JP6303798B2 - Steering device - Google Patents

Description

  The present invention relates to a steering apparatus including an assist mechanism and a gear ratio variable mechanism.

  As a steering device provided with an assist mechanism, there is a device described in Patent Document 1. This steering device is provided with an assist mechanism that assists the driver in steering operation. The assist mechanism includes a motor that applies assist force to the steering mechanism and a control device that controls driving of the motor. The control device detects a steering torque applied to the steering mechanism in accordance with the steering operation of the driver by a torque sensor, and calculates a basic assist component based on the detected steering torque. In addition, the control device detects a rotation angle of the output shaft of the motor with a rotation angle sensor and realizes a superior steering feeling, and a compensation component for supplementing the basic assist component based on the detected motor rotation angle. Is calculated. Examples of the compensation component include a damping compensation component for suppressing a sudden change in the motor rotation angle, that is, a sudden change in the rotation angle (steering angle) of the steering wheel. The control device calculates an assist command value by adding the basic assist component and the compensation component, and controls the power supplied to the motor so that the output torque of the motor follows the calculated assist command value. As a result, an assist force corresponding to the assist command value is applied to the steering mechanism, and the driver's steering operation is assisted.

  On the other hand, as a steering apparatus provided with a gear ratio variable mechanism, there is an apparatus described in Patent Document 2. In the steering device described in Patent Document 2, the steering shaft is divided into a first shaft on the steering wheel side and a second shaft on the steered wheel side. A gear ratio variable mechanism is provided between the first shaft and the second shaft so that the transmission ratio (gear ratio) thereof is variable. The gear ratio indicates the ratio of the rotation angle of the second shaft to the rotation angle of the first shaft. The gear ratio variable mechanism changes the gear ratio according to the driving state of the driver. Thereby, since the amount of change in the turning angle of the steered wheels with respect to the amount of operation of the steering wheel changes according to the driving state of the vehicle, it is possible to obtain a good steering feeling.

JP 2009-269540 A Japanese Patent No. 3539468

  By the way, when both the assist mechanism and the gear ratio variable mechanism as described above are mounted on the steering device, there is a possibility that the operations of the assist mechanism and the gear ratio variable mechanism interfere with each other. That is, if the relative rotation angle of the second shaft with respect to the first shaft is changed by the gear ratio variable mechanism, the rotation angle of the motor may change according to the change in the rotation angle. When the motor rotation angle detected by the rotation angle sensor changes due to this, the compensation component calculated by the assist mechanism control device changes, so the assist force applied from the motor to the steering mechanism changes. That is, the assist force changes as the gear ratio variable mechanism is driven. Such a change in assist force may change the driver's steering feeling, which may cause the driver to feel uncomfortable.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a steering device that can reduce a driver's uncomfortable feeling associated with driving a gear ratio variable mechanism.

  A steering device that solves the above-described problem has a first shaft and a second shaft that are separated from each other, and transmits the rotation of the steering wheel of the vehicle to the turning shaft of the vehicle via the first shaft and the second shaft. A steering mechanism, a gear ratio variable mechanism that changes an operation angle that is a relative rotation angle of the second shaft with respect to the first shaft, a motor that applies assist force to the steering mechanism, and an output torque of the motor An assist mechanism having a control unit that controls driving of the motor based on an assist command value corresponding to a target value of the motor, and the control unit is based on a steering torque applied to the steering wheel in accordance with a steering operation. A basic assist component calculation unit that calculates a basic assist component that is a basic component of the assist command value; and The assist command value based on a value obtained by adding a compensation component calculation unit based on a value obtained by subtracting the operating angle of the second shaft from the rotation angle at the time, and the basic assist component and the compensation component An assist command value calculation unit for calculating.

  If the compensation component is calculated based on the value obtained by subtracting the operating angle of the second shaft from the actual rotating angle of the second shaft as in this configuration, the operating angle is removed based on the rotating angle of the second shaft. Compensation components can be calculated. As a result, the compensation component is less likely to change when the operating angle of the second shaft changes as the gear ratio variable mechanism is driven, so that it is possible to suppress changes in the assist force that accompany the drive of the gear ratio variable mechanism. Therefore, a driver's uncomfortable feeling can be reduced.

  In the steering apparatus, the control unit calculates an angle command value corresponding to a target value of the rotation angle of the second shaft based on an addition value of the steering torque, the basic assist component, and the compensation component. A value calculation unit; and an angle feedback control unit that calculates an angle assist component by executing angle feedback control for causing the actual rotation angle of the second shaft to follow the angle command value. The unit preferably calculates the assist command value based on an addition value of the basic assist component, the angle assist component, and the compensation component.

  When the angle command component obtained through the angle feedback control as described above is included in the assist command value, when the control unit controls the driving of the motor based on the assist command value, the actual rotation angle of the second shaft becomes the angle command value. The assist force of the motor is adjusted so as to follow. Therefore, the actual rotation angle of the second shaft can be made to follow the angle command value. By the way, in a steering device that performs such angle feedback control, a compensation component of an assist command value may be used for calculation of an angle command value. In such a steering device, when the compensation component changes as the gear ratio variable mechanism is driven, the angle command value changes, and as a result, the assist force may change. In this regard, if the angle command value is calculated using a compensation component that does not easily change when the gear ratio variable mechanism is driven as in the above configuration, the change in the angle command value accompanying the drive of the gear ratio variable mechanism can be suppressed. it can. That is, since the change of the assist force accompanying the drive of the gear ratio variable mechanism can be suppressed, the driver's uncomfortable feeling can be reduced.

  The steering device further includes an operation angle detection unit that detects an actual operation angle of the second shaft, and the compensation component calculation unit subtracts an operation of the second shaft from an actual rotation angle of the second shaft. As an angle value, it is preferable to use an actual operating angle value of the second shaft detected by the operating angle detector.

  In the steering apparatus, the gear ratio variable mechanism changes the operating angle of the second shaft by executing feedback control for causing the actual operating angle of the second shaft to follow the operating angle command value. The compensation component calculation unit preferably uses the operating angle command value as the operating angle value of the second shaft to be subtracted from the actual rotation angle of the second shaft.

According to these structures, the calculation which subtracts the operating angle of a 2nd shaft from the actual rotation angle of a 2nd shaft can be performed easily.
For the steering device, an active operating angle command value corresponding to a target value of the operating angle of the second shaft is set to execute active steering control that changes the operating angle of the second shaft without depending on the steering operation. The gear ratio variable mechanism further includes an operation angle command value calculation unit for calculating, and the active steering control is performed by causing the actual operation angle of the second shaft to follow the active operation angle command value. The compensation component calculation unit preferably uses the active operating angle command value as the operating angle value of the second shaft to be subtracted from the actual rotation angle of the second shaft.

  The driver's uncomfortable feeling associated with the drive of the gear ratio variable mechanism becomes more prominent when the gear ratio variable mechanism performs active steering control while the driver is steering the steering wheel. That is, when the driver is holding the steering wheel, the assist force hardly changes. In such a situation, if the assist force changes due to the gear ratio variable mechanism executing active steering control, the driver feels the change sensitively, and the sense of incongruity becomes more noticeable. In this regard, according to the above configuration, the compensation component is calculated based on the value obtained by subtracting the active operating angle command value from the actual rotation angle of the second shaft. Here, the active operating angle command value is substantially equal to the actual operating angle of the second shaft corresponding to the active steering control. Therefore, according to the above configuration, the compensation component can be calculated based on the rotation angle of the second shaft from which the operation angle based on the active steering control is removed. Therefore, when the operating angle of the second shaft changes with the execution of the active steering control, the compensation component becomes difficult to change. As a result, among the changes in the assist force associated with the drive of the gear ratio variable mechanism, it is possible to suppress the change in the assist force associated with the execution of the active steering control in particular, so that the effect of reducing the driver's uncomfortable feeling is great.

  In addition, a steering device that solves the above-described problem has a first shaft and a second shaft that are separated from each other, and rotates the steering wheel of the vehicle via the first shaft and the second shaft. A steering mechanism that transmits to the first shaft, a gear ratio variable mechanism that changes an operating angle that is a relative rotation angle of the second shaft with respect to the first shaft, a motor that applies assist force to the steering mechanism, and An assist mechanism having a control unit that controls driving of the motor based on an assist command value corresponding to a target value of output torque, and the control unit controls the steering torque applied to the steering wheel in accordance with a steering operation. A basic assist component calculation unit for calculating a basic assist component that is a basic component of the assist command value based on the second assist shaft; A correction value calculation unit for calculating a correction value having an absolute value smaller than the operating angle of the second shaft and a compensation component calculation unit for calculating a compensation component based on a value obtained by subtracting the correction value from the actual rotation angle of the second shaft And an assist command value calculation unit that calculates the assist command value based on a value obtained by adding the basic assist component and the compensation component.

  According to this configuration, the operating angle component of the second shaft partially remains in the value obtained by subtracting the correction value from the actual rotation angle of the second shaft. For this reason, when the operating angle of the second shaft changes as the gear ratio variable mechanism is driven, the compensation component calculated by the compensation component calculation unit slightly changes. As a result, when the gear ratio variable mechanism is driven, the assist force can be changed within a range that does not give the driver a sense of incongruity.

  According to the present invention, it is possible to reduce the driver's uncomfortable feeling associated with driving the variable gear ratio mechanism.

The block diagram which shows the schematic structure about 1st Embodiment of a steering device. The block diagram which shows the electrical structure of the VGR control apparatus and brake control apparatus about the steering apparatus of 1st Embodiment. The block diagram which shows the electrical structure of the EPS control apparatus about the steering device of 1st Embodiment. The block diagram which shows the electrical structure of the EPS control apparatus about 2nd Embodiment of a steering device. The block diagram which shows the electrical structure of the EPS control apparatus about the modification of a steering device. The block diagram which shows the schematic structure about the modification of a steering device. The block diagram which shows the schematic structure about the modification of a steering device. The block diagram which shows the electrical structure of the VGR control apparatus and brake control apparatus about the modification of a steering device. The block diagram which shows the electrical structure of the VGR control apparatus and brake control apparatus about the modification of a steering device.

<First Embodiment>
Hereinafter, a first embodiment of the steering device will be described.
As shown in FIG. 1, the steering device 1 includes a steering mechanism 2 that steers the steered wheels 4 a and 4 b based on an operation of the driver's steering wheel 20, and an assist mechanism 3 that assists the steering operation of the driver. ing.

  The steering mechanism 2 includes a steering shaft 21 that serves as a rotating shaft of the steering wheel 20. The steering shaft 21 is divided into a first shaft 21 a connected to the steering wheel 20 and a second shaft 21 b connected to the first shaft 21 a via a variable gear ratio (VGR) mechanism 5. Yes. The end of the second shaft 21 b opposite to the end connected to the gear ratio variable mechanism 5 is connected to the rack shaft 23 via the rack and pinion mechanism 22. In the present embodiment, the rack shaft 23 corresponds to a steered shaft. In the steering mechanism 2, when the first shaft 21a rotates in accordance with the driver's operation of the steering wheel 20 (steering operation), the rotational motion is transmitted to the second shaft 21b via the gear ratio variable mechanism 5, and the second shaft 21b rotates. The rotational motion of the second shaft 21 b is converted into a reciprocating linear motion in the axial direction of the rack shaft 23 via the rack and pinion mechanism 22. Due to the reciprocating linear motion of the rack shaft 23, the turning angles of the left and right steered wheels 4a and 4b connected to both ends thereof are changed, and the traveling direction of the vehicle is changed.

  The gear ratio variable mechanism 5 includes a housing 50 that is coupled to the first shaft 21 a so as to be integrally rotatable, and a VGR motor 51 and a speed reduction mechanism 52 that are accommodated in the housing 50. The VGR motor 51 is a brushless motor or a brushed motor. The speed reduction mechanism 52 includes a mechanism composed of three rotational elements capable of differential rotation, such as a planetary gear mechanism, a wave gear mechanism (strain, wave gearing), and the like. The three rotating elements constituting the speed reduction mechanism 52 are connected to the housing 50, the output shaft 51a of the VGR motor 51, and the second shaft 21b, respectively. That is, in the speed reduction mechanism 52, the rotation speed of the second shaft 21b is uniquely determined by the rotation speed of the housing 50 and the rotation speed of the VGR motor 51. In the gear ratio variable mechanism 5, the rotation of the output shaft 51a of the VGR motor 51 is added to the rotation of the first shaft 21a accompanying the steering operation and transmitted to the second shaft 21b through the speed reduction mechanism 52, thereby transmitting the first shaft 21a. The relative rotation angle of the second shaft 21b with respect to is changed. That is, the gear ratio, which is the ratio of the rotation angle of the second shaft 21b to the rotation angle of the first shaft 21a, is changed. Here, “addition” includes both addition and subtraction. Hereinafter, a relative rotation angle of the second shaft 21b with respect to the first shaft 21a is referred to as an “operation angle of the second shaft 21b”.

  The assist mechanism 3 includes an EPS (Electric Power Steering) motor 31 connected to the second shaft 21 b via the speed reduction mechanism 30. The EPS motor 31 is a brushless motor. In the assist mechanism 3, the rotation of the output shaft 31a of the EPS motor 31 is transmitted to the second shaft 21b via the speed reduction mechanism 30, thereby applying torque to the steering shaft 21 and assisting the driver's steering operation.

  The steering device 1 includes a VGR control device 54 that controls driving of the VGR motor 51 and an EPS control device 33 that controls driving of the EPS motor 31. The VGR control device 54 and the EPS control device 33 can exchange various information via the in-vehicle network 11 such as a CAN (Controller Area Network). Further, the VGR control device 54 and the EPS control device 33 can exchange various information with the brake control device 12 via the in-vehicle network 11. The brake control device 12 is a part that performs overall control related to the brake system of the vehicle.

  The steering device 1 is provided with sensors that detect various state quantities. For example, the first shaft 21 a is provided with a steering angle sensor 6 that detects the rotation angle thereof, that is, the steering angle θs of the steering wheel 20. The second shaft 21b is provided with a torque sensor 7 that detects a steering torque Th applied to the steering shaft 21 when the driver performs a steering operation. The gear ratio variable mechanism 5 is provided with a VGR rotation angle sensor 53 that detects the rotation angle θmv of the output shaft 51 a of the VGR motor 51. The assist mechanism 3 is provided with an EPS rotation angle sensor 32 that detects the rotation angle θme of the output shaft 31 a of the EPS motor 31. The vehicle is provided with wheel speed sensors 8a and 8b for detecting the rotational speeds Vtr and Vtl of the left and right steered wheels 4a and 4b, respectively, and a vehicle speed sensor 9 for detecting the traveling speed V of the vehicle. The vehicle is also provided with a brake switch 10 that outputs a brake signal Sbk indicating that the brake pedal is depressed. Among these, the steering angle sensor 6, the wheel speed sensors 8 a and 8 b, and the vehicle speed sensor 9 are connected to the in-vehicle network 11. Therefore, the VGR control device 54, the EPS control device 33, and the brake control device 12 can capture the outputs of the steering angle sensor 6, the wheel speed sensors 8a and 8b, and the vehicle speed sensor 9 via the in-vehicle network 11. It has become. The output of the VGR rotation angle sensor 53 is directly taken into the VGR control device 54. The outputs of the torque sensor 7 and the EPS rotation angle sensor 32 are directly taken into the EPS control device 33. The output of the brake switch 10 is taken directly into the brake control device 12.

Next, the electrical configurations and operations of the VGR control device 54 and the brake control device 12 will be described.
As shown in FIG. 2, the VGR control device 54 includes a drive circuit 55 for driving the VGR motor 51 and a microcomputer that controls the drive of the VGR motor 51 via the drive circuit 55 (hereinafter abbreviated as “microcomputer”). 56). The drive circuit 55 includes a known inverter circuit that converts AC power supplied from a power source (power supply voltage “+ Vcc”) such as an in-vehicle battery into three-phase (U-phase, V-phase, W-phase) AC power. The drive circuit 55 generates three-phase AC power based on the control signal Scv from the microcomputer 56, and supplies the generated three-phase AC power to the VGR motor 51 via the feed line Wv corresponding to each phase. In FIG. 2, for convenience, the power supply lines Wv for each phase are collectively shown. The microcomputer 56 generates a control signal Scv based on the steering angle θs detected by the steering angle sensor 6, the vehicle speed V detected by the vehicle speed sensor 9, and the VGR motor rotation angle θmv detected by the VGR rotation angle sensor 53. .

  Specifically, the microcomputer 56 includes a VGR operation angle command value calculation unit 57, an adder 58, a feedback (F / B) control unit 59, a control signal generation unit 60, and an operation angle calculation unit 61. The VGR operating angle command value calculator 57 calculates a VGR operating angle command value θa1 * based on the steering angle θs and the vehicle speed V. The VGR operating angle command value θa1 * corresponds to a target value component of the operating angle of the second shaft 21b. The VGR operating angle command value calculator 57 outputs the calculated VGR operating angle command value θa1 * to the adder 58. The adder 58 adds the VGR operating angle command value θa1 * output from the VGR operating angle command value calculation unit 57 and the active operating angle command value θa2 * output from the brake control device 12 to add an operating angle command. The value θa * is calculated, and the calculated operating angle command value θa * is output to the feedback control unit 59.

  The operating angle calculation unit 61 determines the actual operation of the second shaft 21b from the VGR motor rotation angle θmv based on the reduction ratio determined according to the gear ratio between the rotating elements constituting the reduction mechanism 52 of the gear ratio variable mechanism 5. The actual operating angle θa, which is an angle, is calculated, and the calculated actual operating angle θa is output to the feedback control unit 59.

  The feedback control unit 59 calculates the current command value Iv * by executing feedback control based on the deviation so that the actual operating angle θa follows the operating angle command value θa *. The current command value Iv * corresponds to the target value of the supply current of the VGR motor 51. The feedback control unit 59 outputs the calculated current command value Iv * to the control signal generation unit 60. The control signal generator 60 generates a control signal Scv based on the current command value Iv *. The microcomputer 56 outputs the control signal Scv calculated in this way to the drive circuit 55. As a result, three-phase AC power corresponding to the current command value Iv * is supplied from the drive circuit 55 to the VGR motor 51 via the feeder line Wv, and the VGR motor 51 is driven. The drive control of the VGR motor 51 is performed based on the VGR operating angle command value θa1 * set based on the steering angle θs and the vehicle speed V in this way, so that the first shaft 21a and the first shaft 21a Gear ratio variable control in which the gear ratio of the second shaft 21b is changed is executed.

  In addition to the variable gear ratio control, the microcomputer 56 executes active steering control that changes the operating angle of the second shaft 21b without depending on the steering operation. Next, active steering control will be described.

  For example, when the driver performs a brake operation when the vehicle is traveling on a split μ road, that is, when the left and right steered wheels 4a and 4b of the vehicle are traveling on road surfaces with significantly different road resistances, the steered wheels 4a , 4b, the rotational speed of one steered wheel in contact with the low μ road is faster than the rotational speed of the other steered wheel in contact with the high μ road. Therefore, the vehicle turns to the side of the steered wheel that is in contact with the high μ road even though the driver is not performing the steering operation. Such unintentional turning of the vehicle gives the driver a sense of incongruity. Therefore, the gear ratio variable mechanism 5 of the present embodiment drives the VGR motor 51 and operates the operating angle of the second shaft 21b when the driver performs a braking operation while the vehicle is traveling on the split μ road. By changing the turning angle of the steered wheels 4a and 4b in the direction opposite to the turning direction of the vehicle. That is, the counter steer is automatically executed to suppress turning of the vehicle that is not intended by the driver. The brake control device 12 determines whether or not a brake operation has been performed on the split μ road and sets the operating angle of the second shaft 21b.

  Specifically, as shown in FIG. 2, the brake control device 12 includes the brake signal Sbk output from the brake switch 10 and the rotational speeds of the steered wheels 4a and 4b detected by the wheel speed sensors 8a and 8b. Vtr and Vtl are taken in. When the brake control device 12 detects the driver's brake operation based on the brake signal Sbk, the brake control device 12 calculates a difference value between the rotational speeds Vtr and Vtl of the steered wheels 4a and 4b. Then, the brake control device 12 determines that there is a possibility of turning of the vehicle unintended by the driver when the absolute value of the difference value between the rotational speeds Vtr and Vtl is equal to or greater than a predetermined threshold value. At this time, the brake control device 12 calculates an active operating angle command value θa2 * as a control amount for turning the steered wheels 4a and 4b in the direction opposite to the turning direction of the vehicle. The active operating angle command value θa2 * corresponds to a target value component of the operating angle of the second shaft 21b. Specifically, for example, when the rotational speed Vtr of the right-hand steered wheel 4a is faster than the rotational speed Vtl of the left-hand steered wheel 4b, there is a possibility that the vehicle may turn to the left, so the steered angles of the steered wheels 4a, 4b. The active operating angle command value θa2 * is calculated so as to change the value to the right. Thus, in the present embodiment, the brake control device 12 corresponds to the operating angle command value calculation unit. Then, the brake control device 12 transmits the calculated active operating angle command value θa2 * to the VGR control device 54 and the EPS control device 33. At this time, in the VGR control device 54, since the active operating angle command value θa2 * is included in the operating angle command value θa * input to the feedback control unit 59, the feedback control unit 59 is based on the active operating angle command value θa2 *. Perform feedback control. When the VGR motor 51 is driven through feedback control based on the active operating angle command value θa2 *, the operating angle of the second shaft 21b changes by an angle corresponding to the active operating angle command value θa2 *. As a result, the turning angle of the steered wheels 4a and 4b changes in the direction opposite to the turning direction of the vehicle while the steering angle θs is maintained, so that turning of the vehicle unintended by the driver can be suppressed.

  Note that the brake control device 12 cannot detect the brake operation of the driver, and if the absolute value of the difference value between the rotational speeds Vtr and Vtl is less than a predetermined threshold even if the brake operation of the driver can be detected. The active operating angle command value θa2 * is not set (output). That is, in this case, the VGR control device 54 does not perform active steering control.

Next, the electrical configuration and operation of the EPS control device 33 will be described.
As shown in FIG. 3, the EPS control device 33 includes a drive circuit 34 for driving the EPS motor 31 and a microcomputer 35 that controls the drive of the EPS motor 31 via the drive circuit 34. The drive circuit 34 includes a known inverter circuit that converts DC power supplied from a power source (power supply voltage “+ Vcc”) such as an in-vehicle battery into three-phase (U-phase, V-phase, W-phase) AC power. The drive circuit 34 generates three-phase AC power based on the control signal Sce from the microcomputer 35, and supplies the generated three-phase AC power to the EPS motor 31 via the feeder line We corresponding to each phase. The power supply line We is provided with a current sensor 39 that detects each phase current value Ie supplied to the EPS motor 31. In FIG. 3, for convenience, the power supply lines We for each phase and the current sensors 39 for each phase are collectively illustrated. The output of the current sensor 39 is taken into the microcomputer 35.

  The microcomputer 35 detects the steering torque Th detected by the torque sensor 7, the vehicle speed V detected by the vehicle speed sensor 9, the EPS motor rotation angle θme detected by the EPS rotation angle sensor 32, and the active operation transmitted from the brake control device 12. A control signal Sce is generated based on the angle command value θa2 * and each phase current value Ie detected by the current sensor 39.

  Specifically, the microcomputer 35 includes an assist command value calculation unit 36, a current command value calculation unit 37, and a control signal generation unit 38. The assist command value calculator 36 calculates an assist command value Ta * based on the steering torque Th, the vehicle speed V, the EPS motor rotation angle θme, and the active operating angle command value θa2 *. The assist command value Ta * corresponds to the target value of the output torque of the EPS motor 31. The assist command value calculation unit 36 includes a basic assist component calculation unit 40, a compensation component calculation unit 41, and a rotation angle calculation unit 42.

  The basic assist component calculation unit 40 calculates a basic assist component Ta1 * based on the steering torque Th and the vehicle speed V. The basic assist component Ta1 * is a basic component of the assist command value Ta *. For example, the basic assist component calculation unit 40 sets the absolute value of the basic assist component Ta1 * to a larger value as the absolute value of the steering torque Th increases or as the vehicle speed V decreases. Then, the basic assist component calculation unit 40 outputs the calculated basic assist component Ta1 * to the adder 43.

  The rotation angle calculation unit 42 is detected by the EPS rotation angle sensor 32 using the correlation between the EPS motor rotation angle θme and the rotation angle of the second shaft 21b determined based on the reduction ratio of the speed reduction mechanism 30 of the assist mechanism 3. The actual rotation angle θe1 of the second shaft 21b is calculated from the EPS motor rotation angle θme. The rotation angle calculation unit 42 outputs the calculated actual rotation angle θe1 of the second shaft 21b to the subtractor 44.

  The subtractor 44 performs correction by subtracting the active operating angle command value θa2 * from the actual rotation angle θe1 of the second shaft 21b calculated by the rotation angle calculation unit 42, and the corrected rotation angle θe2 ( = Θe1-θa2 *) is output to the compensation component calculation unit 41.

  The compensation component calculation unit 41 calculates a compensation component Ta2 * for compensating for the basic assist component Ta1 * based on the corrected rotation angle θe2 of the second shaft 21b in order to realize a better steering feeling. The compensation component calculation unit 41 calculates, for example, a steering return compensation component for returning the steering wheel 20 to the neutral position as the compensation component Ta2 *. The steering return compensation component assists in a direction in which the steering wheel 20 returns to the neutral position as the absolute value of the corrected rotation angle θe2 of the second shaft 21b increases, that is, as the steering wheel 20 moves away from the neutral position. The value is set to increase the command value Ta *. The compensation component calculation unit 41 not only uses the corrected rotation angle θe2 of the second shaft 21b as it is, but also calculates, for example, the rotation speed ω of the second shaft 21b that is a first-order differential value thereof. Based on the rotational speed ω, the compensation component Ta2 * is calculated. The compensation component calculation unit 41 calculates, for example, a damping compensation component for suppressing a sudden change in the steering angle of the steering wheel 20 as the compensation component Ta2 * based on the rotational speed ω. Note that the damping compensation component is set to a value that attenuates the assist command value Ta * more as the absolute value of the rotational speed ω increases. The compensation component calculation unit 41 outputs the calculated compensation component Ta2 * to the adder 43.

  The adder 43 calculates the assist command value Ta * by adding the basic assist component Ta1 * calculated by the basic assist component calculation unit 40 and the compensation component Ta2 * calculated by the compensation component calculation unit 41. The assist command value calculation unit 36 outputs the assist command value Ta * calculated in this way to the current command value calculation unit 37.

  The current command value calculation unit 37 calculates a d-axis current command value Id * and a q-axis current command value Iq * based on the assist command value Ta *. The d-axis current command value Id * and the q-axis current command value Iq * correspond to the target value of the supply current of the EPS motor 31 in the d / q coordinate system. Specifically, the q-axis current command value Iq * is calculated based on the assist command value Ta *, and the calculated q-axis current command value Iq * is output to the control signal generator 38. In this embodiment, the d-axis current command value Id * is set to “0”, and the current command value calculator 37 also outputs the d-axis current command value Id * to the control signal generator 38.

  The control signal generator 38 includes a d-axis current command value Id * and a q-axis current command value Iq * output from the current command value calculator 37, each phase current value Ie detected by the current sensor 39, and an EPS rotation angle. A control signal Sce is generated based on the EPS motor rotation angle θme detected by the sensor 32. Specifically, the control signal generation unit 38 maps each phase current value Ie to the d / q coordinate system based on the EPS motor rotation angle θme, thereby obtaining the actual current value of the EPS motor 31 in the d / q coordinate system. A certain d-axis current value and q-axis current value are calculated. Then, the control signal generation unit 38 makes the actual d-axis current value follow the d-axis current command value Id *, and the actual q-axis current value follows the q-axis current command value Iq *. A control signal Sce is generated by performing current feedback control based on the deviation. The microcomputer 35 outputs the control signal Sce calculated in this way to the drive circuit 34. As a result, three-phase AC power corresponding to the d-axis current command value Id * and the q-axis current command value Iq * is supplied from the drive circuit 34 to the EPS motor 31 via the feeder line We, and the EPS motor 31 is driven. . As a result, assist control in which an assist force according to the assist command value Ta * is applied from the EPS motor 31 to the second shaft 21b is executed.

According to the configuration described above, it is possible to obtain operations and effects as shown in the following (1) and (2).
(1) As shown in FIG. 1, the second shaft 21 b is connected to the output shaft 31 a of the EPS motor 31 via the speed reduction mechanism 30. Therefore, when the operating angle of the second shaft 21b changes due to the execution of the active steering control in the gear ratio variable mechanism 5, the output shaft 31a of the EPS motor 31 rotates, so that the EPS motor rotation detected by the EPS rotation angle sensor 32 is detected. The angle θme changes. Therefore, the actual rotation angle θe1 of the second shaft 21b calculated by the rotation angle calculation unit 42 in the microcomputer 35 of the EPS control device 33 shown in FIG. 3 also changes. Therefore, if the compensation component computing unit 41 computes the compensation component Ta2 * based on the actual rotational angle θe1 of the second shaft 21b computed by the rotational angle computing unit 42, the compensation component Ta2 * is associated with the execution of the active steering control. Will change. As a result, the assist force of the EPS motor 31 changes with the execution of the active steering control.

  In this regard, the compensation component calculation unit 41 of the present embodiment is based on a value θe2 obtained by subtracting the active operating angle command value θa2 * from the actual rotation angle θe1 of the second shaft 21b calculated by the rotation angle calculation unit 42. Calculate Ta2 *. Here, the active operating angle command value θa2 * is substantially equal to the actual operating angle of the second shaft 21b according to the active steering control. Therefore, the compensation component calculation unit 41 can calculate the compensation component Ta2 * based on the rotation angle of the second shaft 21b from which the operating angle based on the active steering control is removed. As a result, when the operating angle of the second shaft 21b changes along with the execution of the active steering control, the compensation component Ta2 * is less likely to change, so that the change in the assist force accompanying the execution of the active steering control can be suppressed. it can. Therefore, a driver's uncomfortable feeling can be reduced.

  (2) The driver's uncomfortable feeling associated with the driving of the gear ratio variable mechanism 5 becomes more prominent when the gear ratio variable mechanism 5 executes the active steering control while the driver is holding the steering wheel 20. That is, when the driver is steering the steering wheel 20, the assist force hardly changes. In such a situation, if the assist force changes as the gear ratio variable mechanism 5 is driven, the driver feels the change sensitively, and the sense of incongruity becomes more noticeable. In this regard, in the present embodiment, as described in the above (1), among the changes in the assist force accompanying the drive of the gear ratio variable mechanism 5, the change in the assist force particularly accompanying the execution of the active steering control can be suppressed. Therefore, the effect of reducing the driver's discomfort is great.

Second Embodiment
Next, a second embodiment of the steering device will be described. Hereinafter, the difference from the first embodiment will be mainly described.

As shown in FIG. 4, the assist command value calculation unit 36 of the present embodiment includes adders 45 and 46, an angle command value calculation unit 47, and an angle feedback (F / B) control unit 48.
The adder 46 receives the added value “Ta1 * + Ta2 *” of the basic assist component Ta1 * and the compensation component Ta2 * calculated by the adder 43, and the steering torque Th detected by the torque sensor 7. The adder 46 calculates the drive torque Tc (= Ta1 * + Ta2 * + Th) by adding the added value “Ta1 * + Ta2 *” and the steering torque Th, and calculates the calculated drive torque Tc to the angle command value calculation unit 47. Output to.

  The angle command value calculation unit 47 calculates an angle command value θe * based on the ideal model from the drive torque Tc. The angle command value θe * corresponds to the target value of the rotation angle of the second shaft 21b determined according to the ideal model, in other words, the target value of the turning angle of the steered wheels 4a and 4b. The ideal model is obtained by measuring the ideal rotation angle of the second shaft 21b according to the driving torque Tc by experiments and modeling the measurement result. The angle command value calculation unit 47 outputs the angle command value θe * calculated based on the ideal model to the angle feedback control unit 48.

  In addition to the angle command value θe * calculated by the angle command value calculation unit 47, the actual feedback angle θe1 of the second shaft 21b calculated by the rotation angle calculation unit 42 is input to the angle feedback control unit 48. The angle feedback control unit 48 calculates the angle assist component Ta3 * by performing feedback control based on the deviation so that the actual rotation angle θe1 of the second shaft 21b follows the angle command value θe *, and calculates the calculated angle assist. The component Ta3 * is output to the adder 45. The adder 45 adds the assist command value Ta * (= Ta1) by adding the addition value “Ta1 * + Ta2 *” calculated by the adder 43 and the angle assist component Ta3 * calculated by the angle feedback control unit 48. * + Ta2 * + Ta3 *). The assist command value calculation unit 36 outputs the assist command value Ta * calculated in this way to the current command value calculation unit 37.

According to the configuration described above, in addition to the operations and effects (1) and (2) of the first embodiment, the operations and effects shown in the following (3) and (4) can be obtained.
(3) Since the assist command value Ta * includes the angle assist component Ta3 * generated by the angle feedback control, an assist force corresponding to the assist command value Ta * is applied from the EPS motor 31 to the second shaft 21b. Then, the rotation angle of the second shaft 21b is maintained at the rotation angle corresponding to the angle command value θe *. Therefore, reverse input generated in the steering mechanism 2 due to road surface conditions, braking, or the like can be suppressed. That is, even when a reverse input is transmitted from the steered wheels 4a and 4b to the steering mechanism 2, the angle assist component Ta3 is maintained so that the rotation angle of the second shaft 21b is maintained at the rotation angle corresponding to the angle command value θe *. * Is adjusted. Therefore, steering assistance is performed in a direction that cancels the reverse input to the second shaft 21b. Thereby, since the vibration of the steering mechanism 2 resulting from reverse input can be suppressed, the driver's steering feeling can be improved.

  (4) Since the angle command value calculation unit 47 calculates the angle command value θe * based on the compensation component Ta2 * that does not easily change during execution of the active steering control, the angle command value θe * associated with the execution of the active steering control is calculated. Change can be suppressed. As a result, a change in the angle assist component Ta3 * accompanying the execution of the active steering control can be suppressed. Thereby, since the change of the assist force accompanying execution of active steering control can be suppressed, a driver's uncomfortable feeling can be reduced.

<Other embodiments>
In addition, each embodiment can also be implemented with the following forms.
In the EPS control device 33 of the first embodiment, the active operation angle command value θa2 * is used as it is as a value to be subtracted from the actual rotation angle θe1 of the second shaft 21b calculated by the rotation angle calculation unit 42. A value having an absolute value smaller than the operating angle command value θa2 * may be used. Specifically, as shown in FIG. 5, the microcomputer 35 of the EPS control device 33 is provided with a correction value calculation unit 49 that calculates the correction value θr based on the active operating angle command value θa2 *. The correction value calculator 49 calculates the correction value θr by multiplying the active operating angle command value θa2 * by a gain having a value that is larger than “0” and smaller than “1”, for example. The subtractor 44 calculates the corrected rotation angle θe2 of the second shaft 21b by subtracting the correction value θr from the actual rotation angle θe1 of the second shaft 21b calculated by the rotation angle calculation unit 42. According to such a configuration, the component of the operating angle based on the active steering control partially remains in the corrected rotation angle θe2 of the second shaft 21b. Therefore, when the operating angle of the second shaft 21b changes with the execution of the active steering control, the compensation component Ta2 * calculated by the compensation component calculator 41 slightly changes. As a result, when the active steering control is executed, the assist force can be slightly changed within a range that does not give the driver a sense of incongruity. A similar configuration may be employed in the EPS control device 33 of the second embodiment.

  In the angle feedback control unit 48 of the second embodiment, angle feedback control based on the rotation angle of the second shaft 21b is performed. This angle feedback control is performed using a rotation angle that can be converted into a rotation angle of the second shaft 21b, For example, you may perform using the turning angle etc. of the steered wheels 4a and 4b.

  In each embodiment, the brake control device 12 transmits the active operating angle command value θa2 * to the VGR control device 54 and the EPS control device 33, respectively. Instead, as shown in FIG. 6, for example, the brake control device 12 transmits the active operation angle command value θa2 * only to the VGR control device 54, and the microcomputer 56 of the VGR control device 54 causes the active operation angle command value θa2 * to be transmitted. May be transmitted to the EPS control device 33. Alternatively, as shown in FIG. 7, the brake control device 12 transmits the active operation angle command value θa2 * only to the EPS control device 33, and the microcomputer 35 of the EPS control device 33 transmits the active operation angle command value θa2 * to the VGR control device 54. May be sent to.

  In each embodiment, the active operation angle command value θa2 * is calculated by the brake control device 12, but the active operation angle command value θa2 * may be calculated by a device other than the brake control device 12. That is, the operating angle command value calculation unit that calculates the active operating angle command value θa2 * can be changed as appropriate.

  In the EPS control device 33 of each embodiment, the active operation angle command value θa2 * is used as a value to be subtracted from the actual rotation angle θe1 of the second shaft 21b calculated by the rotation angle calculation unit 42. Instead, for example, as shown in FIG. 8, the EPS control device 33 is input with an operation angle command value θa * calculated by the microcomputer 56 of the VGR control device 54 instead of the active operation angle command value θa2 *. To do. Then, the microcomputer 56 of the EPS control device 33 subtracts the operating angle command value θa * from the actual rotation angle θe1 of the second shaft 21b calculated by the rotation angle calculation unit 42, thereby correcting the corrected second shaft 21b. The rotation angle θe2 may be obtained. According to such a configuration, the compensation component calculation unit 41 compensates based on the rotation angle of the second shaft 21b excluding not only the operation angle based on the active steering control but also the operation angle based on the gear ratio variable control. Ta2 * can be calculated. As a result, the compensation component Ta2 * is also applied when the operating angle of the second shaft 21b changes along with the execution of the gear ratio variable control, including when the operating angle of the second shaft 21b changes along with the execution of the active steering control. It becomes difficult to change. Therefore, since the change of the assist force accompanying the drive of the gear ratio variable mechanism 5 can be further suppressed, the driver's uncomfortable feeling can be further reduced.

  As shown in FIG. 9, the actual operating angle θa calculated by the microcomputer 56 of the VGR control device 54 may be input to the EPS control device 33. Even with such a configuration, it is possible to obtain the same effect as that of the modified example illustrated in FIG.

The configuration of the modified example illustrated in FIG. 5 may be adopted with respect to the modified example illustrated in FIGS. 8 and 9.
The VGR control device 54 of each embodiment executes active steering control when the driver performs a brake operation while the vehicle is traveling on a split μ road, but the VGR control device 54 is active. The situation in which the steering control is executed can be changed as appropriate.

  In the VGR control device 54, only the gear ratio variable control may be executed without executing the active steering control. That is, the microcomputer 56 of the VGR control device 54 may perform drive control of the VGR motor 51 based only on the VGR operating angle command value θa1 *. In this case, a configuration similar to the configuration shown in FIG. 8 is adopted, and the VGR control device 54 can transmit the VGR operating angle command value θa1 * to the EPS control device 33 instead of the active operating angle command value θa2 *. It is valid. Alternatively, a configuration similar to the configuration shown in FIG. 9 is adopted, and it is effective for the VGR control device 54 to transmit the actual operating angle θa to the EPS control device 33 instead of the active operating angle command value θa2 *. Thereby, it is possible to suppress the change of the assist force accompanying the execution of the gear ratio variable control.

  In each embodiment, the EPS rotation angle sensor 32 and the rotation angle calculation unit 42 detect the rotation angle of the second shaft 21b, but the rotation angle detection unit that detects the rotation angle of the second shaft 21b is not limited to this. For example, a rotation angle sensor that directly detects the rotation angle of the second shaft 21b may be used.

  In each embodiment, the operating angle of the second shaft 21b is detected by the VGR rotation angle sensor 53 and the operating angle calculator 61, but the operating angle detector that detects the operating angle of the second shaft is not limited to this. For example, a first rotation angle sensor that detects the rotation angle of the first shaft 21a and a second rotation angle sensor that detects the rotation angle of the second shaft 21b are provided, and the difference between the rotation angles detected by these rotation angle sensors is provided. The operating angle of the second shaft 21b may be detected by calculating the value.

  The EPS motor 31 of each embodiment is a brushless motor, but may be a motor with a brush.

  DESCRIPTION OF SYMBOLS 1 ... Steering device, 2 ... Steering mechanism, 3 ... Assist mechanism, 5 ... Gear ratio variable mechanism, 12 ... Brake control device (operation angle command value calculating part), 20 ... Steering wheel, 21a ... 1st shaft, 21b ... 1st 2 shafts, 31 ... EPS motor, 33 ... EPS control device (control unit), 36 ... assist command value calculation unit, 40 ... basic assist component calculation unit, 41 ... compensation component calculation unit, 47 ... angle command value calculation unit, 48 ... an angle feedback control unit, 49 ... a correction value calculation unit, 53 ... a VGR rotation angle sensor (operation angle detection unit), 61 ... an operation angle calculation unit (operation angle detection unit).

Claims (6)

A steering mechanism having a first shaft and a second shaft separated from each other, and transmitting the rotation of the steering wheel of the vehicle to the turning shaft of the vehicle via the first shaft and the second shaft;
A gear ratio variable mechanism that changes an operation angle that is a relative rotation angle of the second shaft with respect to the first shaft;
An assist mechanism having a motor that applies assist force to the steering mechanism, and a control unit that controls driving of the motor based on an assist command value corresponding to a target value of an output torque of the motor;
With
The controller is
A basic assist component calculation unit that calculates a basic assist component that is a basic component of the assist command value based on a steering torque applied to the steering wheel in accordance with a steering operation;
A compensation component calculation unit that calculates a compensation component based on a value obtained by subtracting the operating angle of the second shaft from the actual rotation angle of the second shaft;
A steering apparatus, comprising: an assist command value calculation unit that calculates the assist command value based on a value obtained by adding the basic assist component and the compensation component. The steering apparatus according to claim 1, wherein
The controller is
An angle command value calculation unit that calculates an angle command value corresponding to a target value of the rotation angle of the second shaft based on an addition value of the steering torque, the basic assist component, and the compensation component;
An angle feedback control unit that calculates an angle assist component by executing angle feedback control that causes the actual rotation angle of the second shaft to follow the angle command value;
The steering apparatus according to claim 1, wherein the assist command value calculation unit calculates the assist command value based on an addition value of the basic assist component, the angle assist component, and the compensation component. The steering apparatus according to claim 1 or 2,
An operating angle detector for detecting an actual operating angle of the second shaft;
The compensation component calculating unit is a value of an actual operating angle of the second shaft detected by the operating angle detecting unit as a value of an operating angle of the second shaft to be subtracted from an actual rotation angle of the second shaft. A steering apparatus using the The steering apparatus according to claim 1 or 2,
The gear ratio variable mechanism changes the operating angle of the second shaft by executing feedback control for causing the actual operating angle of the second shaft to follow the operating angle command value.
The steering device according to claim 1, wherein the compensation component calculation unit uses the operating angle command value as the operating angle value of the second shaft to be subtracted from an actual rotation angle of the second shaft. The steering apparatus according to claim 1 or 2,
An operation angle command for calculating an active operation angle command value corresponding to a target value of the operation angle of the second shaft in order to execute active steering control for changing the operation angle of the second shaft without depending on the steering operation. Further comprising a value calculation unit,
The gear ratio variable mechanism performs the active steering control by causing the actual operating angle of the second shaft to follow the active operating angle command value,
The steering device according to claim 1, wherein the compensation component calculation unit uses the active operating angle command value as an operating angle value of the second shaft to be subtracted from an actual rotation angle of the second shaft. A steering mechanism having a first shaft and a second shaft separated from each other, and transmitting the rotation of the steering wheel of the vehicle to the turning shaft of the vehicle via the first shaft and the second shaft;
A gear ratio variable mechanism that changes an operation angle that is a relative rotation angle of the second shaft with respect to the first shaft;
A motor that applies assist force to the steering mechanism, and an assist mechanism that has a control unit that controls driving of the motor based on an assist command value corresponding to a target value of the output torque of the motor, and
The controller is
A basic assist component calculation unit that calculates a basic assist component that is a basic component of the assist command value based on a steering torque applied to the steering wheel in accordance with a steering operation;
A correction value calculation unit for calculating a correction value having an absolute value smaller than the operating angle of the second shaft;
A compensation component calculation unit that calculates a compensation component based on a value obtained by subtracting the correction value from the actual rotation angle of the second shaft;
A steering apparatus, comprising: an assist command value calculation unit that calculates the assist command value based on a value obtained by adding the basic assist component and the compensation component.