Ongoing research projects

IMMC

Ongoing research projects in iMMC (September 2020)


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:

Biomedical engineering

Computational science

Civil and environmental engineering

Dynamical and electromechanical systems

Energy

Fluid mechanics

Processing and characterisation of materials

Chemical engineering

Solid mechanics


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List of projects related to: biomechanics




Designing the next generation of ankle prostheses: towards efficient and lightweight designs
Researcher: François Heremans
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.



AVATAR² - Aortic VAlve TransApically Resected and Replaced
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.



Numerical modeling of growth and remodeling in stented arteries
Researcher: Colin Laville
Supervisor(s): Laurent Delannay

The project aims to predict the evolution of the radial contraction of stented arteries using a continuum mechanics model, with application to bio-resorbable stent development. The capture of the stress state evolution in the artery wall requires a material model that includes:
- the modeling of the main constituents such as collagen, elastin and smooth muscles ;
- time dependent evolution such as growth and structural remodeling.
Some developed tools are also used to predict fracture in bended stainless steels.



Bio-inspired neural control for a new generation of transfemoral prostheses
Researcher: Sophie Heins
Supervisor(s): Renaud Ronsse

Designing mechanical devices to restore natural locomotion for transfemoral amputees still raises many challenges. One of them is the development of an efficient control strategy for the prosthesis active joints, with the objective of making it flexible and intuitive to use. The aim of the PhD thesis is to develop a bio-inspired controller for a new generation of transfemoral prostheses, the CYBERLEGs prosthesis, for level-ground walking and for other locomotion tasks. The controller is based on three fundamental neuro-mechanical principles that were observed in healthy humans: motor primitives, local reflexes and postural support. This work also involves the investigation of the optimal combination of these bio-inspired strategies.



RevealFlight
Researcher: Gennaro Vitucci
Supervisor(s): Renaud Ronsse

Currently under investigation is a reductionist model of flight of birds. Main focuses are a neuromuscular control system and fluid-solid interaction at wing level both for a single agent and large flocks.



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.