Haptic Device with Decoupled Motion for Rehabilitation and Training of the Upper Limb

In this paper, a haptic device is proposed for rehabilitation and training for the upper limb. The proposed design for the haptic device has the main feature of decoupling two type of displacement present in the forward-backward motion: the pulling/pushing of the handle and the downwards displacement. The latter displacement is precisely controlling the strength of the stroke. The proposed haptic device is intended for motor-skill rehabilitation, learning new skills or training alternative. The computation of the actuating torques of the haptic device can be achieved with the hybrid dynamic model, based on the Newton - Euler formalism with Lagrange multipliers. In this modeling approach the position of one of the generalized coordinates (the handle's vertical position, imposed by the user) is known and the corresponding haptic feedback (the pushing/pulling force) is computed. The fast computation of the actuation is increasing the quality of the haptic feedback, allowing dynamic consistency over time.