Hand Exoskeleton to Assess Hand Spasticity

In this paper, a prototype exoskeleton is proposed to perform active finger movements to mimic a therapist for assessment of hand spasticity. Current methods for assessing spasticity are based on the subjective appreciation of physiotherapists as there is no quantifiably standardized method of evaluation and no rigorous method to record data for monitoring. For the purpose of imitating the therapist’s movements and recording data pertaining spasticity, servos are used to manipulate each joint in an index finger in a programmable and controlled way. Film type force sensors are used at fingertip to judge the maximum opening and closing capability of the patient’s hand in relation to the force which would be felt by a therapist due to the patient’s resistance to passive movement. Using potentiometers and positional data from the servo motors the trajectory of the finger joints is recorded in parallel to the fingertip force applied during the movement. The exoskeleton is a three degrees of freedom system which can move the index finger through an entire range of motion. The physical prototype and the software control module have been tested to validate the functionality of the mechanical structure, measuring, and recording capabilities. A GUI software tool is designed to be user friendly for the medical therapists and to produce a report document in a style familiar to them. Positive feedback was obtained from medical therapists about this initial prototype.