Rehabilitation trainer for upper extremities using gravity balancing

Abstract

Rehabilitation devices have been progressively developed over the years to train and assist people who have limbs impairment in movement due to hemiparesis, arthrogryposis and spinal injuries. In order for them to regain their basic function of their limbs, passive gravity balancing technique is one of the ways to train their muscles with the weight of their limbs been removed. Passive gravity balancing has been widely used in many other areas beside rehabilitation devices. This technique has been applied on making equipoised lamp, tower cranes and kitchen cabinets.

This report concerns the design and development of a device for the rehabilitation of the upper arms with passive gravity balancing. This device has 2 rotating links and the gravity balancing is achieved with the use of extension springs, pulleys and cables. The load and center-of-mass of the device are generated with reference to the anthropometry diagrams. The prototype is fabricated according to the specifications of an average human arm. A series of test will be performed to find out the torque induced in the joints and the amount of force occurred in the center-of-mass of the system.

Experiments are set up to test the concept of gravity balancing. Two modes of tests are conducted by measuring the tension in the cable with and without the springs. It is found that the tension on the cable is greatly reduced with the aid of spring. However, the balancing effect is not as significant when the prototype is worn on the human arm. Further improvements are suggested in the report.