Set-point Weighting

4.6 Conclusions

In this chapter the role of the set-point weighting in the PID control law has been underlined and it has been shown how it can be effectively adopted in order to decouple the problem of providing good performance at the same time both in the set-point following and in the load disturbance rejection task. For processes with small normalised dead time, the adoption of a time varying (control error dependent) set-point weight can represent a valid choice to avoid a large overshoot without increasing the rise time. In this context, two methodologies, namely the variable set-point weighting and the fuzzy set-point weighting technique, have been thoroughly analysed in order to provide a clear characterisation of them and to understand their applicability in practical situations. It has been shown that the use of such techniques indeed represents a valuable solution for the implementation of a high-performance controller by retaining at the same time the overall ease of use of a PID controller.