Ongoing research projects
Ongoing research projects in iMMC (May 2022)
This a short description of research projects which are presently under progress in iMMC.
Hereunder, you may select one research direction or choose to apply another filter:
List of projects related to: biomechanics
|ELSA, an ankle-foot prosthesis to restore amputees locomotion |
Researcher: François Heremans
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.
Researcher: Xavier Bollen
Supervisor(s): Benoît Raucent
obtained his master's degree in electromechanical engineering, with specialization in mechatronics in 2011 from the Université catholique de Louvain (UCL), Belgium. In 2016, he obtained his PhD degree from the UCL.
During his thesis, under the supervision of Pr. Benoît Raucent and Pr. Parla Astarci (Cliniques universitaires Saint Luc, Brussels), he developed a new device for minimally aortic valve resection. The device was used on patients undergoing open heart surgery in order to validate its design and its functional principle.
Now he still works on the design of the device and he also works on additive manufacturing inside the IMAP department. Since September 2015, he is invited lecturer at the Polytechnic School of Louvain where he teaches technical drawing to the first year bachelor's students in engineering.
|Modelisation and optimization of bird flight|
Researcher: Victor Colognesi
Supervisor(s): Philippe Chatelain, Renaud Ronsse
This research project aims at modeling and optimizing bird flight. The goal of this modelization is to get a deep understanding of the mechanisms that govern avian flight and the best way to understand it is to re-create it. That is, the flight will be modeled starting from the given anatomy of a bird and the kinematics will be the result of an optimization process aiming at the most optimal flight.
Compared to other existing studies on the subject of bird flight, this project will follow a "bottom-up" approach, all the way from muscle activation, up to the wing aerodynamics and gait optimization. This approach is necessary to be able to evaluate key values such as metabolic rates, ...
This will allow us to answer a few questions such as :
- What are the mechanisms enabling high efficiency in bird flight ?
- How do we achieve a stable flapping flight ?
This work is purely numerical. The bio-mechanical model of the bird is developed using the multi-body solver Robotran developed at UCL. This bio-mechanical model will be coupled to an aerodynamical model based on a vortex particle-mesh code (VPM) developed at UCL as well.
|Flight Control and Wake Characterization of Migratory Birds|
Researcher: Gianmarco Ducci
Supervisor(s): Renaud Ronsse, Philippe Chatelain
The RevealFlight project aims at shedding light on the efficiency optimization mechanisms deployed by biological flyers, with a specific focus on migratory birds. The efficiency-seeking mechanisms will be sought through the numerical reproduction of flight that includes the morphology, the neuro-muscular configuration and the gait generation. This resulting gait then exploits aerodynamics at the scale of an individual (unsteady lift generation) and at the level of the flock (formation flight). This project thus proposes to synthesize the flight mechanics of birds into a unified framework, combining bio-mechanical, sensory, aerodynamic and social interaction models, in order to reproduce the flying gaits and the interactions within a flock.
A neuro-mechanical model of the birds is currently under development, capturing bio-inspired principles both in the wing bio-mechanics (e.g. structure and compliance) and in its coordinated control (through e.g. a network of coordinated oscillators). The dynamics of this model will be solved by means a multi-body solver and in turn, coupled to a massively parallel flow solver (an implementation of the Vortex Particle-Mesh method) in order to capture the bird’s wake up to the scales of the flock. The study of self-organization phenomena and inter-bird interactions are currently beginning on simple conceptual models, and will be gradually extended to more advanced models developed during the project. It will aim at comparing the efficiency of flocks of selfish flyers with that of flocks in which collaboration takes place, whether implicitly or explicitly.
In my global project picture, the following bottom-up strategy will be adopted:
- Wake characterization: This task studies the wake in terms of the vortex dynamics at play over long distances. The candidate will perform simulations of flying agents in long computational domains in order to capture the wake behavior (topology, instabilities and decay) over longer times and larger scales. This will provide another basis of validation of the project results, given the volume of work on bird wakes;
- Flight stabilization in turbulent or wake-impacted flow: This task aims at the realization of a stabilized flight within a perturbed flow. Two perturbations are envisioned: ambient turbulence and an analytical wake composed of two counter-rotating vortices. Il will Combine previously synthesized gaits and control schemes in order to study the stability of the flyer in a turbulent flow or inside a wake;
- Maneuvers: This task realizes the first maneuvers of the virtual flyer: avoidance and trajectory tracking that will be leveraged in the simulation of multiple flyers that need to interact and swap places. In the present task, this trajectory is still prescribed, in a step towards an autonomous decision-making agent. In order to realize maneuvers, this task implements a control layer above the controllers developed in earlier tasks. Complex maneuvers will be achieved by closing the loop between trajectory errors and the inputs of the lower level controller.
|A microCT-based approach for high-resolution characterization of biodegradable metallic intravascular stent materials|
Researcher: Lisa Leyssens
Supervisor(s): Greet Kerckhofs, Pascal Jacques
The goal of my research project is to assess different potential biodegradable metallic intravascular stent materials using high-resolution 3D microfocus X-ray computed tomography (microCT). In a first step, the optimization of microCT and contrast-enhanced microCT (CECT) for the characterization of the 3D microstructure of different blood vessels is performed (aorta, femoral artery, vena cava). Then, this technique is applied to study the degradation behaviour of potential materials for biodegradable metallic intravascular stents. Structural properties are investigated. They are critical because they will influence the mechanical and in vivo behaviour of the stents. The materials (in the shape of wires) are screened to analyze the corrosion and surface changes, before and after immersion tests (in vitro part) and before and after implantation in rat arteries to additionally study interactions between the tissue (artery) and the metal (in vivo part).
|Ex vivo microfocus computed tomography and contrast-enhanced computed tomography applied to the heart and the heart valves|
Researcher: Camille Pestiaux
Supervisor(s): Greet Kerckhofs
The goal of my research project is to characterize in depth the morphological properties of heart and especially heart valves. Their characterization is currently limited to a qualitative description and quantitative information is still highly lacking. The full 3D microstructure of healthy and diseased heart valves is investigated using high-resolution computed tomography (microCT) and contrast-enhanced computer tomography (CECT).