Abstract: A position sensor having a magnetic proximity switch comprising relatively movable reeds (10, 12) having magnetic properties and a magnet (28) adapted to establish a magnetic flux field (18) that envelops the reeds (10, 12) to establish a magnetic attraction between the reeds, the strength of the magnetic flux field depending upon the spacing of the reeds with respect to the magnet, the magnetic attraction of the reeds being sufficient to cause them to move into electrical contact as the magnetic flux field in the vicinity of the reeds is changed in intensity as a magnetic shield (30) is moved through the flux field whereby the opening and the closing of a circuit defined by the reeds provides an indication of the position of the shield (30) with respect to the reeds (10, 12).

Abstract: An electronic control system for a steering system having an electric motor coupled to the steering system for providing power assist. The steering system is of the rack and pinion type having an input gear coupled to the steering wheel and a pinion gear in meshing engagement with the rack. Two torsion sensors are coupled across the input and pinion gears and generate analog output signals. When no input torque is applied to the steering wheel, the output signals from the two torsion sensors are equal. When input torque is applied to the steering wheel, the signals from the torsion sensors vary substantially linearly in opposite directions. An electronic control unit controls operation of the electric power assist motor in accordance with the output signal from one of the torsion sensors. Failsafe circuitry is provided for monitoring the outputs of the redundant torsion sensors to insure proper control of the electric power assist motor.