System identification of non-linear, dynamic EMG-torque relationship about the elbow

The surface electromyogram (EMG) from biceps/triceps muscles of 33 subjects was related to elbow torque, contrasting EMG amplitude (EMGσ) estimation processors, linear/non-linear model structures and system identification techniques. EMG-torque performance was improved by: advanced (i.e., whitened, multiple-channel) EMGσ processors; longer duration training sets (52 s vs. 26 s); and determination of model parameters via the use of the pseudo-inverse and ridge regression methods. Best performance provided an error of 4.65% maximum voluntary contraction (MVC) flexion.