On Control Allocation and its Applicability for Dual-Stage Actuator Systems

The aim of this paper is to study the applicability of the control allocation (CA) framework for dual-stage actuator (DSA) systems - a subclass of overactuated precise positioning devices, characterised by serial connection of a coarse and fine stage. In contrast to the typical control frameworks developed for DSAs, such as master-slave and decoupled design, the CA framework approaches the control in a modular way, clearly separating the motion control from the allocation of efforts among the actuators. To achieve this, the concept of redundant controllability is introduced with the aim to analyse weakly input redundant LTI systems to determine the virtual effort that enables the separation of the system in terms of the CA approach. As a result, it shows that with serially connected actuators, the redundancy is clearly present in the displacement domain. In addition, the application of the framework is shown and the possible control approaches are discussed.