Design of a self-aligning 3-DOF actuated exoskeleton for diagnosis and training of wrist and forearm after stroke

Rehabilitation robotics provides a means of objectively quantifying patient condition before, during and after treatment. This paper describes the design and preliminary validation results of a novel rehabilitation device for the human wrist and forearm. The design features two key aspects: 1) it performs dynamical self-alignment to compensate for misalignment of the human limb and 2) it assists movements within almost the full natural range of motion. Self-alignment is performed by a linkage of parallelograms that allows torque-driven actuation. Advantages are decreased user-device interaction forces and lower don/doff-and setup-times. The full natural range of motion in Flexion/Extension, Radial/Ulnar-deviation and Pronation/Supination allows patients to perform ADL-like exercises during training. Furthermore, in the current design the hand and fingers remain free to perform grabbing activities and the open structure provides simple connection to the patients limb.