Ana Lucia Cruz Ruiz PhD Defense

Low-Dimensional Control Representations for Muscle-Based Characters: Application to Overhead Throwing

The presentation will take place at INRIA Rennes, in room Métivier (C024), on Friday December 2nd, at 10:30am.

PhD committee / Composition du jury:

Michiel van de Panne, Professeur, University of British Columbia / Rapporteur
Philippe Souères, Directeur de Recherche, LAAS-CNRS / Rapporteur
Laurence Chèze, Professeur, Université Claude Bernard Lyon / Examinatrice
Sophie Sakka, Maître de Conférences, École centrale de Nantes / Examinatrice
Georges Dumont, Professeur, École Normale Supérieure de Rennes / Directeur de thèse
Charles Pontonnier, Maître de Conférences, Écoles de Saint-Cyr Coëtquidan, École Normale Supérieure de Rennes / Co-encadrant de thèse


The use of virtual characters in physics-based simulations has applications that range from biomechanics to animation. An essential component behind such applications is the character’s motion controller, which transforms desired tasks into synthesized motions. The way these controllers are designed is being profoundly transformed through the integration of knowledge from biomechanics, which motivates the idea of using more detailed character models, inspired by the human musculoskeletal system (or muscle-based characters). Controlling these characters implies solving an important challenge: control redundancy, or the fact that numerous muscles or actuators need to be coordinated simultaneously to achieve the desired motion task.

The goal of this thesis is to address this challenge by taking inspiration from how the human motor control system manages this redundancy. A control solution for virtual characters is proposed based on the theory of muscle synergies, and applied on the control of throwing motions. Muscle synergies are low-dimensional control representations that allow muscles to be controlled in groups, thus reducing significantly the number of control variables.

Through this solution this thesis has the following contributions: 1) A contribution to the validation of the muscle synergy theory by using it to study a new motion, and challenging it with the control of a virtual character, and 2) a contribution to the variety of domains involving physical simulation with muscle-based characters (e.g, biomechanics, animation) by proposing a control solution that reduces redundancy.

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