A Variable Resistance Suit (VARS) and An Extendable Prosthetic Arm (EXPA) for Physical Rehabilitation and Assistance

This dissertation presents the design, development, and evaluation of two novel wearable assistive technologies – Variable Resistance Suit (VARS) and the Extendable Prosthetic Arm (EXPA) – to improve rehabilitation outcomes and functional independence of individuals with musculoskeletal impairment. VARS is a modular, lightweight, and wearable resistance training system that applies bidirectional, speed-dependent, and variable mechanical resistance to the elbow and knee joints. It addresses the limitations of traditional resistance equipment by offering a portable, safer, and more accessible alternative. Importantly, VARS enables targeted engagement of specific muscle groups during training, minimizing the risk of overloading adjacent or compensatory muscles. VARS was evaluated across a series of studies for its biomechanical validity and training efficacy. Electromyographic testing confirmed device functionality, demonstrating proportional increases in muscle activation (pEMG and iEMG) as resistance levels and movement speeds increased. The final evaluation involved a controlled 8-week training intervention with twelve untrained healthy adults, targeting the biceps brachii, triceps brachii, rectus femoris, and biceps femoris of the non-dominant limbs. Results showed significant improvements in muscle strength: a 49.9% increase in isokinetic force and a 30.6% increase in isometric force. These findings support VARS as a feasible, safe, and effective resistance training tool with potential applicability for clinical populations. EXPA is a wheelchair-mounted, motor-driven extendable prosthetic arm developed to help individuals with mobility impairments access out-of-reach objects. The system features a telescopic extension mechanism capable of providing up to 48 cm of reach, a three-finger underactuated gripper, and an actuated elbow joint, all integrated onto a wheelchair. The gripper is controlled via a single-channel surface EMG signal, allowing users to perform grasping tasks with minimal training. Functional testing confirmed its feasibility, intuitive operation, and potential to enhance independence in daily activities. VARS and EXPA contribute meaningfully to the field of rehabilitation engineering by offering scalable, accessible, and safe solutions for both therapeutic and assistive applications.