JPH07195924A - Grounded condition deciding method of wheel - Google Patents

Abstract

PURPOSE:To simplify the structure and to realize a low cost, by finding a mean relative distance from the detected relative distance between the body and the wheel, and comparing the reduction amount of the mean relative distance to the still condition with a standard value, so as to decide the grounding condition of the wheel by a single sensor and a simple processing circuit. CONSTITUTION:The relative distance between a body and a wheel is detected by a stroke sensor, and the result is input to a mean relative distance operation means 10. In the operation means 10, the input signal is time differetiated to find a mean relative distance between the body and the wheel, and the reduction amount of the mean relative distance to the still condition is given to a comparison means 11. In the comparison means 11, the reduction amount of the mean relative distance is compared with a standard value, and when the reduction amount is smaller than the standard value, it is decided that the grounding condition is good, and when it is larger, it is decided that the grounding condition is not good, and a grounding condition signal is output. In this case, the standard value of the comparison means 11 is decided experimetally according to the characteristics of the wheels, the suspension, and the like. Consequently, only a single sensor is used, and the structure of the circuit can be simplified, so as to realize a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel grounding state determination method.

[0002]

2. Description of the Related Art When a vehicle is running, a vehicle body and wheels vibrate due to road surface irregularities. Generally, the vehicle body resonates due to vibrations from the road surface in the vicinity of 1 Hz to deteriorate the riding comfort, and the wheels resonate in the vicinity of 10 Hz to deteriorate the steering stability. If it is possible to reduce the vibrations in these two resonance regions, it is possible to improve both the riding comfort and the steering stability, but these have contradictory characteristics, and one of the vibrations is reduced in a normal passive suspension. And the other gets worse. Therefore, attempts have been made to solve this problem by suspension control, and one of them is a suspension that applies the skyhook theory. According to this, it is possible to effectively improve the vibration of the vehicle body in the vehicle body resonance region without deteriorating the vibration of the wheel in the wheel resonance region and improve the riding comfort. Not directly improved. In order to improve the vibration in the wheel resonance range, it is necessary to switch to a control law that emphasizes wheel damping in the wheel resonance range.
For this purpose, it is necessary to sense the movement state of the wheels and detect the deterioration of the ground contact state of the wheels.

As this kind of control means, Japanese Patent Laid-Open No. 4-50
There is a device for controlling a chassis according to a traveling route described in Japanese Patent No. 0492. This is provided with a sensor for detecting the shock absorbing force of the shock absorber, a sensor for detecting the elastic compression amount of the wheel with respect to the vehicle body, and a sensor for detecting the wheel acceleration.
The unevenness of the traveling road or the instantaneous value of the temporal variation of the unevenness of the traveling road is detected from the data of each sensor, and the control law of the spring device of the vehicle is switched based on this.

[0004]

According to the above-mentioned prior art, not only is it necessary to provide a plurality of sensors, but also a complicated processing circuit is required for processing the data of these sensors to generate a control signal. There are problems that the configuration becomes complicated and the cost becomes high.

The present invention has been made based on the above point of view, and an object thereof is to determine the ground contact state of a wheel by a single sensor and a simple processing circuit, thereby simplifying the configuration and reducing the cost. It is to provide a method for determining a ground contact state of a wheel that contributes.

[0006]

In the present invention, the relative distance between the vehicle body and the wheels is detected, the average relative distance between the vehicle body and the wheels is determined from the detected relative distance, and the average relative to the stationary state is calculated. The above object is achieved by a wheel grounding state determination method in which the wheel grounding state is determined by comparing the amount of decrease in distance with a predetermined reference value.

[0007]

According to the present inventor, the decrease amount of the average relative distance between the vehicle body and the wheel with respect to the amplitude and frequency of the road surface unevenness substantially corresponds to the increase of the variation range of the ground contact force of the wheel with respect to the road surface unevenness amplitude and frequency. We have experimentally recognized that we are doing.
From this viewpoint, in the present invention, the relative distance between the vehicle body and the wheels is detected, the average relative distance between the vehicle body and the wheels is obtained from this relative distance, and the reduction amount of the average relative distance with respect to the stationary state is set to a predetermined value. The ground contact state of the wheel is determined by comparing with a reference value. According to the present invention, only a single sensor is required to detect the relative distance, and the average value of the relative distance and the reduction amount of the average relative distance with respect to the stationary state are obtained, and the reduction amount and a predetermined reference value are determined. Since only the value is compared, the configuration can be simplified in terms of the circuit.

[0008]

1 is a vehicle model for explaining an embodiment of the present invention.

In FIG. 1, reference numeral 1 is a vehicle body, 2 is a wheel, and a suspension 3 is interposed between the vehicle body 1 and the wheel 2. The suspension 3 has a spring device 3a and a shock absorber 3b. The spring 4 under the wheel 2 is the wheel 2
Represents the tire part. The wheels 2 roll on the traveling path 5. A stroke sensor 6 detects a relative distance between the vehicle body 1 and the wheels 2, and gives a relative distance signal representing a relative distance between the vehicle body 1 and the wheels 2 which changes according to the unevenness of the traveling path 5. .

In the above vehicle model, the inventor of the present invention has a wheel 2 having a mass of 25 kg, a vehicle body 1 having a mass of 250 kg, a spring 4 having a spring constant of 150,000 N / m, and a suspension 3 having a spring constant of 20000 N / m. The extension side damping coefficient of the suspension 3 is 2500 N · s / m, and the contraction side damping coefficient of the suspension 3 is 1000 N · s / m.
And assuming that the road surface displacement of the traveling road 5 is a sine wave,
Road displacement ± 1.5 cm, ± 2.5 cm and ± 5.0
The frequency characteristics of the average relative distance between the vehicle body 1 and the wheels 2 and the frequency characteristics of the ground contact force variation of the wheels 2 were simulated for three conditions of cm. FIG. 2 is a simulation result of the frequency characteristic of the average relative distance between the vehicle body 1 and the wheels 2. The characteristic curve a is ± 1.5 cm for road surface displacement, and the characteristic curve b is ± 2.5 cm for road surface displacement. In the case of, the characteristic curve c represents the case where the road surface displacement is ± 5.0 cm. As is clear from FIG. 2, the average relative distance between the vehicle body 1 and the wheels 2 is in the stationary state (average relative distance =
0.0m), the attenuation starts around 0.5 Hz and reaches the maximum around 10.0 Hz. FIG. 3 is a simulation result of the frequency characteristic of the grounding force fluctuation of the wheel 2, and the characteristic curve d shows that the road surface displacement is ± 1.5 c
In the case of m, the characteristic curve e shows the case where the road surface displacement is ± 2.5 cm, and the characteristic curve f shows the case where the road surface displacement is ± 5.0 cm. As apparent from FIG. 3, the width d _w of the ground force variation of the wheel 2, e _w, f _w is increased relative to the case of the stationary state (ground force variation = 1), from around past the 0.5Hz However, it becomes the maximum around 10.0 Hz. Figure 2
As is clear from the comparison between FIG. 3 and FIG. 3, the frequency characteristic of the average relative distance between the vehicle body 1 and the wheels 2 substantially corresponds to the frequency characteristic of the ground contact force variation of the wheels 2, and therefore Knowing the decrease in the average relative distance between 1 and the wheel 2, the ground contact state of the wheel 2 can be estimated.

FIG. 4 is a block diagram showing an embodiment of the present invention. 10 is an average relative distance calculating means, and 11 is a comparing means. The average relative distance calculating means 10 inputs the relative distance signal from the stroke sensor 6 of FIG. 1 and integrates the input relative distance signal by, for example, time integration to thereby detect the vehicle body 1 and the wheels 2.
The average relative distance between and is calculated, and the decrease amount of the average relative distance with respect to the stationary state is given to the comparison means 11. Comparison means 11
Compares the reduction amount of the average relative distance with a predetermined reference value, and if the reduction amount is smaller than the reference value, it is determined that the grounding state is good,
If the amount of decrease is larger than the reference value, a grounding state determination signal for determining the grounding state as defective is given. The predetermined reference value of the comparison means 11 is experimentally determined according to the characteristics of the wheels, suspensions and the like. The grounding state determination signal provided from the comparison means 11 is used for changing the control law of suspension control.

According to the above configuration, it is only necessary to provide the stroke sensor 6 for detecting the relative distance between the vehicle body 1 and the wheels 2, and the average value of the relative distance and the average relative distance to the stationary state. Is obtained, and the amount of reduction is compared with a predetermined reference value. Therefore, the circuit can be simplified in configuration.

[0013]

As described above, according to the present invention, the amount of decrease in the average relative distance between the vehicle body and the wheels substantially corresponds to the increase in the variation range of the ground contact force of the wheels. The relative distance between the wheel and the wheel is detected, the average relative distance between the vehicle body and the wheel is calculated from this relative distance, and the reduction amount of the average relative distance with respect to the stationary state is compared with a predetermined reference value to determine the wheel Since the ground contact state is determined, it is only necessary to provide a single sensor for detecting the relative distance. Also, the average value of the relative distance and the reduction amount of the average relative distance with respect to the stationary state are obtained, and this reduction amount is calculated. And a predetermined reference value are simply compared, the configuration can be simplified in terms of circuitry, and a wheel grounding state determination method that contributes to the configuration simplification and cost reduction can be provided. .

[Brief description of drawings]

FIG. 1 is a vehicle model for explaining an embodiment of the present invention.

FIG. 2 is a diagram showing a simulation result of frequency characteristics of an average relative distance between a vehicle body and wheels.

FIG. 3 is a diagram showing a simulation result of frequency characteristics of wheel ground contact force fluctuations.

FIG. 4 is a block diagram showing an embodiment of the present invention.

[Explanation of symbols]

 1 vehicle body 2 wheels 3 suspension 5 traveling path 6 stroke sensor 10 average relative distance calculation means 11 comparison circuit

Claims (1)

[Claims] 1. A relative distance between a vehicle body and a wheel is detected,
The average relative distance between the vehicle body and the wheel is calculated from the detected relative distance, and the ground contact state of the wheel is determined by comparing the reduction amount of the average relative distance with respect to the stationary state with a predetermined reference value. State determination method.