Uncalibrated Visual Servo Control of Miniature Magnetic Robots on Planar Surface

The control of magnetic minirobot is an important area of research because it allows precise micromanipulations and micro-assemblies to be carried out, including medical, biological operations, etc. However, the nonlinear dependence of the electromagnetic force on the current makes the control difficult. In this paper, we used an uncalibrated visual servoing contol to drive the magnetic minirobots to a fixed desired position or through trajectories. The visual features through the Jacobian matrix are estimated by recursive least square and were proposed in [1], [2]. This estimation is used in the control law to supply the required currents for the electromagnetic coils. The controller has been implemented and tested on our physical system with different minirobots. It is independent of the robotic system, robot type, camera configurations. From experimental results, the controller achieves a lower average RMSE for straight and curved trajectories which are aproximately between 4.7 and 5.6 pixels or 1 and 1.2 mm. Additionally, the choice of control variable shows a difference of more than 20 % in terms of energy dissipated during motion control.