Torque-Modulated backstepping control for two-dimensional electromagnetic scanners

In this paper, we propose torque-modulated backstepping control for uniform tracking errors in the vertical motion of two-dimensional electromagnetic scanners using only output measurement. Due to manufacturing tolerance, there are parameter uncertainties of two-dimensional electromagnetic scanners so that it is not easy to obtain uniform tracking error performance for the motion control of scanners. In order to resolve the problem, the proposed control law was designed with proportional feedback control with back-stepping approach. We firstly introduce the state-space model of an electromagnetic scanner. The torque-modulated backstepping control was designed for the vertical motion of the mechanical system with only position measurement. Then current tracking controller was implemented with virtual references for the states. We investigated its robust performance via frequency domain analysis with root-locus and sensitivity function. Simulation results are provided to show the effectiveness of the proposed method.