François Heremans
Post-doctoral researcher
Dr. at UCL in 2019

Main project: ELSA, an ankle-foot prosthesis to restore amputees locomotion
Funding: Industrial collaboration
Supervisor(s): Renaud Ronsse

Over the last decade, active lower-limb prostheses demonstrated their ability to restore a physiological gait for lower-limb 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 are developing 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 first contribution concerns the developement of a bio-inspired, lightweight and stiffness adjustable parallel spring, comprising an energy efficient ratchet and pawl mechanism with servo actuation. The second contribution is the addition of a complementary rope-driven series elastic actuator to generate the active push-off.
Our new system produces a sound ankle torque pattern during flat ground walking. 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.

IMMC main research direction(s):
Biomedical engineering
Dynamical and electromechanical systems

medical device

Research group(s): MEED