A novel model Reference Adaptive Controller design for a second order system

In everyday language, “to adapt” means to change a behavior to conform to new circumstances, so adaptive controller is a controller with adjustable parameters and a mechanism for adjusting the parameters. There are two main approaches for constructing adaptive controllers: Model Reference Adaptive Control (MRAC) method and Self-Tuning Control (STC) method. The Model Reference Adaptive Control (MRAC) was originally proposed to solve a problem in which the performance specifications are given in terms of a reference model; this model tells how the process output ideally should respond to the command signal. The conventional method to select the reference model depends on system closed-loop specifications described as the desired rise time, settling time, and steady state error. Then followed by the usual design procedures to obtain the reference behavior modeled as a transfer function, this method needs more time to find the suitable reference model. In this paper a reference model based on a PID controller with the controlled plant is proposed within the MRAC for the adaptive control of a second order system. The corresponding performance is compared to that of an ordinary reference model that was derived from the desired performance specifications. It is found that the proposed reference model saves the design time as well as alleviates the burden of obtaining the reference model. The evaluation is done by means of simulation on MATLAB and Simulink.