Real-Time implementation and performance analysis of robust 2-DOF PID controller for Maglev system using pole search technique

In recent times, Magnetic Levitation (Maglev) technology has gained huge popularity in different fields of research. Transportation, nuclear, aerospace, biomedical, civil and electrical engineering are some of the areas where the presence of Maglev technology is prominent. But because of the inherent nonlinear and unstable behaviour, the task of designing a suitable controller becomes very challenging for the control engineers. In this paper, a simple but effective approach has been proposed for the design of 2-DOF Proportional-Integral-Derivative (PID) controller for the control of Maglev system in simulation and real-time for the very first time, to the best of author's knowledge. The controller parameter values have been analytically obtained by optimizing the location of closed loop poles in the s-plane which eventually minimizes the Integral Square Error (ISE) of the closed loop system along with the controller. As the controller parameters are found by searching the best pole location, we name it as pole search technique. The performance of the controller has been compared with those of the 1 & 2-DOF Integer Order and Fractional Order PID and I-PD controllers designed for the same Maglev plant. The result of the comparison reveals that the 2-DOF PID controller, designed in this paper, outperforms other controllers in terms of maximum overshoot, settling time, Integral Absolute Error (IAE), Integral Time Absolute Error (ITAE) and Integral Time Square Error (ITSE). Moreover, to illustrate the loop robustness property, input and output disturbances have been applied in real-time simulation environment and sensitivity and complementary sensitivity analysis have been performed. Additionally, to show the applicability of the proposed technique apart from Maglev, 2-DOF PID controller has been designed for the Ball and Beam and Coupled Tank system and their performance has been compared with the existing results.