Planar Path Following of 3-D Steering Scaled-Up Helical Micro Swimmers

Helical microswimmers, capable of locomotion in environments with low Reynolds numbers, hold immense promise for a wide array of applications. Numerous artificial magnetically-propelled helical microswimmers have been designed by the scientific community, although they primarily function based on open-loop control. This paper endeavors to explore methodologies relating to the closed-loop command of a magnetically actuated helical swimmer operating in conditions of low Reynolds numbers, employing visual feedback as a primary tool. Given numerous in-vitro implementations, it is essential for these helical swimmers to pass through a defined path, such as through channels with no prerequisite on the velocity profile along the said path. Thus, the primary objective of this paper is to accomplish a velocity-independent planar path following task. Given the planar path following is contingent on the three-dimensional (3-D) steering of the helical swimmer, we introduce a 3-D pose estimation for a helical swimmer, embodying real-time visual tracking facilitated by a stereo vision system. The contribution of this paper is as follows: The 3-D steering of a helical swimmer is accomplished by visual servo control; and the achievement of following a linear path utilizing visual servo control, then compared with open-loop control method. We further expect that these visual servo control mechanisms will empower helical swimmers to follow the reference paths at microscopic scales.