Design and Simulation of an Active Ankle-Foot Orthosis with Parameter Optimization

We present the design and simulation of an assistance device for persons with foot-drop. The device works as an active ankle-foot orthosis (AAFO), and we propose to use optimization algorithms to tune its control variables and to select the resistance of a compliant element. This work introduces the use of a rigid body physics engine to simulate the movement of the tibia under normal gait conditions, using it as a basis to simulate the foot-drop condition that appears when dorsiflexion is absent. We add our AAFO model to the physics simulation to evaluate the performance of the orthosis, using the resulting ankle motion as an indicator of its viability. This complete simulation is subjected to optimization to obtain the best controller gains and stiffness parameters. Our results show that the proposed AAFO design promises be lightweight, resistant and functional for helping to restore the ankle movement of its users.