Modeling and control of a high precision 6-DOF Maglev positioning stage with large range of travel

The purpose of this research is to design a 6-DOF motion control stage that can provide both millimeter scale motion range and sub-micron positioning capability, including the electromagnetic actuation scheme, the measurement scheme using capacitive sensors, the modeling and control design.;A hybrid magnetic suspension actuator (HMSA) is designed and tested in this research. The force model parameters of the proposed actuator are identified by experimental method and multi-dimensional optimization techniques. Three horizontal and three vertical HMSAs are employed for horizontal and vertical actuation scheme respectively in the 6-DOF actuation design, which gives a simple mapping between the position of the floating part and measured air gaps. The designed motion range is 1.1mm x 1 mm x 1mm in translation and 13.3mrad x 16.8mrad x 13.0mrad in rotation respectively.;The challenging aspect of multi-DOF motion control lies in the suppression of coupling between axes. In some applications that demand high throughput, velocity control is also necessary. To address these problems, a full dynamics model coupled with a 6-DOF passive state observer is presented in this research to describe the coupling effect and estimate the real-time velocity information. It has been proven that the velocity estimator is passive and that the position estimator is strictly positive real as long as the gain matrix is chosen to satisfy Kalman-Yakubovich-Popov lemma. Observer-based MIMO decoupling controllers i.e. PID control with feedback linearization technique and robust sliding mode control are presented.;Several experiments are performed to test the performances of the proposed actuator and the positioning stage. In a one-DOF experiment, a levitation gap of 1.1mm and positioning resolution of +/-25 nm are demonstrated in fine measurement mode. In a z-roll-pitch control experiment of a 6-DOF device, the positioning resolution is +/-250 nm and +/-0.5murad in coarse measurement mode and +/-25nm in fine measurement mode respectively.