THE INCREASE OF THE RELIABILITY AND ACCURACY OF POTENTIOMETRIC PICKUPS OF GYROSCOPIC INSTRUMENTS

The article briefly reviews the modern theory of instrument reliability and discusses the use of potentiometers in aircraft instruments in detail from this viewpoint. It is pointed out that the most vulnerable element in a potentiometer is the electrical contact between the potentiometer winding and the wiping contact. Contact failure is the most serious reliability problem in automatic pilot instrumentation. The design of a reliable contact is therefore discussed in detail and a few design examples are described. The possibility of increasing the reliability by providing a second parallel contact is examined and its effect on the potentiometer performance and error is illustrated by specific examples. The reasons for contact failure are discussed, and the case when two parallel contacts are used, one of which is displaced with respect to the other by either one turn or a half a turn of the potentiometer winding, is examined in detail. Povysgenie Nadezhnosti i Tochnosti Potentsiometricheskikh Datchikov Giropriborov, Edited machine trans. of Aviatsionnyi Tekhnolicheskii Institut, Moscow. Trudy (USSR), n59 p3-4, 111-37 1964.