Electronic compass system

An electronic compass for a vehicle, comprising:

• a magnetic sensor circuit for sensing at least two perpendicular components of the Earth's magnetic field vector and for generating output signals representative of the sensed components;
• and
• a processing circuit coupled to said magnetic sensor circuit for receiving the output signals, selecting an approximating geometric pattern that constitutes a best fit to select data points corresponding to the sensed components taken over time, computing a heading of the vehicle as a function of at least two of the sensed components while referencing the selected approximating geometric pattern, and generating a heading signal representing the computed heading.

An electronic compass for a vehicle, comprising:

• a magnetic sensor circuit for sensing three perpendicular components of the Earth's magnetic field vector, and for generating output signals representing the three sensed components;
• and
• a processing circuit coupled to said magnetic sensor circuit for receiving the output signals, determining a geometric pattern, computing a heading of the vehicle as a function of the at least two of the sensed components while referencing the geometric pattern, determining the magnitude of an error vector extending from the perimeter of the geometric pattern to the most recent sensed components from the three sensed perpendicular components, and generating a heading signal representing the computed heading when the magnitude of the error vector does not exceed a predetermined threshold.

An electronic compass for a vehicle, comprising:

• a magnetic sensor circuit for sensing at least two perpendicular components of the Earth's magnetic field vector and for generating output signals representative of the sensed components;
• and
• a processing circuit coupled to said magnetic sensor circuit for receiving the output signals, iteratively selecting an approximating geometric pattern by repeatedly comparing and changing the geometric pattern based on the sensed components taken over time, computing a heading of the vehicle as a function of at least two of the sensed components while referencing the geometric pattern, and generating a heading signal representing the computed heading.

An electronic compass for a vehicle, comprising:

• a magnetic sensor circuit including at least two sensing elements, each for sensing a component of the Earth's magnetic field vector that is perpendicular to the component sensed by the other sensor and for generating output data signals representative of the sensed components;
• and
• a processing circuit coupled to said magnetic sensor circuit for receiving the output data signals, associating the output data signals from each of said sensing elements to establish a data point, applying a smoothing filter to smooth the data point by utilizing a weighted average with the most recent data point given a greater weight than prior data points, computing a heading of the vehicle as a function of the most recent data point, and generating a heading signal representing the computed heading.

An electronic compass for a vehicle, comprising:

• a magnetic sensor circuit including at least two sensing elements, each for sensing a component of the Earth's magnetic field vector that is perpendicular to the component sensed by the other sensor and for generating output data signals representative of the sensed components;
• and
• a processing circuit coupled to said magnetic sensor circuit for receiving the output data signals, associating the output data signals from each of said sensing elements to establish a data point, determining a second derivative of the position of the data point relative to at least one prior data point, comparing the magnitude of the second derivative to a first threshold to determine whether the output data signals of the sensing elements are noisy, computing a heading of the vehicle as a function of the most recent data point, and generating a heading signal representing the computed heading.

An electronic compass for a vehicle, comprising:

• a magnetic sensor circuit including at least two sensing elements, each for sensing a component of the Earth's magnetic field vector that is perpendicular to the component sensed by the other sensor and for generating output data signals representative of the sensed components;
• and
• a processing circuit coupled to said magnetic sensor circuit for receiving the output data signals, associating the output data signals from each of said sensing elements to establish a data point, determining a noise level of the output data signals of the sensing elements by monitoring variations in the sensed levels, setting a delay counter as a function of the noise level, preventing use of the output data signals for geometric approximation until the delay counter has expired, computing a heading of the vehicle as a function of the most recent data point, and generating a heading signal representing the computed heading.

An electronic compass for a vehicle, comprising:

• a magnetic sensor circuit for sensing at least two perpendicular components of the Earth's magnetic field vector and for generating output signals representative of the sensed components;
• and
• a processing circuit coupled to said magnetic sensor circuit for receiving the output signals, selecting an elliptical approximating geometric pattern, computing a heading of the vehicle as a function of at least two of the sensed components while referencing the elliptical approximating geometric pattern, and generating a heading signal representing the computed heading.

An electronic compass for a vehicle, comprising:

• a magnetic sensor circuit for sensing at least two perpendicular components of the Earth's magnetic field vector and for generating output signals representative of the sensed components;
• and
• a processing circuit coupled to said magnetic sensor circuit for receiving the output signals, determining a calibration point based on a number of reference data points derived from the sensed components, determining a noise threshold that varies as a function of the number of reference points used to compute the current calibration point, determining whether the sensed components exceed the noise threshold, computing a heading of the vehicle as a function of the at least two of the sensed components while referencing the calibration point when the sensed components do not exceed the noise threshold, and generating a heading signal representing the computed heading.

An electronic compass for a vehicle, comprising:

• a magnetic sensor circuit for sensing at least two perpendicular components of the Earth's magnetic field vector and for generating output signals representative of the sensed components;
• and
• a processing circuit coupled to said magnetic sensor circuit for receiving the output signals, determining an approximating geometric pattern based on a plurality of reference data points derived from the sensed components, determining a noise threshold that varies as a function of the extent to which the approximating geometric pattern fits the reference data points used to define the approximating geometric pattern, computing a heading of the vehicle as a function of the at least two of the sensed components while referencing the approximating geometric pattern when the sensed components do not exceed the noise threshold, and generating a heading signal representing the computed heading.

An electronic compass for mounting in a rearview mirror housing of a vehicle, comprising:

• a magnetic sensor circuit including first and second sensing elements each for sensing substantially horizontal perpendicular components of the Earth's magnetic field vector, and a third sensing element for sensing a substantially vertical component of the Earth's magnetic field vector, said sensing elements being mounted in the mirror housing and for generating output signals representing the three sensed components;
• and
• a processing circuit coupled to said magnetic sensor circuit for receiving the output signals, determining a tilt angle of the mirror housing by monitoring said third sensing element during travel of the vehicle through a predetermined range of vehicle headings, compensating the sensed components of the first and second sensing elements for the tilt angle of the mirror housing, computing a heading of the vehicle as a function of the sensed components of the first and second sensing elements, and generating a heading signal representing the computed heading.

An electronic compass for a vehicle, comprising:

• a magnetic sensor circuit for sensing at least two perpendicular components of the Earth's magnetic field vector and for generating output signals representative of the sensed components;
• and
• a processing circuit coupled to said magnetic sensor circuit for receiving the output signals, selecting a first approximating geometric pattern based on a first set of reference data points derived from the sensed components, computing a heading of the vehicle as a function of at least two of the sensed components while referencing the first approximating geometric pattern, generating a heading signal representing the computed heading, selecting a second approximating geometric pattern based on reference data points received after the first approximating geometric pattern is selected, utilizing the second approximating geometric pattern if the second approximating geometric pattern is significantly different from the first approximating geometric pattern, and reselecting the first approximating geometric pattern if the subsequently obtained reference data points better fit the first approximating geometric pattern.

An electronic compass for a vehicle, comprising:

• a magnetic sensor circuit for sensing at least two perpendicular components of the Earth's magnetic field vector and for generating output signals representative of the sensed components;
• and
• a processing circuit coupled to said magnetic sensor circuit for receiving the output signals, deriving a first set of reference data points from the sensed components using at least one first threshold, selecting a first approximating geometric pattern based on the first set of reference data points, computing a heading of the vehicle as a function of at least two of the sensed components while referencing the first approximating geometric pattern, generating a heading signal representing the computed heading, deriving a second set of reference data points from the sensed components using at least one second threshold that is more stringent than the first threshold, selecting a second approximating geometric pattern based on the second set of reference data points, utilizing the second approximating geometric pattern if the second approximating geometric pattern is significantly different from the first approximating geometric pattern, and reselecting the first approximating geometric pattern if subsequently obtained reference data points better fit the first approximating geometric pattern.

An electronic compass for a vehicle, comprising:

• a magnetic sensor circuit for sensing at least two perpendicular components of the Earth's magnetic field vector and for generating output signals representative of the sensed components;
• and
• a processing circuit coupled to said magnetic sensor circuit for receiving the output signals, determining an approximating geometric pattern based on at least five reference data points derived from the sensed components, computing a heading of the vehicle as a function of the at least two of the sensed components while referencing the approximating geometric pattern, and generating a heading signal representing the computed heading.

An electronic compass for a vehicle, comprising:

• a magnetic sensor circuit for sensing at least two perpendicular components of the Earth's magnetic field vector and for generating output signals representative of the sensed components;
• and
• a processing circuit coupled to said magnetic sensor circuit for receiving the output signals, determining that the vehicle is moving when the sensed components exhibit a noise level exceeding a minimum noise threshold, computing a heading of the vehicle as a function of the at least two of the sensed components, and generating a heading signal representing the computed heading, wherein said processing circuit does not change the displayed heading when the vehicle is not moving.

An electronic compass for a vehicle, comprising:

• magnetic sensor circuit for sensing at least two perpendicular components of the Earth's magnetic field vector and for generating output signals representative of the sensed components;
• and
• a processing circuit coupled to said magnetic sensor circuit for receiving the output signals, determining an approximating geometric pattern based on reference data points derived from the sensed components, computing an error metric representing the degree to which the approximating geometric pattern fits the reference data points, computing a heading of the vehicle as a function of the at least two of the sensed components while referencing the approximating geometric pattern, and generating a heading signal representing the computed heading.