I. Introduction
Milli/microrobots remotely navigated by magnetic fields have attracted extensive attention due to their potential biomedical applications [1], [2], [3], [4], [5], [6], [7], [8], [9]. Different types of milli/microrobots have been investigated, e.g., spherical [10], [11], [12], helical [13], [14], [15], and bio-hybrid milli/microrobots [16], [17], [18]. Meanwhile, milli/microrobots with different locomotion are also been reported, e.g., millirobots with a composited agglutinate magnetic spray are capable of crawling, walking and rolling [19], soft microrobots consisting of photoactive liquid-crystal elastomers can perform translation and rotation [20], and trimer-like microrobots is able to rolling and chiral rotating [21]. Although various kinds of milli/microrobots have been developed, microrobotic swarms are considered as potential candidates to tackle challenges encountered in low-invasive therapies, such as targeted drug delivery and in-situ sensing [22], [23]. Inspired by the living swarm behaviors in nature, various kinds of mirorobotic swarms have been reported, e.g., vortex-like swarms [24], ribbon-like swarms [25], elliptical swarms [26] and tornado-like swarms [27]. Since microrobotic swarms can hardly be equipped with onboard sensors and circuits, closed-loop control of them is significant for realizing navigated locomotion and pattern adaptive reconfiguration, especially in confined environments [26]. Moreover, tracking a mobile target using microrobotic swarms could be attached with further significances. In this case, dynamic path planning and motion control of the swarms are two important steps to realize the purpose.