The objective of this project is to provide researchers with access to a fully capable and standardized open-source robotic leg research platform, without the immense burden of developing each component from scratch. The outcome will be a robust and inexpensive test bed that can be easily manufactured, assembled, and controlled. One of the greatest challenges to the design and commercialization of robotic prosthetic legs is the control strategy -- that is, the computerized instruction set that specifies the effort level and timing for each component of the mechanism. Challenges in developing control strategies stem from the many different functions that an active robotic limb must accomplish. One important function is to detect the amputee's intention to perform different mobility activities, such as walking on a level surface versus ascending or descending stairs. Another important function is to coordinate the pattern of effort and movement of the prosthetic limb in order to emulate the healthy human body. There are many researchers working independently on better control algorithms to address challenges such as these. To be of value, these algorithms must be tested and validated experimentally. Research groups around the world have created a variety of specialized robotic leg designs for this purpose, representing a significant investment of time and effort. The resources required to obtain a suitable research platform represent a substantial obstacle for new researchers to overcome. Furthermore, the vast difference in designs used by established researchers hinders the comparison of new control strategies across research groups. The accessible, standardized leg platform resulting from this project will lower barriers to entry, allowing new researchers to study the control of robotic legs, to unambiguously compare different control approaches, and to generally advance the field. Finally, the improved prosthetic leg designs arising in the long term from this project will benefit the lives of amputees.
The overall research goals of this project are 1) to identify an electromechanical design for a low cost, high performance, open-source robotic knee and ankle system; 2) to understand how separate prosthesis control strategies can be combined to benefit amputee gait, and 3) to evaluate and compare resulting controllers in amputee experiments. The approach utilizes a novel design methodology employing selectable series elasticity and high-torque motor technology to achieve high performance at low cost. Interchangeable control modules in the open-source architecture allow researchers to investigate new control methods at low, mid, and high levels of the system, that is, motor drive, joint control, and human intent recognition, respectively. In particular, a reflex-based approach and a phase-based approach will be implemented as mid-level control modules and a high-level intent recognition module will enable the robotic leg to automatically switch between different user activities. In all cases, having the new robot leg available together with these algorithms will enable testing in real-world scenarios, rather than being confined to the laboratory. The results of this project will lower the barrier for conducting research and enable fair comparison across different control approaches with standardized leg hardware. Finally, the proposed work will impact students and the community through training, outreach, and dissemination.
