Local Controllability, Trajectory Planning, and Stabilization of a Two-Agent Underactuated Microrobotic System

Multimicroagent systems are appealing to perform targeted therapy, biosensing, and diagnosis. However on most magnetic platforms, the magnetic field is stationary so all the robots experience the same control input, resulting in an underactuated system. However, to date, the controllability of underactuated microsystems had hardly been addressed. This article thus investigates the system local controllability. This result highlights the necessity for the agents to operate in close vicinity to achieve trajectory tracking along an admissible reference trajectory whose choice is discussed. We then propose a backstepping controller to locally stabilize the nonlinear system. Simulations illustrate this approach efficiency and limitations for different designs of the microrobotic system.