Ph.D. Thesis

Modeling and control of contactless magnetic manipulation systems.
Towards improvement of diagnosis in gastrointestinal endoscopy.

Abstract

Diagnostic techniques currently used in gastrointestinal endoscopy do not allow a complete and accurate observation of the small bowel. Endoscopic capsules were designed to solve this problem, but the doctor cannot control their movement once they are swallowed by patients.

In that context, the work developed in this thesis focused on the use of magnetic fields to manipulate an object (such as a capsule) without contact, on a large workspace. For this, magnetic systems with mobile electromagnets are studied.

Magnetic fields created by electromagnets are first studied. An analytical model taking into account the ferromagnetic core of electromagnets is developed. This provides a computation of the magnetic field fast and precise enough to be compatible with a closed loop control system.

Then, a generic system composed of n electromagnets which can move throughout space is studied. A model of the system is developed, integrating the mobility of each electromagnet of the system. This model is then linearized, allowing us to introduce a linearizing control. This control allows independent management of the movement of each electromagnet, and of the current flowing in it.

Finally, the model and the command are tested in simulation and on an experimental device we designed.

Keywords

Magnetism, electromagnetic modeling, linearizing control, contactless manipulation

You may find my PhD thesis (french version only) here

Post-doc

Clinical evaluation of puncture robots

My post-doc research focuses on two robots with medical purposes: LPR and Prosper. These robots were developed at the TIMC-IMAG laboratory. They aim to:

• help the clinician to perform percutaneous puncture of the chest or abdomen in CT or MRI (LPR project);
• attending the urologist during a brachytherapy or prostate biopsy (Prosper project).

In this context, I set up a quality approach and a number of protocols to assess the capabilities of these robots in laboratory conditions and in clinical conditions, meaning on patients and/or volunteers.

This involves the following work:

• design and fabrication of realistic fantoms;
• design and fabrication of robot components;
• robot programming (in C++ with CamiTK);
• intensive robot testing (including accuracy, EMC, sterilization, etc.);
• reglementary and quality documentation (FMECA, etc.);
• clinical evaluation of the LPR robot on volunteers in the MRI;
• etc.

The video hereafter presents clinical trials of the LPR system on healthy volunteers in an MRI.