Design of Optimal PID Controller for Magnetic Levitation System Using Linear Quadratic Regulator Approach - Ismail, Laith S.; Petrescu, Catalin; Lupu, Ciprian; Luu, Duc Lieh (2020 International Symposium on Fundamentals of Electrical Engineering (ISFEE), Fundamentals of Electrical Engineering (ISFEE0, 2020 International Symposium on, 2020)