Abstract

An improved position encoder system for providing an output signal representative of the position of a movable body, relative to a reference position, includes at least one magnetic element fixedly attached to the movable body. The system further includes a first spatially orthogonal fluxgate sensor pair and a second spatially orthogonal fluxgate sensor pair for detecting the magnetic field. The first sensor pair is disposed adjacent to the polar axis at a first predetermined distance, and the second pair is disposed adjacent to the polar axis at a second predetermined distance, preferably twice the first predetermined distance. The system further includes a signal processor for receiving a signal from the first sensor pair and a signal from the second sensor pair. The signal processor produces an output signal that corresponds to a predetermined combination of the signal from the first sensor pair and the signal from the second pair, such that a resulting relationship between the output signal and the position of the movable body is substantially linear. Motion of the movable body may be rotational or linear, such that the encoded position is angular or linear. Proper placement of the sensors along the magnetic element of a linear position encoder enables a range of motion significantly beyond the total length of the magnetic element. Eccentric placement of the magnetic element on a rotatably movable body provides a substantially linear position-to-output signal relationship with relatively little processing of the resulting sensor signals.