Disturbance rejection using Extended State Observer for a MIMO system

In this paper optimal control design is used to build a controller and various design methods is discussed for disturbance rejection in industrial control. ESO minimizes the disturbance from the system and estimates the unknown states and the system becomes stable. An observer FSFESO is introduced to observe the unknown states along with minimization of a scalar disturbance. The performance and robustness is discussed here for various control system problems from industry or laboratory. In the nonlinear MIMO system disturbance rejection is very complicated due to the high nonlinearity of the model. Here in this paper 2-DOF Helicopter by $\mathrm {M}/\mathrm {s}$. QUANSER Innovate Educate is used as a plant. The coupling effect of the model is very strong in both the inputs i.e pitch and yaw angle. If a disturbance signal is given to the pitch angle input a higher disturbance will be generated in the yaw angle of output, due to the coupling of the model. The systems stability is very sensitive and to control such type of system is a big challenge, however one extended state type observer controller is proposed for the stable output of the system using optimal control method.