Observer-based controller for microrobot in pulsatile blood flow

Abstract

Abstract-We propose an observer-based controller for a magnetic microrobot immersed in the human vasculature. The drag force depends on the pulsatile blood velocity and specially acts on the microrobot dynamics. In the design of advanced control laws, the blood velocity is usually assumed to be known or set to a constant mean value to achieve the control objectives, whereas the sole robot position is measured. We prove the stability of the proposed observer-based controller combining a backstepping controller with a mean value theorem (MVT) based observer. The resulting estimation of the blood velocity is then illustrated and compared to high gain observer results through simulations.

Hemodynamics Challenges for the Navigation of Medical Microbots for the Treatment of CVDs

“…However, the hydrodynamics for the case of unsteady cross-flow have been studied far less, with most studies dealing with the enhancement of heat transfer when compared to steady flows and, particularly, focusing on the lock-on effect (i.e., synchronization of vortex shedding frequency with the frequency of the forced pulsations) [ 77 ]. Regarding a numerical approach, the effects of pulsating blood flow on the dynamics of microbots have been recently analyzed by Ferreira and co-workers [ 78 , 79 , 80 , 81 ]; although they considered pulsatile blood velocity to determine the non-linear drag force over the microbot, they did not analyze the blood flow dynamics around the microbot. From the analytical perspective, Plotner et al [ 82 ] investigated the magnetic propulsion of a microbot in pulsating flow; they concluded that gradient fields of around 200–400 mT/m could allow navigation in small blood vessels and reductions in the average and peak blood flow velocity are the key variables for practical use in a clinical environment.…”

2D Observer-Based Control of a Vascular Microrobot

“…Yet, the former lacks from formal convergence proof for this nonlinear system, whilst the latter is known for its output noise sensitivity, especially as the system dimension increases [13]. We have recently proposed an alternative MVT observer-based controller in [14], based on the works of [15], which results in both the stability of the observer-based controller and an improved robustness to output noise. [16] has completed the previous work addressing the robustness to parametric uncertainties.…”

Adaptive control of microrobot in pulsatile flow

“…Since blood velocity is required for control purposes, disturbance rejection is not appropriate either. To circumvent these issues, we have consequently proposed high gain and MVT based observers [15] respectively in [16], [17] to estimate the blood velocity and use it in the control law. Yet the robot modeling involves many physical and physiological parameters whose variability induces parametric uncertainties.…”