JP2002104222A - Steering device and steering torque control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a steering torque act in which a better steering feeling is obtained. SOLUTION: A target torque Tref acted on a steering shaft is operated based on an inputted steering angle θ and a car speed V at a target torque set block 62. Larger is an absolute value of the thus operated target torque Tref and smaller is the car speed V, a larger gain G is set at a gain set block 64. A current instruction value I* of a motor for making a torque act on the steering shaft is operated by multiplying the set gain G to a deviation ΔT of the target torque Tref and the steering torque T. Since the size of the gain G appears as a light and heavy degree on a steering feeling, the steering feeling can be made to a secure feeling at the time immediately after the steering is started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering apparatus and a steering torque control method, and more particularly, to a vehicle-mounted steering apparatus that outputs a steering torque according to an operation of a steering wheel and a target torque according to a steering state of the vehicle. The present invention relates to a method for controlling a steering torque acting on a steering wheel using an electric torque acting means.

[0002]

2. Description of the Related Art Conventionally, a steering apparatus of this type sets a steering torque output from an electric motor based on a compensated torque obtained by phase-compensating a torque acting on a steering shaft and a vehicle speed. Proposed. In this device, a map showing the relationship between the compensated torque, the vehicle speed, and the current command value to the electric motor is created in advance, and when the compensated torque and the vehicle speed are given, the compensated torque given from the map is given. A current command value corresponding to the torque and the vehicle speed is derived, and the steering torque is output from the electric motor. By providing an insensitive area on the map, stability during steering is obtained.

[0003]

However, such a steering device may not provide a good steering feeling. Since the torque that acts on the steering shaft varies depending on the vehicle speed, rotation speed, etc.,
Simply by simply deriving a current command value based on the torque acting on the steering shaft and the vehicle speed and driving the electric motor, it is not possible to obtain a steering feeling suitable for the operating condition of the steering wheel.

[0004] It is an object of the present invention to provide a steering device capable of obtaining a better steering feeling.
Further, a steering torque control method according to the present invention aims to apply a steering torque capable of obtaining a better steering feeling.

[0005] In order to achieve a part of the above-described object, the applicant has proposed a steering torque for turning the steering wheel further and returning the steering wheel based on the steering angle of the steering wheel, the rate of change of the steering angle, and the vehicle speed. To output a steering torque so as to cause hysteresis (Japanese Patent Application No. 2000-1360).
No. 82).

[0006]

Means for Solving the Problems and Their Functions and Effects The steering apparatus and the steering torque control method of the present invention employ the following means in order to achieve at least a part of the above object.

A steering apparatus according to the present invention is an on-vehicle steering apparatus that outputs a steering torque according to an operation of a steering wheel.
Electric torque acting means capable of acting torque on the handle;
Steering torque detecting means for detecting a steering torque acting on a steering wheel, steering state detecting means for detecting a steering state, and a target torque for setting a target torque which is a target value of the steering torque based on the detected steering state Setting means; gain setting means for setting a gain based on the set target torque; and the set target based on the set target torque, the detected steering torque, and the set gain. The gist of the invention is to provide a torque control means for drivingly controlling the electric torque action means so that the torque acts on the steering wheel.

In the steering apparatus according to the present invention, since the gain is set based on the target torque set based on the steering state, the drive of the electric torque operating means can be controlled using a more appropriate gain. As a result, a more appropriate steering feeling can be obtained.

In the steering apparatus according to the present invention, the gain setting means may set a larger value of the gain as the absolute value of the set target torque increases. In this way, when the absolute value of the target torque is set to a small value, a small value of the gain is set. Therefore, a steering feeling with a heavy steering wheel and a so-called firm feeling can be obtained, and the absolute value of the target torque is set to a large value. When this is done, a large gain is set, so that a light steering feeling of the steering wheel can be obtained.

In the steering apparatus of the present invention, the gain setting means sets a smaller value of the gain as the absolute value of the rate of change of the target value of the steering torque with respect to the steering state increases. Can also. In this case, a more comfortable steering feeling can be obtained.

Further, in the steering apparatus according to the present invention, it is possible to provide a vehicle speed detecting means for detecting a vehicle speed, wherein the gain setting means is a means for setting a smaller gain as the vehicle speed increases. In this way, a steering feeling according to the vehicle speed can be obtained.

Alternatively, in the steering apparatus according to the present invention, the torque control means uses a command value obtained based on a deviation between the set target value and the detected steering torque and the set gain. Thus, the electric torque acting means may be a means for controlling the drive.

In the steering apparatus according to the present invention, the steering state detecting means is means for detecting a steering angle of a steering wheel and a vehicle speed as a steering state, and the target torque setting means is a means for detecting the detected steering angle and vehicle speed. And a means for setting the target torque based on the above.

The steering torque control method according to the present invention is a steering torque control method in which a target torque corresponding to a steering state of a vehicle is applied to a steering wheel by using an electric torque operating means.
(A) detecting the steering torque acting on the steering wheel,
(B) setting a gain based on the target torque;
(C) The gist is that drive control of the electric torque action means is performed using a command value obtained based on a deviation between the target torque and the detected steering torque and the set gain.

According to the steering torque control method of the present invention, since the gain is set based on the target torque, the drive of the electric torque acting means can be controlled using a more appropriate gain. As a result, a more appropriate steering feeling can be obtained.

In the steering torque control method according to the present invention, the step (b) may be a step of setting a larger value of the gain as the absolute value of the target torque is larger. In this way, when the absolute value of the target torque is small, a small value of the gain is set. Therefore, a steering feeling with a heavy steering wheel and a so-called firm feeling can be obtained, and when the absolute value of the target torque is large, a large value is set. Since the gain is set, a light steering feeling of the steering wheel can be obtained.

In the steering torque control method according to the present invention, the step (b) is a step of setting a smaller gain as the absolute value of the rate of change of the steering torque target value with respect to the steering state increases. You can also.

In the steering torque control method according to the present invention, the step (b) may be a step of detecting a vehicle speed and setting a smaller gain as the detected vehicle speed increases. . In this way, a steering feeling according to the vehicle speed can be obtained.

[0019]

Next, embodiments of the present invention will be described with reference to examples. FIG. 1 is a configuration diagram schematically showing a configuration of a steering device 20 mounted on a vehicle according to one embodiment of the present invention. The steering device 20 of the embodiment, as illustrated,
The steering wheel 30 and the steering torque of the steering wheel 22 are transmitted to the rack 28 via the pinion gear 26 to control the steering wheels 30 and 3.
2 includes a steering shaft 24 for changing the turning angle of 2, a motor 34 for outputting an output torque to the rack 28 via a reduction gear 36 and a pinion gear 38, and an electronic control unit 50 for controlling the entire apparatus.

The electronic control unit 50 is configured as a microprocessor mainly including a CPU 52, and includes a ROM 54 storing a processing program, a RAM 56 temporarily storing data, and an input / output port (not shown). Prepare. The electronic control unit 50 includes a steering torque T from a torque sensor 40 attached to the steering shaft 24, a steering angle θ from a steering angle sensor 42 attached to the steering shaft 24, and a vehicle speed sensor 5.
The vehicle speed V from 8 is input via an input port. The electronic control unit 50 outputs a drive signal to the motor 34 through an output port.

FIG. 2 is an explanatory diagram exemplifying a control block when the electronic control unit 50 of the steering device 20 of the embodiment operates as a current command value calculation block 60 for calculating a current command value I * of the motor 34. . As shown in the figure, the current command value calculation block 60 calculates a target torque setting block 62 that calculates a target torque Tref of the steering shaft 24 based on the input steering angle θ and the vehicle speed V, and calculates the target torque setting block 62. And a gain setting block 64 for setting a gain G based on the target torque Tref and the vehicle speed V. The current command value calculation block 60 calculates a deviation ΔT (Tref−Th) between the target torque Tref calculated by the target torque setting block 62 and the steering torque T detected by the torque sensor 40.
Is multiplied by the gain G set by the gain setting block 64 to calculate a current command value I *. The current command value I * calculated by the current command value calculation block 60
Are used for drive control of the motor 34 as they are.

FIG. 3 is a block diagram illustrating the function of the target torque setting block 62. The target torque setting block 62 includes a turning-back turning-back determining unit 66 that determines whether the steering wheel 22 is turned or turned back based on the sign of the deviation of the input steering angle θ from the previously input steering angle θ; A target torque calculation unit 68 is provided to calculate a target torque Tref based on the determination result of the determination unit 66, the steering angle θ, and the vehicle speed V so as to have a hysteresis characteristic as illustrated in FIG. In FIG. 4, the horizontal axis is the steering angle θ, and the vertical axis is the target torque Tref. Also, a straight line A,
C is a straight line with a slope of K1, and straight lines B and D are slopes of K2.
And the intercept is a straight line of T2 and -T2. Target torque Tre
f is a straight line E parallel to the straight lines A and C from the origin when it is determined that the steering wheel 22 is turned further from the start of turning.
It is calculated as a value on the straight line B or D from the intersection with the straight line B or D. On the other hand, if it is determined in this state that the steering wheel 22 is to be returned, for example, if it is determined that the steering wheel 22 is to be returned at the point B2, the target torque Tref is changed to the point B2.
Is calculated as a value on a straight line F parallel to the straight lines A and C through Note that the target torque Tref is calculated by changing the shape of the hysteresis for calculating the target torque Tref according to the magnitude of the vehicle speed V, as shown in a target torque setting block 62 in FIG.

In the gain setting block 64, a larger value is set as the absolute value of the target torque Tref is larger, and a smaller value is set as the vehicle speed V is larger, as shown in FIG. Set the gain using the setting map. In the gain setting map illustrated in FIG. 5, the gain G is set using the straight line G1 when the vehicle speed V is less than the threshold value V1, and is set using the straight line G2 when the vehicle speed V is equal to or more than the threshold value V1 and less than the threshold value V2.
When the vehicle speed V is equal to or higher than the threshold value V2, it is set using the straight line G3. Here, the magnitude of the gain G appears light and light as the steering feeling of the steering wheel 22. That is, the smaller the gain G, the heavier the steering feeling with a firm feeling, and the larger the gain G, the lighter the steering feeling with a lighter feeling. In this gain setting map, the smaller the absolute value of the target torque Tref, that is, the steering angle θ
Is smaller, the smaller the gain G is set, the more the steering feeling becomes firm immediately after the start of steering.
Further, since the smaller the gain G is set as the vehicle speed V increases, the steering feeling with a certain firm feeling at the time of steering during high-speed running is more than that during steering at low speed.

Next, the operation of the steering apparatus 20 according to the embodiment configured as described above will be described in detail. FIG. 6 is a flowchart illustrating an example of a torque control routine executed by the electronic control unit 50 of the steering device 20 according to the embodiment. This routine is executed every predetermined time (for example, 8 msec).
Is executed repeatedly.

When this torque control routine is executed,
First, the CPU 52 of the electronic control unit 50 reads the steering angle θ detected by the steering angle sensor 42, the vehicle speed V detected by the vehicle speed sensor 58, and the steering torque T detected by the torque sensor 40 (Step S100),
Using the read steering angle θ and vehicle speed V, target torque Tr
A process for calculating ef is executed (step S102).
The calculation process of the target torque Tref has been described above. Subsequently, the gain G is set using the calculated absolute value of the target torque Tref and the vehicle speed V (step S104). The processing for setting the gain G has also been described above.

Then, the deviation ΔT is calculated by subtracting the steering torque T from the target torque Tref (step S1).
06), a current command value I * is calculated by multiplying the calculated deviation ΔT by the set gain G (step S108), and this routine ends. As described above, the current command value I * calculated in this manner is used for drive control of the motor 34.

According to the steering apparatus 20 of the embodiment described above, the smaller the absolute value of the target torque Tref is, the smaller the gain G is set. Therefore, immediately after the start of steering, a steering feeling with a firm feeling can be obtained. . Further, since the smaller the gain G is set as the vehicle speed V increases, the steering feeling at the time of steering during high-speed running may be more firmly felt than the steering feeling at the time of steering during low-speed running. it can. Naturally, the target torque Tref is calculated based on the determination of whether the steering wheel 22 is turned more or more, so that even if the steering angle sensor 42 has a coarse resolution and performs slow steering, the stable target torque Tref can be obtained. Tref can be calculated, and a good steering feeling can be obtained.

In the steering device 20 of the embodiment, the target torque T
Although the gain G is set using the absolute value of ref and the vehicle speed V, the gain G may be set only using the absolute value of the target torque Tref without using the vehicle speed V.

In the steering device 20 of the embodiment, the steering wheel 22
The target torque Tref with hysteresis is calculated based on the determination of whether the turning angle is increased or returned, but the target torque Tref with hysteresis is calculated based on the change rate of the steering angle θ, the vehicle speed V, the steering torque T, and the like. Alternatively, the target torque Tref having no hysteresis may be calculated.

The embodiments of the present invention have been described with reference to the embodiments. However, the present invention is not limited to these embodiments, and various embodiments may be made without departing from the gist of the present invention. Of course, it can be carried out.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing a configuration of a steering device 20 mounted on a vehicle according to an embodiment of the present invention.

FIG. 2 is an electronic control unit 5 of the steering device 20 according to the embodiment;
FIG. 5 is an explanatory diagram illustrating a control block when 0 operates as a current command value calculation block 60 for calculating a current command value I * of the motor 34;

FIG. 3 is a block diagram illustrating functions of a target torque setting block 62;

FIG. 4 is an explanatory diagram illustrating a state of calculation of a target torque Tref.

FIG. 5 is an explanatory diagram showing an example of a gain setting map.

FIG. 6 is an electronic control unit 5 of the steering device 20 according to the embodiment.
7 is a flowchart illustrating an example of a torque control routine executed by the control unit 0.

[Explanation of symbols]

20 steering device, 22 steering wheel, 24 steering shaft, 26 pinion gear, 28 rack, 30,
32 steering wheel, 34 motor, 36 reduction gear, 38 pinion gear, 40 torque sensor, 42 steering angle sensor, 50 electronic control unit, 52 CPU, 54 R
OM, 56 RAM, 58 vehicle speed sensor, 60 current command value calculation block, 62 target torque setting block, 6
4 gain setting block, 66 additional turning-back and return determining unit, 68 target torque calculating unit.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Eiichi Ono 41-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside of Toyota Central Research Laboratory Co., Ltd. (72) Inventor Toshihiro Takahashi 1 Asahi-cho, Kariya City, Aichi Prefecture 1-chome Toyota Koki Co., Ltd. (72) Inventor Mineichi Mineyama 1-1-1 Asahi-cho, Kariya-shi, Aichi F-term (reference) 3D032 CC08 DA03 DA15 DA23 DB12 DD06 EC23 3D033 CA03 CA13 CA16 CA17 CA21

Claims (10)

[Claims] 1. An on-vehicle steering device for outputting a steering torque according to an operation of a steering wheel, an electric torque operating means capable of applying a torque to the steering wheel, and a steering device detecting a steering torque acting on the steering wheel. Torque detecting means, steering state detecting means for detecting a steering state, target torque setting means for setting a target torque which is a target value of the steering torque based on the detected steering state, and based on the set target torque. Gain setting means for setting a gain by using the electric torque acting means so that the set target torque acts on the steering wheel based on the set target torque, the detected steering torque, and the set gain. And a torque control means for controlling the driving of the steering wheel. 2. The steering apparatus according to claim 1, wherein the gain setting means sets a larger value of the gain as the absolute value of the set target torque increases. 3. The steering apparatus according to claim 1, wherein the gain setting means sets a smaller value of the gain as the absolute value of the rate of change of the target value of the steering torque with respect to the steering state increases. 4. The steering apparatus according to claim 1, further comprising a vehicle speed detecting unit that detects a vehicle speed, wherein the gain setting unit sets a smaller value of the gain as the vehicle speed increases. Steering gear. 5. The electric motor control device according to claim 5, wherein the torque control unit controls the electric torque operation unit using a command value obtained based on a deviation between the set target value and the detected steering torque and the set gain. 2. A drive control means.
5. The steering device according to any one of claims 4 to 4. 6. The steering apparatus according to claim 1, wherein the steering state detection means is means for detecting a steering angle and a vehicle speed of a steering wheel as a steering state, and the target torque setting means is A steering device for setting a target torque based on the detected steering angle and vehicle speed. 7. A steering torque control method in which a target torque according to a steering state of a vehicle is applied to a steering wheel by using an electric torque operating means, wherein (a) detecting a steering torque acting on the steering wheel, b) setting a gain based on the target torque; and (c) using the command value obtained based on the deviation between the target torque and the detected steering torque and the set gain to use the electric torque operation. A steering torque control method for controlling driving of the means. 8. The steering torque control method according to claim 7, wherein the step (b) is a step of setting a larger gain as the absolute value of the target torque is larger. 9. The steering torque control method according to claim 7, wherein the step (b) is a step of setting a smaller gain as the absolute value of the rate of change of the steering torque target value with respect to the steering state increases. . 10. The steering torque control method according to claim 7, wherein the step (b) is a step of detecting a vehicle speed and setting a smaller gain as the detected vehicle speed increases.