A study of wireless torque sensing based on SAW sensors

Recently, electric power steering systems (EPS) are developed to compensate the transmitted steering forces according to the applied torque. To measure the torque via wireless sensing, the purpose of this study is to investigate a measurement system with two SAW sensors via wireless RF signals. In this implementation, the SAW sensors are attached on a rotational axis and micro chip 8051 is used to control the RF chips (C1100) to achieve the transmitting and receiving task. Measuring the shift of the center frequency of SAW sensors can be used to obtain the applied torque of the rotation axis. The measuring system mainly uses the RSSI signal with respect to the frequency to find the SAW center frequency value, and then the value of frequency shift can be transferred to the torque values. Besides, to achieve the wireless transmission, a coupling-type antenna is applied on the axis. Finally, the torque signal is passed through CANBUS to integrate with the other vehicles electron systems.