JP4178068B2 - Steering control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steering control device that performs steering assist so as to cancel a yaw rate change of a vehicle.
[0002]
[Prior art]
Conventionally, for the purpose of turning the vehicle yaw rate in a stable direction, the steering correction amount multiplied by the gain determined according to the vehicle yaw rate and the vehicle speed during steering is calculated, and the steering assist torque is applied to the steering device. As a technique for performing steering assist, for example, a technique described in Patent Document 1 is known.
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 11-147483 (see FIG. 7B).
[0004]
[Problems to be solved by the invention]
However, the technique described in Patent Document 1 is effective in canceling the yaw rate that occurs due to road surface undulation or the like, but the driver steers the yaw rate that occurs when the driver steers intentionally. Since the steering assist is executed on the side opposite to the steering direction to be performed, there is a risk of deteriorating the steering feeling such as feeling heavy steering.
[0005]
Further, the gain given to the yaw rate change described above is larger than the gain of the yaw rate change due to road surface disturbances such as road surface unevenness, so that it is not possible to set a sufficient control gain for the yaw rate change component due to road surface disturbances. However, there was a problem that the effect of improving the vehicle stability could not be obtained.
[0006]
The present invention has been made paying attention to the above-mentioned problems, and can be steered according to the driver's intention, and the steering assist so as to cancel only the change in the yaw rate of the vehicle that is not intended by the driver. An object of the present invention is to provide a steering control device capable of performing the above.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention extracts a predetermined frequency component from the detected yaw rate and cancels the yaw rate of the frequency component set in a predetermined range excluding the low frequency region which is the normal steering region of the driver. Since the steering amount in the direction is given, it is possible to improve both the steering feeling and the vehicle stability against the yaw rate change.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
FIG. 1 is a system diagram showing the overall configuration of a power steering apparatus according to Embodiment 1 of the present invention. First, the configuration will be described. 1 is a steering wheel, 2 is a steering shaft, 3 is a rack and pinion gear mechanism, 5 is a power steering mechanism that assists the steering force of the driver, 6 is an electric motor, 7 is a steering wheel, A control unit 10 controls the power steering mechanism.
[0009]
The power steering mechanism 5 transmits the rotation of the electric motor 6 to a speed reduction mechanism provided on the steering shaft 2. When the driver operates the steering wheel 1, the rotation direction of the electric motor 6 is switched according to the operation direction, and assists the driver's steering force.
[0010]
Further, the steering shaft 2 is provided with a torque sensor 12 for detecting the steering torque of the driver.
[0011]
A steering torque signal from the torque sensor 12, a vehicle speed signal from the vehicle speed sensor 13, and a yaw rate signal from the yaw rate sensor 14 are input to the control unit 10. A command signal is output to the electric motor 6 based on the input signal.
[0012]
FIG. 2 is a block diagram showing the configuration inside the control unit 10. A steering assist control unit 101 calculates a steering assist amount based on the input torque signal and vehicle speed signal. Reference numeral 102 denotes a yaw rate control unit that calculates a stable direction steering amount at which the vehicle is in a stable direction based on the yaw rate signal. The steering torque command value that is finally output to the electric motor 6 is output as the sum of the steering assist amount calculated by the steering assist control unit 101 and the stable direction steering amount calculated by the yaw rate control unit 102.
[0013]
Here, the yaw rate control unit 102 will be described. The yaw rate control unit 102 provides a bandpass filter 102a that extracts a predetermined frequency component from the input yaw rate signal, and gives a control gain to the extracted predetermined frequency component in a direction that cancels the frequency component, and determines a stable direction steering amount. The control gain unit 102b is determined. FIG. 3 is a diagram illustrating the characteristics of the bandpass filter 102a. This band pass filter 102a outputs a value obtained by attenuating a signal in a low frequency range up to (1 / 2πT1) (including a frequency range generated by the driver's steering) by applying a gain corresponding to the frequency. , (1 / 2πT1) to (1 / 2πT3) intermediate frequency range is passed as it is, and the value of (1 / 2πT3) or higher frequency signal attenuated by applying a gain according to the frequency Is output.
[0014]
FIG. 4 is a flowchart showing the control contents of the steering control in the first embodiment.
In step 201, the steering torque and the vehicle speed are read from the torque sensor 12 and the vehicle speed sensor 13.
In step 202, a map for setting a steering torque assist amount corresponding to the vehicle speed is selected.
In step 203, the steering assist amount is calculated based on the map selected in step 202.
In step 204, the yaw rate signal is read.
In step 205, filter processing is executed.
In step 206, the stable steering amount is calculated from the control gain.
In step 207, the final steering amount is calculated as the sum of the steering assist amount and the stable direction steering amount.
In step 208, a steering torque based on the final steering amount is output from the electric motor 6.
[0015]
Specific contents of the control will be described. FIG. 5 shows a yaw rate signal detected by the yaw rate sensor 14, and FIG. 6 shows a filtered yaw rate signal obtained by extracting the detected yaw rate signal by the bandpass filter 102a. The yaw rate signal shown in FIG. 5 includes a low-frequency signal generated by the driver's steering. On the other hand, as shown in FIG. 6, the filtered yaw rate signal obtained by extracting the yaw rate signal shown in FIG. 5 by the bandpass filter 102a is changed with a narrow amplitude, particularly when the low frequency signal generated by the driver's steering is cut. Signal.
[0016]
For the yaw rate signal, the control gain unit 102b gives a gain in a direction to cancel the filtered yaw rate signal shown in FIG. 6 and outputs the gain as a stable direction steering amount.
[0017]
FIG. 7 shows a yaw rate signal generated in the vehicle after executing the yaw rate control, and FIG. 8 shows a filtered yaw rate signal obtained by extracting the yaw rate signal after executing the yaw rate control by the bandpass filter 102a. As shown in FIG. 7, the low frequency generated by the driver's steering is left as it is, and as shown in FIG. 8, the signal in the intermediate frequency range is canceled at a high level.
[0018]
As described above, an intermediate frequency component is extracted from the yaw rate signal detected by the yaw rate sensor 14, and a steering amount for canceling only the extracted yaw rate of the predetermined frequency component is given. Therefore, a steering amount for canceling the yaw rate generated by the driver's steering is not given, and it is possible to achieve both improvement of the vehicle stability against the yaw rate change while executing the steering assist according to the driver's steering. The
[0019]
(Embodiment 2)
FIG. 9 is a system diagram showing the overall configuration of the power steering apparatus according to Embodiment 2 of the present invention. Since the basic configuration is the same as that of the first embodiment, only different points will be described.
[0020]
The yaw rate control unit 102 is provided with a region changing unit 102c that changes the filter constant T1 according to the vehicle speed. The region changing unit 102c changes the threshold values in the intermediate frequency region and the low frequency region so as to increase toward the low frequency side as the vehicle speed decreases in accordance with the vehicle speed signal from the vehicle speed sensor 13.
[0021]
FIG. 10 is a flowchart showing the contents of the filter processing in step 205 of the flowchart of FIG.
In step 301, the vehicle speed is read from the vehicle speed sensor 13.
In step 302, a filter constant T1 corresponding to the vehicle speed is set.
In step 303, a yaw rate signal is read from the yaw rate sensor 14.
In step 304, the filtered yaw rate signal is output.
[0022]
That is, when the vehicle speed is high, the frequency of disturbances such as irregularities input from the road surface is high (many vibrations are input per unit time), and when the vehicle is low, the frequency is low (vibrations input per unit time). Less is). Therefore, the threshold value is changed by changing the filter constant T1 according to the vehicle speed. FIG. 11 is a diagram illustrating bandpass filter characteristics in the filter processing. In this way, by changing the frequency range to pass, in addition to the effects described in the first embodiment, it is possible to obtain the steering feeling in accordance with the vehicle speed.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the overall configuration of a power steering apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating a control circuit in the first embodiment.
FIG. 3 is a diagram illustrating bandpass filter characteristics in the first embodiment.
FIG. 4 is a flowchart showing steering control in the first embodiment.
FIG. 5 is a diagram illustrating a yaw rate signal before yaw rate control in the first embodiment.
FIG. 6 is a diagram illustrating a yaw rate signal after filter processing before yaw rate control in the first embodiment.
FIG. 7 is a diagram illustrating a yaw rate signal after yaw rate control in the first embodiment.
FIG. 8 is a diagram showing a yaw rate signal after filter processing after yaw rate control in the first embodiment.
FIG. 9 is a block diagram illustrating a control circuit in the second embodiment.
FIG. 10 is a flowchart showing filter processing in the second embodiment.
FIG. 11 is a diagram illustrating band pass filter characteristics in the second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3 Gear mechanism 5 Power steering mechanism 6 Electric motor 7 Steering wheel 10 Control unit 12 Torque sensor 13 Vehicle speed sensor 14 Yaw rate sensor

Claims (4)

In a steering control device comprising a steering control means for giving a steering amount in which the vehicle is in a stable direction to the steering device according to the yaw rate generated in the vehicle,
A yaw rate detecting means for detecting a yaw rate around the center of gravity of the vehicle;
A filter that inputs the detected yaw rate and extracts a predetermined frequency component;
Provided,
The steering control device is characterized in that the steering control device gives a steering amount in a direction to cancel a yaw rate of a frequency component set in a predetermined range excluding a low frequency region which is a normal steering region of the driver . In an operation control device comprising a steering control means for giving a steering amount in which the vehicle is in a stable direction to the steering device in accordance with the yaw rate generated in the vehicle,
A yaw rate detecting means for detecting a yaw rate around the center of gravity of the vehicle;
A filter that inputs the detected yaw rate and extracts a predetermined frequency component excluding a low frequency region that is a normal steering region of the driver;
Provided,
The steering control device is characterized in that the steering control means gives a steering amount in a direction to cancel the yaw rate of the extracted predetermined frequency component . In a steering control device comprising a steering control means for giving a steering amount in which the vehicle is in a stable direction to the steering device according to the yaw rate generated in the vehicle ,
A yaw rate detecting means for detecting a yaw rate around the center of gravity of the vehicle;
A filter that inputs the detected yaw rate and extracts a predetermined frequency component;
Provided,
The steering control means gives a steering amount according to the yaw rate of the extracted predetermined frequency component,
The filter is a bandpass filter that outputs a predetermined frequency range,
The predetermined frequency range, and low frequency domain is a normal steering range of the driver, steering control apparatus is characterized in that an intermediate frequency region excluding the high frequency domain which is the resonance range. In the steering control device according to claim 3,
A steering control device comprising: a region changing means for changing the threshold values of the intermediate frequency region and the low frequency region so that the threshold value is increased toward the low frequency side as the vehicle speed is low.

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