SAW torque sensor for marine applications

Design of a torque sensor for aftermarket installation on marine propeller shafts is presented. The sensor is based on UHF SAW resonator sensing elements bonded to plate transducers that are clamped on the shaft and interrogated in a non-contact way through an easily installable RF coupler. A method of calibration of the transducers is described and the torque data logged during a one year period of testing on a ship are presented.