A low cost parallel robot and trajectory optimization method for wrist and forearm rehabilitation using the Wii

A robot called the Closed-chain Robot for Assisting in Manual Exercise and Rehabilitation (CRAMER) was developed to assist impaired persons in making three degree-of-freedom movements of the forearm and wrist (forearm supination/pronation, wrist flexion/extension, and wrist ulnar/radial deviation). With a parts and machining cost of less than $1500, this robot was designed to be inexpensive by using a simple parallel mechanism design and off-the-shelf hobby servomotors. CRAMER is intended to engage patients in their rehabilitation therapy by having them play computerbased exercise games. Toward this goal, the remote for Nintendo's Wii was integrated into the handle of the robot in an attempt to allow patients to play the high-quality yet affordable motion-based games that have been developed for the Wii. A framework for planning robot joint trajectories capable of generating desired accelerometer measurements used by Wii games was developed using function optimization techniques. Results of a preliminary experiment with the bowling and golf games of Wii Sports show the feasibility of playing Wii using robot-assisted wrist movements. However, to make this approach clinically practical, an improved software communication with the Wii would be necessary.