Sensor Offset Compensation for Improved Levitation Performance of Passive Maglev Transport System

Particles are main sources of defects in display manufacturing process and have to be minimized for better productivity. The developed passive magnetic levitation (Maglev) transport system generates no particle and is suitable for vacuum applications because it has a simple and passive moving carrier. All sensors and electromagnetic actuators are installed on the ground and activated automatically depending on the carrier position. However, sensor installation errors cause unwanted fluctuations of the carrier motion and should be compensated for better levitation accuracy. In this paper, we propose sensor offset compensation algorithms to reduce pitching motion of the carrier while actuators are switched on and off. The sensor offsets are estimated from sensor measurements by the linear relation between carrier and sensor geometry. The offset compensation algorithm has been tested and verified through simulations.