Magnetostrictive Torque Sensors — Analysis of Performance Limits

It is shown that the measured materials property of magnetostriction affects sensor output signal in two fundamentally different ways. The dual influence of magnetostriction on sensor output signal has heretofore not been reported.

Five different methods of torque measurement signal detection are identified. For each of these detection methods, equations governing signal output are derived and are discussed. It is found that certain signal detection methods have both superior signal-to-noise performance and minimum sensitivity to variation of air gap. These detection methods are identified in the paper.

Six sensor design configurations are analyzed. In the limit of miniature-size sensor design; performances of all signal detection methods are shown to deteriorate as a consequence of effects due to increased cross-leakage of flux between poles.