Independent and Leader-Follower Control for Two Magnetic Micro-Agents

Microrobotics is a promising field that can revolutionize fields such as minimally invasive surgery. Applications such as micromanipulation can be performed more effectively using multiple microsized agents. These can be performed more accurately with the help of robust controllers. In this letter, we design a leader-follower controller that can be used to perform coordinated motion tasks. A prescribed performance controller is designed for the leader micro-agent whereas a synchronization controller is designed for the follower. The main difference between ourmethod and the literature is that ourmethod can achieve a prespecified control performance. The positions of the micro-agents are obtained using microscopic images and image processing. The velocities and accelerations of the micro-agents are obtained using state observers. The algorithm is tested experimentally on spherical magnetic microparticles that have an average diameter of 100 mu m. Two types of experiments are performed. The first one is related to the leader-follower control, whereas the second one demonstrates the independent control of the two agents. The maximum value of the steady-state errors obtained in the leader-follower control experiments are 14.45 mu m and 10.19 mu m in the x-and y-directions for the leader agent and 6.47 mu m and 7.77 mu m in the x-and ydirections for the follower errors, respectively.