SBIR Phase I: Compliant Nonlinear Quasi-Passive Orthotic Joint

This project seeks to develop an orthotic knee joint system that includes a non-linear torsion spring coupled with a novel concept called Morphological Switching (MorS) that changes the mechanical properties of the joint in response to user behavior. The research objectives are to prototype and functionally test the medial side of a Morphological Switched Orthotic Joint (MSOJ) assembly. Tasks include: a) fabricate and test prototypes of all joint components; b) mechanically integrated all prototype joint components and functionally test the MSOJ with control algorithms; and c) the MSOJ will be tested to assess functional benefits. Telemetry data will be collected during 200 steps at slow, medium and fast walking speeds and descending 200 stairs and be processed with a program that assesses biomechanical benefits. We expect the results to provide convincing quantitative proof of the ability of the MSOJ to create an energy efficient knee brace. The intellectual merit of the proposed project stems from the application of MorS to take the springs in the system, which are clearly passive, and allow the user to perceives the springs as having a dynamic stiffness whose behavior changes dependent on what the user does. The broader impact / commercial potential of this project stems from its impact on the estimated worldwide population of 150 million people who have mild/moderate walking dysfunction not currently addressed by any existing orthosis device. MSOJ offers new biomechanical benefits to this population group including adapting to whatever leg strength the user provides, adapting to the user selected speed and step length, reducing the effort needed to walk, providing complete torso support while ascending and descending stairs and preventing falls due to knee collapse resulting from insufficient leg strength. Novel technologies introduced include a synthesis methodology for designing non-linear hardening spring, actuators that need no battery energy to generate holding forces, sensors for measuring gait parameters and a distributed fault tolerant electronics architecture. The orthoses created with MOSJ would be the first assistive appliance that stores all sensor data and enables real time and/or background access of the data. These joints are expected to allow rehabilitation therapy to be delivered and monitored in remote settings during all Activities of Daily Living. MOSJ components will also be made available to researchers to allow fabrication of custom appliances for their rehabilitation research.