A New Master-slave Control Method for Implementing Force Sensing and Energy Recycling in a Bilateral Arm Training Robot

Recently, bilateral arm training has attracted great attention in the development of rehabilitation robots to provide therapy for hemiplegic patients with a unilaterally disabled limb. It has been proved that bilateral arm exercise can stimulate ipsilateral corticospinal pathways and enhance recovery; also the coordination of the two limbs can reduce hypertonia and abnormal synergies compared to unilateral limb training. In conventional bilateral arm training robots, the healthy limb provides a reference movement and the robot gives an assistant force for the impaired limb to implement mirror image movements, or the healthy limb assists the impaired limb to accomplish the desired movement, whereas no resistant force was supplied for patients with the healthy limb to perform strength enhancement training. This paper introduces a novel masterslave rehabilitation robot to implement bilateral arm coordinated training. The robot supports passive, active-assisted, and active-constrained training modes. No matter in which mode, the corresponding force provided for the impaired limb is from the healthy limb. A prototype was developed with two identical motors. A subject controls the two motors with his/her two limbs to accomplish desired movements. Preliminary tests were conducted, the results confirm the validity of the system in different training modes, and verify the system’s force sensing capability, energy recycling function, and bidirectional controllability.