Control Architectures for a Powered Ankle Foot Orthosis

Control Architectures for a Powered Ankle Foot Orthosis

  In this paper, several control methods for a powered AFO are described and tested. As different as they are in their approach, each of them has certain advantages as well as disadvantages. A control concept that meets the unique requirements for ankle gait assistance is needed. One such approach is the dynamic pace controller. This controller adapts to the users" gait speed. This is accomplished through time modulation and amplitude modulation of the reference command at the input side of the Robotic Tendon actuator. Additionally, a new stiffness-control model has been developed that divides the stance phase of gait into five zones using either velocity or stiffness control for each zone. The design and implementation of these new control algorithms as well as experimental results are presented.