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.

Abstract: A shifting compensation circuit which employs a ranging circuit having a variable direct voltage source, to compensate for abnormally large vehicle magnetic fields. A ranging circuit is coupled between a microcomputer and a flux-gate. The microcomputer monitors the output of an integrator through a buffer amplifier to minimize variations in the integrator output caused by temperature variations, and directs the variable direct voltage source to add a direct voltage reference, in opposition to the vehicle's magnetic field signal and within the output voltage range of the integrator, to the output signal of the flux-gate, such that the combination of the two signals is within the output voltage range of the integrator for all vehicle headings.

Abstract: A scaling system and technique which employs an analog-to-digital converter having at least 10-bit accuracy and a ranging circuit to compensate for abnormally large vehicle magnetic fields. The ranging circuit employs variable resistance negative feedback, which enables an electronic compass system to reduce the output voltage of an integrator to within the fixed output voltage range of the integrator. An analog-to-digital converter of at least 10-bit accuracy makes resolution of heading information possible and enhances the accuracy of subsequently performed calibrations.

Abstract: A method and apparatus for interpreting magnetic directions for an electronic compass system mounted on a moving vehicle such as an automobile. The directions of North, Northeast, East, Southeast, South, Southwest, West and Northwest are each assigned predetermined degree ranges which are included in a look-up table used by a controller. The predetermined degree ranges associated with the directions of North, South, East and West are further each set at equal values, while the predetermined degree ranges of Northeast, Northwest, Southeast and Southwest are set equally at a value that is less than the values of the North, South, East and West directions. A flux-gate senses the Earth's magnetic field and generates an analog signal in accordance therewith. The analog signal is converted into a corresponding digital signal by an analog-to-digital converter. The controller receives the corresponding digital signal and converts the digital signal into a degree heading.

Abstract: A magnetic transient detection technique which alerts a microcomputer of an auto-calibrating compass when electrical transients which produce magnetic transients have occurred. The technique employs an electronic compass control circuit having a sampling rate high enough to isolate electrical transients from transients produced by normal motion of the vehicle. Accelerations in data values defined as the difference between two changes in the coordinates for the center of the earth's magnetic field circle, are calculated and compared to predetermined threshold accelerations. Previous acceleration values and their associated vehicle magnetic field vectors can be stored in the microcomputer. After a magnetic transient is detected, its associated vehicle magnetic field vector is subtracted from the resultant magnetic field to yield vehicle heading. Once detected, magnetic transients are also used to initiate auto-calibration.

Abstract: A windshield wash and wipe after wash circuit responsive to any of a plurality of wash and wipe conditions causes a wiper arm and blade assembly to park with a high rate of consistency at an absolute park position out of the vision of the operator.

Abstract: The method and system described herein calls for the calibration of an electronic compass without using the operator of the vehicle in the process. This eliminates the need for the operator of the vehicle to help to supply information relating to the earth's unknown magnetic field as sensed from the frame of reference of the vehicle in which the electronic compass resides. The method does not need to make use of the unknown magnetic field due to the earth (as sensed from the frame of reference of the vehicle in which the electronic compass resides) in the process of automatically calibrating the compass. This magnetic field, although unknown, is utilized by viewing the position of the vehicle with respect to the earth's field, thereby eliminating the effect on the compass computation of the earth's magnetic field as sensed in the vehicle.