A novel rehabilitation system supporting bilateral arm cooperative training

Numerous rehabilitation robots have been developed to deliver therapy for hemiplegic patients with a unilateral-disabled limb or for aged persons with motor-function degenerated limbs. Recently, much attention has been paid to the development of robots that support bilateral arm training in various patterns. It has been proved that the coordination of two limbs can reduce hypertonia and abnormal synergies compared to unilateral limb training. However, traditional robots realized different modes with the robot providing a corresponding force for the impaired limb. This paper proposes a novel bimanual training system. A subject controls master and slave terminal handles with his/her two limbs. The less impaired limb provides a corresponding force for the more impaired limb to achieve different training patterns. No matter in which mode, the two limbs accomplish symmetric movement. An experimental prototype was built. Frequency response test and training tests on 9 healthy subjects in active-resisted and active-assisted modes were performed. Experimental results confirm that the system can correctly respond a subject's commands if velocity was changed within the frequency range of 30 Hz. For each training mode, the average position error, and RMS (root mean square) values of position errors and velocity errors that between the reference values and actual values of a motion tracking task were reduced after practice. This proves the effectiveness of the system for self-assisted rehabilitation training.