Self-Tuning Pi Controller

This chapter describes a self-tuning algorithm, called process parameters identification (PID) control, which comprises the steps of identification and tuning. The algorithm uses methodology of process identification based on the asymmetric relay feedback test and the locus of a perturbed relay system (LPRS) method. PID control is the main type of control extensively used in various industrial applications. The LPRS method offers an opportunity to improve the indicated accuracy problem. There are a number of tuning criteria that are used for selecting optimal settings of PID controllers. The most well known ones are the minimum of integral absolute error (IAE) and integral time absolute error (ITAE). The methodology that involves fitting of the LPRS obtained analytically through the underlying model of the process to the points of the LPRS measured from the relay feedback test is feasible, efficient, and convenient for using as an add-on to the PID controllers. Simple analytical formulae are derived for a PI-controller; both identification algorithm and the tuning algorithm are implemented in the self-tuning PI-controller.