Optical Coherence Tomography

OCT-based Visual Servoing

Scientific coordinator: Brahim Tamadazte –  brahim.tamadazte@femto-st.fr

 

Nicolas Andreff

Mouloud Ourak

Lesley-Ann Duflot

Guillaume Cottez

Bassem Dahroug

 

One of our interests concerns the design of a vision-guided control law for microrobotic-assisted biomedical applications using OCT system as a vision sensor. More precisely, the developed control law is to servo automatically and in real-time an optical biopsy task using an optical coherence tomography (OCT) system. The OCT images are simultaneously used to perform the optical biopsy and to servo the sample holder (microrobotic workflow).

 

 

As can be shown in the figure bleow, the OCT based visual servoing can perform accuratly a positioning task during an optical biopsy process. To do this, we use a global image information to design an interaction matrix that links the time-variation of this information to the microrobot spatial velocity. 

 

Related publications

coming soon!

 

 

 

Wavelet-based Visual Servoing 

This work deals with the design of a 6 degrees-of-freedom visual servoing controller. Instead of the conventional use of visual features in the visual servoing control law design, the developed controller makes use of the wavelet coefficients. More precisely, it uses the multiple resolution coefficients representing the wavelet transform of an image in the spatial domain. Therefore, we define the multiple resolution wavelet interaction matrix that links the time-variation of wavelet coefficients to the robot spatial velocity and the associated task function controller (figure below).

 

 

 The wavelet-based controller have demonstrated interesting performances in terms of accuracy (micrometric), robustness and convergence (decoupled aspects). 

 

 

The controller behavior (errors and velocities evolution over time) are dipected below. As can be shown the controller presents a decoupled behavior with an exponential decay of the error. 

Related publications

coming soon!