Magnetic Microrobot Control Based on a Designed Nonlinear Disturbance Observer

Medical microrobots show great promise for precision therapy and drug delivery, such as the treatment of chronic total occlusions. However, magnetic medical microrobots are affected by several factors, such as the medium, the geometry of the microrobots, and the imaging procedure. Notably, traditional control approaches make it difficult or even impossible to obtain reliable physical motion performance of the system. Since the microrobots suffers various uncertainties, the dynamics of microrobots in human tissues (blood or body fluids) is highly nonlinear with multiple uncertainties. Therefore, to achieve accurate motion tracking control for microrobots control system, the obstacles mentioned above must be overcome. In this paper, aiming at the motion control problem of magnetically driven microrobots under the conditions of input saturation constraints, unknown disturbances and model uncertainties, an observer-based control scheme is designed, which uses the minimum knowledge of the system to achieve precise control. The proposed controller consists of an observer designed to obtain an unknown nonlinear magnetic driven microrobots system. According to the designed control law, the exponential disturbance tracking is guaranteed. The experimental results show that the proposed method can effectively overcome the interference problem caused by the unknown uncertainties. Besides, the control performance can be guaranteed.