The Research on Torque Measurement System Based on Surface Acoustic Wave Sensor

Abstract

Aiming at torque measurement issue of rotating machinery shafts, a wireless torque measurement system was designed based on SAW resonator. Its forming structure and principle were firstly analyzed. The torque sensor with differential structure was constituted by 45 degrees and 135 degrees SAW senators against central line of the rotating shaft. And then a conclusion of theoretical module was made between the resonance frequency difference and torque. It helped to transfer from torque measurement to frequency measurement. Torque measurement system using SAW sensor was built to acquire torque of transmission shafts. It was composed of a acquisitor-transmitter and a data receiver. Experimental result demonstrated the measurement sensitivity was 0.1443KHz/N.m within a measurement range from 0 to 4000N-m. It was close to result of theoretical derivation. Its relative mean error was 0.63% and maximum relative error was 1.3%. The torque measurement system manifested that the SAW sensor based on the difference frequency measurement owned better performance, compared with the torque sensor of strain-resistor. It was suitable for long-distant transmission against interference. The system could be achieved without amplifier circuit with high-gain and strong common-mode rejection. It contributed to lowering the difficulty of circuit design.