Method and device for automatic calibration of an odometer

• US 6,029,496 A
• Filed: 03/16/1999
• Issued: 02/29/2000
• Est. Priority Date: 09/16/1996
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Kreft, Peter
• Primary Examiner(s): RAEVIS, ROBERT R
• Application Number:
  US09/269,142
• Time in Patent Office: 350 Days
• Field of Search: 702/96, 73/1.37, 73/1.41
• US Class Current: 73/1.37
• CPC Class Codes: G01C 21/28 with correlation of data from several navigational instruments
• CPC Class Codes: G01C 22/02 by conversion into electric waveforms and subsequent integration, e.g. using tachometer generator G01C22/002, G01C22/004, G01C22/006 take precedence
• CPC Class Codes: G01C 25/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass testing, calibrating or compensating compasses G01C17/38

Abstract

A location system for a motor vehicle in which the calibration of a displacement sensor is performed with the aid of satellite signals. A Global Positioning System (GPS) receiver may be used, and the current vehicle speed within a time segment is calculated using the Doppler method. The distance traveled is ascertained from the vehicle speed. By taking a mean, calculating the dispersion, and performing a weighting, a very accurate reference value for calibration of the displacement sensor is achieved.

Claims

1. A method for automatically calibrating a displacement sensor of a vehicle, comprising the steps of:

counting signals from the displacement sensor for a sequence of respective time periods, the signals from the displacement sensor representing a distance traveled;

continuously ascertaining speeds of the vehicle via reception of broadcast signals and via the Doppler effect, the ascertained speeds being associated with the sequence of respective time periods;

forming quotients from products of the ascertained speeds associated with each of the respective time periods, and a number of the signals from the displacement sensor counted in each of the respective time periods;

multiplying each of the quotients by a respective weighting factor;

determining a mean from the weighted quotients; and

calibrating the displacement sensor as a function of the mean.

2. The method according to claim 1, wherein the broadcast signals are from a global positioning system.

3. The method according to claim 1, further comprising the step of:

correlating and comparing the signals from the displacement sensor with the ascertained speeds of the vehicle.

4. The method according to claim 1, wherein each respective weighting factor of each of the quotients depends on a mean error of the quotient.

5. The method according to claim 1, further comprising the steps of:

calculating each respective weighting factor iteratively; and

allocating a fixed value to one respective weighting factor.

6. The method according to claim 5, wherein the fixed value is 1.

7. The method according to claim 5, further comprising the step of:

calculating a ratio between two respective weighting factors from a reciprocal ratio of squares of mean errors of the quotients with which the two respective weighting factors are associated.

8. The method according to claim 1, wherein the mean is calculated by arithmetic averaging of the weighted quotients.