Full vehicle suspension control

• US 5,071,157 A
• Filed: 11/16/1990
• Issued: 12/10/1991
• Est. Priority Date: 11/02/1989
• Status: Expired due to Term

• Current Assignee: BWI Company Limited SA (Shougang Corporation)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Majeed, Kamal N.
• Primary Examiner(s): Marmor, Charles A.
• Assistant Examiner(s): GRAYSAY, TAMARA L
• Application Number:
  US07/614,807
• Time in Patent Office: 389 Days
• Field of Search: 280/702, 280/707, 280/714, 280/709, 280/6.12, 364/424.05
• US Class Current: 280/5.515
• CPC Class Codes: B60G 17/018 characterised by the use of a specific signal treatment or control method
• CPC Class Codes: B60G 17/08 Characteristics of fluid dampers adjusting fluid dampers in general F16F9/44 - F16F9/53
• CPC Class Codes: B60G 2202/413 Hydraulic actuator
• CPC Class Codes: B60G 2202/42 Electric actuator
• CPC Class Codes: B60G 2400/102 vertical
• CPC Class Codes: B60G 2400/106 longitudinal with regard to vehicle, e.g. braking
• 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 2400/40 Steering conditions
• CPC Class Codes: B60G 2400/60 Load
• CPC Class Codes: B60G 2400/63 Location of the center of gravity
• CPC Class Codes: B60G 2400/91 Frequency
• CPC Class Codes: B60G 2500/10 Damping action or damper
• CPC Class Codes: B60G 2600/02 Retarders, delaying means, dead zones, threshold values, cut-off frequency, timer interruption
• CPC Class Codes: B60G 2600/14 Differentiating means, i.e. differential control
• CPC Class Codes: B60G 2600/16 Integrating means, i.e. integral control
• CPC Class Codes: B60G 2600/18 Automatic control means
• CPC Class Codes: B60G 2600/60 Signal noise suppression; Electronic filtering means
• CPC Class Codes: B60G 2600/604 low pass
• CPC Class Codes: B60G 2600/70 : Computer memory; Data storage, e.g. maps for adaptive control
• CPC Class Codes: B60G 2600/76 : Digital systems
• CPC Class Codes: B60G 2800/014 : Pitch; Nose dive
• CPC Class Codes: B60G 2800/916 : Body Vibration Control
• CPC Class Codes: F16F 9/46 : allowing control from a distance , i.e. location of means for control input being remote from site of valves, e.g. on damper external wall attachment of valve units to cylinders F16F9/325

Abstract

A full vehicle suspension control derives the vertical wheel and vertical body corner velocities at each corner of the vehicle body and derives therefrom a set of at least three body state velocity variables descriptive of vertical body motions and attitude. These body state velocity variables may be the body heave, roll and pitch velocities or a plurality of the vertical body corner velocities. The suspension control computes desired forces between each body corner and its corresponding wheel from a linear combination of the vertical wheel velocity of that wheel and the body state velocity variables and derives control signals from the desired forces and, in a semi-active system, the sign of demand power. The control signals are applied to vertical force actuators connected to exert vertical forces between the vehicle body and wheel at the vehicle body corners and capable of response at frequencies sufficient to control wheel as well as body vibrations in real time.

Claims

1. A full vehicle suspension control for a wheeled vehicle having a body suspended by suspension springs at a plurality of points on unsprung, road contacting wheels, the suspension comprising, in combination:

sensing means for deriving the vertical wheel velocity and vertical body corner velocity at each point of suspension;

means for deriving from the vertical wheel and vertical body corner velocities a set of at least three body state velocity variables descriptive of vertical body motions and attitude;

an actuator connected to exert a vertical force between the body and the wheel at each point of suspension, the actuator having a frequency response sufficient to control resonant wheel vibrations;

means for deriving the desired suspension force F_i for each actuator as a linear combination of the vertical wheel velocity of the corresponding wheel and the body state velocity variables; and

means for applying an output force signal derived from each desired force F_i to the corresponding actuator.

2. The suspension control of claim 1 in which the actuators are capable of delivering active power to the suspension and the desired suspension force is derived according to the linear combination which further includes the relative body/wheel position at the corresponding wheel.

3. The suspension control of claim 1 in which the body state velocity variables are the heave, roll and pitch velocities of the body.

4. The suspension control of claim 1 in which the body state velocity variables are a plurality of the vertical body corner velocities.

5. The suspension control of claim 4 in which the vehicle body is essentially rectangular with suspension points located adjacent the four corners thereof and the body state variables are all four of the vertical body corner velocities.

6. The suspension control of claim 1 in which the actuators are dampers having a damping characteristic variable at a frequency sufficient to control resonant wheel vibrations.

7. The suspension control of claim 6 in which the frequency is at least twice the resonant wheel vibration frequency.

8. The suspension control of claim 6 in which the dampers include apparatus providing a first mode of operation characterized by a high damping force and a second mode of operation having a low damping force and including a valve capable of switching the damper between the first and second modes of operation at a frequency sufficient to control resonant wheel vibrations.

9. The suspension control of claim 8 in which the frequency is at least twice the resonant wheel vibration frequency.

10. The suspension control of claim 6 in which the actuators are dampers having a damping characteristic continuously variable over a damping range.

11. The suspension control of claim 1 in which the frequency is at least twice the resonant wheel vibration frequency.