Upper Extremity Rehabilitation Robot
Stroke affects each year more than 15 million people worldwide1. In the US alone, more than 795,000 US people suffer a stroke each year that results in significant deficits in upper/lower Extremity functions and the performance of everyday tasks for those affected2. The problem is further compounded by the constantly growing number of such cases1,2. It is estimated that about two-thirds of stroke survivors incur acute arm impairment3. Therefore, one of the challenging aspects of stroke rehabilitation is upper/lower extremity intervention. The conventional therapeutic approach requires a long time commitment and dedication by both patient and therapist and/or caregiver. There is a pressing need to develop improve treatment/therapeutic approaches to decrease the disability period due to stroke. Citing the constant growth of upper/lower extremity dysfunctions (ULED) and the required prolonged rehabilitation, robot-assisted therapy has already been contributing to upper/lower extremity rehabilitation. Although extensive research has been conducted on rehabilitation robotics, a few robotic therapeutic devices are currently commercially available to provide upper extremity (UE) rehabilitation but are limited to use in a clinical setting. The regulatory approval process4 for medical/therapeutic devices is usually long, as these devices closely work with the human subject.
To provide upper limb rehabilitation therapy, we have developed a 7DOF exoskeleton type therapeutic robot named Smart Robotic Exoskeleton (SREx). The SREx comprises a shoulder motion support part, an elbow and forearm motion support part, and a wrist motion support part. It is designed to be worn on the upper limb’s lateral side to provide (i) shoulder joint vertical and horizontal flexion/extension and internal/external rotation, (ii) elbow flexion/extension motion, (iii) forearm pronation/supination, and (iv) wrist joint radial/ulnar deviation and flexion/extension motion. The exoskeleton was developed based on the upper-limb biomechanics and was designed for use by typical adults. The SREx’s kinematic model was developed based on modified Denavit-Hartenberg notations, and Newton-Euler formulation was used in dynamic modeling. Nonlinear control techniques, including model-based approaches such as sliding mode control5 and adaptive controller6, were used to maneuver the robots to provide active and passive arm movement therapy. The control architecture was executed on a field-programmable gate array (FPGA) in conjunction with a real-time PC. Experiments were carried out with healthy adults where typical rehabilitation exercises for single and multi-joint movements were performed.