SUSPENSION CONTROL SYSTEM

• US 20150290995A1
• Filed: 06/20/2013
• Published: 10/15/2015
• Est. Priority Date: 06/29/2012
• Status: Active Grant

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Inventors: Kanda, Ryoma, Izawa, Masaki
• Granted Patent: US 10,703,162 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60G 17/016 characterised by their responsiveness, when the vehicle is travelling, to specific motion, a specific condition, or driver input B60G17/017 takes precedence
• CPC Class Codes: B60G 17/0161 mainly during straight-line motion B60G17/0164 takes precedence
• CPC Class Codes: B60G 17/0182 involving parameter estimation, e.g. observer, Kalman filter
• CPC Class Codes: B60G 2400/202 Piston speed; Relative velocity between vehicle body and wheel
• CPC Class Codes: B60G 2400/206 Body oscillation speed; Body vibration frequency
• CPC Class Codes: B60G 2400/208 of wheel rotation
• CPC Class Codes: B60G 2500/106 duty rate
• CPC Class Codes: B60G 2600/82 duty rate function
• CPC Class Codes: B60G 2800/162 Reducing road induced vibrations
• CPC Class Codes: B60G 2800/70 Estimating or calculating vehicle parameters or state variables
• CPC Class Codes: B60G 2800/916 Body Vibration Control

Abstract

A suspension control system allows a state variable of a vehicle used for the damper damping force control to be computed at a high precision without regards to the caster angle given to the suspension geometry. A suspension control system for a vehicle provided with a variable damper that can adjust a damping force according to an input signal comprises a wheel rotational speed sensor for detecting a wheel rotational speed, a gain circuit for computing the unsprung load of each wheel according to the wheel rotational speed variation detected by the wheel speed sensor, a single wheel model computing unit for computing the sprung velocity and the stroke speed by inputting the unsprung load to a single wheel model representing the behavior of the vehicle, and a damper control unit for controlling a damping force of the variable damper according to the computed sprung velocity and stroke speed.

Claims

1. A suspension control system for a vehicle provided with a variable damper that can adjust a damping force according to an input signal, comprising:

a wheel rotational speed sensor for detecting a wheel rotational speed;

a base input value computing means for computing a base input value of the vehicle according to a wheel rotational speed variation detected by the wheel speed sensor;

a state variable computing means for computing a state variable of the vehicle from a vehicle model representing a behavior of the vehicle and receiving an input of the base input value; and

a damper control means for controlling a damping force of the variable damper according to the computed state variable.

2. The suspension control system according to claim 1, wherein the base input value includes an unsprung load.

3. The suspension control system according to claim 1, wherein the state variable includes a sprung velocity.

4. The suspension control system according to claim 3, wherein the state variable further includes a suspension stroke speed.

5. The suspension control system according to claim 1, further comprising a first filter for the wheel rotational speed sensor for a first frequency region corresponding to a vibration of a sprung mass, and a second filter for the wheel speed sensor for a second frequency range higher than the first frequency range,

wherein the damper control means includes a sprung damping control means for controlling the damping force of the variable damper according to the wheel speed variation filtered by the first filter, and an unsprung damping control means for controlling the damping force of the variable damper according to the wheel speed variation filtered by the second filter.

6. The suspension control system according to claim 1, further comprising a vehicle body speed estimating means for estimating a vehicle body speed according to a vehicle body acceleration of the vehicle, and a wheel rotational speed correcting means for computing a corrected wheel rotational speed by subtracting an estimated wheel rotational speed estimated from the vehicle body speed from a detected value of the wheel rotational speed sensor,

wherein the base input value computing means is configured to compute the base input value of the vehicle according to a wheel speed variation of the corrected wheel rotational speed.

7. The suspension control system according to claim 6, wherein the vehicle body speed estimating means estimates the vehicle body acceleration of the vehicle according to a drive/brake force of the vehicle and an inclination of a road surface (or a deceleration Fs due to a road inclination).

8. The suspension control system according to claim 7, wherein the vehicle body speed estimating means estimates a traveling resistance of the vehicle according to the detected wheel rotational speed, and estimates the vehicle body acceleration of the vehicle by taking into account the estimated traveling resistance.

9. The suspension control system according to claim 6, further comprising a filter for a frequency range corresponding to a vibration of the sprung mass, the filter filtering the detected value of the wheel rotational speed sensor so as to remove variation in the vehicle body acceleration in the frequency range corresponding to a vibration of the sprung mass.

10. The suspension control system according to claim 1, further comprising a cornering state variable computing means for computing a cornering state variable and a wheel rotational speed correcting means for correcting a detected value of the wheel rotational speed sensor according to the computed cornering state variable,

wherein the base input value computing means computes the base input value of the vehicle according to the wheel speed variation of the corrected wheel rotational speed.

11. The suspension control system according to claim 1, further comprising

a wheel speed variation extracting means for extracting a wheel speed variation of a frequency range corresponding to a sprung vibration of the vehicle according to the detected wheel rotational speed,

a sprung velocity computing means for computing the sprung velocity by using a vehicle model according to the wheel speed variation extracted by the wheel speed variation extracting means,

a stroke speed computing means for computing a suspension stroke speed by using a vehicle model according to the wheel speed variation extracted by the wheel speed variation extracting means, and

a skyhook control means for controlling the damping force of the variable damper according to the computed sprung velocity and the computed stroke speed.

12. The suspension control system according to claim 1, wherein

the wheel rotational speed sensor is provided on a front wheel, and the base input value computing means computes the base input value with respect to the front wheel,

the state variable computing means including a front wheel state variable computing means for computing a state variable of the vehicle associated with the front wheel, and a rear wheel state variable computing means for computing a state variable of the vehicle associated with a rear wheel according to the state variable computed by the front wheel state variable computing means.

13. The suspension control system according to claim 12, wherein the base input value computing means computes a base input value including an unsprung load associated with the front wheel, and the front wheel state variable computing means computes a state variable including an unsprung position associated with the front wheel,

the rear wheel state variable computing means being configured to compute a road surface vertical position associated with the front wheel according to the unsprung load associated with the front wheel and the unsprung position associated with the front wheel, and compute the state variable of the vehicle associated with a rear wheel according to the computed road surface vertical position associated with the front wheel.

14. The suspension control system according to claim 13, wherein the rear wheel state variable computing means is configured to compute a road surface vertical position associated with the rear wheel by applying a time delay corresponding to a vehicle speed to the road surface vertical position associated with the front wheel, and compute the state variable of the vehicle associated with the rear wheel according to the road surface vertical position of the vehicle associated with the rear wheel.

15. The suspension control system according to claim 14, wherein the rear wheel state variable computing means is configured to compute state variables including the sprung velocity and the suspension stroke speed associated with the rear wheel.