A Robust Constrained Control of Upper-Limb Exoskeleton for Isometric Rehabilitation Exercises

The research field of muscle rehabilitation and strength recovery is constantly evolving with new techniques and assistive devices being proposed every year. In particular, the need of specialised structures and clinicians, the cost of the rehabilitation and the rising numbers of patients among injured athletes and elderly people, are making rehabilitation robotics a cost-effective alternative. In the last years, researchers have mainly focused on proposing assistive devices to be used during the rehabilitation or new techniques, in order to make the whole process more effective. Nonetheless, the accessibility and the cost of most of the treatments, still leaves a lot of room to improve for a more inclusive access. Besides giving the freedom to the patient to carry out the rehabilitation at home, it is crucial to properly choose the exercise according to the muscles which need to be trained and the condition of the subject. Especially for injured athletes and for the elderly, isometric exercises and static strength training are a good solution to prevent stressing the joints and moving the damaged muscles. Hence, this paper aims to introduce a new musculoskeletal-specific design framework for upper-limb isometric exercises, after having evaluated with a Hexagon Distribution (HD) the muscle condition of the subject. In addition, a 2-DOF wearable and lightweight exoskeleton is introduced to maintain the correct posture of the arm while performing the task. Finally a randomized controlled trial (RCT) is conducted with a cohort of different groups to show the effectiveness of the proposed method.