JPH10310075A - Vehicle steering system - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To return road surface information indicating a detailed contact relationship between a road surface and a tire to a steering wheel. SOLUTION: A vibration sensor 13 is provided at an arbitrary position on a power transmission path from a steering motor 9 to a steered wheel via a steering shaft. Vibration V detected by vibration sensor 13
b is subjected to a predetermined filtering process (6-
7). The filtered vibration Vb 'and the steered shaft movement amount M' are synthesized (6-8). The steering reaction force value Ts is calculated in consideration of the combined steering shaft movement amount M 'and vibration Vb' (6-4).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention drives a steering motor connected to a steering shaft based on a steering state of a steering wheel and a running state of a vehicle, in which a steering wheel and a steered wheel are disconnected. The present invention relates to a vehicle steering system that applies a reaction force to a steering wheel by driving a steering reaction force motor connected to a steering column shaft.

[0002]

2. Description of the Related Art Conventionally, in a steering apparatus of this type, a steering column shaft and a steering shaft are not connected (linkless), a steering motor is provided on the steering shaft, and a steering reaction motor is provided on the steering column shaft. Concatenate,
The steering motor and the steering reaction motor are individually driven. Such a driving method is called a steer-by-wire method.

In the steer-by-wire system, a target steered shaft stroke position is obtained based on a vehicle speed and a steering angle (steering angular speed), and a target steered shaft stroke position is calculated based on the calculated target steered shaft stroke position. The output value to the steering motor is calculated from the difference. Based on the calculated output value, the steering motor is driven while feeding back a motor output such as a motor current value. Further, the output value to the steering reaction force motor is calculated from the difference between the steering reaction force value and the steering torque after calculating the steering reaction force value from the output value to the turning motor and the vehicle speed. The steering reaction force motor is driven based on the calculated output value.

[0004] Here, the steering kickback having a low frequency is canceled by feeding back the steering shaft stroke position when calculating the output value to the steering motor. In addition, by using the output value to the turning motor when calculating the steering reaction force value, the road surface information corresponding to the kickback at that time is returned to the steering wheel.

However, in the case of a kickback in which the steering motor cannot respond, for example, when there is a momentary kickback of large energy, the road surface information cannot be given to the steering reaction force motor. Therefore, conventionally, the amount of movement of the steered shaft is detected based on a signal from the steered shaft stroke sensor, and the steering reaction force value is calculated in consideration of the detected amount of movement of the steered shaft. ing.

[0006]

However, according to such a conventional steering apparatus, road surface information corresponding to the kickback at that time is not obtained for a kickback having a low frequency or a kickback having a momentarily large energy. Although the road surface can be returned to the steering wheel, road surface information indicating a detailed contact between the road surface and the tire cannot be returned to the steering wheel. This is because the steered shaft stroke sensor detects the amount of movement of the steered shaft between the steered shaft and its housing, and therefore cannot detect the vibration including the steered shaft housing due to the influence of the road surface. For such reasons.

SUMMARY OF THE INVENTION The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a vehicle which can return fine road surface information indicating a contact relationship between a road surface and a tire to a steering wheel. It is to provide a steering device.

[0008]

In order to achieve such an object, a first invention (an invention according to claim 1) provides a power transmission path from a steering motor to a steered wheel via a steering shaft. The vibration detecting means is provided at an arbitrary position, and the reaction force to be applied to the steering wheel is obtained in consideration of the vibration detected by the vibration detecting means. According to the present invention, the vibration applied to the steering system is detected by the vibration detecting means, and the steering reaction force value is obtained in consideration of the vibration.

In a second invention (an invention according to a second aspect), a vibration detecting means is provided at an arbitrary position of a power transmission path from a steering motor to a steered wheel via a steering shaft, and a steering shaft stroke sensor is provided. The reaction force to be applied to the steering wheel is obtained in consideration of the amount of movement of the steered shaft detected based on the sensor signal from the controller and the vibration detected by the vibration detecting means. According to the present invention, the vibration applied to the steering system is detected, and the steering reaction force value is obtained in consideration of the vibration and the amount of movement of the steering shaft.

The third invention (the invention according to claim 3) is the first invention.
In the invention and the second invention, a filter for removing a predetermined vibration component is provided between the vibration detecting means and the steering reaction force calculating means. According to the present invention, a predetermined vibration component (a vibration component unnecessary for grasping the road surface information) is removed from the detected vibration, and the steering reaction force value is calculated by taking into account the vibration from which the predetermined vibration component has been removed. Desired.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. FIG. 2 is a mechanism diagram showing a main part of a steering device using a steer-by-wire system according to an embodiment of the present invention.

In the figure, 1 is a steering column shaft, 2 is a steering angle sensor attached to the steering column shaft 1, 3 is a steering torque sensor attached to the steering column shaft 1, and 4 is connected to the steering column shaft 1. Steering reaction force motor, 6
Is a controller, 7 is a vehicle speed sensor, 8 is a steered shaft, 9 is a steered motor connected to the steered shaft 8 via a gear & ball screw mechanism 10, and 11 is installed on an output shaft of the steered motor 9. A rotary encoder 12, a turning shaft stroke sensor for detecting the moving position of the turning shaft 8, and 13 a power transmission path from a turning motor 9 to a steering wheel (not shown) via the turning shaft 8. The vibration sensor is provided at an arbitrary position (in this example, the steering shaft 13). As the vibration sensor 13, a vibration pickup, a piezoelectric element, or the like is used.

In this steering device, a turning force is applied to the steering column shaft 1 by the driver steering the steering wheel. The rotational force is applied to a steering angle sensor 2 and a steering torque sensor 3 installed on the steering column shaft 1 and the steering column shaft 1
To the steering reaction force motor 4 attached to the tip of the motor.

The controller 6 determines a target steered shaft stroke position based on the sensor signal from the steering angle sensor 2 and the sensor signal from the vehicle speed sensor 7, and the obtained target steered shaft stroke position is obtained. The steering motor 9 is driven as described above. The steering motor 9 applies thrust to the steering shaft 8 via the gear & ball screw mechanism 10. As a result, the steered shaft 8 is displaced, and the steered wheels are steered by changing the direction of a knuckle arm (not shown) mechanically connected to the steered shaft 8.

The moving position of the steered shaft 8 is detected by a steered shaft stroke sensor 12, and the controller 6
Given to. The controller 6 drives the steering reaction force motor 4 so that a steering reaction force according to the motor output value to the steering motor 9 and the vehicle speed is added to the steering wheel steering force. The steering wheel steering force and the force of the steering reaction motor 4 are detected by the steering torque sensor 3 and checked by the controller 6.

The controller 6 confirms the rotation of the steering motor 9 based on a signal from the rotary encoder 11. Further, the abnormality of the steered shaft stroke sensor 12 is determined by monitoring the relationship between the rotation of the steered motor 9 and the sensor signal from the steered shaft stroke sensor 12. When the steering shaft stroke sensor 12 is abnormal, the rotary encoder 11 is used instead.

FIG. 1 shows an outline of processing in the controller 6. The controller 6 calculates the vehicle speed v from the vehicle speed sensor 7 and the steering angle θ from the steering angle sensor 2 based on
Calculates a steered shaft stroke position S _T to the target (target turning shaft stroke calculation process 6-1).

[0018] Then, to calculate the output value Pa to the steering motor 9 from the actual difference between the steering shaft stroke position S _R from the steering shaft stroke position S _T and the steered shaft stroke sensor 12 that the calculated ( Steering motor output calculation processing 6-2). Then, based on the calculated output value Pa, the steering motor 9 is driven while feeding back the motor output such as the motor current value.

The controller 6 performs a predetermined filtering process on the output value Pa to the turning motor 9 in the turning motor output calculation process 6-2 (filtering process 6-3). A steering reaction force value Ts is calculated from the applied output value Pa ′ and the vehicle speed v from the vehicle speed sensor 7 (steering reaction force value calculation processing 6-4).

[0020] Here, the steering to the steering calculation of the reaction force value Ts of the reaction force calculation process 6-4, turning is detected based on the steering shaft stroke position S _R from the steering shaft stroke sensor 12 The amount of movement of the shaft 8 and the vibration detected by the vibration sensor 13 are taken into account.

[0021] That is, the controller 6, those from steering shaft stroke position S _R from the steering shaft stroke sensor 12 minus the target steering shaft stroke position S _T as a force for the steering shaft movement amount M from the road surface Calculation (steering shaft movement amount calculation process 6-5), and a predetermined filtering process is performed on the calculated steering shaft movement amount M (filtering process 6-6). Further, predetermined filtering processing is performed on the vibration Vb detected by the vibration sensor 13 (filtering processing 6-7).

Then, the steering shaft movement amount M 'and the vibration Vb' subjected to the filtering processing are combined (combination processing 6-8), and the combined steering shaft movement amount M 'and vibration Vb' are added. Then, the steering reaction force value Ts is calculated in the steering reaction force value calculation processing 6-4.

In the filtering process 6-7, the motor torque fluctuation component obtained from the current waveform of the steering motor 9 based on the vibration Vb detected by the vibration sensor 13 and the difference between the steering motor 9 and the steering mechanism. The vibration components unnecessary for grasping the road surface information, such as the natural vibration frequency in the gear section and the unpleasant vibration component of the steering system obtained by the actual vehicle measurement, are excluded.

The controller 6 calculates the output value Pb to the steering reaction force motor 4 from the difference between the steering reaction force value Ts calculated in the steering reaction force value calculation processing 6-4 and the steering torque Td from the steering torque sensor 3. (Motor output calculation processing 6-
9) The steering reaction force motor 4 is driven based on the calculated output value Pb.

The steering torque Td detected by the steering torque sensor 3 is fed back to the steering reaction force calculation output, and is matched with the output of the steering reaction force motor 4.
Although not shown here, the steering torque Td detected by the steering torque sensor 3 is also used to check the consistency with the steering angle sensor 2. Further, the steering angle sensor 2 and the steering torque sensor 3 have polarities, and the output polarities are switched according to the respective steering directions.

[0026] [road information feedback] [low frequency steering kickback] low frequency steering kickback is counteracted by steering shaft stroke position S _R when calculating the output value Pa to the steering motor 9 is fed back It is. Further, when calculating the steering reaction force value Ts, the output value P to the turning motor 9 is calculated.
By using a, that is, the output value Pa ′ through the filtering process 6-3, the road surface information corresponding to the kickback at that time is returned to the steering wheel.

[Kickback such that steering motor 9 cannot respond] For example, when there is a momentary kickback of large energy, the steering shaft stroke position S _R
The steering reaction force value Ts is calculated by taking into account the amount of movement M of the steered shaft detected based on the above, that is, the amount of movement M 'of the steered shaft through the filtering process 6-6. Road surface information corresponding to the back is returned to the steering wheel.

[Contact Relationship between Fine Road Surface and Tire] The kickback steering reaction force feedback by the steering shaft stroke sensor 12 cannot detect vibration including the steering shaft housing due to the influence of the road surface due to its configuration. Further, the vibration cannot be detected from the output value Pa to the steering motor 9. This vibration is generated by the vibration sensor 13
Is detected by That is, filtering processing 6
By calculating the steering reaction force value Ts in consideration of the vibration Vb ′ via −7, the road surface information indicating the detailed contact between the road surface and the tire is returned to the steering wheel.

In FIG. 1, the steering reaction force value calculation process 6 is performed.
4, the steering reaction force value Ts is calculated by taking into account the steering shaft movement amount M 'and the vibration Vb' in addition to the output value Pa 'and the vehicle speed v.
Is calculated, but a steering reaction force value set in advance in relation to the steering angle, the steering angular velocity, and the vehicle speed is selected, and the steering shaft movement amount M ′ and the vibration Vb are set to the selected steering reaction force value. The steering reaction force value Ts may be obtained by taking only 'into account.

In FIG. 1, the steering reaction force value Ts is calculated by taking into account the output value Pa 'and the vehicle speed v, the steering shaft movement amount M' and the vibration Vb '. The addition of the amount M ′ may be omitted. That is, the steering reaction force value Ts may be calculated by taking the vibration Vb 'into consideration with the output value Pa' and the vehicle speed v. Also,
In the filtering processes 6-3, 6-6, and 6-7, the steering feeling is slightly lowered, but may be omitted.

In this embodiment, since the vibration sensor 13 does not require high accuracy, an inexpensive electromagnetic pickup can be used. Further, even if the vibration sensor 13 breaks down, only a part of the feedback of the road surface information to the steering wheel is missing, so that no trouble occurs.

[0032]

As is apparent from the above description, according to the present invention, the vibration applied to the steering system is detected by the vibration detecting means, and the steering reaction force value is obtained in consideration of the vibration. Road surface information indicating a fine road surface and tire contact relationship can be returned to the steering wheel, thereby improving the steering feeling.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of processing in a controller shown in FIG. 2;

FIG. 2 is a mechanism diagram showing a main part of a steering device using a steer-by-wire system according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Steering column shaft, 2 ... Steering angle sensor, 3 ... Steering torque sensor, 4 ... Steering reaction force motor, 6 ...
Controller, 7: Vehicle speed sensor, 8: Steering shaft, 9: Steering motor, 10: Gear & ball screw mechanism, 1
Reference numeral 1 denotes a rotary encoder, 12 denotes a steered shaft stroke sensor, and 13 denotes a vibration sensor.

Claims (3)

[Claims] A steering wheel and a steered wheel are not connected to each other, and a steering motor connected to a steering shaft is driven based on a steering state of the steering wheel and a traveling state of the vehicle, while being connected to a steering column shaft. A steering reaction motor that drives the steering reaction force motor to apply a reaction force to the steering wheel, provided at an arbitrary position on a power transmission path from the steering motor to the steered wheels via the steering shaft. A steering apparatus for a vehicle, comprising: a detected vibration detecting means; and a steering reaction force determining means for obtaining a reaction force to be applied to the steering wheel in consideration of the vibration detected by the vibration detecting means. And a steering wheel connected to a steering column shaft based on a steering state of the steering wheel and a running state of the vehicle. A steering device for driving a steering reaction motor to apply a reaction force to the steering wheel; a steering shaft stroke sensor for detecting a moving position of the steering shaft; and a steering shaft from the steering motor. Vibration detecting means provided at an arbitrary position on a power transmission path to the steered wheels via the steering shaft; and a movement amount of the steered shaft detected based on a sensor signal from the steered shaft stroke sensor and the vibration detection. Steering reaction force determining means for obtaining a reaction force to be applied to the steering handle in consideration of vibration detected by the means. Vehicle steering system. 3. A vehicle steering system according to claim 1, wherein a filter for removing a predetermined vibration component is provided between said vibration detecting means and said steering reaction force calculating means.