Patent ID: 8666682

Claim:
A device for measuring the torque applied through a rotating member rotating about a longitudinal axis relative to a fixed member, the device comprising: a first torsion reference member fixedly coupled to the rotating member at a first axial position; a second torsion reference member fixedly coupled to the rotating member at a second axial position; a first detector coupled to the fixed member and configured to detect the passage of the first torsion reference member past the first detector upon each full rotation of the rotating member and to generate a first signal upon each passage of the first torsion reference member; a second detector coupled to the fixed member and configured to detect the passage of the second torsion reference member past the second detector upon each full rotation of the rotating member and to generate a second signal upon each passage of the second torsion reference member; and a controller configured to: calculate a phase difference between the first signal and the second signal relative to a time reference during rotation of the rotating member under a torsional load; compare the phase difference to a reference value; and calculate a torque loading on the rotating member resulting from the torsional load based on the phase difference, wherein the controller is configured to calculate the torque loading based upon a ratio of the phase difference and the reference value.