Tuning of two-DOF-FOPID controller for magnetic levitation system: A multi-objective optimization approach

This paper presents a simple design and parameters tuning approach using multi-objective optimization of two-degree of freedom fractional order proportional-integralderivative (2-DOF-FOPID) controller applied to magnetic levitation system. A multi-objective optimization of various controller parameters is achieved through nondominated sorting genetic algorithm (NSGA-II). The minimization of performance index integrated absolute error (IAE) for both set-point tracking and external disturbance rejection are considered as the objective functions. A generated Pareto optimal solution set is examined and final most reasonable solution is obtained using Nash solution criteria. The comparative performance evaluation of proposed 2-DOF-FOPID controller is assessed against 1-DOF-FOPID and classical PID controllers. The effectiveness of controller for setpoint tracking and rejection of external disturbances is exhibited through proper simulation results and found that the proposed 2-DOF-FOPID controller produces superior results than its conventional counterparts.