High-speed high dynamic range resonant SAW torque sensor for kinetic energy recovery system

The torque sensor capable of working in the extreme environment of race cars has been developed for the Fl kinetic energy recovery system. The sensor was based on two SAW sensing elements containing five one-port resonators that were attached to the KERS shaft. The achieved dynamic range of the sensor was 69 dB, the update period was 310 εs and it could work at the rotational speed up to 18000 rpm and temperatures up to 160°C. The mechanical design of the sensor ensured its small size and provided sufficient mechanical robustness allowing to survive very intense vibrations. Despite its small diameter, the non-contact rotary RF coupler connecting the sensor to the interrogation unit ensured strong enough SAW response at its input, very small rotational errors and small sensitivity to the axial movement. A number of changes in the interrogation algorithm, in particular, in the frequency tracking procedure, significantly improved stability of the sensor performance in dynamic regime. At the end of the development stage, the sensor successfully worked on race cars.