Tuning of internal model control –proportional integral derivative controller for optimized control

Abstract

Time delays are usually unavoidable in the engineering systems like mechanical and electrical systems etc. The presence of delay causes unwanted impacts on the system under consideration which imposes strict limitations on achievable or targeted feedback performance in both continuous and discrete systems. The presence of the delay complicates the design process as well. It makes continuous systems to be infinite dimensional and also it significantly increases the dimensions in discrete systems. As the internal model control based proportional integral derivative controller are simple and robust to handle the model uncertainties and disturbances. But they are less sensitive to noise than proportional integral derivative controller for an actual process in industries. It results in only one tuning parameter which is closed loop time constant λ internal model controller filter factor. It also provides a good solution to the process with significant time delays which is actually the case with working in real time environment. So in this thesis internal model control based proportional integral derivative controller is designed. The Pade’s approximation for the time delay has been used because most of the controller design based on different methods can not be used with the delayed systems. While comparing the responses of the transfer functions of different kinds of orders the internal model control based proportional integral derivative controller will not give the same results as the internal model control strategy because of approximation used for delay time. Also the standard internal model filter from f(s) =1 / (λs + 1) shows good set point tracking. Thus internal model control based proportional integral derivative controller is able to compensate for disturbances and model uncertainty while open loop control is not. Internal model control is also detuned to assure stability even if there is model uncertainty.