Vehicle state value detecting device

Abstract

The vehicle state value detecting device includes a first low pass filter (32, 36) and a second low pass filter (33, 37) having a lower cutoff frequency than the first low pass filter. The device processes a detection signal of a sensor (10, 11) for a motion control of a vehicle such as a yaw rate sensor and a lateral G sensor by selectively using one of the two low pass filters. A signal selecting unit (35, 39) selects the output of the first low pass filter when the control process demands prompt detection of an abrupt changes in the behavior of the vehicle and the output of the second low pass filter when it is not the case and an enhanced stability of the control action has a priority.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Now the present invention is described in the following with reference to the appended drawings, in which:

FIG. 1 is a simplified diagram of an automobile to which the present invention is applied;

FIG. 2 is a block diagram of a vehicle state value detecting device embodying the present invention;

FIG. 3 is a flowchart showing the mode of operation of the vehicle state value detecting device;

FIG. 4 is a graph showing the waveforms of the first and second detection signals GL1 and GL2 and the difference signal ΔGL; and

FIG. 5 is a flowchart showing the control process of an active suspension control.

Claims

1. A vehicle state value detecting device, comprising: a state value detecting unit for detecting a state variable of a vehicle;a first low pass filter that cuts off a high frequency component from an output signal of the state value detecting unit at a first cutoff frequency;a second low pass filter that is connected in parallel with the first lower pass filter and cuts off a high frequency component from an output signal of the state value detecting unit at a second cutoff frequency lower than the first cutoff frequency;a vehicle condition detecting unit for detecting a first condition and a second condition of the vehicle; anda signal selecting unit for selecting an output signal of the first low pass filter when the first condition is detected and an output signal of the second low pass filter when the second condition is detected.

2. The vehicle state value detecting device according to claim 1, wherein the signal selecting unit selects an output signal of the first low pass filter when the second condition is not detected.

3. The vehicle state value detecting device according to claim 1, further comprising a noise determining unit that computes a difference between output signals of the first and second low pass filter, the signal selecting unit selecting the output of the second low pass filter when the difference changes signs by more than a prescribed number of times within a prescribed period.

4. The vehicle state value detecting device according to claim 3, wherein the signal selecting unit selects the output of the first low pass filter when the difference do not change signs by more than a prescribed number of times within a prescribed period.

5. The vehicle state value detecting device according to claim 1, further comprising a steering speed detecting unit for detecting a steering speed, the signal selecting unit selecting the output of the first low pass filter when the detected steering speed is higher than a threshold value.

6. The vehicle state value detecting device according to claim 5, wherein the signal selecting unit selects the output of the second low pass filter when the detected steering speed is lower than the threshold value.

7. The vehicle state value detecting device according to claim 1, further comprising a steering speed detecting unit for detecting a steering speed and a noise determining unit that computes a difference between output signals of the first and second low pass filter, the signal selecting unit selecting the output of the second low pass filter when the detected steering speed is lower than a threshold value or when the difference changes signs by more than a prescribed number of times within a prescribed period.

8. The vehicle state value detecting device according to claim 1, further comprising a stroke sensor for detecting a stroke speed of a suspension system, the signal selecting unit selecting the output of the first low pass filter when the detected stroke speed is higher than a threshold value.

9. The vehicle state value detecting device according to claim 8, wherein the signal selecting unit selects the output of the second low pass filter when the detected stroke speed is lower than the threshold value.

10. The vehicle state value detecting device according to claim 1, further comprising a vertical G sensor for detecting a vertical acceleration of a vehicle body, the signal selecting unit selecting the output of the first low pass filter when the detected vertical acceleration is higher than a threshold value.

11. The vehicle state value detecting device according to claim 10, wherein the signal selecting unit selects the output of the second low pass filter when the detected vertical acceleration is lower than the threshold value.