Adaptive Disturbance Rejection Controller for Pathological Tremor Suppression With Permanent Magnet Linear Motor

This paper presents an adaptive disturbance rejection (ADR) controller developed for the suppression of the pathological tremor in the humans’ wrist. An experimental setup, based on a slotted permanent magnet linear motor (PMLM), was developed to evaluate the ADR’s performance in real-time suppression of the tremor signal recorded from Parkinson’s disease patients. A model-base compensator was utilized to minimize the resistive and cogging forces exhibited by the PMLM. Experimental results showed an average tremor amplitude suppression of 32.61 dB (97.6%) in the first, and 15.23 dB (82.7%) in the second tremor frequency respectively. The average magnitude of the resistance force induced by the system against voluntary motion was 0.36 N. Furthermore, to evaluate the tremor suppression performance of the presented technique the results were compared with two other studies that used pneumatic actuators and magneto-rheological dampers (MRD). The performance of the PMLM was analogous to actively controlled pneumatic actuators and was significantly better than the semi-active controller with MRD.