Robust PI and PID controller design in delta domain

A simple unified tuning method for PI and PID delta-domain controllers for SISO plants is developed. The method can shape the nominal stability, transient performance, static accuracy and control signal. A problem of how to satisfy the robust closed-loop stability and performance is also addressed. The method leads to a parameterised set of controllers that provide the required stability margin for a maximally achievable closed-loop bandwidth in the presence of unstructured plant uncertainties. The developed methodology can be employed as a design tool in a systematic multiobjective optimisation, where in view of the diversity of conflicting goals that must be simultaneously achieved, some trade-off mechanisms should be taken into account. Numerical examples illustrating the method are given