Suspension system state observer

• US 5,434,782 A
• Filed: 05/20/1991
• Issued: 07/18/1995
• Est. Priority Date: 05/20/1991
• Status: Expired due to Fees

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Henry, Rassem R.
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): LOUIS JACQUES, JACQUES H
• Application Number:
  US07/702,875
• Time in Patent Office: 1,520 Days
• Field of Search: 364/424.05, 364/424.01, 280/707, 280/711, 280/689, 280/709, 280/84, 280/840, 280/714, 280/708, 280/6.1
• US Class Current: 701/37
• CPC Class Codes: B60G 17/0157 non-fluid unit, e.g. electric motor
• CPC Class Codes: B60G 17/0182 involving parameter estimation, e.g. observer, Kalman filter
• CPC Class Codes: B60G 2202/42 Electric actuator
• CPC Class Codes: B60G 2400/10 Acceleration; Deceleration
• CPC Class Codes: B60G 2400/104 lateral or transversal with regard to vehicle
• CPC Class Codes: B60G 2400/106 longitudinal with regard to vehicle, e.g. braking
• CPC Class Codes: B60G 2400/202 Piston speed; Relative velocity between vehicle body and wheel
• CPC Class Codes: B60G 2400/204 Vehicle speed
• CPC Class Codes: B60G 2400/206 Body oscillation speed; Body vibration frequency
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2400/41 Steering angle
• CPC Class Codes: B60G 2400/952 of door or bonnet
• CPC Class Codes: B60G 2401/172 Hall effect
• CPC Class Codes: B60G 2500/10 Damping action or damper
• CPC Class Codes: B60G 2500/30 Height or ground clearance
• CPC Class Codes: B60G 2600/02 Retarders, delaying means, dead zones, threshold values, cut-off frequency, timer interruption
• CPC Class Codes: B60G 2600/044 Alarm means
• CPC Class Codes: B60G 2600/18 Automatic control means
• CPC Class Codes: B60G 2600/90 other signal treatment means
• CPC Class Codes: B60G 2800/012 Rolling condition
• CPC Class Codes: B60G 2800/014 : Pitch; Nose dive

Abstract

A suspension system controller uses both linear and nonlinear relations to develop the suspension system state estimation. The linear components include (i) a component linearly related to the previous suspension system state estimation, (ii) a component linearly related to damping or actuator force in the suspension system, (iii) a component linearly related to error between the previously estimated relative suspension system state and measured relative system state and (iv) a component non-linearly related to error between the previously estimated relative system state, the linear and nonlinear components must all be stable, so that the estimated system state tends toward the actual system state. The controller controls the suspension system responsive to the suspension system state estimation.

Claims

1. A method for controlling a variable-force suspension system comprising the steps of:

estimating a quarter car state, the estimated quarter car state having linear and nonlinear components including;

(i) a component linearly related to a previous quarter car state estimation, (ii) a component linearly related to actuator force in the suspension system, (iii) a component linearly related to error between the previously estimated relative suspension system state and a measured relative suspension system state and (iv) a component non-linearly related to error between the previously estimated relative system state and the measured relative suspension system state, the linear and nonlinear components maintaining stability so that the estimated system state is substantially equal to the actual system state;

determining an actuator force control signal responsive to the estimated quarter car state; and

applying the actuator control signal to control the variable force suspension.

2. A quarter car suspension system controller responsive to a signal representative of a state of the quarter car suspension system, the quarter car suspension system state signal including (i) a component linearly related to a previous quarter car state estimation, (ii) a component linearly related to actuator force in the quarter car suspension system, (iii) a component linearly related to error between the previously estimated relative suspension system state and a measured relative suspension system state and (iv) a component non-linearly related to error between the previously estimated relative suspension system state and the measured relative suspension system state, the linear and nonlinear components maintaining stability so that the suspension system state signal comprises a substantially accurate estimation of the suspension system state.

3. The quarter car suspension control system of claim 2 wherein the linear relation of the component linearly related to error between the previously estimated relative suspension system state and measured relative system state consists of a Luenberger matrix.

4. The controller of claim 2 wherein the state of the suspension system comprises (i) position of a sprung mass, (ii) position of an unsprung mass, (iii) velocity of the sprung mass, and (iv) velocity of the unsprung mass.

5. The controller of claim 2 wherein the suspension system includes an electromechanical machine.

6. The controller of claim 2 wherein the non-linear relation is a modified signum function.

7. The controller of claim 2 wherein the non-linear relation is a saturation function.

8. A control system for a vehicle suspension comprising:

means for measuring a relative state of the suspension system and developing a signal representative of the relative suspension system state;

means for developing an error signal representative of error between the relative suspension system state signal and a previous estimation of the relative suspension system state;

means for developing a linear correction signal responsive to the error signal;

means for developing a nonlinear correction signal responsive to the error signal;

means for developing a signal representative of actuator force on the suspension;

means for developing an estimation of a suspension system state, responsive to a linear relation to a previous suspension system state, a linear relation to the actuator force signal, the linear correction signal, and the nonlinear correction signal;

means for developing an estimation of the relative suspension system state responsive to a linear relation to the suspension system state estimation; and

means for controlling the suspension system in response to the estimated suspension system state.