Vehicle compass system with continuous automatic calibration
First Claim
1. A method for calibrating an electronic vehicular compass, comprising:
- receiving electronic data from a sensor circuit in the vehicle, the sensor circuit configured to measure an effect of the earth'"'"'s magnetic field;
calculating a first smoothed data point using data points received from the sensor circuit;
calculating a second smoothed data point using the data points received from the sensor circuit;
calculating a third smoothed data point using the data points received from the sensor circuit;
calculating a center point based on at least the first smoothed data point, second smoothed data point and third smoothed data point;
calculating a fourth smoothed data point using data received from the sensor circuit;
calculating the distance from the fourth smoothed data point to the center point; and
not processing the fourth smoothed data point if a distance between the fourth smoothed data point and the center point is outside of a predetermined range.
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Accused Products
Abstract
The compass system of the present invention utilizes an improved calibration routine in which a processing circuit of the compass recalibrates the compass each time three data points are obtained from a magnetic field sensor that meet predetermined criteria. One such criterion is that the three data points define corners of a triangle that is substantially non-obtuse. When three data points have been obtained that define a triangle meeting this criterion, the processing circuit calculates a center point for a circle upon which all three data points lie by solving the equation x2+y2+Ax+By+C=0 for A, B, and C, using the coordinate values (x,y) for the three data points and defining the center point as (−A/2, −B/2).
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Citations
25 Claims
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1. A method for calibrating an electronic vehicular compass, comprising:
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receiving electronic data from a sensor circuit in the vehicle, the sensor circuit configured to measure an effect of the earth'"'"'s magnetic field; calculating a first smoothed data point using data points received from the sensor circuit; calculating a second smoothed data point using the data points received from the sensor circuit; calculating a third smoothed data point using the data points received from the sensor circuit; calculating a center point based on at least the first smoothed data point, second smoothed data point and third smoothed data point; calculating a fourth smoothed data point using data received from the sensor circuit; calculating the distance from the fourth smoothed data point to the center point; and not processing the fourth smoothed data point if a distance between the fourth smoothed data point and the center point is outside of a predetermined range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A self-calibrating electronic vehicular compass, comprising:
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a sensor circuit configured to measure an effect of the earth'"'"'s magnetic field and communicate measurements as data points; a processing circuit configured to; (i) receive measured data points from the sensor circuit; (ii) provide a first smoothed data point using the measured data points; (iii) provide a second smoothed data point using the measured data points; (iv) provide a third smoothed data point using the measured data points; (v) provide a center point defined by the coordinates of the first smoothed data point, second smoothed data point and third smoothed data point; (vi) provide the distance from a fourth data point and the center point; and (vii) not process the fourth data point if a distance between the fourth data point and the center point is outside of a predetermined range. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A processing circuit for a vehicle compass configured to:
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receive measured data points from a sensor circuit; provide a first smoothed data point; provide a second smoothed data point; provide a third smoothed data point; provide a center point defined by the coordinates of the first smoothed data point, second smoothed data point and third smoothed data point; provide a distance from a fourth data point and the center point; and not use the fourth data point if a distance between the data point and the center point is outside of a predetermined range. - View Dependent Claims (20, 21, 22, 23, 24, 25)
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Specification