Improved torque fidelity in harmonic drive sensors through the union of two existing strategies

The torsional compliance of harmonic drives lends itself to torque sensing, but the elliptical wave generator in harmonic drives introduces a spatially dependent local torque ripple on the flexspline of harmonic drives. It is difficult to extract the applied torque signal from this local torque ripple if the applied torque is sensed at the flexspline of the harmonic drive. Previous methods have used spatially offset Wheatstone bridges or gain tuning to attenuate torque ripple. The authors have found that combining both of these techniques through a different wiring configuration can attenuate local torque ripple to plusmn0.5 Nmiddotm, a better ripple reduction than either method alone. This local ripple reduction is adequate for large-range torque applications, but is not adequate for precision torque applications