Neuromuscular Electrical Stimulation for Stroke Patients by Deterministic Extremum Seeking

A multiparameter and deterministic extremum seeking (ES) algorithm is applied to tune Proportional-Integral-Derivative (PID) controllers for functional neuromuscular electrical stimulation (NMES). The proposed scheme controls the patient's arm such that the desired movements of flexion/extension for its elbow can be generated. The PID tuning using ES eliminates initial off-line tests with patients since the control gains are automatically computed in order to minimize a cost function according to the tracking error between the elbow's angle and the reference trajectory. Experiments with eight stroke patients show advances in terms of reduced root-mean-square error (RMSE) and improved ultimate responses when compared to the initial evaluation cycle.