Semi-active suspension control system

• US 5,550,739 A
• Filed: 03/09/1995
• Issued: 08/27/1996
• Est. Priority Date: 11/13/1990
• Status: Expired due to Term

• Current Assignee: Alfred Teves GmbH (ITT Automotive GmbH)
• Original Assignee: Alfred Teves GmbH (ITT Automotive GmbH)
• Inventors: Hoffmann, Michael, Eckert, Alfred
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Garbowski, Leigh Marie
• Application Number:
  US08/401,337
• Time in Patent Office: 537 Days
• Field of Search: 364/424.05, 364/508, 364/572, 280/707
• US Class Current: 701/37
• CPC Class Codes: B60G 17/018 characterised by the use of a specific signal treatment or control method
• CPC Class Codes: B60G 2400/102 vertical
• CPC Class Codes: B60G 2400/206 Body oscillation speed; Body vibration frequency
• CPC Class Codes: B60G 2400/60 Load
• CPC Class Codes: B60G 2600/184 Semi-Active control means
• CPC Class Codes: B60G 2600/60 Signal noise suppression; Electronic filtering means
• CPC Class Codes: B60G 2600/76 Digital systems
• CPC Class Codes: B60G 2600/90 other signal treatment means

Abstract

A semi-active suspension control system comprises exclusively chassis acceleration sensors (S₁ to S₃) as sensors (1) for obtaining the information for the damping force control. The output signals of these sensors are analyzed in a filter (3), the transmission behavior of which is in linear approximation to the transmission behavior of a discrete Kalman filter, when concentrating on the frequency range between the natural chassis frequency and the natural wheel frequency.

Claims

1. A semi-active suspension control system for automotive vehicles, said system comprising:

a plurality of chassis acceleration sensors for developing chassis acceleration signals representative of acceleration of an automotive vehicle chassis;

a plurality of vibration dampers for controlling vibration of said automotive vehicle chassis;

and electronic circuit means responsive only to said chassis acceleration signals for generating damper-actuating signals to actuate said vibration dampers, said electronic circuit means having;

(a) a filter which;

(i) produces output signals representative of the speed of said vibration dampers, and

(ii) has a transmission characteristic which concentrates on a discrete frequency range having a lower limit approximately 0.1-fold to 0.5-fold of the natural vehicle chassis frequency and an upper limit approximately 1.2-fold to 2-fold of the natural vehicle wheel frequency, and

(b) circuitry for assessing said output signals of said filter to develop said damper-actuating signals.

2. A suspension control system according to claim 1 wherein said transmission characteristic of said filter is concentrated in a range between 0.2 and 20 hertz.

3. A suspension control system according to claim 2 wherein said transmission characteristic of said filter is concentrated in a range between 0.5 and 16 hertz.

4. A suspension control system according to claim 3 wherein said transmission characteristic of said filter is set by calculating a Kalman filter for 1/4 vehicle model and by adapting said Kalman filter for 1/4 vehicle model to a predetermined road pattern.

5. A suspension control system according to claim 3 wherein said transmission characteristic of said filter is set by calculating a Kalman filter for 1/4 vehicle model and by adapting said Kalman filter for 1/4 vehicle model to a predetermined disturbance pattern.

6. A suspension control system according to claim 1 wherein said filter has a continuous transmission function H(s) defined by:

##EQU4## with T_D ≡

M_b /c_F T₁ =(any number 2 through

     5)×

(1/2)×

π

×

f_A

T₂ =(any number 0.5 through 0.8)×

(1/2)×

π

×

f_R

where;

M_b =mass of the vehicle chassis

c_F =spring rate of the wheel suspension

s=Laplace operator

f_A =natural chassis frequency

f_R =natural wheel frequency.

7. A suspension control system according to claim 1 wherein said chassis acceleration sensors are positioned on at least three corners of said automotive vehicle.

8. A suspension control system according to claim 7 wherein said chassis acceleration sensors are positioned at three corners of said automotive vehicle and chassis acceleration at a fourth corner of said vehicle is calculated from said chassis acceleration signals representative of chassis acceleration at said three corners of said automotive vehicle.

9. A suspension control system according to claim 1 wherein said transmission characteristic of said filter is in linear approximation with a transmission characteristic of a filter which covers the entire frequency spectrum.

10. A suspension control system according to claim 9 wherein said filter which covers the entire frequency spectrum is a Kalman filter.