JP2008174160A - Vehicle steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain smooth vehicle behavior even when characteristic difference is present on a turning actuator. <P>SOLUTION: The vehicle steering device 10 is a vehicle steering device each independently provided with turning motors 24 relative to a pair of left and right steered wheels included in the vehicle. A steering angle sensor 34 detects a steering angle input by a driver. A target turning angle setting part 50 sets a target turning angle of the pair of left and right steered wheels according to the detected steering angle. A turning motor control part 66 controls the turning motor 24 so as to become the target turning angle set by the target turning angle setting part 50. An actual turning angle sensor 42 detects the actual turning angles of the pair of left and right steered wheels respectively. An actual turning angle difference comparison part 54 determines whether or not the actual turning angle difference of the pair of left and right steered wheels is larger than a predetermined value. A target turning angle correction part 62 corrects the target turning angle of at least one steered wheel to output it to the turning motor control part 66 when it is determined that the actual turning angle difference is larger than the predetermined value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle steering apparatus for steering a pair of left and right steering wheels included in a vehicle.

2. Description of the Related Art Conventionally, as a vehicle steering apparatus for turning a pair of left and right steering wheels included in a vehicle, a vehicle steering apparatus that has a steering actuator for each steering wheel and can independently steer the steering wheels. Known (for example, Patent Document 1).
Japanese Patent Laying-Open No. 2005-306249

  In the vehicle steering apparatus as described above, if there is a difference in response between the two steering actuators provided on the pair of left and right steering wheels, the maximum operating speed, etc., let the left and right steering wheels be steered in the same way. However, there may be a difference in the turning angle change between the left and right steering wheels, and the transient vehicle behavior may not be smoothly controlled. Therefore, ideally, it is preferable to provide actuators with equivalent characteristics on the left and right steering wheels.

  However, such a characteristic difference between actuators is caused by manufacturing variations in inertia (movable part mass), output characteristics, friction characteristics, etc. in the actuators. It is difficult to eliminate the difference completely.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a vehicle steering apparatus having a steering actuator independently for each pair of left and right steering wheels, even when there is a difference in characteristics of the steering actuator. It is to provide a technology capable of realizing smooth vehicle behavior.

  In order to solve the above-described problems, a vehicle steering apparatus according to an aspect of the present invention is a vehicle steering apparatus that includes a steering actuator independently for each of a pair of left and right steering wheels included in a vehicle. Steering input means for receiving the steering input, steering angle detecting means for detecting the steering angle input to the steering input means, and target turning of the pair of left and right steering wheels according to the steering angle detected by the steering angle detecting means Target turning angle setting means for setting the respective angles, control means for controlling the turning actuator to be the target turning angle set by the target turning angle setting means, and the actual turning angle of the pair of left and right steering wheels Based on the actual turning angle detection means for detecting the steering wheel and the information detected by the actual turning angle detection means, it is determined whether or not the actual turning angle difference between the pair of left and right steering wheels is greater than a predetermined value. Turning angle difference comparison means and actual turning angle difference comparison means If the actual turning angle difference is determined to be greater than the predetermined value, and a correction means for outputting to the control means corrects the target turning angle of at least one of the steerable wheels.

  According to this aspect, when the actual turning angle difference between the pair of left and right steering wheels is larger than a predetermined value, the target turning angle of at least one of the steering wheels can be corrected, so that the vehicle behavior becomes smooth. Thus, the steered wheels can be controlled.

  When the actual turning angle difference comparing means determines that the actual turning angle difference is greater than a predetermined value, the correcting means sets the target turning angle of at least one steered wheel so that the actual turning angle difference becomes small. You may correct | amend and output to a control means. In this case, the vehicle behavior can be controlled smoothly because the actual turning angle difference between the left and right steering wheels can be controlled to be small.

  When the actual turning angle difference comparison unit determines that the actual turning angle difference is greater than the predetermined value, the correction unit is configured to target the target turning of at least one steered wheel so that the actual turning angle difference is equal to or less than the predetermined value. The angle may be corrected and output to the control means. In this case, the turning angle can be controlled so that the actual turning angle difference is equal to or less than a predetermined value. By setting the predetermined value to an appropriate value, the actual turning angle difference does not become too large, so that the vehicle behavior can be controlled smoothly.

  When the actual turning angle difference comparing means determines that the actual turning angle difference is larger than the predetermined value, the correcting means is the difference between the target turning angle set by the target turning angle setting means and the actual turning angle. The target turning angle of the steered wheel with the smaller deviation may be corrected and output to the control means. Also in this case, the steering wheel can be controlled so that the vehicle behavior becomes smooth. Further, the control can be easily performed by correcting the target turning angle of the steered wheel having the smaller deviation between the target turning angle and the actual turning angle.

  According to the present invention, in a vehicle steering apparatus provided with a steering actuator independently for each of a pair of left and right steering wheels, smooth vehicle behavior can be realized even when the steering actuator has a characteristic difference.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a vehicle steering apparatus 10 according to an embodiment of the present invention. The vehicle steering apparatus 10 according to the present embodiment includes a right steering wheel 14R and a left steering wheel 14L of the vehicle (hereinafter, the right steering wheel 14R and the left steering wheel 14L are simply referred to as “steering wheels 14”). It is a vehicle steering device which steers. The vehicle steering apparatus 10 is configured to include a steering actuator independently for each of the pair of left and right steering wheels 14. The vehicle steering device 10 is provided in a vehicle having a four-wheel independent steering mechanism (4WS system) that can independently control the steering angle of each wheel, for example. When provided in a vehicle having a four-wheel independent steering mechanism, the vehicle steering device 10 may control the turning angle of the front wheel of the vehicle, or may control the turning angle of the rear wheel.

  As shown in FIG. 1, the vehicle steering device 10 rotates an operation unit 70 that receives an operation from a driver, an ECU 100, a right steering wheel steering device 25R that steers the right steering wheel 14R, and a left steering wheel 14L. A left steering wheel steering device 25L for steering.

  Each of the steered wheels 14 is rotatably supported by a knuckle arm 40 provided on the vehicle body corresponding to each of the steered wheels 14. The knuckle arm 40 is supported so as to be pivotable about a substantially vertical axis, with the joint portion of the upper arm in the upper portion and the joint portion of the lower arm in the lower portion. Thus, the king pin as a virtual axis is formed by the joint portion of the upper arm and the joint portion of the lower arm. The steered wheel 14 is steered around the kingpin formed in this way.

  A right steering wheel turning device 25R is provided corresponding to the right steering wheel 14R, and a left steering wheel turning device 25L is provided corresponding to the left steering wheel 14L (hereinafter, the right steering wheel turning device 25R, the left steering wheel turning device). When collectively referring to 25L, it is simply referred to as “steering device 25”). The right steering wheel steering device 25R and the left steering wheel steering device 25L are provided with a right steering motor 24R and a left steering motor 24L (hereinafter collectively referred to as “steering motor 24” as necessary). It has been. Each of the steering devices 25 includes a ball screw mechanism 27, a knuckle arm 40, and a tie rod 38 in addition to the steering motor 24.

  The wheel side end of the tie rod 38 is rotatably connected to the knuckle arm 40. A male screw groove is formed on the other outer periphery of the tie rod 38. A nut (not shown) formed in a cylindrical shape is arranged so as to cover the portion of the tie rod 38 where the male screw groove is formed. A female thread groove is formed on the inner periphery of the nut. A plurality of rolling balls are arranged in a rolling path formed by the male thread groove of the tie rod 38 and the female thread groove of the nut, and the ball screw mechanism 27 is configured.

  The steered motor 24 has a rotor and a stator, and the rotor of the steered motor 24 is fixed coaxially with the nut. When the rotor and the nut are rotated by the operation of the steering motor 24, the rotational motion of the steering motor 24 is converted into the axial motion of the tie rod 38 by the ball screw mechanism 27, and the tie rod 38 is propelled in the axial direction. Thereby, the knuckle arm 40 is rotated and the steered wheel 14 is steered around the kingpin.

  The right turning motor 24R and the left turning motor 24L are connected to the ECU 100. Each of the steered motors 24 rotates an angle corresponding to the drive signal when the drive signal is input from the ECU 100. The ECU 100 controls the turning angle of each steered wheel 14 independently by controlling the drive signal input to the turning motor 24. Details of control of the steering motor 24 by the ECU 100 will be described later.

  The right turning motor 24R and the left turning motor 24L are respectively provided with a right actual turning angle sensor 42R and a left actual turning angle sensor 42L (hereinafter collectively referred to as “actual turning” as necessary). Referred to as the steering angle sensor 42). The right actual turning angle sensor 42R detects the right actual turning angle δR, which is the angle that the right steering wheel 14R has actually turned, and the left actual turning angle sensor 42L actually turns the left steering wheel 14L. The left actual turning angle δL is detected. The actual turning angle sensor 42 may be, for example, a sensor that detects the actual turning angle δ from the rotation angle of the turning motor 24, or detects the actual turning angle δ from the amount of movement of the tie rod 38 in the axial direction. It may be a sensor. In the present embodiment, the steering angle of the steering wheel 14 when the vehicle travels straight in the vehicle traveling direction A is zero, and the steering wheel 14 is steered to the right. A case where the steered wheel 14 is steered leftward is defined as a negative steer angle.

  The operation unit 70 includes a steering 32, a steering shaft 33, and a rudder angle sensor 34. The steering 32 is provided in the vehicle interior and functions as an operator that receives an operation input from the driver. The steering 32 may be a joystick or the like. The steering 32 is fixed to a rotatable steering shaft 33, and a steering angle sensor 34 is provided on the steering shaft 33. The steering angle sensor 34 is connected to the ECU 100. When the steering wheel 32 is steered by the driver, the steering angle sensor 34 detects the steering angle of the steering wheel 32 and inputs the detection result to the ECU 100.

  FIG. 2 is a block diagram for explaining the configuration of the vehicle steering apparatus 10 according to the present embodiment. FIG. 2 shows the ECU 100 and components around the ECU 100. A steering angle sensor 34, a right actual turning angle sensor 42R, and a left actual turning angle sensor 42L are connected to the input interface of the ECU 100, and a right turning motor 24R and a left turning motor 24L are connected to the output interface. The

  Note that each block shown in FIG. 2 can be realized in hardware by an element and a mechanical device such as a computer CPU and memory, and in software by a computer program, etc. It is drawn as a functional block realized by the cooperation. Therefore, those skilled in the art will understand that these functional blocks can be realized in various forms by a combination of hardware and software.

  As shown in FIG. 2, the ECU 100 includes a target turning angle setting unit 50, an actual turning angle difference comparison unit 54, a holding unit 60, a target turning angle correction unit 62, and a turning motor control unit 66. .

  The target turning angle setting unit 50 sets a target turning angle, which is a turning angle that the steered wheels 14 should target, according to the steering angle of the steering 32 detected by the steering angle sensor 34. That is, the target turning angle setting unit 50 sets the right target turning angle δR * of the right steering wheel 14R and the left target turning angle δL * of the left steering wheel 14L. In the vehicle steering apparatus 10 according to the present embodiment, equal values are set for the right target turning angle δR * and the left target turning angle δL *.

  Based on the signal from the actual turning angle sensor 42, the actual turning angle difference comparison unit 54 determines the actual turning angle difference | δL that is the absolute value of the difference between the left actual turning angle δL and the right actual turning angle δR. −δR | is calculated, and it is determined whether or not the actual turning angle difference | δL−δR | is greater than a predetermined value ΔK held in the holding unit 60.

  When the actual turning angle difference comparing unit 54 determines that the actual turning angle difference | δL−δR | is equal to or less than the predetermined value ΔK, the actual turning angle difference comparing unit 54 is the target turning angle setting unit 50. The set right target turning angle δR * and left target turning angle δL * are output to the turning motor control unit 66 without correction.

  On the other hand, when the actual turning angle difference comparison unit 54 determines that the actual turning angle difference | δL−δR | is greater than the predetermined value ΔK, the target turning angle correction unit 62 sets the right target turning angle δR *, One of the left target turning angle δL * is corrected and output to the turning motor control unit 66.

  The steered motor control unit 66 controls the right steered motor 24R so that the steered angles of the right steered wheel 14R and the left steered wheel 14L become the input right target steered angle δR * and left target steered angle δL *. The left steering motor 24L is controlled.

  The configuration of the target turning angle correction unit 62 will be described in more detail. As shown in FIG. 2, the target turning angle correction unit 62 includes a deviation comparison unit 58, an actual turning angle comparison unit 64, and a correction value determination unit 68. In the vehicle steering apparatus 10 according to the present embodiment, the target turning angle correction unit 62 uses the target turning angle setting unit 50 so that the actual turning angle difference | δL−δR | is equal to or less than a predetermined value ΔK. The target turning angle of the steered wheel having the smaller deviation between the set target turning angle and the actual turning angle is corrected.

  The deviation comparison unit 58 includes a left steering wheel deviation | δL * −δL | which is an absolute value of a difference between the left actual turning angle δL and the left target turning angle δL *, the right actual turning angle δR, and the right target turning. The right steering wheel deviation | δR * −δR |, which is the absolute value of the difference between the steering angles δR *, is compared to determine which of the right target steering angle δR * and the left target steering angle δL * is to be corrected. To do. When the left steering wheel deviation | δL * −δL | is larger than the right steering wheel deviation | δR * −δR |, the deviation comparison unit 58 performs the target rotation of the right steering wheel 14R that is the steering wheel with the smaller deviation. It is determined that the steering angle δR * is corrected. On the other hand, when the right steering wheel deviation | δR * −δR | is larger than the left steering wheel deviation | δL * −δL |, the target turning angle δL * of the left steering wheel 14L, which is the steering wheel with the smaller deviation. Is determined to be corrected.

  A small deviation between the target turning speed and the actual turning angle means that the actual turning angle can follow the change in the target turning angle. It is considered that the responsiveness and the maximum operating speed are faster. In general, since it is easier to match the steered motor 24 having the higher responsiveness and the maximum operating speed to the steered motor 24 having the slower speed, the vehicle steering apparatus 10 according to the present embodiment has the target steered angle and The target turning angle of the steered wheel 14 having the smaller deviation from the actual turning angle is corrected.

  The actual turning angle comparison unit 64 compares the sizes of the left actual turning angle δL and the right actual turning angle δR based on information from the right actual turning angle sensor 42R and the left actual turning angle sensor 42L. . Here, the magnitudes of the left actual turning angle δL and the right actual turning angle δR are compared between when the steered wheel 14 is steered to the right and when the steered wheel 14 is steered to the left. This is because the processing of the correction value determination unit 68 is different.

  The correction value determination unit 68 determines a correction value for the target turning angle. The correction value of the target turning angle determined by the correction value determination unit 68 is output to the turning motor control unit 66. Since the correction value of the target turning angle varies depending on the determination result in the deviation comparison unit 58 and the actual turning angle comparison unit 64, each case will be described.

The deviation comparison unit 58 determines that the left steering wheel deviation | δL * −δL | is larger than the right steering wheel deviation | δR * −δR |, and the actual turning angle comparison unit 64 sets the right actual turning angle δR to the left. When it is determined that the actual turning angle δL is larger than the actual turning angle δL, the correction value determination unit 68 corrects the right target turning angle δR * as shown in Expression (1) and outputs the correction to the turning motor control unit 66. δR * ′ is the right target turning angle after correction. Such a situation occurs when, for example, the responsiveness and maximum operating speed of the left turning motor 24L are slower than those of the right turning motor 24R, and the steered wheels 14 are turned to the right. Note that the target turning angle set by the target turning angle setting unit 50 is output to the turning motor control unit 66 as it is without being corrected as the left target turning angle δL *.
δR * ′ = MIN (δR *, δL + ΔK) (1)

  In this way, the corrected right target turning angle δR * ′ is set to a value obtained by adding the predetermined value ΔK to the left actual turning angle δL, whereby the actual turning angles of the right steered wheel 14R and the left steered wheel 14L. The difference | δL−δR | can be controlled to be within a predetermined value ΔK. The reason why the term δR * is present on the right side of the equation (1) is to prevent the corrected right target turning angle δR * ′ from becoming larger than the corrected right target turning angle δR *. is there.

Further, the deviation comparison unit 58 determines that the left steering wheel deviation | δL * −δL | is greater than the right steering wheel deviation | δR * −δR |, and the actual turning angle comparison unit 64 determines the right actual turning angle δR. Is determined to be smaller than the actual left turning angle δL, the correction value determining unit 68 corrects the right target turning angle δR * as shown in Expression (2) and outputs the corrected value to the turning motor control unit 66. . Such a situation occurs when, for example, the responsiveness and maximum operating speed of the left turning motor 24L are slower than those of the right turning motor 24R, and the steering wheel 14 is turned leftward. As for the left target turning angle, the left target turning angle δL * set by the target turning angle setting unit 50 is output to the turning motor control unit 66 without being corrected.
δR * ′ = MAX (δR *, δL−ΔK) (2)

  As described above, the corrected right target turning angle δR * ′ is set to a value obtained by subtracting the predetermined value ΔK from the left actual turning angle δL, whereby the actual turning angles of the right steered wheel 14R and the left steered wheel 14L. The difference | δL−δR | can be controlled to be within a predetermined value. The reason why the term δR * exists on the right side of the equation (2) is to prevent the corrected right target turning angle δR * ′ from becoming larger than the corrected right target turning angle δR *. is there.

Further, the deviation comparison unit 58 determines that the right steering wheel deviation | δR * −δR | is greater than the left steering wheel deviation | δL * −δL |, and the actual turning angle comparison unit 64 determines the right actual turning angle δR. Is determined to be smaller than the actual left turning angle δL, the correction value determining unit 68 corrects the left target turning angle δL * as shown in Expression (3) and outputs the corrected value to the turning motor control unit 66. . δL * ′ is the corrected left target turning angle. Such a situation occurs when, for example, the responsiveness and maximum operating speed of the right steering motor 24R are slower than those of the left steering motor 24L and the steered wheels 14 are steered in the right direction. As for the right target turning angle, the right target turning angle δR * set by the target turning angle setting unit 50 is output to the turning motor control unit 66 without being corrected.
δL * ′ = MIN (δL *, δR + ΔK) (3)

  In this way, the corrected left target turning angle δL * ′ is set to a value obtained by adding the predetermined value ΔK to the right actual turning angle δR, so that the actual turning angles of the right steering wheel 14R and the left steering wheel 14L are increased. The difference | δL−δR | can be controlled to be within a predetermined value. Note that the term δL * is present on the right side of the expression (3) so that the corrected left target turning angle δL * ′ does not become larger than the corrected left target turning angle δL *. is there.

Further, the deviation comparison unit 58 determines that the right steering wheel deviation | δR * −δR | is greater than the left steering wheel deviation | δL * −δL |, and the actual turning angle comparison unit 64 determines the left actual turning angle δL. Is determined to be smaller than the actual right turning angle δR, the correction value determination unit 68 corrects the left target turning angle δL * as shown in Expression (4) and outputs the corrected value to the turning motor control unit 66. . Such a situation occurs when, for example, the responsiveness and maximum operating speed of the right steering motor 24R are slower than those of the left steering motor 24L and the steered wheels 14 are steered leftward. As for the right target turning angle, the right target turning angle δR * set by the target turning angle setting unit 50 is output to the turning motor control unit 66 without being corrected.
δL * ′ = MAX (δL *, δR−ΔK) (4)

  As described above, the corrected left target turning angle δL * ′ is set to a value obtained by subtracting the predetermined value ΔK from the right actual turning angle δR, whereby the actual turning angles of the right steered wheel 14R and the left steered wheel 14L. The difference | δL−δR | can be controlled to be within a predetermined value. The reason why the term δL * exists on the right side of the equation (4) is to prevent the corrected left target turning angle δL * ′ from becoming larger than the corrected left target turning angle δL *. is there.

  FIG. 3 is a diagram for explaining the operation of the vehicle steering apparatus 10. The vertical axis in FIG. 3 represents the turning angle, and the horizontal axis represents time. In FIG. 3, a curve 200 represents changes over time in the right target turning angle δR * and the left target turning angle δL * set by the target turning angle setting unit 50. A curve 202 represents a time change of the right actual turning angle δR, and a curve 204 represents a time change of the left actual turning angle δL. Here, the right actual turning angle δR can follow the change in the target turning angle, but the left actual turning angle δL is slow in the response and the maximum operating speed of the left turning motor 24L. The explanation is based on the assumption that changes cannot be followed.

When the steering wheel 14 at time t ₀ is steered so as to steer to the right to start almost simultaneously turning the right steered wheel 14R at time t _0. On the other hand, the left steering wheel 14L is, due to the slow response, to start a little late turning from time t _0.

Thereafter, until the time t ₁ when the actual turning angle difference | δL−δR | exceeds the predetermined value ΔK, the right steered wheel 14R and the left steered wheel 14L have the right target steered angle set by the target steered angle setting unit 50. Steering is performed with δR * and left target turning angle δL * as target values. The right actual turning angle δR steers following the target turning angle, but the left actual turning angle δL cannot follow the target turning angle because the maximum operating speed of the left turning motor 24L is slow. The actual turning angle difference | δL−δR | gradually increases.

Then, the actual turning angle difference at time t ₁ | δL-δR | exceeds a predetermined value [Delta] K, the actual turning angle difference by actual turning angle comparison unit 64 | δL-δR | is determined greater than the predetermined value [Delta] K Then, the deviation comparison unit 58 compares the left steering wheel deviation | δL * −δL | with the right steering wheel deviation | δR * −δR |, and the left target turning angle δL * and the right target turning angle are compared. It is determined which of δR * is to be corrected. Here, since the right steering wheel deviation | δR * −δR | is smaller than the left steering wheel deviation | δL * −δL |, the right target turning angle δR * is corrected. Thereafter, the actual turning angle comparison unit 64 compares the right actual turning angle δR and the left actual turning angle δL. Here, since the right actual turning angle δR is larger than the left actual turning angle δL, the right target turning angle is set to a value obtained by adding the predetermined value ΔK to the left actual turning angle δL as in the above equation (1). The steering angle δR * is corrected. The left target turning angle δR * remains the target turning angle set by the target turning angle setting unit 50.

Then, at time t _2, the so that the time t ₁ at the corrected right target turning angle &Dgr; R * ', right actual turning angle &Dgr; R is changed. In this manner, the time t ₂ later, the actual turning angle difference | δL-δR | such that equal to or less than a predetermined value [Delta] K, the steering wheel 14 is controlled. By determining the threshold value of the actual turning angle difference | δL−δR | at which the predetermined value ΔK is an appropriate value, for example, by performing experiments or simulations, the vehicle behavior is not smooth, and setting the threshold value to a value smaller than the threshold value The vehicle behavior can be controlled smoothly.

  FIG. 4 is a flowchart for explaining the operation of the vehicle steering apparatus 10. The routine shown in the figure is repeatedly executed by the ECU 100 at predetermined time intervals.

  The ECU 100 first acquires the steering angle steered by the driver based on the signal from the steering angle sensor 34 (S10). The target turning angle setting unit 50 calculates the right target turning angle δR * of the right steering wheel 14R and the left target turning angle δL * of the left steering wheel 14L based on the steering angle acquired in S10 ( S12). Here, the same value is set for the right target turning angle δR * and the left target turning angle δL *.

  Further, the ECU 100 acquires the right actual turning angle δR and the left actual turning angle δL based on signals from the right actual turning angle sensor 42R and the left actual turning angle sensor 42L (S14). The actual turning angle comparison unit 64 calculates the actual turning angle difference | δL−δR | based on the right actual turning angle δR and the left actual turning angle δL acquired in S14, and this actual turning angle difference. It is determined whether or not | δL−δR | is greater than a predetermined value ΔK held in the holding unit 60 (S16).

  If it is determined in S16 that the actual turning angle difference | δL−δR | is equal to or smaller than the predetermined value ΔK (N in S16), the actual turning angle comparison unit 64 is set by the target turning angle setting unit 50. The right target turning angle δR * and the left target turning angle δL * are output to the turning motor control unit 66. Then, the turning motor control unit 66 turns right so that the turning angles of the right steering wheel 14R and the left steering wheel 14L become the input right target turning angle δR * and left target turning angle δL *. The steering motor 24R and the left turning motor 24L are controlled (S32). Then, it returns to S10 again and a process is repeated.

  Thus, when the actual turning angle difference | δL−δR | is equal to or less than the predetermined value ΔK, the difference between the left actual turning angle δL and the right actual turning angle δR is not so large, and the vehicle behavior Since the steering wheel 14 can be steered so as to be smooth, the right target turning angle δR * and the left target turning angle δL * set by the target turning angle setting unit 50 are not corrected. The right steering motor 24R and the left steering motor 24L are controlled.

  On the other hand, when it is determined in S16 that the actual turning angle difference | δL−δR | is greater than the predetermined value ΔK (Y in S16), the target turning angle correction unit 62 performs the right target turning angle δR *, the left target One of the turning angles δL * is corrected.

  In this case, first, the deviation comparison unit 58 compares the left steering wheel deviation | δL * −δL | with the right steering wheel deviation | δR * −δR |, and the right target turning angle δR * and the left target turning are compared. It is determined which of the steering angles δL * is to be corrected (S18).

  In S18, when it is determined that the left steering wheel deviation | δL * −δL | is larger than the right steering wheel deviation | δR * −δR | (Y in S18), the deviation comparison unit 58 performs steering with the smaller deviation. It is determined to correct the target turning angle δR * of the right steering wheel 14R that is a wheel.

  Thereafter, the actual turning angle comparison unit 64 compares the left actual turning angle δL and the right actual turning angle δR (S20). When it is determined that the right actual turning angle δR is larger than the left actual turning angle δL (Y in S20), the correction value determination unit 68 sets the right target turning angle δR as shown in the above equation (1). Correction is performed (S22). On the other hand, when it is determined that the left actual turning angle δL is larger than the right actual turning angle δR (N in S20), the correction value determination unit 68 calculates the right target turning angle as in the above equation (2). δR is corrected (24).

  In S18, when it is determined that the right steering wheel deviation | δR * −δR | is larger than the left steering wheel deviation | δL * −δL | (N in S18), the deviation comparison unit 58 performs steering with the smaller deviation. It is determined to correct the target turning angle δL * of the left steered wheel 14L that is a wheel.

  Thereafter, the actual turning angle comparison unit 64 compares the left actual turning angle δL and the right actual turning angle δR (S26). When it is determined that the left actual turning angle δL is larger than the right actual turning angle δR (Y in S26), the correction value determination unit 68 sets the left target turning angle δL as shown in the above equation (3). Correction is performed (S28). On the other hand, when it is determined that the right actual turning angle δR is larger than the left actual turning angle δL (N in S26), the correction value determination unit 68 sets the left target turning angle as in the above equation (4). δL is corrected (S30).

  The target turning angle corrected in S22, S24, S28, and S30 is output to the turning motor control unit 66. Note that the target turning angle of the steered wheel that has not been corrected in S22, S24, S26, and S28 is the target turning angle set by the target turning angle setting unit 50 is directly output to the turning motor control unit 66. Is done. Then, the turning motor control unit 66 turns right so that the turning angles of the right steering wheel 14R and the left steering wheel 14L become the input right target turning angle δR * and left target turning angle δL *. The steering motor 24R and the left turning motor 24L are controlled (S32). Then, it returns to S10 again and a process is repeated.

  In this way, when the actual turning angle difference | δL−δR | is greater than the predetermined value ΔK, the right target turning angle is set so that the actual turning angle difference | δL−δR | One of δR * and the left target turning angle δL is corrected. As a result, it is possible to smoothly control the vehicle behavior in which the actual turning angle difference | δL−δR | is controlled to be equal to or less than the predetermined value ΔK.

  The present invention has been described above based on the embodiment. It should be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention.

  For example, in the above-described embodiment, when the actual turning angle difference | δL−δR | is greater than a predetermined value ΔK, the target of the steered wheel with the smaller deviation between the target turning angle and the actual turning angle is set. Although the actual turning angle difference | δL−δR | is reduced by correcting the turning angle, the target turning of the steered wheel having the larger deviation between the target turning angle and the actual turning angle is provided. You may comprise so that an angle | corner may be correct | amended. Moreover, you may comprise so that the target turning angle of both the left and right steering wheels may be correct | amended.

  In the above-described embodiment, the target turning angle is corrected when the actual turning angle difference | δL−δR | is greater than the predetermined value ΔK. A means for learning the tendency is provided, and the target turning angle is corrected in advance before the actual turning angle difference | δL−δR | becomes larger than the predetermined value ΔK when the turning tendency can be grasped to some extent. It may be configured. With this configuration, the actual turning angle difference | δL−δR | can be further reduced, and the vehicle behavior can be controlled more smoothly.

1 is a schematic configuration diagram of a vehicle steering apparatus according to an embodiment of the present invention. It is a block diagram for demonstrating the structure of the vehicle steering apparatus which concerns on this Embodiment. It is a figure for demonstrating operation | movement of a vehicle steering device. It is a flowchart for demonstrating operation | movement of a vehicle steering device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Vehicle steering device, 14 Steering wheel, 24 Steering motor, 25 Steering device, 32 Steering, 34 Steering angle sensor, 42 Actual steering angle sensor, 50 Target steering angle setting part, 54 Actual steering angle difference comparison part , 58 deviation comparison unit, 60 holding unit, 62 target turning angle correction unit, 64 actual turning angle comparison unit, 66 steering motor control unit, 68 correction value determination unit, 100 ECU.

Claims (4)

A vehicle steering apparatus including a steering actuator independently for each of a pair of left and right steering wheels included in a vehicle,
Steering input means for receiving steering input from the driver;
Steering angle detection means for detecting a steering angle input to the steering input means;
Target turning angle setting means for setting a target turning angle of the pair of left and right steering wheels according to the steering angle detected by the steering angle detection means;
Control means for controlling the turning actuator so as to be the target turning angle set by the target turning angle setting means;
An actual turning angle detecting means for detecting an actual turning angle of the pair of left and right steering wheels;
Based on the information detected by the actual turning angle detection means, actual turning angle difference comparison means for determining whether or not the actual turning angle difference between the pair of left and right steering wheels is greater than a predetermined value;
When the actual turning angle difference comparing means determines that the actual turning angle difference is larger than a predetermined value, the correcting means corrects the target turning angle of at least one of the steered wheels and outputs it to the control means;
A vehicle steering apparatus comprising:   When the actual turning angle difference comparing means determines that the actual turning angle difference is larger than a predetermined value, the correction means is configured to target the target turning of at least one steered wheel so that the actual turning angle difference becomes small. The vehicle steering apparatus according to claim 1, wherein the vehicle steering apparatus corrects an angle and outputs the corrected angle to the control means.   When the actual turning angle difference comparing means determines that the actual turning angle difference is greater than a predetermined value, the correction means is configured to adjust at least one of the steered wheels so that the actual turning angle difference is equal to or less than the predetermined value. The vehicle steering apparatus according to claim 1 or 2, wherein a target turning angle is corrected and output to the control means.   When the actual turning angle difference comparison unit determines that the actual turning angle difference is larger than a predetermined value, the correction unit determines the target turning angle and the actual turning set by the target turning angle setting unit. The vehicle steering apparatus according to any one of claims 1 to 3, wherein a target turning angle of a steered wheel having a smaller deviation from the angle is corrected and output to the control means.

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