Vehicle compass system with continuous automatic calibration

A vehicle compass system, comprising:

• a magnetic field sensor configured to detect the earth's magnetic field and to generate electrical signals representing a direction of the vehicle's travel in relation to the earth's magnetic field;
• and
• a processing circuit coupled to the sensor configured to process the electrical signals generated by the sensor to provide data points representative of the vehicle's heading, wherein the processing circuit is configured to calibrate the system based on data points that define corners of a triangle meeting predetermined criteria, wherein the processing circuit is further configured to calibrate the system by detecting crossings of the data points.

A vehicle compass system, comprising:

• a magnetic field sensor configured to detect the earth's magnetic field and to generate electrical signals representing a direction of the vehicle's travel in relation to the earth's magnetic field;
• and
• a processing circuit coupled to the sensor configured to process the electrical signals generated by the sensor to provide data points representative of the vehicle's heading, wherein the processing circuit is configured to calibrate the system based on data points that define three sides of a triangle meeting predetermined criteria, the processing circuit configured to determine that a triangle defined by the three sides meets the predetermined criteria when the triangle is substantially non-obtuse.

A vehicle compass system, comprising:

• a magnetic field sensor configured to detect the earth's magnetic field and to generate electrical signals representing a direction of the vehicle's travel in relation to the earth's magnetic field;
• and
• a processing circuit coupled to the sensor configured to process the electrical signals generated by the sensor to provide data points representative of the vehicle's heading, wherein the processing circuit is configured to calibrate the system based on data points that define three sides of a triangle meeting predetermined criteria, the processing circuit configured to determine that the three sides define a substantially non-obtuse triangle with sides of lengths a, b, and c when the lengths of the sides satisfy the relationship {square root over (a2+b2)}/c≧0.92 where c is the longest side.

A vehicle compass system, comprising:

• a magnetic field sensor configured to detect the earth's magnetic field and to generate electrical signals representing a direction of the vehicle's travel in relation to the earth's magnetic field;
• and
• a processing circuit coupled to the sensor configured to process the electrical signals generated by the sensor to provide data points representative of the vehicle's heading, wherein the processing circuit is configured to calibrate the system based on three data points that define corners of a triangle meeting predetermined criteria, wherein the processing circuit is configured to determine that a triangle defined by the three data points meets the predetermined criteria when the triangle is substantially non-obtuse.

A vehicle compass system, comprising:

• a magnetic field sensor configured to detect the earth's magnetic field and to generate electrical signals representing a direction of the vehicle's travel in relation to the earth's magnetic field;
• and
• a processing circuit coupled to the sensor configured to process the electrical signals generated by the sensor to provide data points representative of the vehicle's hearing, wherein the processing circuit is configured to calibrate the system based on three data points that define corners of a triangle meeting predetermined criteria, wherein, the processing circuit is configured if the three data points obtained from the sensor do not define a triangle that meets the predetermined criteria, to obtain a fourth data point from the sensor and to determine whether any combination of three of the four data points defines a triangle that meets the predetermined criteria.