Design optimization. Schematic of device parameter optimization process used in the design of the swing assistive orthosis. As a first step, System Dynamics are obtained for a particular model of Human leg motion. Using the dynamics, optimization is carried out to find out device parameters. Error from desired final configuration is taken as objective function. Positive ground clearance at discrete points is taken as a constraint. Comparision is made in simuations with and without passive device before building the hardware.