Coefficient diagram method (CDM) based PID controller design for magnetic levitation system with time delay

This article reports the implementation of the controller for Magnetic Levitation (Maglev) system in the simulation environment. In the field of control system engineering, it is always a tedious task for controlling the system which is nonlinear in nature. Several controlling techniques have already been designed and implemented for linear and stable systems; however, for nonlinear and unstable systems, the number is limited. From those controlling approaches, Coefficient Diagram Method (CDM) is one of the algebraic based methodologies imposed to obtain the design parameters of the controller. Simulation experiments have been performed for step response as well as square input. To validate the superiority and robustness of the proposed controller a modified CDM-PID controller with time delay of 0.1 sec is introduced. The proposed model is also compared with the conventional CDM-PID controller in terms of error indices such as Integral Absolute Error (IAE), Integral Square Error (ISE), Integral Time Square Error (ITSE), Integral Time Absolute Error (ITAE) and transient performance analysis such as settling time (t
_s
), rise time (t
_r
), maximum overshoot (%M
_p
), Phase Margin (PM) and Gain Margin (GM). This proposed modified CDM based PID controller can be effectively employed in a class of other unstable, nonlinear higher order systems.