Qualitative controller for linear systems

A qualitative model for an open loop plant is derived from an approximated mathematical model or directly from the measurement of the values of the plant variables in an identification experiment. The qualitative controller is designed using the plant qualitative model. The main strategy of this controller is to change the input to the plant with a fixed step in a specific direction to drive the output of the plant towards the desired set point. Before teaching this set point with a specific range, the controller changes the direction of the control signal to slow down the response while it is about to reach the set point. The proposed regulator has only two parameters tuned by the operator: the first one is the “gain” which determines the step change of the control signal; and the second one is the “range” which determines a specific threshold after which the controller has slow down the response before reaching the set point. The effect of these control parameters on both transient and steady state responses is investigated. Many computer simulations are used to test the effectiveness of the proposed controller