François Heremans
PhD student
Ir. at UCL in 2015

Main project: Designing the next generation of ankle prostheses: towards efficient and lightweight designs
Funding: F.R.S-FNRS
Supervisor(s): Renaud Ronsse, Bruno Dehez

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 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

medical device

Research group(s): MEED


Recent publications

See complete list of publications

Conference Papers

1. Heremans, François; Vijayakumar, Sethu; Bouri, Mohamed; Dehez, Bruno; Ronsse, Renaud. Bio-inspired design and validation of the Efficient Lockable Spring Ankle (ELSA) prosthesis. In: 2019 IEEE 16th International Conference on Rehabilitation Robotics (ICORR), IEEE, 2019, 9781728127552. doi:10.1109/icorr.2019.8779421.

2. Heremans, François; Dehez, Bruno; Ronsse, Renaud. Design and Validation of a Lightweight Adaptive and Compliant Locking Mechanism for an Ankle Prosthesis. In: 2018 7th IEEE International Conference on Biomedical Robotics and Biomechatronics (Biorob), IEEE, 2018, 978-1-5386-8183-1. doi:10.1109/biorob.2018.8487209.

3. Heremans, François; Ronsse, Renaud. Design of an energy efficient transfemoral prosthesis using lockable parallel springs and electrical energy transfer. In: Rehabilitation Robotics (ICORR), 2017 International Conference on. Vol. 0, no.0, p. 1305-1312 (2017). doi:10.1109/ICORR.2017.8009429.

4. Heremans, François; Van der Noot, Nicolas; Ijspeert, Auke J.; Ronsse, Renaud. Bio-inspired balance controller for a humanoid robot. In: 6th IEEE International Conference on Biomedical Robotics and Biomechatronics (BioRob), IEEE, 2016, 978-1-5090-3287-7, p. 441-448. doi:10.1109/BIOROB.2016.7523667.


1. Heremans, François. Design and evaluation of a lightweight, low-cost and energy efficient active ankle prosthesis, prom. : Ronsse, Renaud ; Dehez, Bruno, 25/11/2019.