Control methodologies for a heterogeneous group of untethered magnetic micro-robots

In this work, we develop methods for controlling multiple untethered magnetic micro-robots (Mag-mu Bots) without the need for a specialized substrate. We investigate Mag-mu Bots that are geometrically and magnetically designed to respond uniquely to the same input magnetic fields. Designs include: (1) geometrically similar Mag-mu Bots with different values of magnetization; (2) geometrically dissimilar Mag-mu Bots with similar magnetization; and (3) geometrically dissimilar Mag-mu Bots with dissimilar magnetization. The responses of both magnetically hard and soft Mag-mu Bots are investigated. By controlling the input magnetic fields, individual and sub-groups of Mag-mu Bots are able to locomote in a parallel fashion. Specifically, the magnitude and frequency of the imposed driving magnetic fields are used as selection methods among the Mag-mu Bots. Various methods for accomplishing motion discrimination are discussed, modeled, and tested. It is found that while fully decoupled control is not possible with this method, parallel actuation of sub-groups of Mag-mu Bots is possible and controllable.