JP2018047876A - Vehicular steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular steering device that can determine by a new method whether a clutch which mechanically connects a steering wheel to a turning mechanism is normal or abnormal.SOLUTION: A vehicular steering device 1 includes: a clutch 6 provided in a power transmission passage between a steering wheel 2 and turning wheels 3; a reaction force motor 14 for applying steering reaction force to the steering wheel 2; a turning motor 31 for turning the turning wheels 3; a shaft-directional load sensor 39, provided in a hub unit of at least one turning wheel 3, for detecting a shaft directional load acting on the turning wheel; and an ECU 40 that drives the reaction force motor 14 when the clutch 6 is in an engagement state, and determines whether the clutch 6 is normal or abnormal, based on a detected value by the shaft-directional load sensor 39 before driving the reaction force motor and a detected value by the shaft-directional load sensor 39 during driving the reaction force motor 14.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a steer-by-wire (SBW) type vehicle steering apparatus capable of mechanically connecting a steering wheel as a steering member and a steering mechanism via a clutch.

  In Patent Document 1 below, a reaction force motor coupled to a steering shaft, a steering motor coupled to a rack shaft serving as a steering shaft via a pinion shaft, and fastening and release between the steering shaft and the rack are disclosed. A vehicle steering apparatus including a backup mechanism having a possible electromagnetic clutch and means for determining whether the backup mechanism is normal or abnormal (hereinafter referred to as “backup mechanism abnormality determination means”) is disclosed. The vehicle steering apparatus disclosed in Patent Document 1 includes a steering angle sensor for detecting a steering angle, a steering side torque sensor for detecting torque acting on the steering shaft, and a rotation for detecting torque acting on the pinion shaft. A rudder side torque sensor, a resolver for detecting the rotation angle of the reaction force motor, a resolver for detecting the rotation angle of the steering motor, and the like are provided.

In the vehicle steering apparatus disclosed in Patent Document 1, when the ignition is off, the electromagnetic clutch is in an engaged state. Then, after the ignition is turned on, when the backup mechanism abnormality determining means determines that the backup mechanism is normal, the electromagnetic clutch is released.
The backup mechanism abnormality determining means of Patent Document 1 determines whether the backup mechanism is normal or abnormal by the following methods (1) to (6).
(1) The backup mechanism abnormality determining means drives the reaction force motor and the turning motor with the same torque in a manner in which the torques cancel each other after the electromagnetic clutch is engaged, and detects the detected value of the steering side torque sensor and the rotation speed. The detection value of the rudder side torque sensor is acquired. The backup mechanism abnormality determining means determines that the backup mechanism is normal if the absolute value of the difference between these detected values is less than or equal to a predetermined value, and the absolute value of the difference between these detected values is less than the predetermined value. If it is larger, it is determined that the backup mechanism is abnormal.
(2) The backup mechanism abnormality determining means drives the reaction force motor and the steering motor with the same torque in a manner in which the torques cancel each other after the electromagnetic clutch is engaged, and detects the detected value of the steering side torque sensor and the steering The detection value of the angle sensor is acquired. Then, the backup mechanism abnormality determining means determines that the backup mechanism is abnormal when the detected value of the steering side torque sensor is larger than a predetermined value or when the detected value of the steering angle sensor is larger than the predetermined value.
(3) The backup mechanism abnormality determining means drives only the reaction force motor after the electromagnetic clutch is engaged, and acquires the detected value of the steering side torque sensor and the detected value of the steering angle sensor. The backup mechanism abnormality determining means determines that the backup mechanism is abnormal when the absolute value of the difference between these detected values is larger than a predetermined value.
(4) The backup mechanism abnormality determining means drives the reaction motor only after the electromagnetic clutch is engaged, and acquires the detected value of the steering side torque sensor and the detected value of the steering angle sensor. The backup mechanism abnormality determining means determines that the backup mechanism is abnormal when the detected value of the steering side torque sensor is less than a predetermined value or when the detected value of the steering angle sensor is larger than the predetermined value.
(5) The backup mechanism abnormality determining means drives only the steering motor after the electromagnetic clutch is engaged, and acquires the detected value of the steering torque sensor and the detected value of the steering angle sensor. The backup mechanism abnormality determining means determines that the backup mechanism is abnormal when the absolute value of the difference between these detected values is larger than a predetermined value.
(6) The backup mechanism abnormality determining means drives only the steering motor after the electromagnetic clutch is engaged, and acquires the rotation angle of the reaction force motor and the rotation angle of the steering motor. The backup mechanism abnormality determination means determines whether the backup mechanism is normal or abnormal by comparing the rotation angle of the reaction force motor and the rotation angle of the steering motor.

Japanese Patent No. 4111191 JP 2007-127253 A

  In the determination methods (1) to (5) by the backup mechanism abnormality determination means described in Patent Document 1, at least one of the rotation angle of the steering shaft, the torque acting on the steering shaft, and the torque acting on the pinion shaft is calculated. It needs to be detected. For this reason, it is necessary to increase the driving force of the reaction force motor or the turning motor driven at the time of determination so that the sensor does not erroneously detect the movement of the shaft.

Further, in the determination methods (3) to (6) by the backup mechanism abnormality determination means of Patent Document 1 described above, only one of the reaction force motor or the turning motor is driven at the time of determination, and thus the steering wheel moves slightly. As a result, the driver may feel uncomfortable.
If the reaction force motor and the steering motor are driven in the opposite directions with the same torque at the time of determination, the steering wheel can be prevented from rotating, but for this purpose, the input side and the output side of the electromagnetic clutch are in the opposite direction with the same torque at the same timing. Need to be driven. For this purpose, since it is necessary to drive the reaction force motor or the turning motor after compensating for the performance variation of each motor, the speed reducer, the ECU, etc., the control becomes complicated.

  An object of the present invention is to provide a vehicle steering apparatus that can determine whether a clutch that mechanically connects a steering wheel and a steering mechanism is normal or abnormal by a novel method.

  The invention according to claim 1 includes a steering member (2) for steering the vehicle, a turning mechanism (4) for turning the steered wheel (3), the steering member and the steered wheel, And a reaction force motor connected to a portion closer to the steering member than the clutch in the power transmission path for applying a steering reaction force to the steering member. (14), a steered motor (31) coupled to the steered wheel side portion of the power transmission path with respect to the steered wheel, and at least one hub unit for the steered wheel An axial load sensor (39) for detecting an axial load acting on the steered wheels, and driving the reaction force motor when the clutch is engaged, before driving the reaction force motor. Detection of the axial load sensor A determination means (90) for determining whether the clutch is normal or abnormal based on a value and a detection value of the axial load sensor during driving of the reaction force motor. is there. In addition, although the alphanumeric characters in parentheses represent corresponding components in the embodiments described later, of course, the scope of the present invention is not limited to the embodiments. The same applies hereinafter.

In this configuration, an axial load sensor provided on the hub unit of at least one steered wheel and detecting an axial load acting on the steered wheel is used to determine whether the clutch is normal or abnormal. Can be determined. That is, it becomes possible to determine whether the clutch is normal or abnormal by a novel method.
According to a second aspect of the present invention, the determination means drives the reaction force motor, means for acquiring the detection value of the axial load sensor as a first detection value when the clutch is engaged, Means for obtaining a detection value of the axial load sensor as a second detection value while the reaction force motor is driven, and an absolute value of a difference between the first detection value and the second detection value Is determined to be equal to or greater than a predetermined threshold, and when the absolute value is equal to or greater than the threshold, it is determined that the clutch is normal, and when the absolute value is less than the threshold, The vehicle steering apparatus according to claim 1, further comprising means for determining that the clutch is abnormal.

FIG. 1 is an illustrative view for explaining the configuration of a vehicle steering apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing an electrical configuration of the ECU. FIG. 3 is an illustrative view for explaining the configuration of the steered motor. FIG. 4 is a functional block diagram for explaining the operation of the steered motor control unit in the steer-by-wire mode. FIG. 5 is a functional block diagram for explaining the operation of the reaction force motor control unit in the steer-by-wire mode. FIG. 6 is a flowchart illustrating a procedure of clutch abnormality determination processing by the clutch control unit.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing a schematic configuration of a vehicle steering apparatus according to an embodiment of the present invention.
The vehicle steering apparatus 1 includes a steering wheel 2 as a steering member for steering the vehicle, a steering mechanism 4 for steering the steered wheels 3, a steering shaft 5 connected to the steering wheel 2, A clutch 6 for mechanically connecting and separating the steering shaft 5 (steering wheel 2) and the steering mechanism 4 is included. In this embodiment, the clutch 6 is an electromagnetic clutch. The clutch 6 includes an input shaft 6A and an output shaft 6B, and has a function of transmitting and interrupting torque between the input and output shafts.

The steering shaft 5 connects the first shaft 7 connected to the steering wheel 2, the second shaft 9 integrally connected to the input shaft 6 </ b> A of the clutch 6, and the first shaft 7 and the second shaft 9. Including a torsion bar 8.
A reaction force motor 14 is connected to the second shaft 9 via a speed reducer 13. The reaction force motor 14 is an electric motor for applying a steering reaction force (torque in the direction opposite to the steering direction) to the steering wheel 2. The speed reducer 13 is engaged with a worm shaft (not shown) that is integrally connected to the output shaft of the reaction force motor 14, meshes with the worm shaft, and is rotatably connected to the second shaft 9. The worm gear mechanism includes a worm wheel (not shown). The reaction force motor 14 is provided with a rotation angle sensor 15 for detecting the rotation angle of the reaction force motor 14.

  The turning mechanism 4 includes a first pinion shaft 16 integrally connected to the output shaft 6B of the clutch 6, a rack shaft 17 as a turning shaft, and a turning for applying a turning force to the rack shaft 17. Actuator 30. The steered wheel 3 is connected to each end of the rack shaft 17 via a tie rod 18 and a knuckle arm (not shown). A first pinion 19 is connected to the tip of the first pinion shaft 16. The rack shaft 17 extends linearly along the left-right direction of the automobile. A first rack 20 that meshes with the first pinion 19 is formed at a first end of the rack shaft 17 in the axial direction.

  The steering actuator 30 includes a steering motor 31, a speed reducer 32, a second pinion shaft 33, a second pinion 34, and a second rack 35. The second pinion shaft 33 is disposed separately from the steering shaft 5. The speed reducer 32 is engaged with a worm shaft (not shown) that is integrally connected to the output shaft of the steering motor 31, meshes with the worm shaft, and is rotatably connected to the second pinion shaft 33. And a worm gear mechanism including a worm wheel (not shown).

  The second pinion 34 is connected to the tip of the second pinion shaft 33. The second rack 35 is provided on the second end side opposite to the first end of the rack shaft 17 in the axial direction. The second pinion 34 meshes with the second rack 35. The turning motor 31 is provided with a rotation angle sensor 36 for detecting the rotation angle of the turning motor 31. In the vicinity of the rack shaft 17, a stroke sensor (hereinafter referred to as “steering angle sensor”) 37 for detecting the axial movement amount of the rack shaft 17 is disposed. The turning angle δ of the steered wheels 3 is detected from the axial movement amount of the rack shaft 17 detected by the turning angle sensor 37.

  At least one of the hub units (not shown) for the two steered wheels 3 has an axial direction for detecting an axial load acting on the corresponding steered wheels 3 (hereinafter referred to as “axial load F”). A load sensor 39 is provided. In this embodiment, an axial load sensor 39 is provided on one of the hub units (not shown) of the two steered wheels 3. As the axial load sensor 39, for example, a sensor device disclosed in Japanese Unexamined Patent Application Publication No. 2007-127253 (Patent Document 2) can be used.

The detection signals of the rotation angle sensors 15 and 36, the turning angle sensor 37, the vehicle speed sensor 38, and the axial load sensor 39 and the ignition key state detection signal are input to an ECU (Electronic Control Unit) 40. The ECU 40 controls the clutch 6, the reaction force motor 14, and the turning motor 31 based on these input signals.
The vehicle steering apparatus 1 has a steer-by-wire mode, a fail-safe mode, and the like as operation modes. The steer-by-wire mode is a mode in which the steered wheels 3 are steered in a state where the steering wheel 2 and the steered mechanism 4 are not mechanically connected (a state where the clutch 6 is released). The fail-safe mode is a mode in which the steered wheels 3 are steered in a state where the steering wheel 2 and the steered mechanism 4 are mechanically coupled (the clutch 6 is engaged). This mode is automatically set when any abnormality occurs. The fail-safe mode may be a manual steering mode in which steering is performed only manually, and a power steering mode (a steering assist force corresponding to steering torque or the like is generated by at least one of the reaction force motor 14 and the steering motor 31). EPS mode).

FIG. 2 is a block diagram showing an electrical configuration of the ECU 40.
The ECU 40 is controlled by the microcomputer 41, a drive circuit (inverter circuit) 42 that is controlled by the microcomputer 41 and supplies power to the steered motor 31, a current detector 43 that detects a motor current flowing through the steered motor 31, A drive circuit (inverter circuit) 44 that is controlled by the microcomputer 41 and supplies electric power to the reaction force motor 14 and a current detection unit 45 that detects a motor current flowing through the reaction force motor 14 are provided. The ECU 40 is controlled by a microcomputer 41 and includes a drive circuit 46 for driving the clutch 6.

  The microcomputer 41 includes a CPU and a memory (ROM, RAM, non-volatile memory, etc.), and functions as a plurality of function processing units by executing a predetermined program. The plurality of function processing units include a steered motor control unit 50 for controlling the steered motor 31, a reaction force motor control unit 70 for controlling the reaction force motor 14, and a clutch 6 for controlling the clutch 6. And a clutch control unit 90. The clutch control unit 90 has a clutch abnormality determination function for determining whether the clutch 6 is normal or abnormal.

  For example, the clutch 6 is always in an engaged state, and is in a released state by being energized. When the ignition key is operated to the on position, the clutch control unit 90 determines whether the clutch 6 is normal or abnormal. Details of this determination method will be described later. When it is determined that the clutch 6 is abnormal, the clutch control unit 90 outputs an alarm, for example, and prohibits starting of the engine. When it is determined that the clutch 6 is normal, the clutch control unit 90 puts the clutch 6 into a released state. Thereby, the vehicle steering device 1 operates in the steer-by-wire mode. When the ignition key is operated from the on position to the off position, the clutch control unit 90 puts the clutch 6 into the engaged state. Further, the clutch control unit 90 puts the clutch 6 into the engaged state when any abnormality occurs in the steer-by-wire mode. In this case, the vehicle steering apparatus 1 operates in the fail-safe mode described above.

  The steered motor control unit 50 includes the steering angle θh given from the reaction force motor control unit 70, the vehicle speed V detected by the vehicle speed sensor 38, the steered angle δ detected by the steered angle sensor 37, and the rotation angle sensor 36. The drive circuit 42 is controlled based on the output signal and the current detected by the current detector 43. Thereby, the steering motor control part 50 implement | achieves steering control according to a steering state.

The reaction force motor control unit 70 is based on the steered side target steering angle θht ^* given from the steered motor control unit 50, the output signal of the rotation angle sensor 15, and the current detected by the current detection unit 45, and the drive circuit 44 To control. Thereby, the reaction force motor control part 70 implement | achieves reaction force control according to a steering state.
The steered motor 31 is, for example, a three-phase brushless motor, and includes a rotor 100 as a field and U-phase, V-phase, and W-phase stator windings 101, 102, and 103, as schematically shown in FIG. Including the stator 105. The steered motor 31 may be of an inner rotor type in which a stator is disposed facing the outside of the rotor, or may be of an outer rotor type in which a stator is disposed facing the inside of a cylindrical rotor.

Three-phase fixed coordinates (UVW coordinate system) are defined in which the U, V, and W axes are taken in the direction of the stator windings 101, 102, and 103 of each phase. Further, a two-phase rotational coordinate system (dq coordinate system) in which the d axis (magnetic pole axis) is taken in the magnetic pole direction of the rotor 100 and the q axis (torque axis) is taken in a direction perpendicular to the d axis in the rotation plane of the rotor 100. The actual rotating coordinate system) is defined. The dq coordinate system is a rotating coordinate system that rotates with the rotor 100. In the dq coordinate system, since only the q-axis current contributes to the torque generation of the rotor 100, the d-axis current may be set to zero and the q-axis current may be controlled according to the desired torque. The rotation angle (rotor angle (electrical angle)) θs of the rotor 100 is a rotation angle of the d axis with respect to the U axis. The dq coordinate system is an actual rotating coordinate system according to the rotor angle θs. By using this rotor angle θs ₋ , coordinate conversion between the UVW coordinate system and the dq coordinate system can be performed. The reaction force motor 14 is composed of, for example, a three-phase brushless motor, and has the same structure as the steered motor 31.

FIG. 4 is a block diagram for explaining the operation of the steered motor control unit 50 in the steer-by-wire mode.
The steered motor control unit 50 includes an angular velocity calculating unit 51, a steered side target steering angle setting unit 52, a target steered angle setting unit 53, an angle deviation calculating unit 54, and a PI (proportional integration) control unit 55. , Angular velocity deviation calculation unit 56, PI control unit 57, current deviation calculation unit 58, PI control unit 59, dq / UVW conversion unit 60, PWM (Pulse Width Modulation) control unit 61, and UVW / dq conversion A unit 62 and a rotation angle calculation unit 63.

The steered side target steering angle setting unit 52 is controlled by a steering angle θh (rotation angle of the second shaft 9) calculated by a steering angle calculation unit 83 (see FIG. 5) in the reaction force motor control unit 70 and a vehicle speed sensor 38. Based on the detected vehicle speed V, a steered side target steering angle θht ^* which is a target value of the rotation angle (steering angle) of the steering wheel 2 is calculated. For example, the steered side target steering angle setting unit 52 sets the steered side target steering angle θht ^* according to the vehicle speed V and the steering angle θh using a predetermined transfer function. That is, the steered side target steering angle setting unit 52 sets the steered side target steering angle θht ^* based on the detection value (steering state detection value) representing the steering state.

The target turning angle setting unit 53 sets a target turning angle δ ^* , which is a target value of the turning angle, based on the turning side target steering angle θht ^* set by the turning side target steering angle setting unit 52. To do. The target turning angle δ ^* set by the target turning angle setting unit 53 is given to the angle deviation calculation unit 54.
The angle deviation calculating unit 54 is a deviation Δδ (= δ ^* −δ) between the target turning angle δ ^* set by the target turning angle setting unit 53 and the turning angle δ detected by the turning angle sensor 37. Is calculated.

The PI control unit 55 calculates a target turning angular velocity ωt ^* that is a target value of the turning angular velocity by performing a PI calculation on the angle deviation Δδ calculated by the angle deviation calculating unit 54. The target turning angular velocity ωt ^* calculated by the PI control unit 55 is given to the angular velocity deviation calculating unit 56.
The angular velocity calculation unit 51 calculates the angular velocity (steering angular velocity) ωt of the turning angle δ by differentiating the turning angle δ detected by the turning angle sensor 37 with respect to time. The turning angular velocity ωt calculated by the angular velocity calculator 51 is given to the angular velocity deviation calculator 56.

The angular velocity deviation calculation unit 56 calculates a deviation Δωt (= ωt ^* −ωt) between the target turning angular velocity ωt ^* calculated by the PI control unit 55 and the turning angular velocity ωt calculated by the angular velocity calculation unit 51.
The PI control unit 57 calculates a target current that is a target value of a current to be passed through the coordinate axes of the dq coordinate system by performing a PI calculation on the angular velocity deviation Δωt calculated by the angular velocity deviation calculating unit 56. Specifically, the PI control unit 57 calculates a target d-axis current I _d ^* and a target q-axis current I _q ^* (hereinafter collectively referred to as “target two-phase current I _dq ^* ”). More specifically, the PI control unit 57 calculates the target q-axis current I _q ^* as a significant value, while setting the target d-axis current I _d ^* to zero. The target two-phase current I _dq ^* calculated by the PI control unit 57 is given to the current deviation calculation unit 58.

The rotation angle calculation unit 63 calculates the rotation angle (electrical angle; hereinafter referred to as “rotor angle θs”) of the rotor of the steered motor 31 based on the output signal of the rotation angle sensor 36.
The current detection unit 43 includes the U-phase current I _U , the V-phase current I _V, and the W-phase current I _W (hereinafter, collectively referred to as “three-phase detection current I _UVW ”) of the steered motor 31. To detect. The three-phase detection current I _UVW detected by the current detection unit 43 is given to the UVW / dq conversion unit 62.

The UVW / dq converter 62 converts the three-phase detection current I _UVW (U-phase current I _U , V-phase current I _V and W-phase current I _W ) in the UVW coordinate system detected by the current detector 43 into the dq coordinate system. _Are converted into two-phase detection currents I _d and I _q (hereinafter collectively referred to as “two-phase detection current I _dq ”). These are given to the current deviation calculator 58. For the coordinate conversion in the UVW / dq conversion unit 62, the rotor angle θs calculated by the rotation angle calculation unit 63 is used.

The current deviation calculation unit 58 calculates a deviation between the target two-phase current I _dq ^* calculated by the PI control unit 57 and the two-phase detection current I _dq given from the UVW / dq conversion unit 62. More specifically, the current deviation calculation unit 58 calculates the deviation of the d-axis detection current I _d with respect to the target d-axis current I _d ^* and the deviation of the q-axis detection current I _q with respect to the target q-axis current I _q ^* . These deviations are given to the PI control unit 59.

The PI control unit 59 performs a PI calculation on the current deviation calculated by the current deviation calculation unit 58, thereby causing the target two-phase voltage V _dq ^* (the target d-axis voltage V _d ^* and the target to be applied to the steered motor 31. q-axis voltage V _q ^* ) is generated. This target two-phase voltage V _dq ^* is given to the dq / UVW conversion unit 60.
The dq / UVW conversion unit 60 converts the target two-phase voltage V _dq ^* into the target three-phase voltage V _UVW ^* . For this coordinate conversion, the rotor angle θs calculated by the rotation angle calculation unit 63 is used. The target three-phase voltage V _UVW ^* includes a target U-phase voltage V _U ^* , a target V-phase voltage V _V ^*, and a target W-phase voltage V _W ^* . This target three-phase voltage V _UVW ^* is given to the PWM control unit 61.

The PWM controller 61 includes a U-phase PWM control signal, a V-phase PWM control signal, and a W-phase PWM having a duty corresponding to the target U-phase voltage V _U ^* , the target V-phase voltage V _V ^*, and the target W-phase voltage V _W ^* , respectively. A control signal is generated and supplied to the drive circuit 42.
The drive circuit 42 includes a three-phase inverter circuit corresponding to the U phase, the V phase, and the W phase. The power elements constituting the inverter circuit are controlled by a PWM control signal supplied from the PWM control unit 61, whereby a voltage corresponding to the target three-phase voltage V _UVW ^* is changed to the stator winding 101 of each phase of the steered motor 31. , 102, 103.

The angle deviation calculation unit 54 and the PI control unit 55 constitute angle feedback control means. By the operation of this angle feedback control means, the turning angle δ of the steered wheels 3 is controlled so as to approach the target turning angle δ ^* set by the target turning angle setting unit 53. The angular velocity deviation calculating unit 56 and the PI control unit 57 constitute angular velocity feedback control means. By the operation of the angular velocity feedback control means, the turning angular velocity ωt is controlled to approach the target turning angular velocity ωt ^* calculated by the PI control unit 55. Further, the current deviation calculation unit 58 and the PI control unit 59 constitute a current feedback control unit. By the function of this current feedback control means, the motor current flowing through the steered motor 31 is controlled so as to approach the target two-phase current I _dq ^* calculated by the PI control unit 57.

FIG. 5 is a block diagram for explaining the operation of the motor control unit 70 in the steer-by-wire mode.
The reaction force motor control unit 70 includes a reaction force side target steering angle setting unit 71, an angle deviation calculation unit 72, a PI control unit 73, an angular velocity deviation calculation unit 75, a PI control unit 76, and a current deviation calculation unit 77. A PI controller 78, a dq / UVW converter 79, a PWM controller 80, a UVW / dq converter 81, a rotation angle calculator 82, a steering angle calculator 83, and an angular velocity calculator 84. Including.

The rotation angle calculation unit 82 calculates the electrical angle θ _R and the mechanical angle θ _M of the rotor of the reaction force motor 14 based on the output signal of the rotation angle sensor 15. Steering angle calculating section 83, by dividing the mechanical angle theta _M of the rotor of the reaction force motor 14 at the speed reduction ratio of the reduction gear 13, calculates the steering angle [theta] h. In this embodiment, the steering angle calculation unit 83 calculates the amount of rotation (rotation angle) in both the forward and reverse directions of the second shaft 9 from the neutral position (reference position) of the second shaft 9, and from the neutral position. The amount of rotation in the right direction is output as a positive value, for example, and the amount of rotation in the left direction from the neutral position is output as a negative value, for example.

The reaction force side target steering angle setting unit 71 rotates the second shaft 9 based on the turning side target steering angle θht ^* set by the turning side target steering angle setting unit 52 in the turning motor control unit 50. A reaction force side target steering angle θhr ^* which is a target value of the angle is set. In this embodiment, the reaction force side target steering angle setting unit 71 sets the turning side target steering angle θht ^* set by the turning side target steering angle setting unit 52 as the reaction force side target steering angle θhr ^* .

The angle deviation calculation unit 72 is a deviation Δθh (= θhr ^*) between the reaction force side target steering angle θhr ^* set by the reaction force side target steering angle setting unit 71 and the steering angle θh calculated by the steering angle calculation unit 83 ^. -Θh) is calculated.
The PI control unit 73 calculates a target steering angular velocity ωh ^* that is a target value of the steering angular velocity by performing a PI calculation on the angle deviation Δθh calculated by the angle deviation calculating unit 72. The target steering angular velocity ωh ^* calculated by the PI control unit 73 is given to the angular velocity deviation calculating unit 75.

The angular velocity calculator 84 calculates the angular velocity (steering angular velocity) ωh of the steering angle θh by differentiating the steering angle θh calculated by the steering angle calculator 83 with respect to time. The steering angular velocity ωh calculated by the angular velocity calculator 84 is given to the angular velocity deviation calculator 75.
The angular velocity deviation calculator 75 calculates a deviation Δωh (= ωh ^* −ωh) between the target steering angular velocity ωh ^* calculated by the PI controller 73 and the steering angular velocity ωh calculated by the angular velocity calculator 84.

The PI control unit 76 calculates a target current, which is a target value of the current to be passed through the coordinate axes of the dq coordinate system, by performing a PI calculation on the angular velocity deviation Δωh calculated by the angular velocity deviation calculating unit 75. Specifically, the PI control unit 76 calculates a target d-axis current i _d ^* and a target q-axis current i _q ^* (hereinafter, collectively referred to as “target two-phase current i _dq ^* ”). More specifically, the PI control unit 76 calculates the target q-axis current i _q ^* as a significant value, while setting the target d-axis current i _d ^* to zero. The target two-phase current i _dq ^* calculated by the PI control unit 76 is given to the current deviation calculation unit 77.

The current detection unit 45 uses the U-phase current i _U , the V-phase current i _V and the W-phase current i _W of the reaction force motor 14 (hereinafter, collectively referred to as “three-phase detection current i _UVW ”). To detect. The three-phase detection current i _UVW detected by the current detection unit 45 is given to the UVW / dq conversion unit 81.
The UVW / dq conversion unit 81 converts the three-phase detection current i _UVW (U-phase current i _U , V-phase current i _V and W-phase current i _W ) in the UVW coordinate system detected by the current detection unit 45 into the dq coordinate system. To two-phase detection currents i _d and i _q (hereinafter collectively referred to as “two-phase detection current i _dq ”). These are given to the current deviation calculation unit 77. The coordinate transformation in UVW / dq converter 81, computed by the rotation angle calculation unit 82 an electrical angle theta _R is used.

The current deviation calculation unit 77 calculates the deviation between the target two-phase current i _dq ^* output from the PI control unit 76 and the two-phase detection current i _dq provided from the UVW / dq conversion unit 81. More specifically, the current deviation calculation unit 77 calculates the deviation of the d-axis detection current i _d with respect to the target d-axis current i _d ^* and the deviation of the q-axis detection current i _q with respect to the target q-axis current i _q ^* . These deviations are given to the PI control unit 78.

The PI control unit 78 performs a PI calculation on the current deviation calculated by the current deviation calculation unit 77, so that the target two-phase voltage v _dq ^* (the target d-axis voltage v _d ^* and the target d-axis voltage to be applied to the reaction force motor 14 ₎ ^. q-axis voltage v _q ^* ) is generated. This target two-phase voltage v _dq ^* is given to the dq / UVW converter 79.
The dq / UVW conversion unit 79 converts the target two-phase voltage v _dq ^* into the target three-phase voltage v _UVW ^* . The coordinate transformation, the electrical angle theta _R computed by the rotation angle calculation unit 82 is used. The target three-phase voltage v _UVW ^* includes a target U-phase voltage v _U ^* , a target V-phase voltage v _V ^*, and a target W-phase voltage v _W ^* . The target three-phase voltage v _UVW ^* is given to the PWM control unit 80.

The PWM control unit 80 includes a U-phase PWM control signal, a V-phase PWM control signal, and a W-phase PWM having a duty corresponding to the target U-phase voltage v _U ^* , the target V-phase voltage v _V ^*, and the target W-phase voltage v _W ^* , respectively. A control signal is generated and supplied to the drive circuit 44.
The drive circuit 44 includes a three-phase inverter circuit corresponding to the U phase, the V phase, and the W phase. The power elements constituting the inverter circuit are controlled by a PWM control signal supplied from the PWM control unit 80, so that a voltage corresponding to the target three-phase voltage v _UVW ^* is applied to the stator windings of each phase of the reaction force motor 14. Applied.

The angle deviation calculation unit 72 and the PI control unit 73 constitute angle feedback control means. By the action of the angle feedback control means, the steering angle θh is controlled so as to approach the reaction force side target steering angle θhr ^* set by the reaction force side target steering angle setting unit 71. Further, the angular velocity deviation calculating unit 75 and the PI control unit 76 constitute angular velocity feedback control means. By the operation of the angular velocity feedback control means, the steering angular velocity ωh is controlled so as to approach the target steering angular velocity ωh ^* calculated by the PI control unit 73. Further, the current deviation calculation unit 77 and the PI control unit 78 constitute a current feedback control unit. By the action of this current feedback control means, the motor current flowing through the reaction force motor 14 is controlled so as to approach the target two-phase current I _dq ^* output from the PI control unit 76.

FIG. 6 is a flowchart showing a procedure of clutch normal / abnormal determination processing by the clutch control unit 90.
When the ignition key is operated to the on position (step S1), the clutch control unit 90 does not put the clutch 6 in the energized state (released state), that is, with the clutch 6 in the engaged state, the axial load The axial load F detected by the sensor 39 is acquired as the first axial load F1 (step S2).

Next, the clutch control unit 90 drives the reaction force motor 14 to rotate in one direction while keeping the clutch 6 engaged (step S3). In order to rotationally drive the reaction force motor 14 in one direction, the clutch control unit 90, for example, as shown by a two-dot chain line in FIG. _dq ^* may be given. Thereby, a rotational force is generated by the reaction force motor 14. The rotational force generated by the reaction force motor 14 is transmitted to the first pinion shaft 16 via the speed reducer 13 and the clutch 6 if the clutch 6 is normal. The rotational force transmitted to the first pinion shaft 16 is converted into the axial force of the rack shaft 17 by the first pinion 19 and the first rack 20 and transmitted to the steered wheels 3. The axial load F acting on the steered wheels 3 is detected by an axial load sensor 39 provided in a hub unit (not shown).

  The clutch control unit 90 acquires the axial load F detected by the axial load sensor 39 as the second axial load F2 while the reaction force motor 14 is being driven (step S4). The clutch control unit 90 determines that the absolute value | F2−F1 | of the difference between the first axial load F1 acquired in step S2 and the second axial load F2 acquired in step S4 is a predetermined threshold value. It is determined whether or not α (α> 0) or more (step S5).

If the absolute value | F2-F1 | is equal to or greater than the threshold value α (step S5: YES), the clutch control unit 90 determines that the clutch 6 is normal, and proceeds to step S6. This is because the axial load F acting on the steered wheels 3 changes when the reaction force motor 14 is driven if the clutch 6 is normally engaged.
In step S <b> 6, the clutch control unit 90 stops driving the reaction force motor 14. Thereafter, the clutch control unit 90 energizes the clutch 6 to place the clutch 6 in a released state (step S7). Then, the clutch control unit 90 causes the steered motor control unit 50 and the reaction force motor control unit 70 to start control in the steer-by-wire mode (SBW mode) (step S8).

  If it is determined in step S5 that the absolute value | F2-F1 | is less than the threshold value α (step S5: NO), the clutch control unit 90 determines that the clutch 6 is abnormal and After stopping the driving of the force motor 14 (step S9), the process proceeds to a fail-safe process for clutch abnormality (step S10). In the fail-safe process of clutch abnormality, for example, the clutch control unit 90 performs display for notifying that the clutch 6 is abnormal and prohibits starting of the engine.

In the above embodiment, the clutch 6 is normal or abnormal by using the axial load sensor 39 provided in the hub unit of the steered wheel 3 and detecting the axial load F acting on the steered wheel 3. Can be determined.
As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form. For example, in the above-described embodiment, the steering angle θh is calculated based on the output of the rotation angle sensor 15 that detects the rotation angle of the reaction force motor 14. However, as indicated by a one-dot chain line 11 in FIG. 1, a steering angle sensor for detecting the rotation angle of the steering shaft 5 may be provided in the vicinity of the steering shaft 5, and the steering angle θh may be detected by the steering angle sensor. . In this case, the steering angle calculation unit 83 in the reaction force motor control unit 70 can be omitted.

In the above-described embodiment, the turning angle sensor 37 detects the turning angle δ. However, the turning angle sensor 36 detects the turning angle of the turning motor 31, and the turning angle sensor 36 detects the turning angle. The angle δ may be calculated. In this case, the turning angle sensor 37 can be omitted.
The present invention can be modified in various ways within the scope of the matters described in the claims.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle steering device, 2 ... Steering wheel, 6 ... Clutch, 3 ... Steering wheel, 4 ... Steering mechanism, 5 ... Steering shaft, 14 ... Reaction force motor, 15 ... Rotation angle sensor, 31 ... Steering motor, 36: Rotation angle sensor, 37: Steering angle sensor, 39 ... Axial load sensor, 40 ... ECU, 41 ... Microcomputer, 50 ... Steering motor control unit, 70 ... Reaction force motor control unit, 83 ... Steering angle calculation Part, 90 ... clutch control part

Claims (2)

A steering member for steering the vehicle;
A steering mechanism for turning the steered wheels;
A clutch provided in a power transmission path between the steering member and the steered wheel;
A reaction force motor coupled to a portion closer to the steering member than the clutch in the power transmission path, and for applying a steering reaction force to the steering member;
A steered motor that is connected to the steered wheel side of the clutch in the power transmission path, and steers the steered wheel;
An axial load sensor provided on a hub unit of at least one steered wheel for detecting an axial load acting on the steered wheel;
When the clutch is engaged, the reaction force motor is driven, and the detected value of the axial load sensor before the reaction force motor is driven and the detected value of the axial load sensor during the driving of the reaction force motor. A vehicle steering apparatus including: a determination unit that determines whether the clutch is normal or abnormal based on the determination unit. The determination means includes
Means for acquiring a detection value of the axial load sensor as a first detection value when the clutch is engaged;
Means for driving the reaction force motor and obtaining a detection value of the axial load sensor as a second detection value in a state where the reaction force motor is driven;
Means for determining whether an absolute value of a difference between the first detection value and the second detection value is equal to or greater than a predetermined threshold;
The means for determining that the clutch is normal when the absolute value is equal to or greater than the threshold value, and means for determining that the clutch is abnormal when the absolute value is less than the threshold value. The steering apparatus for vehicles as described.

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