Apparatus for determining steer angle of a motor vehicle

• US 6,498,971 B2
• Filed: 03/13/2001
• Issued: 12/24/2002
• Est. Priority Date: 03/13/2001
• Status: Expired due to Fees

• Current Assignee: BWI Company Limited SA (Shougang Corporation)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Leaphart, Eldon Gerrald
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Donnelly, Arthur D.
• Application Number:
  US09/805,487
• Publication Number:
  US 20020133278A1
• Time in Patent Office: 651 Days
• Field of Search: 701/41, 701/42, 701/48, 701/72, 180/142, 180/148, 180/141, 340/73, 340/56, 340/55
• US Class Current: 701/41
• CPC Class Codes: B60G 2400/0523 Yaw rate
• CPC Class Codes: B60G 2400/104 lateral or transversal with regard to vehicle
• CPC Class Codes: B60G 2400/208 of wheel rotation
• CPC Class Codes: B60G 2400/412 of steering wheel or column
• CPC Class Codes: B60G 2400/4122 Neutral position detection
• CPC Class Codes: B60G 2401/26 Resistance type, e.g. as level indicator
• CPC Class Codes: B60G 2800/22 Braking, stopping
• CPC Class Codes: B60G 2800/24 Steering, cornering
• CPC Class Codes: B60G 2800/7022 Calibration of a sensor, e.g. automatically
• CPC Class Codes: B60G 2800/91 Suspension Control
• CPC Class Codes: B60G 2800/922 EBV - Electronic brake force distribution
• CPC Class Codes: B60G 2800/94 Electronic Stability Program (ESP, i.e. ABS+ASC+EMS)
• CPC Class Codes: B62D 15/02 Steering position indicators ; Steering position determination; Steering aids

Abstract

A steering angle sensor providing an output signal indicating relative position within a full rotation, such as a relative dual track steering sensor, provides a signal to a digital processor coupled to a non-volatile memory for storing retained values of a centered vehicle steer angle, a rotation count and a mounting bias angle. The processor derives three test steer angle values utilizing, respectively, (1) the retained rotation count, (2) one greater than the retained rotation count and (3) one less than the retained rotation count and chooses as an initialized steer angle one of the three test steer angles that differs from the retained value of a centered vehicle steer angle by less than a first calibration value. If such an initialized steer angle is found, the processor verifies that the initialized steer angle differs from an estimated steer angle derived in response to signals from the vehicle yaw rate sensor and lateral acceleration sensor by less than a second calibration value less than the first calibration value and, if so, accepts the verified initialized steer angle as the centered vehicle steer angle. If not, the processor preferably reverts to a full recalibration without use of the retained values in the non-volatile memory. Preferably, the first calibrated value is 180 rotational degrees, so that the initialized steering angle value may be assumed to be within the same rotation as the centered angle.

Claims

1. Apparatus for generating a centered vehicle steer angle sensor signal comprising, in combination:

a vehicle steer angle sensor uniquely responsive to absolute rotational position over a full rotation of a steering shaft to generate a steer angle signal;

a vehicle yaw rate sensor;

a vehicle lateral acceleration sensor;

a non-volatile memory for storing retained values of a centered vehicle steer angle, a rotation count and a mounting bias angle;

digital processing means responsive to an activating signal to perform the following steps;

(a) deriving three test steer angle values as the sum of the retained value of a mounting bias angle, a value derived from the steer angle signal and a rotation angle derived from, respectively for the three test steer angle values, (1) the retained rotation count, (2) one greater than the retained rotation count and (3) one less than the retained rotation count;

(b) choosing as an initialized steer angle one of the three test steer angles that differs from the retained value of a centered vehicle steer angle by less than a first calibration value;

(c) verifying that the initialized steer angle chosen in step (b) differs from an estimated steer angle derived in response to signals from the vehicle yaw rate sensor and lateral acceleration sensor in a first process by less than a second calibration value less than the first calibration value and, if so, accepting the verified initialized steer angle as the centered vehicle steer angle.

2. The apparatus of claim 1 wherein the first calibration value is 180 rotational degrees.

3. The apparatus of claim 2 wherein the second calibration value is greater than 30 degrees.

4. The apparatus of claim 1 wherein the digital processing means alternatively, if no verified initialized steer angle is identified in steps (a) through (c), generates the centered vehicle steer angle by recalibrating the vehicle steer angle sensor responsive to the sensed vehicle yaw rate and lateral acceleration without regard to the retained values of a centered vehicle steer angle, a rotation count or a mounting bias angle in the non-volatile memory.

5. The apparatus of claim 4 wherein the first calibration value is 180 rotational degrees.