Developing a Quasi-Static Controller for a Paralyzed Human Arm: A Simulation Study

Individuals with paralyzed limbs due to spinal cord injuries lack the ability to perform the reaching motions necessary to every day life. Functional electrical stimulation (FES) is a promising technology for restoring reaching movements to these individuals by reanimating their paralyzed muscles. We have proposed using a quasi-static model-based control strategy to achieve reaching controlled by FES. This method uses a series of static positions to connect the starting wrist position to the goal. As a first step to implementing this controller, we have completed a simulated study using a MATLAB based dynamic model of the arm in order to determine the suitable parameters for the quasi-static controller. The selected distance between static positions in the path was 6 cm, and the amount of time between switching target positions was 1.3 s. The final controller can complete reaches of over 30 cm with a median accuracy of 6.8 cm.

I. Introduction

Functional electrical stimulation (FES) is a promising technology that restores movement to paralyzed muscles by delivering electrical current to the nerves and muscles directly. Using FES to control reaching motions could allow individuals with paralysis from spinal cord injuries to regain their independence.