Fig. 4

Torque (A) and angle sensor (B–D) validation results. A Linear regression for estimating torque applied to the transducer given a voltage measurement with root-mean-squared error (RMSE). Refer to Additional file 1 for torque sensor sensitivity to out-of-plane loads. B Linear regression relating angle sensor output to motion capture with RMSE; a positive angle corresponds to plantarflexion (PF). C Time series angle measurement with RMSE. D Comparison of sensor-estimated joint velocity to the motion capture result. Refer Additional file 1 for a comparison of sensor and motor velocity estimates during validation (Additional file 1: Fig. S5B)