Development of a Fuzzy Sliding Mode Controller with adaptive tuning technique for a MRI guided robot in the human vasculature

The concept of using a Magnetic Resonance Imaging (MRI) device for chemotherapy, by employing a micro robot, consisting of a polymer bound aggregate of ferromagnetic particles, is explored in this paper. We primarily contribute towards the design of a Fuzzy Sliding Mode Controller (FSMC) for trajectory tracking of the micro robot in the human vasculature considering a highly non-linear model available in literature. An adaptive algorithm based on Lyapunov stability theory is used to estimate the parameters associated with the FSMC. The proposed FSMC is able to eliminate the chattering phenomenon completely which is present in conventional sliding mode control. Since the system in consideration is a biological one, many parameters are difficult to estimate resulting in parametric uncertainties. A significant merit of the proposed framework is its ability to estimate the dielectric density of blood on-line with great accuracy. Simulation results also indicate perfect tracking with very fast dynamical response. To illustrate the efficacy of our controller, a detailed comparison is made between the performances of a state-of-the-art adaptive backstepping control and our proposed control action in the presence of bounded model uncertainties for micro-robots made up of different ferromagnetic materials.