Multiobjective design using various control techniques

This paper discusses three different multiobjective control schemes: multiobjective PID control, multiobjective critical control and multiobjective eigenstructure assignment. The multiobjective PID control considers a set of frequency-domain performance requirements, such as gain margin, phase margin, crossover frequency and steady-state error. The multiobjective critical control addresses the robust control design of multivariable critical systems with external and internal uncertainties. The design problem formulated as a set of objectives includes the output performance criteria in the time domain and the robust performance criterion in the frequency domain. The multiobjective eigenstructure assignment studies robust eigenstructure assignment with multiobjective criteria for multivariable control systems. Various performance functions in the objectives that are taken into account are individual eigenvalue sensitivity functions and the system robustness functions. Based on those above performance functions, the performance criteria for each multiobjective scheme are expressed by a set of inequalities. The paper introduces various optimisation techniques to make full use of the freedom provided by PID, critical control and eigenstructure assignment to formulate the controller design of satisfying the system performance criteria.