A Multi-Purpose Finite State-Based Standing Controller for a Powered Transfemoral Prosthesis

Abstract

This thesis presents the design and testing of a standing controller for a powered transfemoral prosthesis that is capable of real-time ground slope adaptation and sit-to-stand and stand-to-sit transitions. The controller is implemented as a finite state machine that performs state transitions based upon mechanical signals measured in the prosthesis. The ground slope adaptation is enabled by an inertial measurement algorithm that utilizes accelerometers and gyroscopes. The performance of the controller is compared to a commercially-available passive prosthesis through testing on an amputee subject. The prosthesis is shown to provide biomechanically normal ankle impedances while standing on a range of ground slopes. Additionally, the test subject’s weight bearing distribution while using the powered prosthesis is improved on all tested slopes relative to the passive prosthesis.