The basic control task is to control the vertical position of the freely levitating ball in the magnetic field of the coil. The Magnetic Levitation Apparatus is a non-linear, dynamic system with one input and one output. The Magnetic Levitation Apparatus shows control problems with non-linear, unstable systems. The apparatus consists of a steel ball held in a magnetic field produced by a current-carrying coil. Any imbalance and the ball will move away from the set-point position. A sensor measures the position of the ball. At equilibrium, the downward force on the ball due to gravity is balanced by the upward magnetic force of attraction of the ball towards the coil. A power amplifier with overheat protection drives the coil.
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