Automatic curve sensor calibration method for an automotive CW/ICC system

• US 6,202,027 B1
• Filed: 06/10/1999
• Issued: 03/13/2001
• Est. Priority Date: 08/27/1997
• Status: Expired due to Term

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Alland, Stephen William, Searcy, James Fredrick
• Primary Examiner(s): NGUYEN, TAN QUANG
• Application Number:
  US09/329,643
• Time in Patent Office: 642 Days
• Field of Search: 701/301, 701/93, 701/96, 701/41, 340/435, 340/903, 367/99, 367/103, 367/98
• US Class Current: 701/301
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 15/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S15/46
• CPC Class Codes: G01S 15/931 of land vehicles
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 2013/932 using own vehicle data, e.g. ground speed, steering wheel direction
• CPC Class Codes: G01S 2013/9321 Velocity regulation, e.g. cruise control
• CPC Class Codes: G01S 2013/93271 in the front of the vehicles
• CPC Class Codes: G01S 7/4004 of parts of a radar system
• CPC Class Codes: G01S 7/4026 Antenna boresight
• CPC Class Codes: G01S 7/403 in azimuth, i.e. in the horizontal plane
• CPC Class Codes: G01S 7/4091 during normal radar operation
• CPC Class Codes: G01S 7/4972 Alignment of sensor
• CPC Class Codes: G01S 7/52004 Means for monitoring or calibrating short-range imaging G01S7/5205

Abstract

An improved system for accurately determining the travel path of a host vehicle and the azimuth angle of a target vehicle through an automatic calibration that detects and compensates for FLS mis-alignment and curve sensor drift. Selected FLS tracking data (range and azimuth angle) are transformed to cartesian coordinates and characterized by a second order curve fitting technique to determine both FLS misalignment and curve sensor bias. Successively determined FLS misalignment and curve sensor bias values are averaged and used to correct subsequently supplied azimuth angle and curve sensor data, thereby compensating an underlying control for both sensor misalignment and curve sensor bias.

Claims

1. A bias calibration method for a host vehicle system that predicts a travel path of the host vehicle based on vehicle velocity and curve data obtained from a curve sensor subject to bias, the host vehicle including a forward looking sensor that measures range and azimuth angle data of a target forward of the host vehicle, the method comprising the steps of:

receiving a set of range and azimuth angle data for each of a plurality of successive segments of travel of the host vehicle, and for each received set of range and azimuth angle data;

computing a lateral distance between the host vehicle and the target based on such range and azimuth angle data and said predicted travel path; and

determining a location point of the target in terms of its measured range and the computed lateral distance;

processing the determined location points to characterize the calculated lateral distance as a second order function of the measured range, such second order function having a second order coefficient related to a bias of said curve sensor;

determining the bias of said curve sensor from said second order coefficient; and

adjusting the curve data obtained from said curve sensor based on the determined bias of said curve sensor.

2. The bias calibration method of claim 1, wherein the second order function has a first order coefficient related to a misalignment of said forward looking sensor with respect to the travel path of said host vehicle.

3. The bias calibration method of claim 2, including the steps of:

determining the misalignment of said forward looking sensor from said first order coefficient; and

adjusting the azimuth angle provided by said forward looking sensor based on the determined misalignment of said forward looking sensor.

4. The bias calibration method of claim 1, wherein the step of determining a location point of the target includes the steps of:

transforming said measured range computed lateral distance to cartesian coordinates.

5. The bias calibration method of claim 1, wherein the step of processing the determined location points includes performing a least squares curve fit procedure.

6. The bias calibration method of claim 1, including the steps of:

determining curve sensor biases for a plurality of different sets of range and azimuth angle data; and

adjusting the curve data obtained from said curve sensor based on an average of the determined curve sensor biases.