H-infinity Model Reference Controller Design for Magnetic Levitation System


In this paper, a new robust approach based on combining the model reference control with H-infinity technique is proposed. The goal of the proposed controller is to obtain an adequate transient response which may not be obtained when only H-infinity technique is used. This is done by adding the model reference block to the standard H-infinity feedback configuration. Then the overall block diagram is formulated by linear fractional transformation (LFT). The Magnetic Levitation which is a highly nonlinear, open loop unstable and uncertain system is used to show the effectiveness of the proposed controller. The results show that the proposed controller is very effective in compensating the system parameters variations with forcing the system output to track the output of the model reference. A variation of ±10% in system parameters is considered.