Virtual internal model tuning for cascade control systems

Abstract

Cascade control is used in many practical applications. To realize the desired specification of the cascade control systems, accurate mathematical models of the plant are not only inner but also outer loops required. However, there are also many situations where it is difficult to execute ideal experiments for obtaining mathematical models for practical reasons. In such situations, it is expected that the direct usage of the data for control design enables us to obtain desired controllers. From these backgrounds, we propose a controller tuning method for the two controllers in a cascade control system. Here, we apply virtual internal model tuning proposed by the authors to update the cascade control system. In this proposed method, specifications of the inner and the outer loops can be set independently. The optimal parameters of the controller in each loop can be obtained using the least square method. Finally, the validity and usefulness of the proposed method are illustrated using experiments.

Keywords

• cascade control system
• controller design
• data-driven control
• virtual internal model tuning