Design and evaluation of exoskeleton device for rehabilitation of index finger using nature-inspired algorithms

This work proposes a novel robotic exoskeleton for rehabilitation of the index finger. Though all motions of index finger are essential, the major range of motion is covered by flexion/extension motion. Hence, a Stephenson III six-bar mechanism has been synthesized for the robotic exoskeleton device for a pre-defined trajectory to address post stroke rehabilitation of patients. The flexion/extension trajectory was obtained experimentally using image processing. Based on the trajectory, a mathematical model was formulated which was used as the objective function for the optimization problem. To eliminate any defects that may be encountered during the synthesis, “loop-by-loop defect rectification” procedure was implemented along with well-established optimization algorithms such as TLBO, BWP, GWO and PSO for synthesis of the desired mechanism. It has been found that TLBO outperformed all the others as it could reduce the objective function value to 0.69849. whereas, BWP reduced it to 8.9952, GWO reduced it to 13.1388, and PSO could only reduce it to 6 × 10⁵. Therefore, the design obtained using TLBO was considered for developing the prototype of the device. The device was validated experimentally using image processing, and it is found to cover the prescribed range of motion. Thus, the proposed exoskeleton is deemed to be a viable solution for post stroke index-finger rehabilitation.