Seminars and thesis defenses
Design and validation of a bio-inspired active ankle prosthesis
By François Heremans (iMMC / MEED)
Over the last decade, active lower-limb prostheses demonstrated their ability to restore a physiological gait for transfemoral amputees by supplying the required positive energy balance during daily life locomotion activities. However, the added-value of such devices is significantly impacted by their limited energetic autonomy, excessive weight and cost preventing their full appropriation by the users. There is thus a strong incentive to produce active yet affordable, lightweight and energy efficient devices. To address these issues, we developed the ELSA (Efficient Lockable Spring Ankle) prosthesis embedding both a lockable parallel spring and a series elastic actuator, tailored to the walking dynamics of a sound ankle. The parallel spring system is bio-inspired, lightweight and stiffness adjustable, comprising an energy efficient ratchet and pawl mechanism with servo actuation. The complementary rope-driven series elastic actuator is able to generate the active push-off required during daily life activities. Up to 50% of the peak torque is generated passively at a negligible energetic cost (0.1 J/stride). By design, the total system is lightweight (1.2 kg) and low cost. This talk will detail the electro-mechanical design and the validation of the complete system.