Affiliations: [a] Department of Mechanical Engineering, Ibaraki
University, Ibaraki, Japan | [b] Department of Human and Information Systems
Engineering, Gifu University, Gifu, Japan | [c] Department of Biocybernetics, Niigata University,
Niigata, Japan
Abstract: This paper presents a passivity based control method combined with
velocity estimation by an extended Kalman filter for a magnetically levitated
flexible beam with both ends free by two electromagnets. An energy-based
analysis concludes that the system can be decomposed into two passive
subsystems: a mechanical subsystem consisting of the flexible beam and an
electrical subsystem consisting of the electromagnets. We designed a passivity
based controller independently for each subsystem. An output feedback
controller for the mechanical subsystem computes the desired force that is
required to achieve position convergence and vibration suppression of the
flexible beam. A feed forward controller for the electrical subsystem computes
the input voltage for the electromagnets to generate the desired force. In a
practical point of view, structural and economic considerations restrict
simultaneous usage of both position sensors and velocity sensors while the
control strategy requires accurate measurements of the position and velocity of
the flexible beam. We employ the extended Kalman filtering technique in order
to estimate the velocity of the flexible beam from the measured
micro-displacement vibration at a high sampling frequency. Effectiveness of the
proposed controller and velocity estimator is demonstrated by a numerical simulation.
Keywords: Passivity, flexible beam, magnetic levitation, extended kalman filter
