Figure 1
EMG-driven model for muscle force estimation. The EMG for muscles M1,2,3 (or more) is rectified and low-pass filtered for envelope extraction. Neuromuscular excitation, u(t), is the input for the activation dynamics. Activation, a(t), drives the contraction dynamics, which is integrated to produce the tendon force. The joint torque, which is compared to the joint torque measured by the dynamometer, is estimated by the sum of the tendon forces multiplied by their respective moment arms (either positive or negative, depending on if the muscle actuates as an extensor or a flexor).