Implementation of Rehabilitation Modalities Using a Low-Cost PAM Actuated Robotic Orthosis

Abstract

Robotic rehabilitation is a solution for recovery from neuromuscular diseases and supports physical therapists in performing high-intensity and repetitive training activities. The main reason for the limitations of rehabilitation robot utilization is economic factors because rehabilitation robot technology requires high levels of investment and relatively costly routine operation and maintenance. To facilitate widespread adoption of rehabilitation robots, low-cost, highly compliant, and simple-to-operate robotic rehabilitation devices are required. In this study, to introduce a novel alternative solution to the aforementioned problem, a low-cost, highly transparent, single pneumatic artificial muscle (PAM) actuated robotic therapy orthosis that enables the patient to perform all training modalities is introduced. A novel control approach was developed by combining admittance control and inverse-dynamics-based compliant controls. By means of simple counterweight loads and compliant control, quasi-static movement of the orthosis for active exercises is achieved for the full operation range of PAM without any jerky transitions. A new assist-active modality named 'Patient Activated Assistance' (PAAM) was introduced, in which the patient was the master, and the exercise was performed as long as the patient was active, avoiding slacking. Assistance was provided by sharing the load force in accordance with the applied gain. The orthosis performance in realizing the training modalities was verified using surface electromyogram (sEMG) measurements. The results demonstrated that the proposed low-cost single-PAM-actuated robotic orthosis could be a solution to robotic rehabilitation demands, especially in low-middle-income countries (LMIC).