Multi-time Scale Control of Dual-Stage Nanopositioning Systems

Abstract

In this paper, a novel multi-time scale control technique is applied to a serial dual-stage nanopositioning system. Dual-stage nanopositioning systems combine a high-speed, short-range actuator and a low-speed, long-range actuator to achieve long-range and high-speed positioning. This results in a system that has relatively complicated dynamics due to the physical interaction between the two actuators and their different time-scales. In addition, models of these actuators can be ill-conditioned, which can lead to issues with numerical simulations and controller design. These issues make dual-stage nanopositioning systems well suited to multi-time scale control algorithms. In the proposed algorithm, the system is split (decoupled) into a set of subsystems, where each subsystem has an individual time scale and is independently controlled via state feedback. This alleviates the issues associated with ill-conditioning and simplifies controller design. This paper introduces the novel multi-time scale control design concept and its application to single-axis dual-stage nanopositioners - although it can be easily expanded to more complex systems, e.g., multi-axes, nanopositioning devices. The proposed control technique is validated through simulations of an experimentally obtained serially coupled dual-stage nanopositioning model.