JP2020168952A - Steering control device - Google Patents

Abstract

To provide a steering control device by which a steering torque required to steer a steering wheel can appropriately be altered according to various traveling situations.SOLUTION: A target reaction torque computing unit 62 comprises a reaction component computing unit 82 that computes a reaction component Fir. The reaction component computing unit 82 comprises: an angle axial force computing unit 101 that computes an angle axial force Fib that does not include road surface information indicating a condition of a road surface; an electric current axial force computing unit 102 that computes an electric current axial force Fer including road surface information; and a distributed axial force computing unit 103 that computes, as a reaction component Fir, distributed axial force obtained by adding the angle axial force Fib and the electrical current axial force Fer at an individually set distribution ratio. Based on a vehicle body speed Vb of a vehicle and wheel speeds Vfl, Vfr of the vehicle, the distributed axial force computing unit 103 computes an amount of first slip status and an amount of second slip status indicating a slip status of a steering wheel and, based on them, adjusts the distribution ratio.SELECTED DRAWING: Figure 3

Description

The present invention relates to a steering control device.

Conventionally, as a kind of steering device, there is a steer-by-wire type in which the power transmission between the steering unit steered by the driver and the steering unit that steers the steering wheel according to the steering of the driver is separated. .. In such a steering device, the road surface reaction force or the like received by the steering wheel is not mechanically transmitted to the steering wheel. Therefore, in the steering control device that controls the steering device of the same type, the road surface information is transmitted to the driver by applying a steering reaction force in consideration of the road surface information to the steering wheel by the steering side actuator. is there.

For example, in the steering control device of Patent Document 1, attention is paid to the axial force acting on the steering shaft to which the steering wheels are connected, and the angular axial force calculated from the target steering angle according to the target steering angle of the steering wheel is used. The steering reaction force is determined in consideration of the distribution axial force, which is the sum of the road surface axial force calculated from the drive current of the steering side motor, which is the drive source of the steering side actuator, and the distribution ratio set individually.

JP-A-2017-165219 JP-A-2016-144974

By the way, in recent years, in a steer-by-wire type steering device, a more appropriate steering reaction force is applied according to various driving conditions, that is, a steering torque required for steering a steering wheel is more appropriate according to various driving conditions. It is becoming necessary to change to. However, even if the above-mentioned conventional configuration is adopted, it cannot be said that the required level has been reached. Therefore, it has been required to create a new technology capable of more appropriately changing the steering torque required for steering the steering wheel according to various driving conditions.

It should be noted that such a problem is not limited to the steering control device that controls the steering device of the steer-by-wire type. For example, as described in Patent Document 2, a steering control device whose control target is an electric power steering device that applies an assist force for assisting a steering operation to the steering mechanism by an assist mechanism using a motor as a drive source also rotates. The same can occur if the target value of the assist torque is determined based on the axial force acting on the steering shaft.

An object of the present invention is to provide a steering control device capable of appropriately changing the steering torque required for steering the steering wheel according to various traveling conditions.

The steering control device that solves the above problems targets a steering device that changes the steering torque required for steering the steering wheel by the motor torque applied by the actuator that uses the motor as a drive source, and sets the target value of the motor torque as the control target. A target torque calculation unit for calculating the target torque is provided, and the operation of the motor is controlled so that the motor torque corresponding to the target torque is generated. The target torque calculation unit is used from the steering wheel of the steering device. As the axial force acting on the steering shaft to which the steering wheels are connected, an angular axial force that does not include road surface information indicating the state of the road surface, and information that can be transmitted through changes in the lateral behavior of the vehicle among the road surface information. The vehicle state quantity axial force including the above, and the axial force calculation unit that calculates at least two of the road surface axial forces including the road surface information, and the at least two axial forces are distributed by adding them at a predetermined distribution ratio. A distribution axial force calculation unit for calculating the axial force is provided, and the target torque is calculated based on the distribution axial force. The distribution axial force calculation unit calculates the vehicle body speed of the vehicle and the wheels of the vehicle. The slip state amount indicating the slip state of the steering wheel is calculated based on the speed, and the distribution ratio is adjusted based on the slip state amount.

According to the above configuration, since the motor torque is controlled based on the distribution axial force whose distribution ratio is adjusted according to the slip state amount, the steering torque required for steering the steering wheel is set to an appropriate torque according to the slip state. , Excellent steering feeling can be realized.

In the steering control device, the steering device has a structure in which power transmission between the steering unit and the steering unit that steers the steering wheel according to the steering input to the steering unit is separated. The motor is a steering side motor that applies the motor torque as a steering reaction force that is a force that opposes steering input to the steering unit, and the target torque calculation unit is the steering reaction as the target torque. A configuration that calculates the target reaction force torque, which is the target value of the force, can be adopted.

In the steering control device, the steering device has a steering mechanism for steering the steering wheels based on the operation of the steering wheel, and the motor is the motor as an assist force for assisting the steering operation. It is an assist motor that applies torque, and the target torque calculation unit can adopt a configuration that calculates a target assist torque that is a target value of the assist force as the target torque.

In the steering control device, the distribution axial force calculation unit calculates a value obtained by subtracting the wheel speed from the vehicle body speed as the slip state amount, and adjusts the distribution ratio based on the slip state amount and the vehicle body speed. It is preferable to do so.

According to the above configuration, it is possible to reduce the calculation load related to the calculation of the slip state amount indicating the slip state of the steering wheel.
In the steering control device, it is preferable that the distribution axial force calculation unit subtracts the wheel speed from the vehicle body speed and divides the subtracted value by the vehicle body speed to calculate the slip state amount.

According to the above configuration, it is possible to reduce the calculation load related to the calculation of the distribution ratio based on the slip state amount.
In the steering control device, the distribution axial force calculation unit calculates the angular axial force, and when the slip state amount indicates the locked state of the steering wheel, the angular axis When the distribution ratio of at least one axial force other than the force is increased and the axial force calculation unit calculates the road surface axial force and the slip state amount indicates the locked state of the steering wheel, the road surface It is preferable to increase the distribution ratio of the axial force.

According to the above configuration, when the steering wheel is locked due to slipping, the distribution ratio of the axial force including the road surface information becomes high, so that the value indicates that the distributed axial force is in the locked state. Then, since the target torque is calculated based on the distributed axial force, it is possible to inform the driver that the steering wheel is in the locked state through the change in the steering torque required for steering the steering wheel.

In the steering control device, the distribution axial force calculation unit calculates the angular axial force, and when the slip state amount indicates the idling state of the steering wheel, the angular axis When the distribution ratio of at least one axial force other than the force is increased and the axial force calculation unit calculates the road surface axial force and the slip state amount indicates the idling state of the steering wheel, the road surface It is preferable to increase the distribution ratio of the axial force.

According to the above configuration, when the steering wheel is in an idling state due to slipping, the distribution ratio of the axial force including the road surface information becomes high, so that the value indicates that the distributed axial force is in the idling state. Then, since the target torque is calculated based on the distributed axial force, it is possible to inform the driver that the steering wheel is in an idling state through a change in the steering torque required for steering the steering wheel.

According to the present invention, the steering torque required for steering the steering wheel can be appropriately changed according to various traveling conditions.

The schematic block diagram of the steering apparatus of 1st Embodiment. The block diagram of the steering control device of 1st Embodiment. The block diagram of the target reaction force torque calculation part of 1st Embodiment. The block diagram of the distribution axial force calculation part of 1st Embodiment. The block diagram of the distribution axial force calculation part of 2nd Embodiment. The schematic block diagram of the steering apparatus of 3rd Embodiment. The block diagram of the steering control device of the 3rd Embodiment.

(First Embodiment)
Hereinafter, the first embodiment of the steering control device will be described with reference to the drawings.
As shown in FIG. 1, the steering device 2 to be controlled by the steering control device 1 of the present embodiment is configured as a steer-by-wire type steering device. The steering device 2 includes a steering unit 4 that is steered by the driver via the steering wheel 3, and a steering unit 6 that steers the steering wheel 5 in response to the steering of the steering unit 4 by the driver.

The steering unit 4 includes a steering shaft 11 to which the steering wheel 3 is fixed, and a steering side actuator 12 that applies a steering reaction force that is a force that opposes steering to the steering wheel 3 via the steering shaft 11. The steering side actuator 12 includes a steering side motor 13 that serves as a drive source, and a steering side speed reducer 14 that decelerates the rotation of the steering side motor 13 and transmits the rotation to the steering shaft 11. That is, the steering side motor 13 applies the motor torque as a steering reaction force. For the steering side motor 13 of the present embodiment, for example, a three-phase brushless motor is adopted.

The steering unit 6 includes a pinion shaft 21, a rack shaft 22 as a steering shaft connected to the pinion shaft 21, a rack housing 23 that reciprocally accommodates the rack shaft 22, and a pinion shaft 21 and a rack shaft 22. The rack and pinion mechanism 24 is provided. The pinion shaft 21 and the rack shaft 22 are arranged at a predetermined intersection angle, and the rack and pinion mechanism 24 has a pinion tooth 21a formed on the pinion shaft 21 and a rack tooth 22a formed on the rack shaft 22. It is configured by meshing. That is, the pinion shaft 21 corresponds to a rotation shaft that can be converted into a steering angle of the steering wheel 5. Tie rods 26 are connected to both ends of the rack shaft 22 via rack ends 25 made of ball joints, and the tips of the tie rods 26 are connected to knuckles (not shown) to which the left and right steering wheels 5 are assembled. ..

Further, the steering unit 6 includes a steering side actuator 31 that applies a steering force for steering the steering wheel 5 to the rack shaft 22. The steering side actuator 31 includes a steering side motor 32 as a drive source, a transmission mechanism 33, and a conversion mechanism 34. Then, the steering side actuator 31 transmits the rotation of the steering side motor 32 to the conversion mechanism 34 via the transmission mechanism 33, and the conversion mechanism 34 converts the rotation into the reciprocating motion of the rack shaft 22 to convert the steering unit 6 into a reciprocating motion. Gives steering force to. That is, the steering side motor 32 applies the motor torque as a steering force. A three-phase brushless motor is adopted for the steering side motor 32 of the present embodiment, a belt mechanism is adopted for the transmission mechanism 33, and a ball screw mechanism is adopted for the conversion mechanism 34, for example. There is.

In the steering device 2 configured in this way, the steering angle of the steering wheel 5 is increased by applying the motor torque as the steering force from the steering side actuator 31 to the rack shaft 22 in response to the steering operation by the driver. Be changed. At this time, the steering reaction force against the steering of the driver is applied to the steering wheel 3 from the steering side actuator 12. That is, in the steering device 2, the steering torque Th required for steering the steering wheel 3 is changed by the steering reaction force which is the motor torque applied from the steering side actuator 12.

Next, the electrical configuration of this embodiment will be described.
The steering control device 1 is connected to the steering side motor 13 and the steering side motor 32, and controls their operation. The steering control device 1 includes a central processing unit (CPU) and a memory (not shown), and the CPU executes a program stored in the memory at predetermined calculation cycles. As a result, various controls are executed.

A torque sensor 41 that detects the steering torque Th applied to the steering shaft 11 is connected to the steering control device 1. The torque sensor 41 is provided on the steering wheel 3 side of the steering shaft 11 connected to the steering side reducer 14, and detects the steering torque Th based on the twist of the torsion bar 42. Further, the steering control device 1 is connected to a left front wheel sensor 44l and a right front wheel sensor 44r provided on a hub unit 43 that rotatably supports the steering wheel 5 via a drive shaft (not shown). The left front wheel sensor 44l detects the wheel speed Vfl of the steering wheel 5 which is the left front wheel, and the right front wheel sensor 44r detects the wheel speed Vfr of the steering wheel 5 which is the right front wheel. Further, the steering control device 1 includes a steering side rotation sensor 45 that detects the rotation angle θs of the steering side motor 13 at a relative angle within a range of 360 ° as a detection value indicating the steering amount of the steering unit 4, and a steering unit. A steering-side rotation sensor 46 that detects the rotation angle θt of the steering-side motor 32 as a relative angle is connected as a detection value indicating the steering amount of 6. The steering torque Th and the rotation angles θs and θt are detected as positive values when steering to the right and negative values when steering to the left, for example.

Further, the steering control device 1 is communicably connected to the braking control device 47 provided outside the steering control device 1. The braking control device 47 controls the operation of a braking device (not shown), and calculates the vehicle body speed Vb of the vehicle body. Specifically, the braking control device 47 includes a left front wheel sensor 44l and a right front wheel sensor 44r, a left rear wheel sensor 48l that detects the wheel speed Vrl of the left rear wheel (not shown), and a right rear wheel wheel (not shown). A right rear wheel sensor 48r that detects the speed Vrr is connected. Then, the braking control device 47 of the present embodiment calculates the average of each wheel speed Vfl, Vfr, Vrl, and Vrr as the vehicle body speed Vb. The vehicle body speed Vb calculated in this way is output to the steering control device 1. The unit of the vehicle body speed Vb and the unit of each wheel speed Vfl, Vfr, Vrl, Vrr are calculated so as to be the same.

Then, the steering control device 1 controls the operation of the steering side motor 13 and the steering side motor 32 based on each state quantity input from each of these sensors and the braking control device 47.
Hereinafter, the configuration of the steering control device 1 will be described in detail.

As shown in FIG. 2, the steering control device 1 has a steering side control unit 51 that outputs a steering side motor control signal Ms, and a steering side that supplies drive power to the steering side motor 13 based on the steering side motor control signal Ms. It includes a drive circuit 52. The steering side control unit 51 detects each phase current value Ius, Ivs, Iws of the steering side motor 13 flowing through the connection line 53 between the steering side drive circuit 52 and the motor coil of each phase of the steering side motor 13. The current sensor 54 is connected. In FIG. 2, for convenience of explanation, the connection line 53 of each phase and the current sensor 54 of each phase are shown together as one.

Further, the steering control device 1 is a steering side that supplies drive power to the steering side control unit 56 that outputs the steering side motor control signal Mt and the steering side motor 32 based on the steering side motor control signal Mt. It includes a drive circuit 57. In the steering side control unit 56, each phase current value of the steering side motor 32 flowing through the connection line 58 between the steering side drive circuit 57 and the motor coil of each phase of the steering side motor 32 Iut, Ivt, A current sensor 59 that detects Iwt is connected. In FIG. 2, for convenience of explanation, the connection line 58 of each phase and the current sensor 59 of each phase are shown together as one. A well-known PWM inverter having a plurality of switching elements such as FETs is adopted in the steering side drive circuit 52 and the steering side drive circuit 57 of the present embodiment, respectively. Further, the steering side motor control signal Ms and the steering side motor control signal Mt are gate on / off signals that define the on / off state of each switching element, respectively.

Then, the steering side control unit 51 and the steering side control unit 56 output the steering side motor control signal Ms and the steering side motor control signal Mt to the steering side drive circuit 52 and the steering side drive circuit 57, thereby mounting the vehicle on the vehicle. Drive power is supplied from the power source B to the steering side motor 13 and the steering side motor 32, respectively. As a result, the steering side control unit 51 and the steering side control unit 56 control the operation of the steering side motor 13 and the steering side motor 32.

First, the configuration of the steering side control unit 51 will be described.
The steering side control unit 51 executes each calculation process shown in each of the following control blocks at a predetermined calculation cycle to generate a steering side motor control signal Ms. In the steering side control unit 51, the steering torque Th, the vehicle body speed Vb, the wheel speeds Vfl, Vfr, the rotation angle θs, the phase current values Ius, Ivs, Iws, and the q-axis current which is the drive current of the steering side motor 32. The value Iqt is entered. Then, the steering side control unit 51 generates and outputs the steering side motor control signal Ms based on each of these state quantities.

Specifically, the steering side control unit 51 includes a steering angle calculation unit 61 that calculates the steering angle θh of the steering wheel 3 based on the rotation angle θs, and a target reaction force torque Ts as a target torque that is a target value of the steering reaction force. It includes a target reaction force torque calculation unit 62 as a target torque calculation unit for calculating *, and a steering side motor control signal calculation unit 63 for calculating the steering side motor control signal Ms.

The rotation angle θs of the steering side motor 13 is input to the steering angle calculation unit 61. The steering angle calculation unit 61 acquires the rotation angle θs by counting the number of rotations of the steering side motor 13 from the steering neutral position, for example, by converting it into an absolute angle including a range exceeding 360 °. Then, the steering angle calculation unit 61 calculates the steering angle θh by multiplying the rotation angle converted to the absolute angle by a conversion coefficient based on the rotation speed ratio of the steering side speed reducer 14. The steering angle θh calculated in this way is output to the target reaction force torque calculation unit 62.

Steering torque Th, vehicle body speed Vb, wheel speeds Vfl, Vfr, steering angle θh, and q-axis current value Iqt are input to the target reaction force torque calculation unit 62. The target reaction force torque calculation unit 62 calculates the target reaction force torque Ts * based on these state quantities as described later, and outputs the target reaction force torque Ts * to the steering side motor control signal calculation unit 63. Further, the target reaction force torque calculation unit 62 sets the target steering angle θh *, which is the target value of the steering angle θh of the steering wheel 3 obtained in the process of calculating the target reaction force torque Ts *, to the steering side control unit 56. Output.

In addition to the target reaction force torque Ts *, the rotation angle θs and the phase current values Ius, Ivs, and Iws are input to the steering side motor control signal calculation unit 63. The steering side motor control signal calculation unit 63 of the present embodiment has a d-axis target current value Ids * on the d-axis and a q-axis target current value Iqs on the q-axis based on the target reaction force torque Ts *. Calculate *. The target current values Ids * and Iqs * indicate the target current value on the d-axis and the target current value on the q-axis in the dq coordinate system, respectively. Specifically, the steering side motor control signal calculation unit 63 calculates the q-axis target current value Iqs * having a larger absolute value as the absolute value of the target reaction force torque Ts * increases. In the present embodiment, the d-axis target current value Ids * on the d-axis is basically set to zero. Then, the steering side motor control signal calculation unit 63 generates the steering side motor control signal Ms to be output to the steering side drive circuit 52 by executing the current feedback control in the dq coordinate system. In the following, the word feedback may be referred to as "F / B".

Specifically, the steering side motor control signal calculation unit 63 maps the phase current values Ius, Ivs, and Iws on the dq coordinates based on the rotation angle θs, so that the actual current of the steering side motor 13 in the dq coordinate system The d-axis current value Ids and the q-axis current value Iqs, which are the values, are calculated. Then, the steering side motor control signal calculation unit 63 d is to make the d-axis current value Ids follow the d-axis target current value Ids * and to make the q-axis current value Iqs follow the q-axis target current value Iqs *. A target voltage value is calculated based on each current deviation on the axis and the q-axis, and a steering side motor control signal Ms having a duty ratio based on the target voltage value is generated.

The steering side motor control signal Ms calculated in this way is output to the steering side drive circuit 52. As a result, the steering side motor 13 is supplied with drive power corresponding to the steering side motor control signal Ms from the steering side drive circuit 52. Then, the steering side motor 13 applies the steering reaction force indicated by the target reaction force torque Ts * to the steering wheel 3.

Next, the steering side control unit 56 will be described.
The steering side control unit 56 executes each calculation process shown in each of the following control blocks at a predetermined calculation cycle to generate a steering side motor control signal Mt. The rotation angle θt, the target steering angle θh *, and the phase current values Iut, Ivt, and Iwt of the steering side motor 32 are input to the steering side control unit 56. Then, the steering side control unit 56 generates and outputs a steering side motor control signal Mt based on each of these state quantities. In the steering device 2 of the present embodiment, the steering angle ratio, which is the ratio of the steering angle θh to the steering correspondence angle θp, is set to be constant at a ratio of 1: 1 and is a target value of the steering correspondence angle θp. The target steering angle is equal to the target steering angle θh *.

Specifically, the steering side control unit 56 includes a steering correspondence angle calculation unit 71 that calculates a steering correspondence angle θp, which is a rotation angle of the pinion shaft 21 based on the rotation angle θt, and the target value of the steering force. A target steering torque calculation unit 72 that calculates a target steering torque Tt *, and a steering side motor control signal calculation unit 73 that outputs a steering side motor control signal Mt are provided.

The rotation angle θt of the steering side motor 32 is input to the steering corresponding angle calculation unit 71. The steering corresponding angle calculation unit 71 acquires the input rotation angle θt by converting it into an absolute angle, for example, by counting the number of rotations of the steering side motor 32 from the neutral position where the vehicle travels straight. Then, the steering corresponding angle calculation unit 71 multiplies the rotation angle converted to the absolute angle by a conversion coefficient based on the reduction ratio of the transmission mechanism 33, the lead of the conversion mechanism 34, and the rotation speed ratio of the rack and pinion mechanism 24. The steering angle θp is calculated. That is, the steering angle θp corresponds to the steering angle θh of the steering wheel 3 when it is assumed that the pinion shaft 21 is connected to the steering shaft 11. The steering correspondence angle θp calculated in this way is output to the target steering torque calculation unit 72.

The target steering angle θh * and the steering corresponding angle θp are input to the target steering torque calculation unit 72. The target steering torque calculation unit 72 calculates the target steering torque Tt * by executing an angle F / B calculation that causes the steering correspondence angle θp to follow the target steering angle θh * which is the target steering correspondence angle. .. Specifically, the target steering torque calculation unit 72 includes a steering angle F / B control unit 74 that performs an angle F / B calculation. The steering angle F / B control unit 74 is input with an angle deviation Δθp obtained by subtracting the steering corresponding angle θp from the target steering angle θh * which is the target steering angle in the subtractor 75. Then, the target steering torque calculation unit 72 calculates the sum of the output values of the proportional element, the integrating element, and the differential element that input the angle deviation Δθp as the target steering torque Tt *. The target steering torque Tt * calculated in this way is output to the steering side motor control signal calculation unit 73.

In addition to the target steering torque Tt *, the rotation angle θt and the phase current values Iut, Ivt, and Iwt are input to the steering side motor control signal calculation unit 73. The steering side motor control signal calculation unit 73 calculates the d-axis target current value Ids * on the d-axis and the q-axis target current value Iqt * on the q-axis based on the target steering torque Tt *. To do. Specifically, the steering side motor control signal calculation unit 73 calculates the q-axis target current value Iqt * having a larger absolute value as the absolute value of the target steering torque Tt * increases. In the present embodiment, the d-axis target current value Idt * on the d-axis is basically set to zero. Then, the steering side motor control signal calculation unit 73 outputs to the steering side drive circuit 57 by executing the current F / B calculation in the dq coordinate system in the same manner as the steering side motor control signal calculation unit 63. The steering side motor control signal Mt is generated. The q-axis current value Iqt calculated in the process of generating the steering side motor control signal Mt is output to the target reaction force torque calculation unit 62.

The steering side motor control signal Mt calculated in this way is output to the steering side drive circuit 57. As a result, the steering side motor 32 is supplied with drive power corresponding to the steering side motor control signal Mt from the steering side drive circuit 57. Then, the steering side motor 32 applies the steering force indicated by the target steering torque Tt * to the steering wheels 5.

Next, the target reaction force torque calculation unit 62 will be described.
As shown in FIG. 3, the target reaction force torque calculation unit 62 calculates the torque F / B component Tfbt as the input torque basic component which is the force for rotating the steering wheel 3 in the steering direction of the driver. The unit 81 is provided. Further, the target reaction force torque calculation unit 62 calculates a reaction force component Fir, which is a force that opposes the rotation of the steering wheel 3 by the driver's steering, that is, an axial force that acts on the rack shaft 22 from the steering wheel 5. The component calculation unit 82 is provided. Further, the target reaction force torque calculation unit 62 has a target steering angle calculation unit 83 that calculates a target steering angle θh * that is a target value of the steering angle θh, and a steering angle F / B that calculates the steering angle F / B component Tfbh. It includes a control unit 84. Then, the target reaction force torque calculation unit 62 calculates the target reaction force torque Ts * based on the torque F / B component Tfbt and the steering angle F / B component Tfbh.

Specifically, the steering torque Th is input to the input torque basic component calculation unit 81. The input torque basic component calculation unit 81 includes the target steering torque calculation unit 91 that calculates the target steering torque Th *, which is the target value of the steering torque Th to be input to the steering unit 4, and the torque F by executing the torque F / B calculation. It is provided with a torque F / B control unit 92 that calculates the / B component Tfbt.

In the target steering torque calculation unit 91, the drive torque Tc obtained by adding the torque F / B component Tfbt to the steering torque Th in the adder 93 is input. The target steering torque calculation unit 91 calculates the target steering torque Th *, which becomes a larger absolute value as the absolute value of the drive torque Tc increases. The drive torque Tc is a torque for steering the steering wheel 5 when the steering portion 4 and the steering portion 6 are mechanically connected, and is approximately balanced with the axial force acting on the rack shaft 22. .. That is, the drive torque Tc corresponds to the calculated axial force that estimates the axial force acting on the rack shaft 22.

The torque F / B control unit 92 is input with the steering torque Th and the torque deviation ΔTh obtained by subtracting the target steering torque Th * from the steering torque Th in the subtractor 94. Then, the torque F / B control unit 92 calculates the torque F / B component Tfbt by performing the torque F / B calculation that causes the steering torque Th to follow the target steering torque Th * based on the torque deviation ΔTh. Specifically, the torque F / B control unit 92 calculates the sum of the output values of the proportional element, the integrating element, and the differential element that input the torque deviation ΔTh as the torque F / B component Tfbt. The torque F / B component Tfbt calculated in this way is output to the adders 85 and 93 and the target steering angle calculation unit 83.

The vehicle body speed Vb, wheel speeds Vfl, Vfr, the q-axis current value Iqt of the steering side motor 32, and the target steering angle θh * are input to the reaction force component calculation unit 82. The reaction force component calculation unit 82 calculates the reaction force component Fir according to the axial force acting on the rack shaft 22 based on these state quantities as described later, and outputs the reaction force component Fir to the target steering angle calculation unit 83. The reaction force component Fir corresponds to an calculated axial force that estimates the axial force acting on the rack shaft 22.

The vehicle body speed Vb, steering torque Th, torque F / B component Tfbt, and reaction force component Fir are input to the target steering angle calculation unit 83. The target steering angle calculation unit 83 associates the input torque Tin *, which is a value obtained by adding the steering torque Th to the torque F / B component Tfbt and subtracting the reaction force component Fir, from the target steering angle θh * (1) below. The target steering angle θh * is calculated using the steering model formula of.

Tin * = C ・ θh *'＋ J ・ θh *''… (1)
In this model formula, the steering wheel 3 and the steering wheel 5 are mechanically connected, that is, the steering unit 4 and the steering wheel 6 are mechanically connected, and the steering wheel 3 is rotated. The relationship between the torque of the rotating rotating shaft and the rotation angle is defined and expressed. Then, this model formula is expressed by using a viscosity coefficient C that models the friction of the steering device 2 and an inertia coefficient J that models the inertia of the steering device 2. The viscosity coefficient C and the inertial coefficient J are variably set according to the vehicle body speed Vb. Then, the target steering angle θh * calculated by using the model formula in this way is output to the target steering torque calculation unit 72 and the reaction force component calculation unit 82.

An angle deviation Δθh obtained by subtracting the steering angle θh from the target steering angle θh * in the subtractor 86 is input to the steering angle F / B control unit 84. Then, the steering angle F / B control unit 84 calculates the steering angle F / B component Tfbh by performing an angle F / B calculation that causes the steering angle θh to follow the target steering angle θh * based on the angle deviation Δθh. To do. Specifically, the steering angle F / B control unit 84 calculates the sum of the output values of the proportional element, the integrating element, and the differential element that input the angle deviation Δθh as the steering angle F / B component Tfbh. The steering angle F / B component Tfbh calculated in this way is output to the adder 85.

Then, the target reaction force torque calculation unit 62 calculates the value obtained by adding the steering angle F / B component Tfbh to the torque F / B component Tfbt in the adder 85 as the target reaction force torque Ts *. The target reaction force torque Ts * calculated in this way is output to the steering side motor control signal calculation unit 63. As described above, the target reaction force torque calculation unit 62 calculates the target steering torque Th * used for the torque F / B calculation based on the driving torque Tc which is the axial force in the calculation, and also calculates the angle F / B. The target steering angle θh * used in the above is calculated based on the reaction force component Fir which is the axial force in the calculation, and these are added together to calculate the target reaction force torque Ts *. Therefore, the steering reaction force applied by the steering side motor 13 is basically a force that opposes the steering of the driver, but due to the deviation between the calculated axial force and the actual axial force acting on the rack shaft 22. Can also be a force to assist the driver in steering.

Next, the reaction force component calculation unit 82 will be described.
The reaction force component calculation unit 82 includes an angle axis force calculation unit 101 that calculates the angle axis force Fib, and a current axis force calculation unit 102 that calculates the current axis force Fer. The angular axial force Fib and the current axial force Fer are calculated by the torque dimension (Nm). In the present embodiment, the axial force calculation unit is composed of the angle axial force calculation unit 101 and the current axial force calculation unit 102. Further, the reaction force component calculation unit 82 predeterminedly distributes the angular axial force Fib and the current axial force Fer so that the axial force applied to the steering wheel 5 from the road surface, that is, the road surface information transmitted from the road surface is reflected. It is provided with a distribution axial force calculation unit 103 that calculates the distribution axial force summed up by the distribution ratios individually set so as to be a ratio as a reaction force component Fir.

The target steering angle θh * and the vehicle body speed Vb, which are the target steering corresponding angles, are input to the angle axial force calculation unit 101. The angle axial force calculation unit 101 calculates the axial force acting on the steering wheel 5, that is, the transmission force transmitted to the steering wheel 5, based on the target steering angle θh *. That is, the angular axial force Fib is an ideal value of the axial force in an arbitrarily set model, and affects minute irregularities that do not affect the lateral behavior of the vehicle and the lateral behavior of the vehicle. Axial force that does not include road surface information such as steps to be given. Specifically, the angle axial force calculation unit 101 calculates so that the larger the absolute value of the target steering angle θh *, the larger the absolute value of the angle axial force Fib. Further, the angle axial force calculation unit 101 calculates so that the absolute value of the angular axial force Fib increases as the vehicle body speed Vb increases. The angle axial force Fib calculated in this way is output to the distribution axial force calculation unit 103.

The q-axis current value Iqt of the steering side motor 32 is input to the current axial force calculation unit 102. The current axial force calculation unit 102 calculates the axial force acting on the steering wheel 5 based on the q-axis current value Iqt. That is, the current axial force Fer is an estimated value of the axial force acting on the steering wheel 5, and is one of the road surface axial forces including the road surface information. Specifically, the current axial force calculation unit 102 assumes that the torque applied to the rack shaft 22 by the steering side motor 32 and the torque corresponding to the force applied to the steering wheel 5 from the road surface are balanced, and the q-axis The calculation is performed so that the larger the absolute value of the current value Iqt, the larger the absolute value of the current axial force Fer. The current axial force Fer calculated in this way is output to the distribution axial force calculation unit 103.

In addition to the angular axial force Fib and the current axial force Fer, the vehicle body speed Vb and the wheel speeds Vfl and Vfr are input to the distribution axial force calculation unit 103. The distribution axial force calculation unit 103 calculates the first slip state amount S1 and the second slip state amount S2 based on the vehicle body speed Vb and the wheel speeds Vfl and Vfr, and adjusts the distribution ratio based on these. Then, the distribution axial force calculation unit 103 adds up the angular axial force Fib and the current axial force Fer at the distribution ratio adjusted based on the first slip state quantity S1 and the second slip state quantity S2. The force is calculated as the reaction force component Fir.

Specifically, as shown in FIG. 4, the distribution axial force calculation unit 103 determines the distribution gain for determining the distribution ratio between the angular axial force Fib and the current axial force Fer based on the vehicle body speed Vb and the wheel speeds Vfl and Vfr. The distribution gain calculation unit 111 for calculating Ga is provided. Then, the distribution axial force calculation unit 103 calculates the reaction force component Fir by distributing the angular axial force Fib and the current axial force Fer according to the distribution gain Ga.

More specifically, the distribution gain calculation unit 111 includes a first slip state amount calculation unit 121 that calculates a first slip state amount S1 indicating a slip state of the left front wheel, and a first distribution gain according to the first slip state amount S1. It is provided with a first distribution gain calculation unit 122 that calculates Ga1. Further, the distribution gain calculation unit 111 calculates the second slip state amount calculation unit 123 that calculates the second slip state amount S2 indicating the slip state of the right front wheel, and the second distribution gain Ga2 corresponding to the second slip state amount S2. It is provided with a second distribution gain calculation unit 124 for calculation.

The vehicle body speed Vb and the wheel speed Vfl of the left front wheel are input to the first slip state amount calculation unit 121. Then, the first slip state quantity calculation unit 121 calculates a value obtained by subtracting the wheel speed Vfl of the left front wheel from the vehicle body speed Vb, that is, a value corresponding to the slip ratio as the first slip state quantity S1, and calculates the first distribution gain. Output to unit 122. The vehicle body speed Vb and the wheel speed Vfr of the right front wheel are input to the second slip state quantity calculation unit 123. Then, the second slip state amount calculation unit 123 calculates a value obtained by subtracting the wheel speed Vfr of the right front wheel from the vehicle body speed Vb as the second slip state amount S2, and outputs the value to the second distribution gain calculation unit 124.

Here, the first slip state amount S1 and the second slip state amount S2 are zero or substantially zero, respectively, that is, when there is no difference or almost no difference between the vehicle body speed Vb and the wheel speeds Vfl and Vfr. , Indicates that the steering wheel 5 is not slipping. On the other hand, when the values of the first slip state amount S1 and the second slip state amount S2 are large positive values, that is, when the vehicle body speed Vb is larger than the wheel speeds Vfl and Vfr, the steering wheel 5 is used. Indicates that it is locked. Further, when the values of the first slip state amount S1 and the second slip state amount S2 are large negative values, that is, when the vehicle body speed Vb is larger than the wheel speeds Vfl and Vfr, the steering wheel 5 is used. Indicates that the vehicle is idling.

The first slip state quantity S1 and the vehicle body speed Vb are input to the first distribution gain calculation unit 122. The first distribution gain calculation unit 122 includes a map that defines the relationship between the first slip state amount S1 and the vehicle body speed Vb and the first distribution gain Ga1. By referring to the map, the first slip state amount S1 And the first distribution gain Ga1 according to the vehicle body speed Vb is calculated. In this map, the first distribution gain Ga1 becomes "1" in the region where the first slip state quantity S1 is near zero, and when the absolute value of the first slip state quantity S1 becomes larger than a certain level, the first slip state quantity S1 The first distribution gain Ga1 is set to linearly decrease based on the increase in the absolute value. That is, the first distribution gain Ga1 is set to decrease as the absolute value of the first slip state quantity S1 increases, that is, as the steering wheel 5 approaches the locked state or the idling state. Further, this map is set so that the region where the first distribution gain Ga1 becomes "1" becomes wider as the vehicle body speed Vb increases. This is because the absolute value of the deviation between the vehicle body speed Vb and the wheel speed Vfl tends to increase as the vehicle body speed Vb increases, and the first slip state amount S1 represented by the deviation is erroneously set on the steering wheel 5. This is to prevent the vehicle from showing a locked state or an idling state. The first distribution gain Ga1 calculated in this way is output to the multiplier 125.

The second slip state quantity S2 and the vehicle body speed Vb are input to the second distribution gain calculation unit 124. The second distribution gain calculation unit 124 includes a map that defines the relationship between the second slip state amount S2 and the vehicle body speed Vb and the second distribution gain Ga2. By referring to the map, the second slip state amount S2 And the second distribution gain Ga2 according to the vehicle body speed Vb is calculated. This map is set in the same manner as the map of the first distribution gain calculation unit 122. The second distribution gain Ga2 calculated in this way is output to the multiplier 125.

Then, the distribution gain calculation unit 111 calculates the distribution gain Ga by multiplying the first distribution gain Ga1 and the second distribution gain Ga2 in the multiplier 125. The distribution gain Ga calculated in this way is output to the multiplier 112 and the subtractor 113.

In addition to the distribution gain Ga, the angular axial force Fib is input to the multiplier 112. The distribution axial force calculation unit 103 outputs the multiplication value Aib obtained by multiplying the distribution gain Ga by the angular axial force Fib in the multiplier 112 to the adder 114. On the other hand, in addition to the distribution gain Ga, the constant "1" is always input to the subtractor 113. The distribution axial force calculation unit 103 outputs the subtraction value Gb obtained by subtracting the distribution gain Ga from the constant "1" to the multiplier 115 in the subtractor 113. The distribution axial force calculation unit 103 outputs the multiplication value Aer obtained by multiplying the subtraction value Gb by the current axial force Fer in the multiplier 115 to the adder 114. Then, the distribution axial force calculation unit 103 outputs the distribution axial force formed by adding the multiplication values Aib and Aer in the adder 114 as the reaction force component Fir.

That is, the distribution axial force is set so that the sum of the distribution ratio of the angular axial force Fib and the distribution ratio of the current axial force Fer is "1". When the steering wheel 5 is not slipping, the distribution axial force is dominated by the distribution ratio of the angular axial force Fib, and the closer the slip state of the steering wheel 5 is to the locked state or the idling state, the more the current axial force is applied. The distribution ratio of Fer becomes large. As a result, when the slip state of the steering wheel 5 approaches the locked state or the idling state, the distribution ratio of the current axial force Fer increases, so that a steering reaction force reflecting the road surface information is applied, and the steering wheel 5 It becomes easier for the driver to recognize that 5 is slipping.

Next, the operation and effect of this embodiment will be described.
(1) The distribution axial force calculation unit 103 calculates the first slip state quantity S1 and the second slip state quantity S2 based on the vehicle body speed Vb and the wheel speeds Vfl and Vfr, and these first slip state quantities S1 and second. Based on the slip state quantity S2, the distribution gain Ga indicating the distribution ratio of the angular axial force Fib and the current axial force Fer is adjusted. Then, the steering control device 1 controls the motor torque applied as the steering reaction force based on the reaction force component Fir, which is the distribution axial force whose distribution ratio is adjusted according to the slip state of the steering wheel 5. Therefore, the steering torque Th required for steering the steering wheel 3 can be set to an appropriate torque according to the slip state, and an excellent steering feeling can be realized.

(2) The distribution axial force calculation unit 103 calculates the values obtained by subtracting the wheel speeds Vfl and Vfr from the vehicle body speed Vb as the first slip state quantity S1 and the second slip state quantity S2, and these first slip state quantities S1 and The distribution gain Ga indicating the distribution ratio is adjusted based on the second slip state amount S2 and the vehicle body speed Vb. Since the first slip state quantity S1 and the second slip state quantity S2 can be calculated only by subtraction in this way, the first slip state quantity S1 and the second slip state quantity S2 can be calculated as compared with the case where division is performed in addition to subtraction, for example. The calculation load related to the calculation can be reduced.

(3) In the distribution axial force calculation unit 103, when the first slip state amount S1 and the second slip state amount S2 indicate the locked state of the steering wheel 5, the distribution ratio of the current axial force Fer, which is the road surface axial force, is set. The distribution gain Ga is calculated so as to be large. Therefore, when the steering wheel 5 is locked due to slipping, the distribution ratio of the current axial force Fer including the road surface information becomes high, so that the reaction force component Fir, which is the distributed axial force, is in the locked state. It becomes the value shown. Then, since the target reaction force torque Ts * is calculated based on the reaction force component Fir, the driver knows that the steering wheel 5 is in the locked state through the change in the steering torque required for steering the steering wheel 3. Can be told to.

(4) When the first slip state quantity S1 and the second slip state quantity S2 indicate the idling state of the steering wheel 5, the distribution axial force calculation unit 103 determines that the distribution ratio of the current axial force Fer, which is the road surface axial force, is The distribution gain Ga is calculated so as to be large. Therefore, when the steering wheel 5 is in an idling state due to slipping, the distribution ratio of the current axial force Fer including the road surface information becomes high, so that the reaction force component Fir, which is the distributed axial force, is in the idling state. It becomes the value shown. Then, since the target reaction force torque Ts * is calculated based on the reaction force component Fir, the driver knows that the steering wheel 5 is in an idling state through a change in the steering torque required for steering the steering wheel 3. Can be told to.

(Second Embodiment)
Next, a second embodiment of the steering control device will be described with reference to the drawings. For convenience of explanation, the same components are designated by the same reference numerals as those in the first embodiment, and the description thereof will be omitted.

As shown in FIG. 5, the first slip state quantity calculation unit 221 of the present embodiment subtracts the wheel speed Vfl of the left front wheel from the vehicle body speed Vb, and the subtracted value is divided by the vehicle body speed Vb, that is, slip. The rate is calculated as the first slip state quantity S1. Further, the second slip state amount calculation unit 223 subtracts the wheel speed Vfr of the right front wheel from the vehicle body speed Vb, and divides the subtracted value by the vehicle body speed Vb to calculate as the second slip state amount S2.

Only the first slip state amount S1 is input to the first distribution gain calculation unit 222, and the vehicle body speed Vb is not input. The first distribution gain calculation unit 222 includes a map that defines the relationship between the first slip state amount S1 and the first distribution gain Ga1. By referring to the map, the first slip state amount S1 corresponds to the first. 1 Calculate the distribution gain Ga1. In this map, the first distribution gain Ga1 becomes "1" in the region where the first slip state quantity S1 is near zero, and when the absolute value of the first slip state quantity S1 becomes larger than a certain level, the first slip state quantity S1 The first distribution gain Ga1 is set to linearly decrease based on the increase in the absolute value. The first distribution gain Ga1 calculated in this way is output to the multiplier 225.

Only the second slip state quantity S2 is input to the second distribution gain calculation unit 224, and the vehicle body speed Vb is not input. The second distribution gain calculation unit 224 includes a map that defines the relationship between the second slip state amount S2 and the second distribution gain Ga2, and by referring to the map, the second slip state amount S2 corresponds to the second. 2 Calculate the distribution gain Ga2. This map is set in the same manner as the map of the first distribution gain calculation unit 222. The second distribution gain Ga2 calculated in this way is output to the multiplier 225.

The distribution gain calculation unit 111 calculates the distribution gain Ga by multiplying the first distribution gain Ga1 and the second distribution gain Ga2 in the multiplier 225. Then, the distribution axial force calculation unit 103 calculates the reaction force component Fir, which is the distribution axial force, based on the distribution gain Ga as in the first embodiment.

As described above, in this embodiment, in addition to the same actions and effects as those of (1), (3), and (4) of the first embodiment, the following actions and effects are exhibited.
(5) The distribution axial force calculation unit 103 subtracts the wheel speeds Vfl and Vfr from the vehicle body speed Vb, and divides the subtracted values by the vehicle body speed Vb to obtain the first slip state amount S1 and the second slip state amount. Calculate as S2. Then, the distribution axial force calculation unit 103 calculates the first distribution gain Ga1 based only on the first slip state amount S1, and calculates the second distribution gain Ga2 based only on the second slip state amount S2. The distribution gain Ga indicating the distribution ratio is calculated by multiplying the 1 distribution gain Ga1 and the second distribution gain Ga2. Since the distribution gain Ga is calculated based only on the first slip state amount S1 and the second slip state amount S2 in this way, the first slip state amount S1 and the second slip state are compared with the case where, for example, the vehicle body speed Vb is also taken into consideration. The calculation load related to the calculation of the distribution ratio based on the quantity S2 can be reduced.

(Third Embodiment)
Next, a third embodiment of the steering control device will be described with reference to the drawings. For convenience of explanation, the same components are designated by the same reference numerals as those in the first embodiment, and the description thereof will be omitted.

As shown in FIG. 6, the steering device 301 of the present embodiment is configured as an electric power steering device (EPS). The steering device 301 includes a steering mechanism 302 that steers the steering wheel 5 based on the operation of the steering wheel 3 by the driver, and an assist mechanism 303 that imparts an assist force to assist the steering operation to the steering mechanism 302. ing.

The steering mechanism 302 includes a steering shaft 311 to which the steering wheel 3 is fixed. Further, the steering mechanism 302 racks the rotation of the rack shaft 312 as a steering shaft connected to the steering shaft 311 and the cylindrical rack housing 313 through which the rack shaft 312 is reciprocally inserted, and the steering shaft 311. It is equipped with a rack and pinion mechanism 314 that converts the reciprocating motion of the shaft 312. The steering shaft 311 is configured by connecting a column shaft 315, an intermediate shaft 316, and a pinion shaft 317 in order from the side where the steering wheel 3 is located.

The rack shaft 312 and the pinion shaft 317 are arranged in the rack housing 313 with a predetermined crossing angle. The rack and pinion mechanism 314 is configured by engaging the rack teeth 312a formed on the rack shaft 312 and the pinion teeth 317a formed on the pinion shaft 317. Further, tie rods 319 are rotatably connected to both ends of the rack shaft 312 via rack ends 318 made of ball joints provided at the shaft ends. The tip of the tie rod 319 is connected to a knuckle (not shown) to which the steering wheel 5 is assembled. Therefore, in the steering device 301, the rotation of the steering shaft 311 accompanying the steering operation is converted into the axial movement of the rack shaft 312 by the rack and pinion mechanism 314, and this axial movement is transmitted to the knuckle via the tie rod 319. As a result, the steering angle of the steering wheel 5, that is, the traveling direction of the vehicle is changed.

The assist mechanism 303 is a conversion mechanism 323 that converts the rotation transmitted via the assist motor 321 which is the drive source, the transmission mechanism 322 that transmits the rotation of the assist motor 321 and the transmission mechanism 322 into the reciprocating motion of the rack shaft 312. And have. Then, the assist mechanism 303 transmits the rotation of the assist motor 321 to the conversion mechanism 323 via the transmission mechanism 322, and the conversion mechanism 323 converts the rotation into the reciprocating motion of the rack shaft 312 to impart an assist force to the steering mechanism 302. To do. That is, in the steering device 301, the steering torque Th required for steering the steering wheel 3 is changed by the assist force as the motor torque given by the assist mechanism 303. The assist motor 321 of the present embodiment employs, for example, a three-phase brushless motor, the transmission mechanism 322 employs, for example, a belt mechanism, and the conversion mechanism 323 employs, for example, a ball screw mechanism.

A torque sensor 331 that detects the steering torque Th applied to the steering shaft 311 is connected to the steering control device 300 of the present embodiment. The torque sensor 331 is provided on the pinion shaft 317, and detects the steering torque Th based on the twist of the torsion bar 332. Further, a left front wheel sensor 44l and a right front wheel sensor 44r are connected to the steering control device 300. Further, the steering control device 300 is connected to a rotation sensor 333 that detects the motor angle θm of the assist motor 321 at a relative angle within a range of 360 °. The steering torque Th and the motor angle θm are detected as positive values when steering to the right and negative values when steering to the left, for example. Further, the steering control device 300 is communicably connected to the braking control device 47 provided outside the steering control device 300. The vehicle body speed Vb calculated by the braking control device 47 is input to the steering control device 300.

Then, the steering control device 300 supplies driving power to the assist motor 321 based on each state quantity input from each of these sensors and the braking control device 47, thereby operating the assist mechanism 303, that is, the steering mechanism 302. The assist force applied to reciprocate the rack shaft 312 is controlled.

Next, the configuration of the steering control device 300 will be described.
As shown in FIG. 7, the steering control device 300 includes a microcomputer 351 that outputs a motor control signal Ma, and a drive circuit 352 that supplies drive power to the assist motor 321 based on the motor control signal Ma. The drive circuit 352 of the present embodiment employs a well-known PWM inverter having a plurality of switching elements such as FETs. The motor control signal Ma output by the microcomputer 351 defines the on / off state of each switching element. As a result, each switching element is turned on and off in response to the motor control signal Ma, and the energization pattern for the motor coil of each phase is switched, so that the DC power of the vehicle-mounted power supply B is converted into the three-phase drive power of the assist motor. It is output to 321.

The steering torque Th, the motor angle θm, the vehicle body speed Vb, and the wheel speeds Vfl and Vfr are input to the microcomputer 351. Further, each phase current value Iu, Iv, Iw of the assist motor 321 detected by the current sensor 354 provided on the connection line 353 between the drive circuit 352 and the motor coil of each phase is input to the microcomputer 351. To. In FIG. 7, for convenience of explanation, the connection line 353 of each phase and the current sensor 354 of each phase are shown together as one. Then, the microcomputer 351 outputs the motor control signal Ma based on each of these state quantities.

Specifically, the microcomputer 351 generates a target assist torque calculation unit 361 as a target torque calculation unit that calculates a target assist torque Ta * as a target torque corresponding to an assist force to be applied to the steering mechanism 302, and a motor control signal Ma. It is provided with a motor control signal calculation unit 362 for calculation.

The target assist torque calculation unit 361 includes an input torque basic component calculation unit 371 that calculates the torque F / B component Tfbt as an input torque basic component, and a reaction force component calculation unit 372 that calculates the reaction force component Fir. The steering torque Th is input to the input torque basic component calculation unit 371. The input torque basic component calculation unit 371 includes a target steering torque calculation unit 381 that calculates the target steering torque Th * and a torque F / B control unit 382 that calculates the torque F / B component Tfbt. The torque F / B component Tfbt is calculated by the same calculation process as that of the input torque basic component calculation unit 81 of the embodiment. The torque F / B component Tfbt calculated in this way is output to the adders 373 and 383.

The vehicle body speed Vb, the wheel speeds Vfl, Vfr, the q-axis current value Iq of the assist motor 321 and the target steering correspondence angle θp * are input to the reaction force component calculation unit 372. The reaction force component calculation unit 372 calculates the reaction force component Fir by the same calculation process as the reaction force component calculation unit 82 of the first embodiment. As a result, the reaction force component Fir, which is the distribution axial force whose distribution ratio is adjusted according to the slip state of the steering wheel 5, is calculated, and the motor torque applied as the assist force is controlled based on the reaction force component Fir. Rudder.

Further, the target assist torque calculation unit 361 includes a steering corresponding angle calculation unit 374, a target steering corresponding angle calculation unit 375, and a steering angle F / B control unit 376. The motor angle θm is input to the steering corresponding angle calculation unit 374. The steering correspondence angle calculation unit 374 calculates the steering correspondence angle θp indicating the rotation angle of the pinion shaft 317 by the same calculation processing as the steering correspondence angle calculation unit 71 of the first embodiment based on the motor angle θm. Calculate. The steering correspondence angle θp calculated in this way is output to the subtractor 377.

Steering torque Th, torque F / B component Tfbt, reaction force component Fir, and vehicle body speed Vb are input to the target steering corresponding angle calculation unit 375. Based on these state quantities, the target steering angle calculation unit 375 calculates the target steering angle θp * by using the model formula as in the target steering angle calculation unit 83 of the first embodiment. To do.

In the subtractor 377, the steering angle F / B control unit 376 is input with an angle deviation Δθp obtained by subtracting the steering correspondence angle θp from the target steering correspondence angle θp *. Then, the steering angle F / B control unit 376 calculates the steering angle F / B component Tfbp by the same calculation processing as the steering angle F / B control unit 84 of the first embodiment. The steering angle F / B component Tfbp calculated in this way is output to the adder 373.

Then, the target assist torque Ta * calculates the target assist torque Ta * by adding the torque F / B component Tfbt and the steering angle F / B component Tfbp in the adder 373.
The target assist torque Ta * is input to the motor control signal calculation unit 362. The motor control signal calculation unit 362 calculates the motor control signal Ma by the same calculation processing as the steering side motor control signal calculation unit 63 of the first embodiment.

The motor control signal Ma calculated in this way is output to the drive circuit 352. As a result, the assist motor 321 is supplied with the drive power corresponding to the motor control signal Ma from the drive circuit 352. Then, the assist motor 321 applies the assist force indicated by the target assist torque Ta * to the steering mechanism 302.

The target assist torque calculation unit 361 calculates the target steering torque Th * used for the torque F / B calculation based on the drive torque Tc which is the axial force in the calculation, and the target steering used for the angle F / B calculation. The corresponding angle θp * is calculated based on the reaction force component Fir, which is the axial force in the calculation, and these are added together to calculate the target assist torque Ta *. Therefore, the steering reaction force applied by the assist motor 321 is basically a force that assists the driver in steering, but depending on the deviation between the calculated axial force and the actual axial force acting on the rack shaft 22. , It can also be a force against the steering of the driver.

As described above, in this embodiment, in addition to the same actions and effects as those of (1) to (4) of the first embodiment, the following actions and effects are exhibited.
Each of the above embodiments can be modified and implemented as follows. Each of the above embodiments and the following modifications can be combined with each other within a technically consistent range.

-In each of the above embodiments, the average value of each wheel speed Vfl, Vfr, Vrl, Vrr is used as the vehicle body speed Vb, but the present invention is not limited to this, and for example, the second of the respective wheel speeds Vfl, Vfr, Vrl, Vrr. And the average of the third fastest wheel speed may be used, and the calculation method of the vehicle body speed Vb can be changed as appropriate. Further, the vehicle body speed Vb may be a value obtained by integrating the front-rear acceleration of the vehicle without using the wheel speed. Further, for example, even if a positioning signal from an artificial satellite for GPS (Global Positioning System) is received and the estimated vehicle speed estimated from the position change of the vehicle per time based on the received positioning signal is used as the vehicle body speed Vb. Good.

-In each of the above embodiments, the steering control devices 1, 300 may calculate the vehicle body speed Vb based on each wheel speed Vfl, Vfr, Vrl, Vrr, or the like.
-In each of the above embodiments, the shape of the map of the first distribution gain calculation units 122 and 222 can be changed as appropriate. For example, the first distribution gain Ga1 may be set to a value smaller than "1" in the region where the first slip state quantity S1 is near zero. That is, even when the steering wheel 5 is not slipping, the current axial force Fer may be distributed to the reaction force component Fir, which is the distributed axial force. Similarly, the shape of the map included in the second distribution gain calculation units 124 and 224 can be changed as appropriate.

In each of the above embodiments, the first slip state amount S1 and the second slip state amount S2 indicating the slip states of the steering wheels 5 of the left front wheel and the right front wheel are calculated, and the distribution ratio is adjusted based on these. Was calculated. However, the present invention is not limited to this, and the slip state amount indicating the slip state of the two rear wheels and the slip state amount of the front wheels and the four rear wheels may be calculated and the distribution ratio may be adjusted based on these. Further, it may be configured to calculate only the slip state amount of one wheel and adjust the distribution ratio based on this. In this case, the target wheel may be configured to select, for example, the one with the slowest wheel speed or the one with the second slowest wheel speed.

-In each of the above embodiments, the distribution axial force as the reaction force component Fir is calculated by summing the angular axial force Fib and the current axial force Fer at a distribution ratio individually set so as to have a predetermined distribution ratio. However, the distributed axial force may be calculated by allocating at least two of the angular axial force, the road surface axial force, and the vehicle state quantity axial force.

In addition to the current axial force Fer, the road surface axial force is based on, for example, the axial force based on the detection value of the axial force sensor that detects the axial force acting on the rack shaft 22, and the tire force detected by the hub unit 43. There is axial force. Further, as the vehicle state quantity axial force, for example, the lateral force Fy calculated by inputting the yaw rate γ of the vehicle and the lateral acceleration LA in the following equation (2) can be used. That is, the vehicle state quantity axial force is an estimated value in which the axial force acting on the steering wheel 5 is approximately regarded as the lateral force Fy acting on the steering wheel 5, and the behavior of the vehicle in the lateral direction. It is an axial force that does not include road surface information that does not cause a change, but includes information that can be transmitted through changes in the lateral behavior of the vehicle among the road surface information.

Fy = Kla x LA + Kγ x γ'... (2)
In addition, "γ'" indicates a differential value of yaw rate γ, and "Kla" and "Kγ" indicate a coefficient set in advance by a test or the like, and are variably set according to the vehicle body speed Vb.

When calculating the distribution axial force by allocating at least two of the angular axial force, the road surface axial force, and the vehicle state quantity axial force in this way, the adjustment of the distribution ratio according to the slip state is as follows. Can be done.

That is, when the distributed axial force includes the angular axial force Fib, for example, when the first slip state amount S1 and the second slip state amount S2 indicate the locked state of the steering wheel 5, the axial force other than the angular axial force Fib Increase at least one allocation ratio of. As an example, when the distribution axial force is calculated by distributing the angular axial force Fib and the vehicle state quantity axial force, the distribution ratio of the vehicle state quantity axial force is increased when the steering wheel 5 is locked. Further, when the distributed axial force includes the road surface axial force, for example, when the first slip state amount S1 and the second slip state amount S2 indicate the locked state of the steering wheel 5, the distribution ratio of the road surface axial force is increased. To do. As an example, when the distribution axial force is calculated by distributing the current axial force Fer and the vehicle state quantity axial force, the distribution ratio of the current axial force Fer is increased when the steering wheel 5 is locked.

Further, when the distributed axial force includes the angular axial force Fib, for example, when the first slip state amount S1 and the second slip state amount S2 indicate the idling state of the steering wheel 5, the axial force other than the angular axial force Fib Increase at least one allocation ratio of. As an example, when the distribution axial force is calculated by distributing the angular axial force Fib and the vehicle state quantity axial force, the distribution ratio of the vehicle state quantity axial force is increased when the steering wheel 5 is in an idling state. Further, when the distributed axial force includes the road surface axial force, for example, when the first slip state amount S1 and the second slip state amount S2 indicate the idling state of the steering wheel 5, the distribution ratio of the road surface axial force is increased. To do. As an example, when the distribution axial force is calculated by distributing the current axial force Fer and the vehicle state quantity axial force, the distribution ratio of the current axial force Fer is increased when the steering wheel 5 is in an idling state.

-In each of the above embodiments, the reaction force component calculation units 82 and 372 may calculate a value obtained by adding other reaction forces to the distribution axial force as the reaction force component Fir. As such another reaction force, for example, when the absolute value of the steering angle of the steering wheel 3 approaches the steering angle threshold value, an end reaction force which is a reaction force that resists further incision steering can be adopted. .. The rudder angle threshold is set to be closer to the neutral position than the mechanical rack end position where the axial movement of the rack shaft 22 is restricted by, for example, the rack end 25 coming into contact with the rack housing 23. The steering correspondence angle θp at the position can be used.

-In the first and second embodiments, the current axial force Fer is calculated based on the q-axis current value Iqt, but the present invention is not limited to this, and for example, the current axial force Fer may be calculated based on the q-axis target current value Iqt *. Similarly, in the third embodiment, the current axial force Fer may be calculated based on, for example, the q-axis target current value Iq *.

-In the first and second embodiments, the angular axial force Fib is calculated based on the target steering angle θh * which is the target steering angle, but the present invention is not limited to this, for example, the steering angle θh and the steering angle θp. It may be calculated based on the above, or it may be calculated by another method such as adding other parameters such as steering torque Th. Similarly, in the third embodiment, the angular axial force Fib may be calculated by another method.

-In the first and second embodiments, the torque F / B component Tfbt calculated by executing the torque F / B control that causes the target steering torque Th * to follow the steering torque Th * is used as the input torque basic component, and the torque F is used. The target reaction torque Ts * was calculated by adding the / B component Tfbt and the steering angle F / B component Tfbh. However, not limited to this, the calculation mode of the target reaction force torque Ts * can be changed as appropriate. For example, as a calculation mode of the input torque basic component, the larger the absolute value of the steering torque Th, the larger the absolute value of the input torque basic component may be calculated. Further, the target reaction torque Ts * is directly calculated based on the input torque Tin * without executing the steering angle F / B control, or the target reaction torque Ts * is directly calculated based on the reaction component Fir. It is possible to adopt the mode of Further, for example, the target steering torque is calculated based on the reaction force component Fir, and the value obtained by executing the torque F / B control that makes the steering torque Th follow the target steering torque is calculated as the target reaction force torque Ts *. May be good. Similarly, in the third embodiment, the calculation mode of the target assist torque Ta * can be changed as appropriate.

-In the first and second embodiments, the steering device 2 to be controlled has a linkless structure in which the power transmission between the steering unit 4 and the steering unit 6 is separated, but the present invention is not limited to this. A steering device having a structure in which the power transmission between the steering unit 4 and the steering unit 6 can be separated by a clutch may be controlled.

1,300 ... Steering control device, 2,301 ... Steering device, 3 ... Steering wheel, 4 ... Steering unit, 5 ... Steering wheel, 6 ... Steering unit, 11,311 ... Steering shaft, 13 ... Steering side motor, 21 , 317 ... Pinion shaft, 22, 312 ... Rack shaft, 32 ... Steering side motor, 51 ... Steering side control unit, 56 ... Steering side control unit, 62 ... Target reaction force torque calculation unit, 82, 372 ... Reaction force Component calculation unit, 101 ... Angle axial force calculation unit, 102 ... Current axial force calculation unit, 103 ... Distribution axial force calculation unit, 111 ... Distribution gain calculation unit, 121,221 ... First slip state quantity calculation unit, 122, 222 ... 1st distribution gain calculation unit, 123, 223 ... 2nd slip state amount calculation unit, 124, 224 ... 2nd distribution gain calculation unit, 302 ... Steering mechanism, 321 ... Assist motor, 351 ... Microcomputer, 352 ... Drive circuit, 361 ... Target assist torque calculation unit, Fer ... Current axial force, Fib ... Angle axial force, Ga ... Distribution gain, Ga1 ... 1st distribution gain, Ga2 ... 2nd distribution gain, S1 ... 1st slip state amount, S2 ... 1st 2 Slip state amount, Ta * ... target assist torque, Ts * ... target reaction force torque, Vb ... vehicle body speed, Vfl, Vfr, Vrl, Vrr ... wheel speed.

Claims (7)

The control target is a steering device that changes the steering torque required for steering the steering wheel by the motor torque applied by the actuator that uses the motor as the drive source.
In a steering control device that includes a target torque calculation unit that calculates a target torque that is a target value of the motor torque, and controls the operation of the motor so that the motor torque corresponding to the target torque is generated.
The target torque calculation unit is
As the axial force acting from the steering wheel of the steering device to the steering shaft to which the steering wheel is connected, an angular axial force that does not include the road surface information indicating the state of the road surface, and the lateral behavior of the vehicle among the road surface information. Axial force calculation unit that calculates at least two of the vehicle state amount axial force including information that can be transmitted through the change of the road surface information and the road surface axial force including the road surface information.
It is provided with a distribution axial force calculation unit that calculates the distribution axial force by adding up the at least two axial forces at a predetermined distribution ratio.
The target torque is calculated based on the distributed axial force.
The distribution axial force calculation unit calculates a slip state amount indicating a slip state of the steering wheel based on the vehicle body speed of the vehicle and the wheel speed of the vehicle, and adjusts the distribution ratio based on the slip state amount. Steering control device. In the steering control device according to claim 1,
The steering device has a structure in which power transmission between the steering unit and the steering unit that steers the steering wheel according to the steering input to the steering unit is separated.
The motor is a steering side motor that applies the motor torque as a steering reaction force that is a force that opposes steering input to the steering unit.
The target torque calculation unit is a steering control device that calculates a target reaction force torque that is a target value of the steering reaction force as the target torque. In the steering control device according to claim 1,
The steering device has a steering mechanism for steering the steering wheel based on the operation of the steering wheel.
The motor is an assist motor that applies the motor torque as an assist force for assisting the steering operation.
The target torque calculation unit is a steering control device that calculates a target assist torque, which is a target value of the assist force, as the target torque. In the steering control device according to any one of claims 1 to 3.
The distribution axial force calculation unit is a steering control device that calculates a value obtained by subtracting the wheel speed from the vehicle body speed as the slip state amount, and adjusts the distribution ratio based on the slip state amount and the vehicle body speed. In the steering control device according to any one of claims 1 to 3.
The distribution axial force calculation unit is a steering control device that subtracts the wheel speed from the vehicle body speed and calculates the value obtained by dividing the subtracted value by the vehicle body speed as the slip state amount. In the steering control device according to any one of claims 1 to 5.
The distribution axial force calculation unit
When the axial force calculation unit calculates the angular axial force and the slip state amount indicates the locked state of the steering wheel, the distribution ratio of at least one of the axial forces other than the angular axial force is increased. ,
A steering control device that increases the distribution ratio of the road surface axial force when the slip state amount indicates the locked state of the steering wheel when the axial force calculation unit calculates the road surface axial force. In the steering control device according to any one of claims 1 to 6.
The distribution axial force calculation unit
When the axial force calculation unit calculates the angular axial force, if the slip state amount indicates the idling state of the steering wheel, the distribution ratio of at least one of the axial forces other than the angular axial force is increased. ,
A steering control device that increases the distribution ratio of the road surface axial force when the slip state amount indicates an idling state of the steering wheel when the axial force calculation unit calculates the road surface axial force.