Contacless Medium Accuracy Absolute Position Sensor

There are not many space-qualified contactless absolute position sensors with a measurement accuracy of a few tenth of degrees available on the market. Sensors used to control mechanisms that are operated over an extended lifetime (60 Mrevs) are usually based on optical encoders and therefore sensitive to radiation and mechanical alignment. If the high resolution provided by those optical encoders is not requested for a particular application, the use of a more robust and cost-effective solution should be envisaged. The position sensor qualified for the MetOp-SG 3MI Filter Wheel Mechanism (FWM) fills this gap: a medium accuracy magneto-resistive position sensor used for industrial applications has been enhanced to increase its robustness against environmental loads. This paper will present the sensor working principle and the improvements made to make an industrial sensor suitable for space applications.