Vehicle compass compensation
First Claim
1. A vehicular electronic compass system comprising:
- a magneto-responsive sensor assembly for sensing a magnetic field, said magneto-responsive sensor comprising at least a two-axis sensor for sensing two components of a magnetic field, said two-axis sensor comprising a first axis sensing element and a second axis sensing element, one of said first axis sensing element and said second axis sensing element being generally aligned with a direction of travel of a vehicle when the vehicular electronic compass system is operated in the vehicle;
an electronic circuit responsive to said two-axis sensor for distinguishing the Earth magnetic field from a deviating field of the vehicle in order to determine a directional heading of the vehicle;
said electronic circuit including a microprocessor and an analog-to-digital converter;
said distinguishing the Earth magnetic field from a deviating field of the vehicle incluiding an initial calibration mode that brings the output signal of at least one of said first axis and second axis sensing elements to be within the operable range of said analog-to-digital converter and wherein said electronic circuit detects a first peak value of the Earth magnetic field by said microprocessor of data sensed by one of said first axis and second axis sensing elements, wherein said electronic circuit detects a second peak value of the Earth magnetic field by processing by said microprocessor of data sensed by said one of said first axis and second axis sensing elements, wherein said electronic circuit calculates a zero reference value using said detected first and second peak values, wherein said electronic circuit detects a third peak value of the Earth magnetic field by processing by said microprocessor of data sensed by the other one of said first axis and second axis sensing elements, and wherein said electronic circuit algorithmically calculates a fourth peak value of the Earth magnetic field using said detected first, second and third peak values without a need for the vehicle to turn through a 360 degree circle; and
an electronic display coupled with said electronic circuit, said electronic display displaying the directional heading of the vehicle at least during said initial calibration mode.
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Abstract
A compass compensation system is provided for automatically and continuously calibrating an electronic compass for a vehicle, without requiring an initial manual calibration or preset of the vehicle magnetic signature. The system initially adjusts a two axis sensor of the compass in response to a sampling of at least one initial data point. The system further calibrates the compass by sampling data points that are substantially opposite to one another on a plot of a magnetic field and averaging an ordinate of the data points to determine a respective zero value for the Earth magnetic field. The system also identifies a change in magnetic signature and adjusts the sensor assembly.
180 Citations
86 Claims
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1. A vehicular electronic compass system comprising:
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a magneto-responsive sensor assembly for sensing a magnetic field, said magneto-responsive sensor comprising at least a two-axis sensor for sensing two components of a magnetic field, said two-axis sensor comprising a first axis sensing element and a second axis sensing element, one of said first axis sensing element and said second axis sensing element being generally aligned with a direction of travel of a vehicle when the vehicular electronic compass system is operated in the vehicle;
an electronic circuit responsive to said two-axis sensor for distinguishing the Earth magnetic field from a deviating field of the vehicle in order to determine a directional heading of the vehicle;
said electronic circuit including a microprocessor and an analog-to-digital converter;
said distinguishing the Earth magnetic field from a deviating field of the vehicle incluiding an initial calibration mode that brings the output signal of at least one of said first axis and second axis sensing elements to be within the operable range of said analog-to-digital converter and wherein said electronic circuit detects a first peak value of the Earth magnetic field by said microprocessor of data sensed by one of said first axis and second axis sensing elements, wherein said electronic circuit detects a second peak value of the Earth magnetic field by processing by said microprocessor of data sensed by said one of said first axis and second axis sensing elements, wherein said electronic circuit calculates a zero reference value using said detected first and second peak values, wherein said electronic circuit detects a third peak value of the Earth magnetic field by processing by said microprocessor of data sensed by the other one of said first axis and second axis sensing elements, and wherein said electronic circuit algorithmically calculates a fourth peak value of the Earth magnetic field using said detected first, second and third peak values without a need for the vehicle to turn through a 360 degree circle; and
an electronic display coupled with said electronic circuit, said electronic display displaying the directional heading of the vehicle at least during said initial calibration mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A vehicular electronic compass system comprising:
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a magneto-responsive sensor for sensing a magnetic field, said magneto-responsive sensor comprising at least a two-axis sensor for sensing two components of a magnetic field, said two-axis sensor comprising a first axis sensing element and a second axis sensing element, one of said first axis sensing element and said second axis sensing element being generally aligned with a direction of travel of a vehicle when the vehicular electronic compass system is operated in the vehicle;
an electronic circuit responsive to said two-axis sensor for distinguishing the Earth magnetic field from a deviating field of the vehicle in order to determine a directional heading of the vehicle;
said electronic circuit including a microprocessor;
said distinguishing the Earth magnetic field from a deviating field of the vehicle including an initial calibration mode that comprises said electronic circuit detecting a first peak value of the Earth magnetic field by processing by said microprocessor of data sensed by one of said first axis and second axis sensing elements, said electronic circuit detecting a second peak value of the Earth magnetic field by processing by said microprocessor of data sensed by said one of said first axis and second axis sensing elements, said electronic circuit calculating a zero reference value using said detected first and second peak values, said electronic circuit detecting a third peak value of the Earth magnetic field by processing by said microprocessor of data sensed by the other one of said first axis and second axis sensing elements, and said electronic circuit algorithmically calculating a fourth peak value of the Earth magnetic field using said detected first, second and third peak values without a need for the vehicle to turn through a 360 degree circle;
an electronic display coupled with said electronic circuit for displaying the directional heading of the vehicle; and
wherein said directional heading of the vehicle displayed by said electronic display is within a range of accuracy relative to the true Earth magnetic field acceptable to an operator of the vehicle. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57)
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58. A vehicular electronic compass system comprising:
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a magneto-responsive sensor for sensing a magnetic field, said magneto-responsive sensor comprising at least a two-axis sensor for sensing two components at a magnetic field, said two-axis sensor comprising a first axis sensing element and a second axis sensing element, one of said first axis sensing element and said second axis sensing element being generally aligned with a direction of travel of a vehicle when the vehicular electronic compass system is operated in the vehicle;
an electronic circuit responsive to said two-axis sensor for distinguishing the Earth magnetic field from a deviating field of the vehicle in order to determine a directional heading of the vehicle;
said electronic circuit including a microprocessor;
said distinguishing the Earth magnetic field from a deviating field of the vehicle including an initial calibration mode that comprises said electronic circuit detecting a first peak value of the Earth magnetic field by processing by said microprocessor of data sensed by one of said first axis and second axis sensing elements, said electronic circuit detecting a second peak value of the Earth magnetic field by processing by said microprocessor of data sensed by said one of said first axis and second axis sensing elements, said electronic circuit calculating a zero reference value using said detected first and second peak values;
said system switching to another calibration mode after said initial calibration mode is completed;
an electronic display coupled with said electronic circuit for displaying the directional heading of the vehicle;
said directional heading of the vehicle displayed by said electronic display being within a range of accuracy relative to the true Earth magnetic field acceptable to an operator of the vehicle; and
wherein said electronic display displays said directional heading of the vehicle at least during said initial calibration mode. - View Dependent Claims (59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86)
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Specification