The Circumduction Therapy on Exoskeleton Rehabilitation Robot

While the aging society goes, more and more elders suffer from stroke or frozen shoulder, two most common diseases, which lead to upper-limb motor impairments. These diseases need appropriate physical therapy to regain health. However, the traditional therapies are always labor-intensive and fail to extremely accurate. In order to implement accurate physical therapies and alleviate the burden of both therapists and caregivers, we develop a rehabilitation robot to improve this situation. In this research, a traditional rehabilitation therapy, called circumduction with some new characteristics, is implemented on the rehabilitation robot NTUH-II. The circumduction therapy includes three modes, passive mode, active-assistive mode, and active mode. The circumduction therapy rehabilitates the omnidirectional Range of Motion(ROM), and also allows patients to interact with robot effectively and so that they can recover their muscle strength better. More specifically, NTUH-II has large ROM which facilitates the complete circumduction therapies. Moreover, the proposed active-assistive control strategy accompanied with active control strategy makes the interaction between human and robot smoother and the hand trajectory will approach to a circular trajectory after some transient. As for passive mode circumduction, the radius and hand velocity along the drawn circular trajectory are given by therapist, and the robot will move the patient’s arm so that his/her hand will trace a perfect circular trajectory. Patients have no need to apply force on robot. As for active-assistive mode, robot will apply an assistive force to patient’s arm, so that the patient only needs to pay little effort to move his arm. Incidentally, the exact force exerted by the patient to the robot will be recorded for further assessment. We also provide active circumduction, which lets the patient take a free motion while applying force to the robot, also for the purpose of drawing a circular trajectory with hand through visual feedback. Then, we will compare the motion trajectory with the most fitted circular trajectory, and do assessment. This is a novel method implemented on rehabilitation robot for assessment of recovery level. Extensive experiments are done to verify the feasibility and performance of therapy under three different modes circumduction.