Robust control of integrating systems using CDM‐based two‐loop control structure

Robust control of any system requires that the controller must perform satisfactorily for a family of plants and should ensure stability and performance despite the disturbances and modelling uncertainties. In this context, we propose a novel robust control method for interval plants that gives robustness against wide variations of plant parameters. The method is based on the two‐loop model following control (MFC) and the coefficient diagram method (CDM). In our proposed method, we modify the two‐loop control structure in accordance with the CDM. The controller is designed using CDM to satisfy the desired performance specifications. We establish mathematically the conditions that provide robustness to the type 1 integrating systems. We apply the proposed control strategy to two examples of interval plants from the existing literature and find the results to support the derived mathematical analysis. Using bounded phase condition, we also determine the parametric stability margins for both the examples.