JPH1134631A - Electronically controlled suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately control a suspension device without affected by noise components by removing the amplitude of an unpleasant frequency component as a noise, when a state where the amplitude of the unpleasant frequency component is a prescribed value or less continues for a prescribed time. SOLUTION: A value ΔVwK2 obtained by multiplying a second gain adjustment coefficient K2 of an unpleasant frequency component ΔVw2 to a noise removal means 7, which is inputted from the second gain adjustment means 6, is judged whether the absolute value is a prescribed threshold value L or more (S1). When it is less than the threshold, one of the values of a noise detection counter CNT is counted up (S2) so as to judge whether the noise detection counter CWT is a prescribed value (noise stability continuing frequency N) or more (S4). In this situation, the small-amplitude and high-frequency vibration is hardly continued for several seconds (for example two seconds) or more and it can be thought to be a noise component, and if it is a prescribed value or more, the processing is completed as ΔVwK2C=0 so that it is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically controlled suspension device for a vehicle.

[0002]

2. Description of the Related Art As a conventional electronically controlled suspension device, for example, a device as disclosed in Japanese Patent Application Laid-Open No. 7-315029 has been known. A conventional electronic control suspension device will be described with reference to the drawings. FIG. 4 is a block diagram showing a configuration of a conventional electronically controlled suspension device. In the figure, 11, 12, 13, and 14 are front, rear, left, and right wheels of the vehicle, respectively, and provided with wheel speed sensors 21, 22, 23, and 24, respectively. Signals from the respective wheel speed sensors 21, 22, 23, and 24 are input to an electronic control unit 100 (hereinafter, referred to as an ECU), and are filtered by a filter 50 to generate a sprung resonance frequency component (1-2 Hz),
An unpleasant frequency component (4 to 8 Hz) and an unsprung resonance frequency component (10 to 16 Hz) are extracted.

The ECU 100 is provided with each wheel speed sensor 2
The vehicle speed is calculated using the wheel speeds, wheel accelerations, and the like calculated from the signals from 1, 22, 23, and 24 to determine the posture deformation of the vehicle, and the vehicle speed is calculated according to the magnitude of the vehicle speed. The reference damping force of the suspension 31, 32, 33, 34 is determined in order to secure and improve the running stability of the vehicle.

Further, each of the frequency components extracted as described above is compared with at least one threshold value, and the level of the magnitude of each frequency component is detected based on the comparison result. Accordingly, the damping force that is added or subtracted from the reference damping force is determined in order to improve the ride comfort by eliminating the fluffy, lumpy, and rattling feelings of the occupant. By controlling the damping force of the shock absorbers 41, 42, 43, 44 using these reference damping force and the damping force adjusted to the reference damping force for improving ride comfort, the suspensions 31, 32, 33, Adjust the stiffness of 34.

[0005]

In the above-described conventional electronic control suspension device, a noise component may be included in a wheel speed signal from a wheel speed sensor. The frequency of this noise component is approximately the same as the unpleasant frequency component, 4 to 8.
Hz has been experimentally confirmed. As described above, when the wheel speed signal includes a noise component of 4 to 8 Hz, the conventional electronic control suspension apparatus extracts a sprung resonance frequency component, an unpleasant frequency component, and a unsprung resonance frequency component from the wheel speed signal. The level of the magnitude of each frequency component is determined, the damping force of the shock absorber is controlled in accordance with the magnitude, and the rigidity of the suspension is adjusted. According to the magnitude of the component, the damping force of the shock absorber is controlled to adjust the stiffness of the suspension, so that precise control becomes impossible and there is a problem that the ride quality is deteriorated.

It is a well-known technique to use a filter to remove a noise component. However, as described above, a filter is used because an unpleasant frequency component and a noise component required for control have almost the same frequency. In addition, not only the noise component but also a necessary unpleasant frequency component is removed, and there is a problem that precise control becomes impossible.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. Even if a noise component is included in a wheel speed signal of a wheel speed sensor, precise control is performed without being affected by the noise component. It is an object of the present invention to provide an electronically controlled suspension device capable of preventing the deterioration of ride comfort.

[0008]

According to the present invention, there is provided an electronic control suspension device for detecting a wheel speed of a vehicle, and extracting a vertical acceleration from the wheel speed detected by the wheel speed detecting device. Vertical acceleration extracting means, a sprung resonance frequency component extracting means for extracting a low frequency sprung resonance frequency component from the vertical acceleration extracted by the vertical acceleration extracting means, and a high frequency unpleasant frequency component An unpleasant frequency component extracting means that outputs zero when the state where the amplitude of the extracted unpleasant frequency component is equal to or less than a predetermined value continues for a predetermined period, and otherwise passes the extracted unpleasant frequency component Noise elimination means, and adjustment of suspension characteristics based on the output of the noise elimination means and the sprung resonance frequency component. And control means for outputting an instruction signal instructing, those having a characteristic changing means for changing the characteristics of the suspension of the vehicle based on the instruction signal from the control means.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. An embodiment of the present invention will be described. FIG. 1 is a block diagram showing one embodiment of the configuration of the electronically controlled suspension device according to the present invention. In the figure, reference numeral 1 denotes a wheel speed detecting means for detecting a wheel speed Vw based on a signal from a wheel speed sensor attached to a wheel. The wheel speed Vw detected by the wheel speed detecting means 1 is input to the vertical acceleration extracting means 2. The vertical acceleration extracting means 2 is composed of a band-pass filter, and its passing frequency is, for example, 0.4 to 8 Hz. The wheel speed Vw includes a sprung resonance frequency component (for example, 1 to 2 Hz) that makes the occupant feel fluffy and an unpleasant frequency component (for example, 4 to 8 Hz) that makes the occupant feel fluffy. The vertical acceleration ΔVw is extracted.

Reference numeral 3 denotes a sprung resonance frequency component extracting means comprising a low-pass filter that passes a frequency component of, for example, 3.8 Hz or less, and extracts a sprung resonance frequency component ΔVw1. The sprung resonance frequency component ΔVw1 is input to the first gain adjustment means 4 and multiplied by the first gain adjustment coefficient K1 to become ΔVwK1. Numeral 5 denotes an unpleasant frequency component extracting means comprising a high-pass filter, which extracts the unpleasant frequency component ΔVw2 and inputs it to the second gain adjusting means 6. The second gain adjusting means 6 multiplies the unpleasant frequency component ΔVw2 by the second gain adjusting coefficient K2 and inputs the result to the noise removing means 7 as ΔVwK2.

The noise removing means 7 removes a noise component according to the flowchart shown in FIG. ΔVwK2 is supplied to the noise removing unit 7 input from the second gain adjusting unit 6.
First, in step S1, it is determined whether or not the absolute value is equal to or greater than a predetermined threshold L. If it is less than the threshold value, the process proceeds to step S2, and the noise determination counter CN
T is incremented by one and the process proceeds to step S4. In step S4, it is determined whether or not the noise determination counter CNT is greater than or equal to a predetermined value (the number N of noise determination continuations). If it is greater than or equal to the predetermined value, the process proceeds to step S5, where ΔVwK2C = 0.
And the process ends. On the other hand, if the noise determination counter CNT is equal to or smaller than the predetermined value in step S4, the process proceeds to step S6
Then, the process is terminated assuming that ΔVwK2C = ΔVwK2.

If the absolute value of .DELTA.VwK2 is equal to or larger than the predetermined threshold value L in step S1, the process proceeds to step S3, where the noise determination counter CNT is reset. In step S6, the process ends with .DELTA.VwK2C = .DELTA.VwK2. I do.

In the flow chart of FIG. 2 described above, it is determined that a minute vibration smaller than a predetermined threshold has continued for a predetermined time or more. The reason why the noise component can be removed by making such a determination will be described. It has been experimentally confirmed that the above-mentioned noise component has a smaller amplitude than the actual discomfort frequency component. Also, considering the state in which the vehicle is traveling on the road, it is almost impossible for vibrations having a small amplitude and a high frequency to continue for several seconds (for example, two seconds) or more, and can be considered to be noise components. . That is, by the operation of the flowchart shown in FIG. 2 described above, it is possible to detect a vibration having a small amplitude and continuing for a predetermined time or more. By determining this vibration as a noise component and removing it (ΔVwK2C = 0), the noise component can be removed from the input signal.

Next, a more detailed description will be given with reference to the waveform diagram shown in FIG. FIG. 3A shows a sprung resonance frequency component obtained by passing a signal Vw from the wheel speed detecting means 1 through a vertical acceleration extracting means 2 comprising a band-pass filter, which gives the occupant a fluffy feeling. Vertical acceleration ΔVw including an unpleasant frequency component that gives a sense of sensation
It is. This ΔVw is used as the sprung resonance frequency component extraction means 3
And input to the unpleasant frequency component extracting means 5. In the sprung resonance frequency component extracting means 3, only a low frequency component is passed by a low-pass filter, and only a low frequency component (a sprung resonance frequency component that makes a passenger feel fluffy) as shown in FIG. 3B is extracted. . The first gain adjusting means multiplies the extracted sprung resonance frequency component by a first gain adjustment coefficient K1 to generate a signal (ΔVw) as shown in FIG.
K1) is obtained.

On the other hand, only the high-frequency component of the unpleasant frequency component 5 is passed by a high-pass filter, and a high-frequency unpleasant frequency component ΔVw2 as shown in FIG. 3D is extracted.
A second gain adjustment coefficient K is added to the extracted uncomfortable frequency component.
2 and a signal (ΔVwK) as shown in FIG.
2) and input to the noise removing means 7. The noise removing means 7 performs the processing according to the flowchart shown in FIG. 2 described above, and the signal (ΔVwK2
C) is output. That is, the unpleasant frequency component ΔVwK2C after the removal of the noise component is not determined to be a noise component until the time β, as shown in FIG. At the time β when the count-up reaches a predetermined value, it is determined that the signal is a noise component, and thereafter, the input signal Δ
The amplitude 0 is output regardless of VwK2. If the noise determination threshold value L is exceeded at time γ, it is determined that the noise component is not a noise component, and the input signal ΔVwK2 is output as it is.

The sprung resonance frequency component ΔVwK1 obtained as described above and the unpleasant frequency component Δ
By adding VwK2C by the adding means 8, it is possible to obtain the vertical acceleration VwG which is not affected by the noise component as shown in FIG. This VwG is input to the power spectrum amount extracting means 9 and is subjected to Fourier transform in the power spectrum amount extracting means 9 to be decomposed into a frequency spectrum, and a fluffy degree FF corresponding to a sprung resonance frequency component.
T1 and lumpy degree FFT corresponding to unpleasant frequency components
3 is calculated. The suspension characteristic determining means 10 determines the characteristic of the suspension (not shown) based on the fluffy degree FFT1 and the lumpy degree FFT3,
By controlling the damping force of a shock absorber (not shown),
Adjust suspension stiffness.

According to the embodiment of the present invention described above, even if an input signal contains a noise component having a frequency substantially equal to that of a signal necessary for control, the noise component of the noise component experimentally confirmed is included. Utilizing the characteristics, the required signal and noise component are separated, the noise component is removed, and control is performed based on the signal after this removal, so precise control is possible and the adjustment of suspension rigidity is optimized. This can prevent the deterioration of the riding comfort due to the noise component.

In the above embodiment, the operation shown in the flowchart of FIG. 2 is desirably executed every main program cycle of suspension control, for example, every 10 msec. In addition, since the time required for noise determination is determined by the operation execution cycle and the noise determination continuation number N, in the above-described embodiment, for example, the operation execution cycle is set every 10 msec, and the noise determination continuation number is set to 200 times. The time required for noise determination is 2 seconds
c. Since the characteristics of the noise component change depending on the state of attachment of the wheel speed sensor to the vehicle, etc., the characteristics are confirmed experimentally, and the time required for the noise determination is adjusted according to the characteristics. It can play more effectively.

In the above embodiment, the sprung resonance frequency component ΔVwK1 and the unpleasant frequency component Δ
VwK2C is added by the adding means 8, and the addition result VwG
Is Fourier-transformed to adjust the stiffness of the suspension. However, the stiffness of the suspension may be adjusted by separately analyzing the sprung resonance frequency component ΔVwK1 and the uncomfortable frequency component ΔVwK2C after noise removal. Needless to say.

[0020]

The electronic control suspension apparatus according to the present invention described above detects wheel speeds of a vehicle, and extracts vertical acceleration from the wheel speeds detected by the wheel speed detecting means. Vertical acceleration extraction means, sprung resonance frequency component extraction means for extracting low sprung resonance frequency components from the vertical acceleration extracted by the vertical acceleration extraction means, and high frequency unpleasant frequency components An unpleasant frequency component extracting means, which outputs zero when a state in which the amplitude of the extracted unpleasant frequency component is equal to or less than a predetermined value continues for a predetermined period, and otherwise outputs noise that passes the extracted unpleasant frequency component Removing means, and adjusting suspension characteristics based on the output of the noise removing means and the sprung resonance frequency component. A control means for outputting an instruction signal for instructing; and a characteristic changing means for changing characteristics of a vehicle suspension based on the instruction signal from the control means. Even when noise components of the same frequency are included, the noise component is removed by separating the required signal from the noise component by using the characteristics of the noise component experimentally confirmed, and based on the signal after the removal. Therefore, precise control is possible, suspension rigidity can be adjusted optimally, and deterioration of ride comfort due to noise components can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an electronically controlled suspension according to the present invention.

FIG. 2 is a flowchart showing an embodiment of an electronically controlled suspension according to the present invention.

FIG. 3 is a waveform diagram showing an embodiment of an electronic control suspension according to the present invention.

FIG. 4 is a block diagram showing a configuration of a conventional electronic control suspension.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 wheel speed detecting means 2 vertical acceleration extracting means 3 sprung resonance frequency component extracting means 5 unpleasant frequency component extracting means 7 noise removing means 8 adding means 9 power spectrum amount extracting means 10 suspension characteristic determining means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuki Ishiguro 5-33-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation (72) Inventor Noriko Hayase 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Automotive Industry Co., Ltd.

Claims (1)

[Claims] 1. A wheel speed detecting means for detecting a wheel speed of a vehicle, a vertical acceleration extracting means for extracting a vertical acceleration from the wheel speed detected by the wheel speed detecting means, and a vertical acceleration extracting means. A sprung resonance frequency component extracting means for extracting a low sprung resonance frequency component from the vertical acceleration extracted by the above, an unpleasant frequency component extracting means for extracting a high frequency unpleasant frequency component, and the extracted unpleasant frequency A noise removing unit that outputs zero when the state in which the amplitude of the component is equal to or less than the predetermined value continues for a predetermined period, and otherwise passes the extracted uncomfortable frequency component; and an output of the noise removing unit and the spring. Control means for outputting an instruction signal for instructing adjustment of suspension characteristics based on the upper resonance frequency component; An electronically controlled suspension device, comprising: a characteristic changing unit that changes a characteristic of a vehicle suspension based on the characteristic.