Steering angle determaination method and apparatus

• US 5,948,030 A
• Filed: 07/25/1997
• Issued: 09/07/1999
• Est. Priority Date: 07/25/1997
• Status: Expired due to Fees

• Current Assignee: Pacific Century Motors, Inc. (Aviation Industry Corporation of China, Ltd.), GM Global Technology Operations Incorporated (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Miller, Randy Scott, Murphy, Paul Ashby
• Primary Examiner(s): Zanelli, Michael J.
• Application Number:
  US08/900,671
• Time in Patent Office: 774 Days
• Field of Search: 701/41, 180/443, 702/104, 702/105, 702/87, 702/151
• US Class Current: 701/41
• CPC Class Codes: B62D 15/02 Steering position indicators ; Steering position determination; Steering aids

Abstract

In a vehicle with a hand wheel, steerable wheels positionally responsive to the hand wheel and a steering position sensor coupled to the handwheel and providing a handwheel angle signal indicative of an angular position of the handwheel, a steering angle determination method comprising the steps of: first filtering the handwheel angle signal to provide a first filter output; defining a comparison window around the first filter output; comparing the handwheel angle signal to the comparison window; when the handwheel angle signal is within the comparison window, second filtering the handwheel angle signal to provide a second filter output; when the handwheel angle signal is not within the comparison window, maintaining the second filter output fixed; and determining a steer angle signal as the difference between the handwheel angle signal and the second filter output, wherein offsets between the handwheel angle signal and steered positions of the steerable wheels are compensated for.

Claims

1. In a vehicle with a hand wheel, steerable wheels positionally responsive to the hand wheel and a steering position sensor coupled to the handwheel and providing a handwheel angle signal indicative of an angular position of the handwheel, a steering angle determination method comprising the steps of:

first filtering the handwheel angle signal to provide a first filter output;

defining a comparison window around the first filter output;

comparing the handwheel angle signal to the comparison window;

when the handwheel angle signal is within the comparison window, second filtering the handwheel angle signal to provide a second filter output;

when the handwheel angle signal is not within the comparison window, maintaining the second filter output fixed; and

determining a steer angle signal as a difference between the handwheel angle signal and the second filter output, wherein offsets between the handwheel angle signal and steered positions of the steerable wheels are compensated for.

2. A steering angle determination method according to claim 1, wherein the first and second filtering are done only when measured vehicle speed is above a threshold value.

3. In a vehicle with a hand wheel, steerable wheels positionally responsive to the hand wheel and a steering position sensor coupled to the handwheel and providing a handwheel angle signal indicative of an angular position of the handwheel, a steering angle determination apparatus comprising:

a first filter having a first input and a first output, wherein the first input receives the handwheel angle signal from the steering position sensor and the first output provides a first filtered signal;

a window comparator having a center input, a data input and a comparison output, wherein the first filtered signal is coupled to the center input and the handwheel angle signal is coupled to the data input, wherein the window comparator defines a window around the first filtered signal at the center input and provides a positive comparison signal at the comparison output when the handwheel angle signal at the data input is within the window;

a second filter having a second input and a second output, wherein the second input receives the handwheel angle signal and the second output provides a second filtered signal that (a) is updated in response to the handwheel angle signal when the comparison output provides the positive comparison signal and (b) remains substantially fixed when the comparison output does not provide the positive comparison signal, wherein the second filtered signal represents an offset between the handwheel angle signal and a steered position of the steerable wheels.

4. A steering angle determination apparatus according to claim 3, wherein the first and second filters are active only when the vehicle speed is above a minimum threshold value.

5. A steering angle determination apparatus according to claim 3, wherein the first and second filters each have time constants of at least fifteen minutes.