Conception and Design of a Hardware Simulator for Restoring Lost Biomechanical Function

The Prosthesis-User-in-the-Loop simulator concept represents an approach to integrate users to prosthetic development by a holistic simulation of gait with a prosthesis. It aims at a more user-centered design of lower limb prosthetic devices by utilizing user experience and assessment. As this requires a complex mechanical robot design and sophisticated control strategies that allow for restoring lost biomechanical function, this paper presents the conception and design of a hardware simulator for proof-of-concept studies of those issues. For those investigations, the ankle joints of healthy praticpants are locked mechanically to induce a temporary disability. The task of the simulator is to provide a simulation of physiological gait by artificially restoring ankle functionality. Therefore, the biody-namic behaviour of the locked ankle joint and the enviroment have to be mimicked mechnically. After introducing Prosthesis-User-in-the-Loop simulator idea, the conception of a proof-of-concept simulator is presented. From this, an analytical model is derived and inverse dynamics simulation are used for design. The resulting mechanism is limited to sagittal plane movements and thus has three degrees of freedom. The actuators are dimensioned to meet the requirements of walking motions in the human subject with maximum body height among the test population.