The Cascade Linear Quadratic Gaussian (LQG) Controller for Automatic Landing Systems in Aircraft

In this note, we present the controller design by cascade LQG controller for automatic landing system. The problem in automatic landing system (ALS) is uncertain weather conditions which during take-off or landing can get stuck in turbulence and microburst conditions. We apply the LQG controller to overcome the noise caused by turbulence and microburst conditions. LQG controller is able to set the flight states according to the desired reference in noise conditions. The noise rejections are performed by Kalman filtering to estimate the state of the system dynamic. If the plant of automatic landing system is unstable system, the inner loop controller is performed by using pole placement technique solved by Ricati equation. The estimated state via the output of Kalman filtering becomes the state feedback of LQG controller. Based on the result of simulation LQG controller can be implemented in automatic landing system in which the noise composed to the system.