Boundary self-adaptation scheme for proportional poppet valve pressure control

• US 6,692,088 B1
• Filed: 09/26/2001
• Issued: 02/17/2004
• Est. Priority Date: 07/31/2001
• Status: Expired due to Term

• Current Assignee: Kelsey-Hayes Co. (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: Kelsey-Hayes Co. (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Zheng, Yuhong
• Primary Examiner(s): Schwartz, Christopher P.
• Assistant Examiner(s): TORRES WILLIAMS, MELANIE
• Application Number:
  US09/965,103
• Time in Patent Office: 874 Days
• Field of Search: 303/113.1, 303/113.4, 303/113.3, 303/115.2, 303/114.1, 303/155, 303/166, 303/157, 303/158, 303/84.1, 303/84.2, 303/119.1, 701/70, 701/71
• US Class Current: 303/113.1
• CPC Class Codes: B60T 8/326 Hydraulic systems
• CPC Class Codes: B60T 8/36 including a pilot valve responding to an electromagnetic force
• CPC Class Codes: B60T 8/3655 Continuously controlled electromagnetic valves

Abstract

A method of boundary self-adaptation for proportional poppet valve pressure control comprises implementing an estimator to estimate a boundary deviation of the valve. Then, a pressure command signal is detected. Next, a pressure command derivative over time is obtained. Then, determining which closing boundary should be updated is decided based on the sign of the pressure command derivative. Next, a pressure error is obtained by subtracting an actual wheel brake pressure from its pressure command. Then a modified pressure error is calculated. Next, a pressure command signal is evaluated to determine whether a braking maneuver is gentle. Next, the modified pressure error is implemented in the estimation. Finally, a boundary table is updated using the resultant boundary deviation estimate.

Claims

1. A method for adapting a closing boundary for a proportional poppet valve comprising:

(a) detecting a pressure command signal;

(b) obtaining a pressure command derivative over time;

(c) using the sign of the pressure command derivative over time to determine which closing boundary should be updated;

(d) obtaining a pressure error by subtracting an actual wheel brake pressure from its pressure command;

(e) calculating a modified pressure error;

(f) implementing the modified pressure error in the estimation;

(g) implementing an estimator to estimate a boundary deviation of the valve; and

(h) updating a boundary table using the resultant boundary deviation estimate.

2. The method defined in claim 1 wherein a gain scheduler is used for the estimator.

3. The method defined in claim 2 wherein the modified pressure error for a first valve has alternating signs that result from an over-compensated deadband and wherein the modified pressure errors with alternating signs give a negative boundary deviation estimate.

4. The method defined in claim 3 wherein the modified pressure error for a second valve has alternating signs that result from an over-compensated deadband and wherein the modified pressure errors with alternating signs give a positive boundary deviation estimate.

5. The method defined in claim 1 wherein the estimators are updated only during gentle braking maneuvers.

6. The method defined in claim 5 wherein gentle braking is braking where the absolute value of the pressure command derivative over time is less than a pre-specified value that further is less than the maximum allowable rate of change for wheel brake pressure for the valve.

7. The method defined in claim 6 wherein the pre-specified value is fixed across an entire operating pressure range for a braking system.

8. The method defined in claim 6 wherein the pre-specified value varies with pressure conditions.

9. The method defined in claim 8 wherein the pressure conditions comprise wheel brake pressure and pressure differential across the valve.

10. The method defined in claim 1 wherein a feedforward mismatch and a control deadzone are excluded from the pressure error.

11. The method defined in claim 1 wherein a first and second estimator are used to estimate boundary deviations of a first and second valve at each channel.

12. The method defined in claim 11 wherein the sign of the pressure command derivative over time is used to determine whether a first or second estimator is updated.