In this thesis, we design a novel gait rehabilitation passive orthosis to training the people who lost their walking ability due to neurological injuries, such as spinal cord injury and stroke. As known, the movements of pelvis play an important role in balance and propulsion during a gait cycle. In this research, we present and simulate a passive orthosis to assist the motion of pelvis of gait patients for regaining their initial walking pattern. This optimized pelvic device is un-motorized and contains only passive elements. The accomplished simulations are based on presentation of a proper 3D dynamic model of human body by focusing on motions of lower legs during gait on treadmill. Based on solutions of direct dynamics and inverse dynamics, two optimization problems are defined to derive optimum structural parameters of orthosis. The optimization results of direct dynamics show that the optimized time trajectories of pelvic rotations are close to corresponding desired diagrams. Also, by simulating the inverse dynamics, we could obtain the minimum values of torque vector of assumed actuator of hip joint of stance leg. Furthermore, the fabrication of device is performed and experimental results are presented. However, to validate modeling and study the feasibility of using device, we conduct the initial experiments on a healthy subject. We study (a) rotational movements of pelvis and (b) energy expenditure of subject with and without device during walking on treadmill. Increasing range of motion of pelvic and decreasing energy consumption upon using device confirm the validation of simulation results and proper performance of device for gait rehabilitation. Keywords Pelvic rotations, Gait, Passive orthosis, Dynamic model, Optimization, Experimental results.
