Antoine ANDRE :Robust visual measurement with large range to resolution ratio of 3D pose of encoded periodic patterns : applications to microrobotics

Abstract : Pose measurement at the microscale is a major challenge with multiple applications in the microrobotics field where high resolution sensors are expected. At a macroscopic scale, computer vision allows the 3D pose measurement of objects with great resolution and robustness. However, as the size of observed objects decreases, the problems inherent to microscopy such as short depth of focus, small field of view or microscope objectives orthographic projection imply a better structuration of objects of interest.
This thesis tackles this problematic with the use of periodic patterns. The structured redundancy of information contained in these ones allow resolution up to one thousands of a pixel by using the phase of these patterns. The inherent problem of the range of measure reduced to the microscope's field of view is solved by integrating a binary sequence without inducing phase disturbances, preserving the resolution capabilities of the method. Resulting pseudo-periodic pattern provides a range of measure of 10^5 x 10^5 px².
By relying on local phase-based thresholds, the method demonstrates a great robustness against various noises, occultations, defocus and makes this method appropriate for the microrobotics field of application.
this method has been validated by multiple experiments demonstrating a planar resolution of 1 nm in translation on a 10 x 10 cm² range and a 4.5 µrad. resolution in orientation over 2pi rad. Measure of out-of-plane orientations show a resolution of 100 µrad. in a [-pi/8; pi/8] rad. range. Finally, this manuscript presents the use of this pose measurement method in multiple microrobotics applications where a resolute and contactless method is required.

Jury composition : 

1. Guillaume LAURENT Maître de conférences Université Bourgogne Franche-Comté  PhD Director
2. Eric MARCHAND Professeur des universités Université de Rennes 1 Reviewer
3. Youcef MEZOUAR Professeur des universités SIGMA Clermont-Ferrand Reporter
4. Peter STURM Directeur de recherche INRIA - Grenoble Rhône-Alpes Reporteur
5. Patrick SANDOZ Chargé de recherche Université Bourgogne Franche-Comté PhD Co-supervisor
6. Maxime JACQUOT Professeur des universités Université Bourgogne Franche-Comté PhD Co-supervisor

Localization : Amphithéâtre Jules Haag - ENSMM 26, Rue de l'Epitaphe 25000 Besançon