Preliminary results on energy efficient 3D prosthetic walking with a powered compliant transfemoral prosthesis

Abstract

This work presents the preliminary experimental validation of a systematic prosthetic control strategy on a custom compliant transfemoral prosthesis with the end result being energy efficient 3-dimension (3D) multi-contact prosthetic walking. In particular, with the goal of capturing essential components of realistic amputee-prosthesis system, a 3D asymmetric hybrid system model is presented — this forms the foundation for formal gait design and control construction. Based on this model, a two-step direct collocation optimization method is utilized to design an energy efficient multi-contact prosthetic gait in 3D. The designed gaits are also subject to various practical constraints such as human-likeness constraints and comfortability constraints. For experimental validation, a 3D capable powered transfemoral prosthetic device is custom built so as to be amendable to realizing the designed 3D prosthetic gaits. Differentiating this device from existing powered prosthesis, compliant components are added to the three joints (two pitch joints and one roll joint) for the purpose of energy saving and human-like behaviors. Combining the presented control methodology and the novel hardware design, the end result is experimentally realized 3D multi-contact prosthetic walking with improved energy efficiency compared to other devices and control methods.