Active Magnetic Bearings and Control

Active magnetic bearings (AMBs) are a typical mechatronics product. The hardware is composed of mechanical components combined with electronic elements such as sensors and power amplifiers, and an information processing part, usually in the form of a microprocessor. In addition, an increasingly important part is software, which specifies coordination of bearing forces to sensed rotor motion, and consequently dictating the dynamic properties of the complete system. The inherent ability for sensing, information processing and actuation give the magnetic bearing the potential to become a key element in smart and intelligent machines.

Examples of Active Magnetic Bearings in RoMaDyC

The Center has conducted AMB studies in the areas including energy minimization and active vibration control. RoMaDyC has also been successful in applying AMBs as actuators in specialized applications such as structural health monitoring and smart machining.

*AMB Test Rig Configured to Study Energy Conservation in Presence of the Gyroscopic Effect.*

A well formulated performance assessment tool for evaluating controllers for AMB systems (and practically any other essentially linear system with primarily steady state performance objectives) can be efficiently constructed in the form of a μ-analysis problem. The Center RoMaDyC has conducted study of μ-synthesized control of AMB machining spindles for improved cutting performance.

*Structure of the full model for controller synthesis and assessment.*

*Comparison of two μ-controllers; one is optimized for machining.*

Sawicki, J.T., Maslen, E.H., and Bischof, K.R., “Modeling and Performance Evaluation of Machining Spindle with Active Magnetic Bearings,” Journal of Mechanical Science and Technology, 21(6), pp. 847-850, 2007.
Barbaraci, G., Pesch, A.H. and Sawicki, J.T., “Experimental Investigations of Minimum Power Consumption Optimal Control for Variable Speed AMB Rotor,” ASME Paper IMECE2010-40044, ASME International Mechanical Engineering Congress and Exposition, Vancouver, Canada, November 12-18, 2010.
Sawicki, J.T. and Maslen, E.H., “Toward Automated AMB Controller Tuning: Progress in Identification and Synthesis,” The Eleventh International Symposium on Magnetic Bearings (ISMB-11), Nara, Japan, August 26-29, 2008.
Maslen, E.H. and Sawicki, J.T., “μ-Synthesis for Magnetic Bearings: Why Use Such a Complicated Tool?,” ASME International Mechanical Engineering Congress and Exposition, Seattle, Washington, USA, November 12-15, 2007.