Non-contact torque sensors based on SAW resonators

A detailed model of an interrogation system performing a continuous tracking of the resonant frequencies of the two SAW resonators is developed and the results of computer simulations are presented. A relationship is established between the amount of noise in the system, the Q-factor of the resonators, parameters of the frequency tracking system and the system bandwidth and the resolution. A variation of the SAW torque transducer sensitivity with temperature is discussed. A theoretical model describing this variation is presented and SAW sensors with a reduced sensitivity variation are suggested and experimentally tested.