Pulsed interrogation of the SAW torque sensor for electrical power assisted steering

A contactless torque sensor, based on four one-port SAW resonators on quartz substrates working in the 430-437 MHz frequency range, is presented in this paper. The design of the sensor allows full compensation of the bending effect. A single stationary interrogation unit is used to measure resonant frequencies of all four resonators attached to the rotating shaft. The interrogation method is based on a pulsed excitation of the natural oscillations and their subsequent spectral analysis. The achieved standard deviation of the measured frequency difference is sufficient for electrical power assisted-steering applications in the automotive industry.