Electromagnetic Levitation System Based on a PID Controller

The development of educative prototypes of industrial control techniques has increased in the past few years, since its importance lies in their low cost compared to real systems. This study presents the design, modeling, and implementation of a magnetic levitator. The complete system is formed by amplifiers, an optoelectronic sensor, a coil used as an electromagnet, and a metallic sphere used as an object to levitate. The information from the sensor is used to feed the proportional-integral-derivative (pid) controller, and with this regulate the incoming current that flows through the coil by means of a power amplifier with the objective of maintaining the metallic sphere at the balance point. The pid controller is designed based on dominating poles in a closed loop (s=−4 ± j4) being ±180°, assuring that the zeros contribute to the same angle. The proposed system levitates a metallic sphere with an inertial mass of 24.75 g and a diameter of 12 mm to a distance of 4mm.