Abstract: An electronic compass system for use in an adjustable fixture in a vehicle such as an automobile including a sensor for detecting a magnetic field and for providing electrical signals representative of the direction of the vehicle with respect to the magnetic field. Relative position sensors provide electronic compass orientation relative to the vehicle. A circuit coupled to said sensing means resolve the direction and relative position electrical signals into a number of data points from which the detected direction of the vehicle may be calculated. The circuit also provides heading output signals representing heading information corresponding to the detected direction.

Abstract: A method and apparatus for calibrating an electronic compass of the type having a compass sensor, a calibration table and a display. A computer operating under program control is used to update the calibration table of the electronic compass in response to physical movement of at least the electronic compass sensor and an angular rate gyroscope through a 360 degree movement. A pointing device associated with the electronic compass is initially directed to a known landmark position and is also directed to the known landmark position after completing the 360 degree movement. The computer utilizes global positioning system receiver, the known landmark position and a heading provided by the sensor to generate a correction value. The output of the sensor is compared with data generated based upon the gyroscope during the 360 degree movement to generate correction values for other compass headings. The correction values are transmitted to the electronic compass for updating its calibration table.

Abstract: An electronic compass system using information on a communications bus to eliminate magnetic noise which is integrated with an instrument cluster. A vehicle accessory, such as a blower motor, generates a known, consistent, magnetic field of intensity sufficient to cause a static magnetic offset in the electronic compass for each of its' electrical states. An electronic controller commands the vehicle accessory to change electrical states and transmits a vehicle event message on a communications bus. A magnetic field sensor detects a combination of Earth's magnetic field and the stray magnetic field produced by the vehicle accessory. A controller is coupled to the communications bus and uses the vehicle event message to look up a predetermined correction factor, corresponding to the electrical state, to eliminate the effect of the static magnetic offset. The controller then displays a heading unaffected by the static magnetic offset.

Abstract: The present invention provides methods and devices that enable correction of gyroscope bias and gyroscope bias drift in low-cost, vehicular navigation and positioning systems without using estimates of position and heading, and subsequent correction of heading and position errors resulting from gyroscope bias and bias drift, without relying on assumptions regarding gyroscope bias or predetermined time-dependent gyroscope bias drift profiles. The invention improves over existing GPS/DR systems that do not compensate for actual gyroscope bias instability, but instead correct the heading and position error that is induced by the bias instability and then correct estimates of gyroscope bias based on the corrected position and heading. The inventive methods provided herein can be used with any DR vehicle positioning system that uses a gyroscope.

Abstract: A system for calibrating an electronic compass for a vehicle of the type employing a Forward and Lateral magnetoresistive magnetic field sensor. As the vehicle changes headings, the system periodically samples and digitally stores the peaks of the sensor outputs. When the stored peaks indicate a minimum change in the output of the sensors, the system microcomputer calculates a “box” surrounding the subscribed arc of heading changes and computes the center of the “box” as the center of the locus of anticipated peaks for all quadrants and shifts the locus (i.e., “box”) to be within the domain of the A/D converter to prevent saturation, which could otherwise occur in the presence of strong remnant magnetic fields in the vehicle. The “box” is updated with each sampling of sensor outputs until the vehicle is eventually headed through all four cardinal compass headings, and the compass is then considered to be fully modeled in the microcomputer.

Abstract: An arrangement for measuring the direction of the geomagnetic field {right arrow over (B)}E, in the proximity of a magnetic jamming device with a magnetic field direction variable as a function of time, which is distinguished by the fact that at least two magnetic field measuring devices are provided, each of which measures all three vector components of the total magnetic field ({right arrow over (B)}1,{right arrow over (B)}2), the magnetic field measuring devices have a position, ({right arrow over (r)}0,{right arrow over (r)}1,{right arrow over (r)}2) which is invariable as a function of time and is fixed relative to one another and relative to the jamming device, and the measured values can be called up synchronously and can be evaluated according to {right arrow over (B)}E=({right arrow over (B)}1+{right arrow over (B)}2)/2+P·({right arrow over (B)}1−{right arrow over (B)}2), P({right arrow over (r)}0,{right arrow over (r)}1,{right arrow over (r)}2) describing the geometric

Abstract: An electronic compass system using magnetic signatures to detect a vehicle event which is integrated with an instrument cluster. A vehicle accessory, such as a rear defrost grid, generates a known, consistent, magnetic field of intensity sufficient to cause a static magnetic offset in the electronic compass for each of its' electrical states. This known consistent, magnetic field has a magnetic signature. A magnetic field sensor detects a combination of Earth's magnetic field and the stray magnetic field produced by the vehicle accessory. A controller is coupled to the magnetic field sensor and searches the magnetic field signal for the magnetic signature. The controller then looks up a predetermined correction factor, or uses an algorithm to determine a correction factor, corresponding to the magnetic signature, to eliminate the effect of the static magnetic offset. The controller then displays a heading unaffected by the static magnetic offset.

Abstract: An electronic compass system for eliminating magnetic noise which is integrated with an instrument cluster. A vehicle accessory, such as a stepper motor, also located in the instrument cluster, generates a known, consistent, magnetic field of intensity sufficient to cause a static magnetic offset in the electronic compass for each of its' electrical states. A magnetic field sensor detects a combination of The Earth's magnetic field and this stray magnetic field. A controller uses a predetermined correction factor, corresponding to the electrical state, to eliminate the effect of the static magnetic offset. The controller then displays a heading unaffected by the static magnetic offset.

Abstract: A method for correcting yaw in a DGPS (global positioning system) based guidance system mounted on a vehicle. The method corrects for a yaw induced heading/cross track error due to a DGPS antenna being mounted a significant distance from the point of operation (e.g., the vehicle operator's location, the center of the vehicle, etc.). The method determines a ground track of a vehicle using a DGPS system and a coupled antenna mounted on the vehicle. A heading of the vehicle is also determined using a compass mounted on the vehicle. The heading and the ground track are compared to determine whether a difference exits and the magnitude of the difference. Using the difference, the DGPS determined position is adjusted to be the position of the operator/center of the vehicle. Using this guidance information, an indication is generated operable for directing the vehicle to maintain a desired ground track.

Abstract: An electronic compass system of the present invention includes a sensor for detecting the earth's magnetic field and for providing electrical signals representing the direction of the vehicle, a heading indicator for indicating vehicle headings in response to received vehicle heading signals, and a processor coupled to the sensor for receiving the electrical signals and coupled to the heading indicator for supplying the vehicle heading signals to the heading indicator.

Abstract: A passive position fix system for a vehicle in which a gyro first provides a first gyro position of the vehicle, a map storage means which receives the first gyro position and in response thereto provides map-sets containing a set of gravity gradients and a gravity anomaly associated with geographic positions in the vacinity of the first gyro position, a gravity sensor for providing a GSS-set comprising a sensed set of gravity gradients values and a gravity anomaly at the position of the vehicle, a comparing means for sequentially receiving the map-sets so as to determine when there is a match between the GSS-set and a map-set and providing a displacement vector, and a processor for placing a second gyro position in the gyro based on the first gyro position and the displacement vector.

Abstract: A method of calibrating a three-axis magnetometer is provided. In accordance with the method, calibration is effected by first establishing a three-axis magnetic field simulator having a center position portion. Suitable measures are taken to substantially compensate for the earth's magnetic field at least at that center position portion. A three-axis magnetometer is then disposed in the magnetic field simulator and successively actuated in predetermined manner to generate a set of measured parameter values. The measured parameter values are normalized using a predetermined standard output factor, and a square pre-calibration matrix C is generated from the normalized measured parameter values. An inverse matrix operation is thereafter performed upon the pre-calibration matrix C to generate a square calibration matrix D having a plurality of coefficients respectively indicative of orthonormal compensation coefficients.

Abstract: A vehicle direction correcting apparatus comprises: a first filter for passing therethrough a low frequency component contained in the output voltage of a relative direction detecting unit to thereby produce a first output voltage; a second filter having delay time different from that of the first filter, for passing therethrough a low frequency component contained in the output voltage of the relative direction detecting unit to thereby produce a second output voltage; a voltage judging unit for judging as to whether or not the first output voltage of the first filter is made coincident with the second output voltage of the second filter within a predetermined error range; and a control unit for setting an output voltage of the relative direction detecting unit as the central point potential in the case that the voltage judging unit judges that the first output voltage is made coincident with the second output voltage within the predetermined error range.

Abstract: A first value (V), which corresponds to the angular units covered during two actual position values successively transmitted via the data transmission link at the maximum rotational speed of the encoder shaft (W), and a second value (D) which corresponds to the difference between the maximum travel of the angular position encoder (MAX) and the first value (V), are stored in a store. A processing unit determines the direction of rotation of the shaft (W) depending on whether two actual position values (X11, X12; X21, X22; X31, X32) lie in the range between the zero point (NP) of the angular position encoder and an actual position value (L2) corresponding to the magnitude of the first stored value (V), or in the range between an actual position value (L1) corresponding to the magnitude of the second stored value (D) and the maximum travel (MAX), or outside these ranges.

Abstract: A vehicular traveling direction measuring system derives a weighting constant based on a monitored magnitude of the geomagnetic disturbance around a vehicle. Variance values of geomagnetism indicative data and a deviation magnitude from a standard azimuth circle may be used to estimate the geomagnetic disturbance magnitude. Mean data is derived from current cycle data and prior cycle data of the monitored geomagnetism using the weighting constant. The weighting constant determines a rate of dependency upon the current cycle data and the prior cycle data when deriving the mean data. The vehicular traveling direction is derived based on the derived mean data.

Abstract: A method of installing a compass system includes the steps of mounting the electronic compass in a vehicle, coupling the electronic compass to a power source of the vehicle, downloading precalibration data into the electronic compass after the electronic compass has been mounted in the vehicle, and initiating a precalibration routine in the vehicle that is headed in a predetermined direction. The method may further include the steps of identifying characteristics of the vehicle and selecting precalibration data corresponding to the identified vehicle characteristics. The precalibration data selected corresponds to a make and model of the vehicle in which the compass may be installed and further may correspond to sets of vehicle options that may affect vehicular magnetism. If the electronic compass is provided as part of a trip computer, the precalibration data is preferably downloaded at the same time that the fuel tank size is downloaded into the trip computer.

Abstract: An electronic vehicle accessory includes a non-volatile memory, and a controller coupled to the non-volatile memory and to a speed sensor of the vehicle for receiving speed data representing the vehicle's current speed. The controller determines when the vehicle's current speed falls below a predetermined threshold and stores variable data in the non-volatile memory when the vehicle's speed is below the predetermined threshold. The electronic vehicle accessory may be an instrument panel, an electronic compass, and/or a mini-trip computer, which may be housed in an overhead housing. By storing variable data in the non-volatile memory as a function of the vehicle's speed, the present invention ensures that the most up-to-date data is stored in the non-volatile memory before the vehicle's ignition is turned off while eliminating excessive stores that shorten the lifetime of the non-volatile memory.

Abstract: An electronic compass system and method in which an automatic calibration process is available while the vehicle is in use. The procedure uses a binning process to collect and count data points which automatically triggers the automatic calibration process, and which is also used for manual calibration. Also, there is a procedure for detecting and rejecting anomalous magnetic events outside the vehicle through a jitter phenomenon.

Abstract: A method for determining the direction of the Earth's magnetic field, which may be interfered with by magnetic materials built into equipment and by electric currents, using an electronic magnetic compass which contains three magnetic field sensors and two devices for measuring inclination is provided. The electronic magnetic compass is arranged in N different spatial positions, in each of these N positions, the inclination sensor signals and the magnetic field sensor signals being measured and inclination values and magnetic field values being determined from these signals. On the basis of these inclination values and magnetic field values, the magnitude of the Earth's magnetic field vector is determined using the vector equationconst=b.sub.g =b.sub.E sin(i)=g.sup.T L(b.sub.E)=g.sup.T m(b.sub.mes -b.sub.o)with ##EQU1## N having to be at least equal to the number of parameters to be determined in the vector equation.

Abstract: Disclosed is a method of stabilizing the horizon of magnetic compasses. At measuring points measurements are taken of spatial components of the geomagnetic field vector and of an overall acceleration vector that is equal to the difference of the acceleration vector due to gravity and the acceleration vector of the magnetic compass. Taking into account the time rates of change of the measured components, the positional relation of the current horizon of the magnetic compass is determined relative to the stable horizon. Using quality functions that signal the deviation of the new spatial position relative to the one previously defined, an estimation method is used to evaluate the accuracy of the stabilized horizon of the system. A horizon can be produced that is largely unsusceptible to movement-induced accelerations of the device equipped with a magnetic compass.

Abstract: In a sourceless orientation sensor, the sensor measures the three orientation angles azimuth, elevation and roll in a fixed reference three-dimensional coordinate frame. The sensor utilizes a three-axis magnetic sensor to measure changes in the Earth's magnetic field in order to determine the azimuth and roll (or elevation) angles after the elevation (or roll) angle has been determined by other means. A first embodiment utilizes a separate sensor to measure the elevation (or roll) angle in a fixed reference three-dimensional coordinate frame while a three axis magnetic sensor is used to measure the Earth's magnetic field. The azimuth and the roll (or elevation) angles are then determined from these measurements. A second embodiment utilizes a combination of a three-axis accelerometer to sense the Earth's gravity to measure the absolute elevation and roll angles for slow motions and a two-axis rate sensor to measure the azimuth and elevation velocities in the sensor frame.

Abstract: The apparatus for determining turning rate, particularly of a motor vehicle, includes two sensor systems (1,3), each of which generate at least one output signal depending on the turning rate. The sensor signals from both sensor systems are combined by a microcontroller including a memory to determine the turning rate accounting for offset drift and sensitivity drift. The first sensor system (1) includes an electronic compass with at least two sensor components (10) each including at least one magnetoresistive element (19) arranged in a Wheatstone bridge for detecting an X-component, a Y-component or a Z-component of the earth's magnetic field. The second sensor system (3) generates a sensor signal according to a Coriolis force experience by an oscillating structure. Each sensor component (10) of the first sensor system also includes an integrated field compensation coil (L.sub.F) and a set/reset coil (L.sub.

Abstract: Although sensors are typically registered before the live event, a sensor's location, orientation and/or field of view can be altered during the event. A system for re-registering a sensor during a live event allows for the determination that a sensor is not properly registered. If such a determination is made, the system accumulates valid data during the live event. The valid data is compared to the data from the improperly registered sensor in order to determine the amount of error. The variables that define the sensor's registration are changed to reduce the error.

Abstract: An electronic compass (10) for use in a boring tool (12) which will provide an orientation of the boring tool relative to the earth's magnetic field. In addition, a more straightforward left or right deviation from an initial bearing can be determined. The invention can correct for pitch angle and roll angle variation as well. The magnetic field is sensed by an axial magnetic field (12), a radial magnetic field sensor (18) and a plane-normal magnetic sensor (24) which are preferably magnetoresistive sensors.

Abstract: A method for converting distorted compass data values into corrected data values which employs linear transforms. A linear transform is formulated and programmed into the read only memory of the microcomputer of the electronic compass system. The microcomputer uses the linear transform to transform compass data readings distorted by ferrous metals in the environment of the vehicle into corrected data readings and then uses the corrected data readings to compute headings.