Magnetic levitation is a new technology gaining popularity for use in many applications,the most notable being rail transportation. Magnetic levitation, or maglev, utilises high powered magnets to suspend objects off the ground. Electromagnets are known to exhibit severe nonlinear characteristics and providing precise control of position is no simple task.
The ECP Model 730 magnetic levitation development system was studied in this project as the basis for the design of a suitable control system. The system model was developed and the system nonlinearities were identified. A linearised approximation of the system model was developed and a PID controller designed. The designed controller was simulated in Simulink and managed to force the magnet position to settle in 790 ms with 5.6% overshoot. It was found that nonlinearities caused the controller effectiveness to degrade as the magnet position moved away from the desired operating point.
A piecewise model of the system was developed and controllers were designed to de- signed to work over the entire range of operation. An adaptive control strategy based on gain scheduling was implemented into the system and an improvement of 200 ms and 2.47% overshoot was observed for a 0.5 cm change in operating condition. The controller managed to switch between operating points but was shown to exhibit poor disturbance rejection when its position was continuously changed.
Results suggested that an adaptive PID controller is capable of adapting to changes in its operating condition, but tuning it to achieve desired performance specifications is difficult, and other controllers may be more appropriate
