Vision-based magnetic actuator positioning for wireless control of microrobots

Abstract

This work is concerned with targeted drug delivery inside the human body using magnetic microrobots. It proposes a vision-based magnetic platform for guiding microrobots in both open-loop/closed-loop schemes. The open-loop scheme can be used for example in the case of the inner ear, where the microrobots cannot be localized in real time. On the other hand, for more accuracy, closed-loop scheme can be used for organs as the human eye since microrobots can be localized using a vision sensor. For both schemes, the platform is designed to compensate for human body movements. It is composed of a new magnetic actuator mounted on a robot end-effector and a hybrid vision system. The latter consists of a camera and two microscopes, while the newly proposed magnetic actuator is built using four permanent magnets. The proposed actuator has been designed to create a local maximum of the magnetic field magnitude in a planar workspace. This results in a convergence point for magnetic microrobots that are in its influence zone, making possible open-loop control with a satisfactory accuracy. The procedures for calibrating each component of the proposed platform are described and validated. Finally, several experiments have been carried out to validate the modeling part and to show the feasibility of the concept. The obtained experimental results show that using such platform, the microrobots guiding can be achieved in open-loop under reasonable perturbations and in closed-loop with an accuracy of 200 μm.