Estimation of Input Rotation Speed in Gauge-Sensorized Strain Wave Gears

Most modern robotic joints are equipped with strain wave gears (SWG) as well as measurement devices like encoders and torque transducers. Torque information can also be gained without torque transducers from strain gauge sensors that are mounted on the flex spline, the deformable part of SWGs. These sensor signals provide, in addition, information about the input rotation speed and can therefore be exploited for its estimation. This paper focuses on this input rotation speed estimation by means of a peak-to-peak scheme, a trigonometric function approach by utilizing an alternative sensor setup, an extended Kalman filter (EKF), and a frequency-locked loop. The analysis leads to the conclusion that the EKF shows the highest potential to accomplish this task.