Hector Francisco ORTIZ VILLASUSO : "Microrobots compacts à articulations fluidiques actionnés par champ électrique : modélisation, contrôle et développement d’un microrobot parallèle à 3 degrés de liberté

Abstract : Miniaturizing microrobots to the microscale remains challenging due to limitations in actuation technologies and unique physical constraints at small scales. Conventional actuation methods, effective at the macroscale, often fail when scaled down. This PhD thesis presents a microrobot architecture utilizing surface tension forces, where fluid joints (liquid droplets linking solid parts) act as both mechanical linkers and actuators, driven by electric fields. A simulator combining a kinetostatic model and Surface Evolver simulation software was developed to analyze forward and inverse kinematics of microrobots with fluid joints. This tool facilitated workspace analysis and inverse kinematics solutions for a three-degree-of-freedom microrobot, significantly advancing simulation capabilities for design and control. Open-loop control of a 3 μL single droplet achieved displacements up to 140 μm with errors below 10%, while closed-loop control with a 50 nL droplet achieved displacements up to 50 μm with submicron precision, confirming the approach’s feasibility and reliability. The experimental development of a microrobot actuated by fluid joints driven by electric fields demonstrated 3D open-loop position control with errors under 10 μm. For the first time, open-loop control of a robot with fluid joints following a predefined path was demonstrated experimentally. The microrobot, measuring 2.6×2.8×1.0 mm overall, achieved displacements up to 50 μm with 0.1 μL fluid joints. A model-less closed-loop control approach was also studied in simulations. This microrobot architecture shows great potential for minimally invasive applications, supporting further miniaturization to enable even more compact and adaptable designs.

Jury composition :

Mme Aude BOLOPION Directrice de recherche Université Marie et Louis Pasteur Directrice de thèse

1. Antoine BARBOT Chargé de recherche Université Marie et Louis Pasteur Co-directeur de thèse

Quan ZHOU Professeur Aalto University Rapporteur

Pierre RENAUD Professor INSA Strasbourg Rapporteur

Michaël GAUTHIER Directeur de recherche Université Marie et Louis Pasteur Examinateur

Pierre LAMBERT Professeur Université libre de Bruxelles (ULB) Examinateur

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