Synthesis of a Watt II six-bar linkage in the design of a hand rehabilitation robot

• Fingertip trajectory of index finger was captured by using motion capture system.
• Regression was applied to the collection of trajectory data.
• Single DoF Watt II six-bar linkage was decided to be designed to follow desired trajectory.
• Body guidance kinematic synthesis was used to calculate construction parameters.
• Overall rehabilitation device was manufactured as a standalone lightweight system.

As a result of neurological disorders such as stroke, brain and spinal cord injuries, disability in body regions might occur. In case of similar situations, rapid therapeutic training in early stages has chance to prevent permanent disability by retraining motor movements. In regular treatments, therapists help to carry out regular exercises to train motor movements of the disabled region. However, continuous increase in cases, tough working conditions, dependability on expertise and human body limitations make the procedures cumbersome and ineffective. Incorporating robots into therapeutic training not only allows executing treatments in a delicate repeatability but also opens new possibilities in terms of exercise types and speeds. In the light of recent developments in robotic rehabilitation this paper presents the design of a hand rehabilitation robot for human four fingers that solely targets hand disabilities by utilizing real grasping motion data of the forefinger into kinematic synthesis of Watt II six-bar linkage. During the design geometrical synthesis was used for the first loop in order to attain continuous input rotation and the body-guidance synthesis was used for the second loop for the end effector to follow the desired trajectory in desired orientations.