steering unit 4 is steered by a driver via a steering wheel 3 of the vehicle, which is an operating member. The steering unit 6 steers left and right steerable wheels 5 of the vehicle in accordance with steering input to the steering unit 4 by the driver. In the steering device 2, for example, a power transmission path between the steering unit 4 and the steering unit 6 is mechanically separated at all times. A power transmission path between a steering actuator 12 (described later) and a steering actuator 31 (described later) is mechanically separated at all times.

[0009] The steering unit 4 includes a steering shaft 11 and a steering actuator 12. The steering wheel 3 is connected to the steering shaft 11. The steering shaft 11 has a torsion bar 41a, an input shaft 41b, and an output shaft 41c. The input shaft 41b is the portion of the steering shaft 11 to which the steering wheel 3 is connected. The output shaft 41c is the portion of the steering shaft 11 to which the steering actuator 12 is connected. The torsion bar 41a connects the input shaft 41b and the output shaft 41c to each other.

[0010] The first end 11a of the steering shaft 11 has a stopper mechanism 11c. The first end 11a is the tip of the output shaft 41c and is the end of the steering shaft 11 opposite the second end 11b to which the steering wheel 3 is connected. The second end 11b is the tip of the input shaft 41b. The stopper mechanism 11c 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 11c. For example, the steering wheel 3 is rotatable within a rotation range between a right rotation limit position 3a and a left rotation limit position 3b.

[0011] The steering actuator 12 has a steering motor unit 13A and a steering reduction mechanism 14. The steering motor unit 13A includes a steering motor 13, which is a drive source of the steering actuator 12, and a steering motor angle sensor 42. The steering motor 13 is a reaction motor that applies a steering reaction force, which is a force that resists the steering by the driver, to the steering shaft 11 as a steering force. The steering motor 13 is connected to the output shaft 41c via the steering reduction mechanism 14, which is, for example, a worm and wheel. The steering motor 13 is, for example, a three-phase brushless motor.

[0012] The steering unit 6 includes a pinion shaft 21, a steering shaft 22, and a rack housing 23. The pinion shaft 21 and the steering shaft 22 are connected at 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 steering shaft 22. In other words, 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 houses the rack-and-pinion mechanism 24. A first end of the pinion shaft 21 is housed inside the rack housing 23 and is connected to the steering shaft 22. A second end of the pinion shaft 21, opposite the first end, protrudes from the rack housing 23. Both ends of the steering shaft 22 protrude from both axial ends of the rack housing 23. Tie rods 26 are connected to both ends of the steered shaft 22 via rack ends 25 made up of ball joints. The ends of the tie rods 26 are connected to knuckles to which the left and right steered wheels 5 are attached, respectively.

[0013] The steering unit 6 includes a steering actuator 31. The steering actuator 31 has a steering motor unit 32A, a transmission mechanism 33, and a conversion mechanism 34. The steering motor unit 32A includes a steering motor 32 that is the drive source of the steering actuator 31, and a steering motor angle sensor 43. The steering motor 32 applies a steering force that steers the steered wheels 5 to the steering 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 steering shaft 22 via the conversion mechanism 34, which is, for example, a ball screw mechanism. The steering motor 32 is, for example, a three-phase brushless motor.

[0014] In the steering device 2 configured in this manner, the steering actuator 31 applies a motor torque to the steering shaft 22 as a steering force in response to the steering operation by the driver, thereby changing the steering angle θi of the steered wheels 5. At this time, the steering actuator 12 applies a steering reaction force that resists the steering by the driver to the steering wheel 3. As a result, in the steering device 2, the torque Th required to steer the steering wheel 3 is changed by the steering reaction force, which is the motor torque applied from the steering actuator 12. In other words, a sense of control can be given to the driver who is steering the steering wheel 3.

[0015] The reason for providing pinion shaft 21 is to support steered shaft 22 together with pinion shaft 21 inside rack housing 23. A support mechanism provided in steering device 2 supports steered shaft 22 so that it can move along its axial direction, and presses it toward pinion shaft 21. In this way, steered shaft 22 is supported inside rack housing 23. However, another support mechanism may be provided that supports steered shaft 22 in rack housing 23 without using pinion shaft 21.

[0016] 1, the steering motor 13 and the turning motor 32 are connected to the vehicle steering device 1. The vehicle steering device 1 controls the operation of the steering motor 13 and the turning motor 32.

[0017] Detection results of various sensors are input to the vehicle steering system 1. The various sensors include, for example, a torque rotation angle sensor 41, a steering motor angle sensor 42, a turning motor angle sensor 43, and a vehicle speed sensor 44.

[0018] The torque rotation angle sensor 41 is provided on a portion of the steering shaft 11 closer to the steering wheel 3 than the steering reduction mechanism 14. The torque rotation angle sensor 41 outputs a torque electric signal St, a first rotation angle electric signal Sg1, and a second rotation angle electric signal Sg2. The torque electric signal St is an electric signal corresponding to the rotation of the steering shaft 11 and is used to calculate a torque Th. The torque Th is a torque acting on the torsion bar 41a due to the driver's steering operation, and is, for example, a positive value when the steering shaft 11 is steered rightward and a negative value when the steering shaft 11 is steered leftward. The first rotation angle electric signal Sg1 and the second rotation angle electric signal Sg2 are electric signals corresponding to the rotation of the steering shaft 11 and are used to calculate an absolute angle θabs. The absolute angle θabs is an angle corresponding to the rotation of the steering shaft 11, and is, for example, a positive value when the steering shaft 11 is steered rightward and a negative value when the steering shaft 11 is steered leftward. The output of various electric signals by the torque rotation angle sensor 41 will be described later.

[0019] The steering motor angle sensor 42 is provided on the steering motor 13. The steering motor angle sensor 42 detects the steering motor angle θa as a relative angle within a range of 360°. The steering motor angle θa is the rotation angle of the rotary shaft of the steering motor 13 and is used to calculate the steering control angle θs. The steering control angle θs is an angle used to control the steering of the vehicle, and is, for example, a positive value when the vehicle is steered to the right and a negative value when the vehicle is steered to the left. The steering motor 13 and the steering shaft 11 are linked via a steering reduction mechanism 14. Therefore, there is a correlation between the steering motor angle θa and the rotation angle of the steering shaft 11.

[0020] Steering motor angle sensor 43 is provided on steering motor 32. Steering motor angle sensor 43 detects steering motor angle θb as a relative angle within a range of 360°. Steering motor angle θb is the angle of the rotation shaft of steering motor 32 and is used to calculate pinion angle θp. Pinion angle θp is the rotation angle of pinion shaft 21 and, for example, is a positive value when steering to the right and a negative value when steering to the left. Steering motor 32 and pinion shaft 21 are linked via transmission mechanism 33, conversion mechanism 34, and rack-and-pinion mechanism 24. Therefore, there is a correlation between steering motor angle θb and pinion angle θp. Therefore, pinion angle θp can be determined based on steering motor angle θb. Pinion shaft 21 is also meshed with steering shaft 22. Therefore, there is also a correlation between pinion angle θp and the amount of movement of steering shaft 22. The pinion angle θp is angle information that indicates the steered state of the steered wheels 5, and is a value that reflects the steered angle θi, which is the steered position of the steered wheels 5.

[0021] The vehicle speed sensor 44 is provided in the vehicle. The vehicle speed sensor 44 detects the vehicle speed V, which is the traveling speed of the vehicle. The vehicle speed V is acquired by each device of the vehicle, including the vehicle steering device 1, via the vehicle network 8, which is provided in the vehicle system 100 and will be described later.

[0022] A power supply system 46 is connected to the vehicle steering device 1. The power supply system 46 includes a battery 47. The battery 47 is a secondary battery mounted on the vehicle, and serves as the power source for supplying power to operate the steering motor 13 and the turning motor 32. The battery 47 serves as the power source for supplying power to operate the vehicle steering device 1.

[0023] A vehicle start switch 48 ("SW" in FIG. 1), such as an ignition switch, is provided between the vehicle steering device 1 and the battery 47. The start switch 48 is provided midway on the power feeder L2, which branches off from the power feeder L1, one of two power feeders L1, L2 that connect the vehicle steering device 1 and the battery 47. The start switch 48 is operated when activating various functions to activate a drive source for running the vehicle, such as an engine, to enable operation of the vehicle. The conduction of the power feeder L2 is turned on and off through operation of the start switch 48. For example, 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 device 1 depending on the operating state of the vehicle steering device 1.

[0024] <Function of the Torque Rotation Angle Sensor> As shown in FIG. 1 , the torque rotation angle sensor 41 includes a torque magnetic sensor 41d, a first rotation angle magnetic sensor 41e, and a second rotation angle magnetic sensor 41f. A cylindrical multi-pole magnet that rotates in conjunction with the input shaft 41b is attached to the input shaft 41b. The torque magnetic sensor 41d outputs a torque electric signal St. The torque electric signal St is an electric signal corresponding to changes in the magnetic flux of the cylindrical multi-pole magnet that rotates in conjunction with the input shaft 41b. A first rotation angle detection gear and a second rotation angle detection gear that rotate in conjunction with the output shaft 41c are attached to the output shaft 41c. The first rotation angle magnetic sensor 41e is attached, for example, integrally with the first rotation angle detection gear so as to correspond to the output shaft 41c. The first rotation angle magnetic sensor 41e outputs a first rotation angle electric signal Sg1. The first rotation angle electric signal Sg1 is an electric signal corresponding to a change in magnetic flux generated from a first rotation angle detection magnet attached to a first rotation angle detection gear that rotates in conjunction with the output shaft 41c. The first rotation angle electric signal Sg1 is an electric signal corresponding to the output shaft 41c of the steering shaft 11. The second rotation angle magnetic sensor 41f is attached, for example, integrally to the second rotation angle detection gear so as to correspond to the output shaft 41c. The second rotation angle magnetic sensor 41f outputs a second rotation angle electric signal Sg2. The second rotation angle electric signal Sg2 is an electric signal corresponding to a change in magnetic flux generated from a second rotation angle detection magnet attached to a second rotation angle detection gear that rotates in conjunction with the output shaft 41c. The second rotation angle electric signal Sg2 is an electric signal corresponding to the output shaft 41c of the steering shaft 11.

[0025] The torque magnetic sensor 41d, the first rotation angle magnetic sensor 41e, and the second rotation angle magnetic sensor 41f are, for example, Hall sensors using Hall elements. Furthermore, among the torque rotation angle sensors 41, the resolution of the first rotation angle magnetic sensor 41e and the second rotation angle magnetic sensor 41f is lower than the resolution of the steering motor angle sensor 42. In this case, the accuracy of the absolute angle θabs obtained from the first rotation angle magnetic sensor 41e and the second rotation angle magnetic sensor 41f is lower than the accuracy of the steering control angle θs obtained from the steering motor angle sensor 42.

[0026] <Details of Vehicle System and Vehicle Steering Device> As shown in FIGS. 1 and 2 , the vehicle system 100 includes a vehicle steering device 1 , a vehicle network 8 , and a vehicle control device 9 .

[0027] The vehicle network 8 is mounted on the vehicle steering device 1, i.e., the vehicle on which the steering device 2 is mounted. The vehicle network 8 is, for example, an in-vehicle communication device such as a Controller Area Network (CAN, registered trademark). The vehicle network 8 communicatively connects the torque rotation angle processing unit 50, the reaction force control unit 60, the turning control unit 70, and the vehicle control device 9. The torque rotation angle processing unit 50, the reaction force control unit 60, the turning control unit 70, and the vehicle control device 9 can communicate with each other via the vehicle network 8.

[0028] The vehicle control device 9 is mounted on the vehicle together with the vehicle steering device 1, i.e., the steering device 2. The vehicle control device 9 is, for example, a device that controls a drive system related to vehicle traveling or a device that controls a brake system related to vehicle braking. The vehicle control device 9 has a vehicle CPU 91. The vehicle CPU 91 receives a signal including the absolute angle θabs and the midpoint N. The absolute angle θabs and the midpoint N are signals obtained from the torque rotation angle processing unit 50, i.e., the rotation angle processing unit 52, via the vehicle network 8. The vehicle CPU 91 executes processing to calculate a control amount for controlling the device that controls the drive system related to vehicle traveling or the brake system related to vehicle braking, based on the absolute angle θabs and the midpoint N.

[0029] As shown in FIG. 2 , vehicle steering device 1 has torque rotation angle processing unit 50, reaction force control unit 60, and turning control unit 70. Torque rotation angle processing unit 50 and reaction force control unit 60 are connected to each other so as to be able to communicate with each other via vehicle network 8. Torque rotation angle processing unit 50 and turning control unit 70 are connected to each other so as to be able to communicate with each other via vehicle network 8. Reaction force control unit 60 and turning control unit 70 are connected to each other so as to be able to communicate with each other via a first local network 81. First local network 81 is, for example, a first communication device for a device such as serial communication. Torque rotation angle processing unit 50 and reaction force control unit 60 are connected to each other so as to be able to communicate with each other via a second local network 82. Second local network 82 is, for example, a second communication device for a device such as serial communication.

[0030] More specifically, as shown in FIG. 2 , the torque rotation angle processing unit 50 has a torque calculation unit 51 and a rotation angle processing unit 52. The torque calculation unit 51 has a torque CPU 51a. The torque magnetic sensor 41d is connected to the torque calculation unit 51. The torque CPU 51a receives the torque electric signal St. The torque CPU 51a executes a process to calculate the torque Th acting on the torsion bar 41a based on the torque electric signal St. The torque CPU 51a then outputs the torque Th obtained through the process of calculating the torque Th via the second local network 82.

[0031] The rotation angle processing unit 52 has a rotation angle CPU 52a and a nonvolatile memory 52b. The nonvolatile memory 52b stores a midpoint N, a right end angle θre, and a left end angle θle. The midpoint N is a value that indicates, for example, the neutral position of the steering wheel 3, i.e., the steering shaft 11, when the vehicle is traveling straight. The right end angle θre is a value that indicates the right rotation limit position 3a of the steering wheel 3, i.e., the right end position of the steering shaft 11. The left end angle θle is a value that indicates the left rotation limit position 3b of the steering wheel 3, i.e., the left end position of the steering shaft 11. The process of storing the midpoint N, the right end angle θre, and the left end angle θle in the nonvolatile memory 52b will be described later.

[0032] The first rotation angle magnetic sensor 41e and the second rotation angle magnetic sensor 41f are connected to the rotation angle processing unit 52. The first rotation angle electric signal Sg1 and the second rotation angle electric signal Sg2 are input to the rotation angle CPU 52a. The rotation angle CPU 52a executes processing to calculate the absolute angle θabs based on the first rotation angle electric signal Sg1 and the second rotation angle electric signal Sg2.

[0033] As shown in FIG. 3 , in the rotation angle CPU 52a, the process of calculating the absolute angle θabs includes a process of calculating a relative angle of the first rotation angle detection gear rotation angle θg1 within a range of 360° based on the first rotation angle electrical signal Sg1. The first rotation angle detection gear rotation angle θg1 is a value indicating the rotation angle of the first rotation angle detection gear. The process of calculating the absolute angle θabs also calculates a second rotation angle detection gear rotation angle θg2 as a relative angle within a range of 360° based on the second rotation angle electrical signal Sg2. The second rotation angle detection gear rotation angle θg2 is a value indicating the rotation angle of the second rotation angle detection gear. The first rotation angle detection gear and the second rotation angle detection gear are designed to have different numbers of teeth. Therefore, an angle difference occurs between the first rotation angle detection gear rotation angle θg1 and the second rotation angle detection gear rotation angle θg2 due to the difference in the number of teeth. In other words, the process of calculating the absolute angle θabs includes a process of calculating the integrated angle θg, which is integrated in accordance with the rotation of the steering shaft 11, by taking into account the angle difference between the first rotation angle detection gear rotation angle θg1 and the second rotation angle detection gear rotation angle θg2.

[0034] Furthermore, the process of calculating the absolute angle θabs includes a process of converting the integrated angle θg into an absolute angle based on the neutral position of the steering shaft 11, using the integrated angle θg and the midpoint N stored in the non-volatile memory 52b. Thus, the rotation angle CPU 52a calculates the absolute angle θabs, which is the difference between the integrated angle θg and 0°, by setting the value of the integrated angle θg corresponding to the midpoint N to 0°. The integrated angle θg and the absolute angle θabs are calculated by a process using the first rotation angle electric signal Sg1 and the second rotation angle electric signal Sg2, which are electric signals corresponding to the output shaft 41c, and therefore are the rotation angle corresponding to the output shaft 41c. The rotation angle CPU 52a then outputs the absolute angle θabs obtained through the process of calculating the absolute angle θabs via the vehicle network 8. The rotation angle CPU 52a also outputs the absolute angle θabs, as well as the midpoint N, right end angle θre, and left end angle θle stored in the nonvolatile memory 52b, via the vehicle network 8.

[0035] In this embodiment, the process of calculating the torque Th executed by the torque CPU 51a is an example of a torque calculation unit. The process of calculating the absolute angle θabs executed by the rotation angle CPU 52a is an example of an absolute angle calculation unit. The midpoint N, the right end angle θre, and the left end angle θle stored in the nonvolatile memory 52b are examples of reference values ​​that serve as the basis for the integrated angle θg.

[0036] 2, the reaction force control unit 60 has a reaction force CPU 61 and a volatile memory 62. The midpoint N, the right end angle θre, and the left end angle θle are stored in the volatile memory 62. The process for storing the midpoint N, the right end angle θre, and the left end angle θle in the volatile memory 62 will be described later.

[0037] The reaction force CPU 61 receives as input the steering motor angle θa and the absolute angle θabs. The steering motor angle θa is a signal obtained from the steering motor angle sensor 42. The absolute angle θabs is a signal obtained from the torque rotation angle processing unit 50, i.e., the rotation angle processing unit 52, via the vehicle network 8. The reaction force CPU 61 executes processing to calculate the steering control angle θs based on the steering motor angle θa, the absolute angle θabs, and the midpoint N.

[0038] As shown in FIG. 3, in the reaction force CPU 61, the process of calculating the steering control angle θs includes a process of converting the steering motor angle θa into an integrated angle including a range exceeding 360° by counting the number of rotations of the steering motor 13 based on the absolute angle θabs.

[0039] Furthermore, the process of calculating the steering control angle θs includes a process of converting the integrated steering motor angle θa into an absolute angle using the integrated steering motor angle θa and the midpoint N stored in the volatile memory 62, with reference to the neutral position of the steering shaft 11. As a result, the reaction force CPU 61 sets the value of the integrated steering motor angle θa corresponding to the midpoint N to 0°, thereby calculating the steering control angle θs, which is the difference between the integrated steering motor angle θa and 0°.

[0040] The reaction force CPU 61 also receives inputs of signals including the torque Th and the vehicle speed V in addition to the steering motor angle θa and absolute angle θabs. The torque Th is a signal obtained from the torque calculation unit 51 via the second local network 82. The vehicle speed V is a signal obtained from the vehicle speed sensor 44 via the vehicle network 8. The reaction force CPU 61 executes processing to calculate a control variable for controlling the operation of the steering motor 13 based on signals including the torque Th, a steering control angle θs obtained based on the steering motor angle θa and absolute angle θabs, and the vehicle speed V. In this manner, vehicle steering control by the steering motor 13 in accordance with the driver's steering is realized. In addition, the processing in the reaction force CPU 61 to calculate a control variable for controlling the operation of the steering motor 13 includes processing to output the steering control angle θs used to control the operation of the steering motor 13 to the steering control unit 70 via the first local network 81. In this embodiment, the reaction force control unit 60 is an example of a steering control unit.

[0041] As shown in FIG. 2 , steering control unit 70 has a steering CPU 71. Steering control unit 70 receives as input signals including steering control angle θs, steering motor angle θb, and vehicle speed V. Steering control angle θs is a signal obtained from reaction force control unit 60, i.e., reaction force CPU 61, via first local network 81. Steering motor angle θb is a signal obtained from steering motor angle sensor 43. Vehicle speed V is a signal obtained from vehicle speed sensor 44 via vehicle network 8. Steering CPU 71 executes processing to calculate a control amount for controlling the operation of steering motor 32, based on the signals including steering control angle θs, vehicle speed V, and steering motor angle θb. In this way, steering control of left and right steered wheels 5 by steering motor 32 in accordance with the driver's steering is achieved. Furthermore, in steering CPU 71, the process of calculating a control variable for controlling the operation of steering motor 32 includes a process of calculating a steering control angle θp* based on steering control angle θs and vehicle speed V. The steering control angle θp* is a target value for the amount of rotation of pinion shaft 21. For example, the larger the steering control angle θs is and the smaller the vehicle speed V is, the smaller the value of steering control angle θp* becomes. Furthermore, the process of calculating a control variable for controlling the operation of steering motor 32 includes a process of calculating a control variable for controlling the operation of steering motor 32 by feedback control of the steering control angle θp* and pinion angle θp calculated based on steering motor angle θb.

[0042] <Storage Processing in Vehicle Assembly Process> As shown in Fig. 4, the process for storing the midpoint N, the right end angle θre, and the left end angle θle in the non-volatile memory 52b is executed in the vehicle assembly process. More specifically, the vehicle assembly process uses a command device 200, the steering unit 4, and the torque rotation angle processing unit 50. The command device 200 is connected to the steering unit 4 and the torque rotation angle processing unit 50. The command device 200 is, for example, software that runs on a computer and accepts operations by an operator through a computer interface. The operator can operate the command device 200 by operating the computer interface.

[0043] The command device 200 executes processing related to the lock-to-lock operation based on the operator's operation. The lock-to-lock operation includes automatically rotating the steering wheel 3 to the left or right. The lock-to-lock operation includes, for example, a first operation in which the steering wheel 3 is automatically rotated to the right until it reaches the right rotation limit position 3a. The lock-to-lock operation also includes, for example, a second operation in which the steering wheel 3 is automatically rotated to the left until it reaches the left rotation limit position 3b.

[0044] In command device 200, the processing related to the lock-to-lock operation includes processing for instructing the reaction force CPU 61 to perform the lock-to-lock operation. The processing for instructing the execution of the lock-to-lock operation includes processing for outputting a first operation command signal for instructing the execution of a first operation, and processing for outputting a second operation command signal for instructing the execution of a second operation.

[0045] First, in the vehicle assembly process, the command device 200 outputs a first operation command signal to the reaction force CPU 61 to instruct the execution of a first operation. When the reaction force CPU 61 receives the first operation command signal, it executes a process to calculate a control amount for performing the first operation of the steering unit 4, i.e., for rotating the steering wheel 3 to the right. The rotation angle CPU 52a executes a process related to N-point learning during the first operation in which the reaction force CPU 61 executes a process to calculate a control amount for performing the first operation. The N-point learning process includes a process to calculate the value of the integrated angle θg. The N-point learning process also includes a sensor value acquisition process and a rotation limit position arrival determination process. The sensor value acquisition process includes a process in which the rotation angle CPU 52a acquires detection values ​​from various sensors. The rotation limit position arrival determination process is a process for determining that the steering wheel 3 has reached the right rotation limit position 3a corresponding to the first operation when all of the following four conditions (A1) to (A4) are met:

[0046] (A1) Ia≧Ith where Ia is the absolute value of the current supplied to the steering motor 13. Ith is the current threshold value. The current threshold value Ith is set based on the viewpoint of detecting an increase in the current of the steering motor 13 that accompanies an increase in the load on the steering motor 13 after the steering wheel 3 reaches the right rotation limit position 3a.

[0047] (A2) Th≦Tth where “Th” is the absolute value of the torque. “Tth” is a torque threshold value that is set based on the viewpoint of detecting a state in which the steering wheel 3 is not being operated by the driver.

[0048] (A3) ω≦ωth where "ω" is the absolute value of the steering angular velocity of the steering motor 13. "ωth" is an angular velocity threshold value, which is set based on the viewpoint of detecting a state in which the steering wheel 3 is not being operated by the driver.

[0049] (A4) t≧tth, where "t" is the time when the three conditions A1 to A3 are satisfied. "tth" is a time threshold value that is set, for example, based on the viewpoint of preventing erroneous determination that the steering wheel 3 has reached the right rotation limit position 3a when the three conditions A1 to A3 are satisfied instantaneously.

[0050] The processing related to N-point learning includes processing for storing the integrated angle θg when it is determined that the steering wheel 3 has reached the right rotation limit position 3a as the right end angle θre in the area 52ba of the non-volatile memory 52b.

[0051] Subsequently, after the first operation is completed, in the vehicle assembly process, the command device 200 outputs a second operation command signal to the reaction force CPU 61 to instruct the execution of the second operation. When the reaction force CPU 61 receives the second operation command signal, it executes processing to calculate a control amount for performing the second operation of the steering unit 4, i.e., for rotating the steering wheel 3 to the left. During the second operation in which the reaction force CPU 61 executes processing to calculate a control amount for performing the second operation, the rotation angle CPU 52a executes processing related to N-point learning, as during the first operation. In other words, the processing related to N-point learning includes processing to store the integrated angle θg when it is determined that the steering wheel 3 has reached the left rotation limit position 3b in an area 52bb of the non-volatile memory 52b as the left end angle θle.

[0052] Subsequently, after the first operation and the second operation are completed, the processing for N-point learning includes a process for calculating a neutral angle θn, which is an angle value indicating the neutral position of the steering shaft 11, based on the right end angle θre and the left end angle θle. The process for calculating the neutral angle θn is a process for calculating half the sum of the right end angle θre and the left end angle θle as the neutral angle θn, as expressed by the following equation (1).

[0053] θn=(θre+θle) / 2 (1) The process for N-point learning includes a process for storing the neutral angle θn as the midpoint N in the area 52bc of the nonvolatile memory 52b.

[0054] This completes the process for storing the midpoint N, the right end angle θre, and the left end angle θle in the nonvolatile memory 52b. Note that, after instructing the lock-to-lock operation of the steering unit 4, the command device 200 may instruct the reaction force CPU 61 to execute the third operation by outputting a third operation command signal. The third operation is, for example, an operation for automatically rotating the steering wheel 3 until it reaches the neutral angle θn. As a result, after completing the process for storing the midpoint N, the right end angle θre, and the left end angle θle in the nonvolatile memory 52b, the steering wheel 3 can be adjusted to the neutral position.

[0055] Finally, the vehicle assembly process is completed by assembling the steering device 2 and the vehicle control device 9 to the vehicle together with the vehicle steering device 1 in which the midpoint N, the right end angle θre, and the left end angle θle are stored in the non-volatile memory 52b. After the vehicle assembly process is completed, the vehicle undergoes a predetermined inspection process and is then shipped to the market.

[0056] <Storage Processing in the Startup Sequence Processing> The startup sequence processing executed by the reaction force CPU 61 after the reaction force CPU 61 is started by turning on the start switch 48 is configured to include a memory check processing. The startup sequence processing is a processing for checking, at startup, whether steering control by the steering motor 13 in response to the driver's steering can be normally executed before the steering control is executed. The memory check processing is a processing for checking whether the midpoint N of the volatile memory 62 is stored in an appropriate storage area. In addition to the memory check processing, the startup sequence processing includes, for example, a circuit check processing for checking whether the hardware constituting the reaction force CPU 61 can operate normally, and a processing for initializing information such as variables set in relation to the processing executed by the reaction force CPU 61. After the startup sequence processing confirms that steering control by the steering motor 13 in response to the driver's steering can be normally executed, the reaction force CPU 61 transitions to a steering control state. In the steering control state, the reaction force CPU 61 executes a processing for calculating a control amount for controlling the operation of the steering motor 13 using the steering control angle θs.

[0057] 5, in the memory check process, the reaction force CPU 61 determines whether or not the midpoint N is present in the volatile memory 62 (step 501). In step 501, the reaction force CPU 61 performs a process of making a determination by reading information from an appropriate storage area in which the midpoint N is stored from the volatile memory 62. Note that in step 501, the reaction force CPU 61 may determine whether or not any of the midpoint N, the right end angle θre, and the left end angle θle, i.e., the reference value, is present, rather than just the midpoint N. Alternatively, in step 501, the reaction force CPU 61 may determine whether or not all of the midpoint N, the right end angle θre, and the left end angle θle are present.

[0058] Next, in step 501, if the reaction force CPU 61 determines that the midpoint N exists in the volatile memory 62 (step 501: YES), it ends the memory check process. On the other hand, if the reaction force CPU 61 determines that the midpoint N does not exist in the volatile memory 62 (step 501: NO), it acquires the midpoint N from the rotation angle processing unit 52 via the vehicle network 8 (step 502). Thereafter, the reaction force CPU 61 stores the midpoint N acquired in step 502 in an appropriate storage area of ​​the volatile memory 62 (step 503), and ends the memory check process. In step 502, the reaction force CPU 61 includes a process of acquiring the right end angle θre and the left end angle θle, along with the midpoint N, via the vehicle network 8. In addition, in step 503, the reaction force CPU 61 includes a process of storing the right end angle θre and the left end angle θle acquired in step 502 in an appropriate storage area of ​​the volatile memory 62. In addition, in step 501, if the reaction force CPU 61 determines whether or not all of the midpoint N, right end angle θre, and left end angle θle exist, in step 502, the reaction force CPU 61 may acquire only the information that is determined not to exist.

[0059] <Functions and Effects of the Present Embodiment> For example, due to the characteristics of the volatile memory 62, it is conceivable that the information stored therein may be lost. Such a situation may occur when the battery 47 connected to the vehicle steering device 1 is removed. That is, when the battery 47 is removed from the vehicle, the power supply to the reaction force control unit 60 is cut off. In this case, the volatile memory 62 loses the midpoint N stored therein due to the cutoff of the power supply. In addition, for example, when the voltage supplied from the battery 47 to the reaction force control unit 60 drops momentarily, causing the reaction force control unit 60, i.e., the reaction force CPU 61, to perform a reset operation, the volatile memory 62 also loses the midpoint N stored therein.

[0060] In view of this, the start-up sequence process executed after the reaction force CPU 61 is started up by turning on the start-up switch 48 is configured to include a memory check process.

[0061] 5, the memory check process includes a process (step 501) for determining whether or not the midpoint N exists in the volatile memory 62. If it is determined that the midpoint N does not exist in the volatile memory 62 (step 501: NO), the memory check process also includes a process (step 502) for acquiring the midpoint N from the torque rotation angle processing unit 50 via the vehicle network 8. The memory check process also includes a process (step 503) for storing the midpoint N acquired in step 502 in an appropriate storage area of ​​the volatile memory 62.

[0062] According to this embodiment, the nonvolatile memory 52b of the torque rotation angle processing unit 50 can maintain the state in which the midpoint N, the right end angle θre, and the left end angle θle are stored, regardless of, for example, the battery being detached from the vehicle. Therefore, the midpoint N, the right end angle θre, and the left end angle θle are not lost in the vehicle steering device 1 due to, for example, the battery being detached. As a result, even in a situation in which the prior art requires a lock-to-lock operation due to the loss of the midpoint N, the right end angle θre, and the left end angle θle due to the battery being detached, the vehicle steering device 1 of this embodiment does not require this. In other words, even in a situation in which the midpoint N, the right end angle θre, and the left end angle θle are lost in the prior art, the vehicle steering device 1 of this embodiment only needs to acquire the midpoint N, the right end angle θre, and the left end angle θle from the nonvolatile memory 52b via the torque rotation angle processing unit 50 instead of performing a lock-to-lock operation. Therefore, a vehicle steering device 1 that can perform smooth steering control can be realized. This also applies to the vehicle system 100 including the vehicle steering device 1, and it is possible to realize the vehicle system 100 that can smoothly control the behavior of the vehicle.

[0063] <Effects of this embodiment> According to the embodiment described above, the following effects can be further achieved. (1-1) Among the reference values, the midpoint N is a value indicating the neutral position of the steering shaft 11. Therefore, the position of 0°, which is the reference for the steering control angle θs, can be made to coincide with the neutral position of the steering shaft 11. Here, the steering control angle θs is a reference for steering control and cannot be sensed by the driver. On the other hand, the neutral position of the steering shaft 11 is an apparent reference and can be sensed by the driver. In other words, the vehicle steering device 1 of this embodiment can align the control reference with the apparent reference. This is advantageous from the perspective of adjusting the driver's feeling.

[0064] (1-2) The reaction force control unit 60 does not need to acquire the midpoint N, the right end angle θre, and the left end angle θle from the torque rotation angle processing unit 50 while at least the midpoint N is present in the volatile memory 62. In other words, while at least the midpoint N is present in the volatile memory 62, the reaction force control unit 60 can calculate the steering control angle θs using the midpoint N, the right end angle θre, and the left end angle θle stored in the volatile memory 62. Therefore, compared to a case where the midpoint N, the right end angle θre, and the left end angle θle are obtained one by one from the torque rotation angle processing unit 50, the vehicle steering device 1 of this embodiment can improve responsiveness when calculating the steering control angle θs. This is effective in improving the control responsiveness of the vehicle steering device 1.

[0065] (1-3) If at least the midpoint N is not present in the volatile memory 62 upon startup, the reaction force control unit 60 simply re-stores the midpoint N, right end angle θre, and left end angle θle acquired from the torque rotation angle processing unit 50 in the volatile memory 62. For example, in the prior art, a lock-to-lock operation would be required in the startup sequence processing upon startup to re-store the midpoint N, right end angle θre, and left end angle θle due to their loss. Even in a similar situation, the vehicle steering device 1 of this embodiment can acquire the midpoint N, right end angle θre, and left end angle θle from the torque rotation angle processing unit 50 instead of performing a lock-to-lock operation in the startup sequence processing upon startup. Therefore, when the midpoint N, right end angle θre, and left end angle θle are re-stored, the time from startup of the reaction force control unit 60 to re-storing the midpoint N, right end angle θre, and left end angle θle in the volatile memory 62 can be shortened.

[0066] (1-4) The reaction force control unit 60 acquires the midpoint N, the right end angle θre, the left end angle θle, and the absolute angle θabs from the torque rotation angle processing unit 50 as needed through communication via the vehicle network 8. In addition to the vehicle steering device 1, the vehicle control device 9 is also connected to the vehicle network 8. Therefore, the midpoint N, the right end angle θre, the left end angle θle, and the absolute angle θabs can be acquired not only by the vehicle steering device 1, i.e., the reaction force control unit 60, but also by the vehicle control device 9 through communication via the vehicle network 8. In other words, the midpoint N, the right end angle θre, the left end angle θle, and the absolute angle θabs can be shared between the reaction force control unit 60 and the vehicle control device 9. This allows for a wider range of control over the behavior of the vehicle.

[0067] (1-5) When the resolution of the first rotation angle magnetic sensor 41e and the second rotation angle magnetic sensor 41f is lower than the resolution of the steering motor angle sensor 42, the accuracy of the absolute angle θabs will be lower than the accuracy of the steering control angle θs obtained from the steering motor angle sensor 42. Therefore, from the perspective of steering control, by using the steering control angle θs, it is possible to achieve control with higher accuracy than when using only the absolute angle θabs.

[0068] Second Embodiment A second embodiment will now be described with reference to the drawings. This embodiment differs from the first embodiment in that the steering control angle θp* is calculated based on information obtained from torque rotation angle processing unit 50. For this reason, the same components as those in the first embodiment are denoted by the same reference numerals, and their description will be omitted.

[0069] As shown in Figure 6, when the steering CPU 71 of this embodiment is unable to obtain the steering control angle θs from the reaction force CPU 61 via the first local network 81, it obtains the absolute angle θabs from the rotation angle CPU 52a via the vehicle network 8. In this case, in the process of calculating the steering control angle θp*, the steering CPU 71 calculates the steering control angle θp* by using the absolute angle θabs instead of the steering control angle θs.

[0070] <Effects of this embodiment> According to the second embodiment described above, the same actions and effects as those of the first embodiment can be obtained, and further, the following effects can be obtained.

[0071] (2-1) For example, if the steering control angle θs cannot be obtained from the reaction force CPU 61 via the first local network 81, it is assumed that, for example, the reaction force CPU 61 is unable to operate normally, or the first local network 81 is unable to communicate normally.

[0072] On the other hand, even if an event occurs in which steering control unit 70 is unable to obtain steering control angle θs from reaction force control unit 60 via first local network 81, it is still possible to obtain absolute angle θabs from torque rotation angle processing unit 50 via vehicle network 8. Therefore, in the process of calculating steering control angle θp*, even if an event occurs in which steering control angle θs cannot be obtained, steering control unit 70 can continue to calculate steering control angle θp* using absolute angle θabs obtained instead of steering control angle θs. This is effective in improving the reliability of vehicle steering device 1.

[0073] Third Embodiment A third embodiment will now be described with reference to the drawings. This embodiment differs from the above-described embodiments in that the rotation angle CPU 52a calculates the steering angle θc. Therefore, the same components as those in the above-described embodiments are denoted by the same reference numerals, and their description will be omitted.

[0074] 7, the rotation angle CPU 52a of this embodiment executes a process to calculate the steering angle θc based on the absolute angle θabs and the torque electrical signal St. The steering angle θc is a rotation angle corresponding to the input shaft 41b. In this embodiment, the rotation angle CPU 52a that executes the process to calculate the steering angle θc, i.e., the rotation angle processing unit 52, is an example of a steering angle calculation unit.

[0075] More specifically, in the rotation angle CPU 52a, the process of calculating the steering angle θc includes a process of calculating the torsion angle θtb corresponding to the torsion of the torsion bar 41a occurring between the input shaft 41b and the output shaft 41c using the following equation (2).

[0076] θtb=Th / Ktb (2) In equation (2), Th is the torque acting on the torsion bar 41a, and Ktb is the spring constant of the torsion bar 41a.

[0077] The process of calculating the steering angle θc also includes a process of calculating the steering angle θc by adding the absolute angle θabs to the calculated torsion angle θtb. Here, the absolute angle θabs is the rotation angle of the steering shaft 11 corresponding to the output shaft 41c. Therefore, adding the absolute angle θabs to the torsion angle θtb of the torsion bar 41a is equivalent to converting the absolute angle θabs to the rotation angle of the steering shaft 11 corresponding to the input shaft 41b, i.e., the steering angle θc.

[0078] The rotation angle CPU 52a then outputs the steering angle θc obtained through processing to calculate the steering angle θc via the vehicle network 8. <Actions and Effects of This Embodiment> According to the third embodiment described above, actions and effects similar to those of the above embodiments can be obtained, and the following effects can also be obtained.

[0079] (3-1) The torque rotation angle processing unit 50 can provide not only the absolute angle θabs but also the steering angle θc to the vehicle. As a result, in a vehicle equipped with the vehicle steering device 1 of this embodiment, the steering angle θc, which is the rotation angle corresponding to the input shaft 41b, can be acquired even if a separate sensor is not provided to obtain the rotation angle corresponding to the input shaft 41b. In other words, in a vehicle that is equipped with a separate sensor to obtain the rotation angle corresponding to the input shaft 41b, by installing the vehicle steering device 1 of this embodiment, the separate sensor can be eliminated.

[0080] Fourth Embodiment A fourth embodiment will be described below with reference to the drawings. This embodiment differs from the above-described embodiments in that the torque rotation angle processing unit 50 does not have a non-volatile memory 52b. Therefore, the same components as those in the above-described embodiments are denoted by the same reference numerals, and their description will be omitted.

[0081] 8, the rotation angle processing unit 52 of this embodiment has a volatile memory 52c instead of the nonvolatile memory 52b. The volatile memory 52c stores the midpoint N, the right end angle θre, and the left end angle θle.

[0082] The vehicle control device 9 of this embodiment also includes a nonvolatile memory 92 having a configuration corresponding to the nonvolatile memory 52b of each of the above embodiments. The nonvolatile memory 92 stores the midpoint N, the right end angle θre, and the left end angle θle.

[0083] <Regarding storage processing in the vehicle assembly process> In this embodiment, unlike the above-described embodiments, the processing for storing the midpoint N, the right end angle θre, and the left end angle θle in the non-volatile memory 92 is executed after the steering device 2 is assembled to the vehicle together with the vehicle steering device 1. In this case, the vehicle control device 9 is also assembled to the vehicle.

[0084] For example, the rotation angle CPU 52a stores the midpoint N, the right end angle θre, and the left end angle θle in the storage area of ​​the volatile memory 52c during lock-to-lock operation, as in the first embodiment. Subsequently, the rotation angle CPU 52a outputs the midpoint N, the right end angle θre, and the left end angle θle via the vehicle network 8. The vehicle control device 9 then acquires the midpoint N, the right end angle θre, and the left end angle θle from the rotation angle CPU 52a, i.e., the rotation angle processing unit 52, via the vehicle network 8, and stores them in the non-volatile memory 92. Thereafter, the vehicle undergoes a predetermined inspection process before being shipped to market.

[0085] <Regarding storage processing in startup sequence processing> In this embodiment, the memory check processing is a process of acquiring the midpoint N, the right end angle θre, and the left end angle θle from the non-volatile memory 92 of the vehicle control device 9 via the vehicle network 8, instead of the processing of step 502 in the first embodiment.

[0086] The rotation angle CPU 52a is also configured to execute a memory check process similar to that executed by the reaction force CPU 61 in the first embodiment. That is, in the rotation angle CPU 52a, the memory check process includes a process of determining whether or not the midpoint N exists in the volatile memory 52c. In the rotation angle CPU 52a, the memory check process includes a process of acquiring the midpoint N from the vehicle control device 9, i.e., the non-volatile memory 92, via the vehicle network 8, if it is determined that the midpoint N does not exist in the volatile memory 52c. In the rotation angle CPU 52a, the memory check process includes a process of storing the midpoint N acquired via the vehicle network 8 in an appropriate storage area of ​​the volatile memory 52c.

[0087] According to the fourth embodiment described above, the same actions and effects as those of the above embodiments can be obtained. <Other Embodiments> The above embodiments may be modified as follows. In addition, the following other embodiments may be combined with each other within the scope of not causing technical contradiction.

[0088] In the first embodiment, the rotation angle CPU 52a may be configured to execute the processing executed by the torque CPU 51a instead. Similarly, the torque CPU 51a may be configured to execute the processing executed by the rotation angle CPU 52a instead. The other embodiments described herein can be similarly applied to the second to fourth embodiments.

[0089] In the first embodiment, the torque rotation angle processing unit 50 may include a torque rotation angle CPU as a CPU that integrates the torque CPU 51a and the rotation angle CPU 52a. In this case, the torque rotation angle CPU may be configured to execute some or all of the processes executed by the torque CPU 51a and the rotation angle CPU 52a. The other embodiments described herein can be similarly applied to the second to fourth embodiments.

[0090] In the first embodiment, at least one of the midpoint N, the right end angle θre, and the left end angle θle may be used as the reference value. For example, if only the midpoint N is used, the right end angle θre and the left end angle θle are obtained by adding or subtracting half of the design value of the rotation range between the right rotation limit position 3a and the left rotation limit position 3b defined by the stopper mechanism 11c to or from the midpoint N. In this case, the right end angle θre and the left end angle θle are used as temporary values ​​in the vehicle assembly process. Alternatively, two of the midpoint N, the right end angle θre, and the left end angle θle may be used as the reference point. The other embodiments described herein can be similarly applied to the second to fourth embodiments.

[0091] In the first embodiment, it is not necessary to store all of the midpoint N, the right end angle θre, and the left end angle θle in the nonvolatile memory 52b and the nonvolatile memory 92. For example, only the right end angle θre and the left end angle θle may be stored, and the midpoint N may be calculated appropriately using equation (1) as needed. The other embodiments described herein can be similarly applied to the second to fourth embodiments.

[0092] In the first embodiment, when obtaining the absolute angle θabs and the midpoint N, the reaction force CPU 61 may obtain the absolute angle θabs and the midpoint N from the rotation angle processing unit 52 via the second local network 82 instead of the vehicle network 8. The other embodiments described herein can be similarly applied to the second and third embodiments.

[0093] In the first embodiment, in the vehicle assembly process, the command device 200 may execute the sensor value acquisition process and the rotation limit position arrival determination process instead of the rotation angle CPU 52a. In this case, when the command device 200 determines that the steering wheel 3 has reached the right rotation limit position 3a or the left rotation limit position 3b, it sends a flag indicating this to the rotation angle CPU 52a. The rotation angle CPU 52a stores the integrated angle θg at the time the flag is received as the right end angle θre or the left end angle θle in the corresponding area of ​​the non-volatile memory 52b. Similarly, the reaction force CPU 61 may execute the sensor value acquisition process and the rotation limit position arrival determination process instead of the command device 200. The other embodiments described herein can be similarly applied to the second and third embodiments.

[0094] In the first embodiment, in the vehicle assembly process, the command device 200 may execute the neutral angle calculation process instead of the rotation angle CPU 52a. In this case, the command device 200 calculates the neutral angle θn based on equation (1) and transmits the calculated neutral angle θn to the rotation angle CPU 52a. The rotation angle CPU 52a stores the received neutral angle θn as the midpoint N in a corresponding area of ​​the non-volatile memory 52b. Similarly, the reaction force CPU 61 may execute the sensor value acquisition process and the rotation limit position arrival determination process instead of the command device 200. The other embodiments described herein can be similarly applied to the second and third embodiments.

[0095] In the first embodiment, the timing for storing the midpoint N, the right end angle θre, and the left end angle θle in the non-volatile memory 52b during the vehicle assembly process is arbitrary. For example, the midpoint N, the right end angle θre, and the left end angle θle may be stored in the non-volatile memory 52b after all of the first, second, and third operations are completed. The other embodiments described herein can be similarly applied to the second and third embodiments.

[0096] In the first embodiment, the reaction force CPU 61 may calculate the absolute angle θabs instead of the rotation angle CPU 52a. In this case, the reaction force CPU 61 obtains the integrated angle θg from the rotation angle CPU 52a and calculates the absolute angle θabs. The other embodiments described here can be similarly applied to the second to fourth embodiments.

[0097] In the second embodiment, the steering CPU 71 may calculate the absolute angle θabs instead of the rotation angle CPU 52a. In this case, the steering CPU 71 obtains the integrated angle θg from the rotation angle CPU 52a and calculates the absolute angle θabs.

[0098] In the second embodiment, the steering CPU 71 may always acquire the absolute angle θabs from the rotation angle CPU 52a via the vehicle network 8, not just when it is unable to acquire the steering control angle θs from the reaction force CPU 61. In this case, the steering CPU 71 can selectively use the steering control angle θs acquired via the first local network 81 and the absolute angle θabs acquired via the vehicle network 8 depending on the situation.

[0099] In the fourth embodiment, the rotation angle processing unit 52 does not have to have the volatile memory 52c. In this case, in the vehicle assembly process, the midpoint N, the right end angle θre, and the left end angle θle are stored in the volatile memory 62 instead of the volatile memory 52c. Then, in the startup sequence process, the reaction force CPU 61 performs a memory check process on the volatile memory 62.

[0100] In the fourth embodiment, in the vehicle assembly process, the rotation angle CPU 52a may perform the lock-to-lock operation before the vehicle control device 9 is assembled to the vehicle. In this case, the midpoint N, the right end angle θre, and the left end angle θle may be acquired by the vehicle control device 9 at any timing when communication between the rotation angle CPU 52a and the vehicle control device 9 via the vehicle network 8 becomes possible.

[0101] In the fourth embodiment, during the vehicle assembly process, the rotation angle CPU 52a may transmit the midpoint N, the right end angle θre, and the left end angle θle to the vehicle control device 9 via the command device 200 instead of via the vehicle network 8.

[0102] In each embodiment, the first rotation angle magnetic sensor 41e and the second rotation angle magnetic sensor 41f may be resolvers. <Others> As described above, each component of the vehicle steering device 1 is equipped with a CPU and a memory. Each component of the vehicle steering device 1 performs various processes by the CPU executing a program stored in the memory at a predetermined calculation cycle. The CPU and memory constitute a microcomputer, which is a processing circuit. The memory includes computer-readable media such as RAM (Random Access Memory) and ROM (Read Only Memory). However, realizing various processes by software is one example. The processing circuit of each component of the vehicle steering device 1 may be configured to realize at least a part of the processes by a hardware circuit such as a logic circuit.

Claims

1. A vehicle steering device comprising: a steering control unit configured to control a steering motor unit including a steering motor connected to a steering shaft to generate a steering force on the steering shaft to which a steering wheel is connected, and a steering motor angle sensor that detects the steering motor angle, which is the angle of the rotation axis of the steering motor, as a relative angle; and a rotation angle processing unit including: a non-volatile memory configured to store a reference value that serves as a reference for an integrated angle that is integrated according to the rotation of the steering shaft, and an absolute angle calculation unit configured to calculate an absolute angle based on the integrated angle and the reference value, wherein the steering control unit is configured to execute a process to calculate a steering control angle used to control the steering of the vehicle while controlling the operation of the steering motor, and the process to calculate the steering control angle includes a process to calculate the steering control angle based on the reference value and the absolute angle obtained from the rotation angle processing unit, and the steering motor angle obtained from the steering motor angle sensor.

2. A vehicle steering system according to claim 1, wherein the reference value is a value indicating the neutral position of the steering shaft.

3. A vehicle steering device as described in claim 1, wherein the steering control unit includes a volatile memory that stores the reference value obtained from the rotation angle processing unit, and when the reference value exists in the volatile memory, the steering control unit is configured to calculate the steering control angle based on the reference value stored in the volatile memory, the absolute angle obtained from the rotation angle processing unit, and the steering motor angle obtained from the steering motor angle sensor.

4. A vehicle steering device as described in claim 3, wherein the steering control unit is configured to execute a startup sequence process when the steering control unit is started, and the steering control unit is configured to store the reference value obtained from the rotation angle processing unit in the volatile memory if the reference value does not exist in the volatile memory during the startup sequence process.

5. A vehicle steering device as described in claim 1, wherein the vehicle on which the vehicle steering device is mounted is provided with a vehicle network that connects the vehicle steering device to a vehicle control device separate from the vehicle steering device so as to enable communication between the vehicle steering device and the vehicle control device, the steering control unit and the rotation angle processing unit are connected so as to be able to communicate via the vehicle network, and the steering control unit is configured to obtain the reference value and the absolute angle from the rotation angle processing unit by communication via the vehicle network.

6. The steering control unit is a reaction force control unit configured to control the steering motor which generates a steering reaction force which is the steering force, and the vehicle steering device includes: a steering control unit configured to control a steering motor unit including a steering motor which generates a steering force in a steering shaft which is configured so that power transmission between the steering shaft and the steering control unit is separated; and a local network which connects the reaction force control unit and the steering control unit so as to enable communication between them, and the steering control unit and the rotation angle processing unit are connected so as to be able to communicate via the vehicle network, and the steering control unit is configured to obtain the steering control angle from the reaction force control unit by communication via the local network, and the steering control unit is configured to execute processing to control the operation of the steering motor by using a steering control angle calculated based on the steering control angle, and when the steering control angle cannot be obtained from the reaction force control unit by communication via the local network, the steering control unit is configured to obtain the absolute angle from the rotation angle processing unit by communication via the vehicle network instead of the steering control angle, 6. The vehicle steering device according to claim 5, wherein the process of controlling the operation of the steering motor includes a process of using the absolute angle instead of the steering control angle when the steering control angle cannot be obtained from the reaction force control unit.

7. A vehicle steering device as described in claim 1, wherein the steering shaft is provided with a torsion bar that connects an input shaft to which the steering wheel is connected and an output shaft to which the steering motor is connected, and the integrated angle is an angle detected by a rotation angle magnetic sensor provided in correspondence with the output shaft of the input shaft and the output shaft.

8. A vehicle steering device as set forth in claim 7, wherein the rotation angle processing unit is a torque rotation angle processing unit that is configured to further include a torque calculation unit and a steering angle calculation unit in addition to the absolute angle calculation unit, wherein the absolute angle calculation unit is configured to execute processing to calculate the absolute angle corresponding to the output shaft of the input shaft and the output shaft, the torque calculation unit is configured to execute processing to calculate the torque acting on the torsion bar, and the steering angle calculation unit is configured to execute processing to calculate a steering angle, which is the angle corresponding to the input shaft of the input shaft and the output shaft, based on the torque and the absolute angle.

9. A vehicle steering device according to claim 7 or 8, wherein the resolution of the rotation angle magnetic sensor is lower than the resolution of the steering motor angle sensor.

10. A vehicle system comprising: a vehicle steering device; a vehicle control device separate from the vehicle steering device; and a vehicle network connecting the vehicle steering device and the vehicle control device so as to enable communication between them, wherein the vehicle steering device is configured to execute the following processes: a process for controlling a steering motor unit including a steering motor connected to a steering shaft to generate a steering force on the steering shaft to which a steering wheel is connected, and a steering motor angle sensor for detecting a steering motor angle, which is the rotation angle of the steering motor, as a relative angle; and a process for calculating an absolute angle based on an integrated angle integrated in accordance with the rotation of the steering shaft and a reference value serving as a reference for the integrated angle; the vehicle control device includes a non-volatile memory for storing the reference value; the process for controlling the steering motor unit includes a process for calculating a steering control angle used to control the steering of the vehicle while controlling the operation of the steering motor; and the process for calculating the absolute angle includes a process for obtaining the reference value from the vehicle control device by communication via the vehicle network; a processing for calculating the steering control angle based on the reference value obtained from the vehicle control device by communication via the vehicle network, the absolute angle obtained in the processing for calculating the absolute angle, and the steering motor angle obtained from the steering motor angle sensor.

Images