Variable Coefficient Active Disturbance Rejection Control for Crane System

A variable gain active disturbance rejection control method is proposed for the underactuated crane system. Firstly, a kinematics model is derived for the two-dimensional crane system. Then a second-order extended state observer is designed to estimate the overall disturbances, contributed by trolley displacement and payload swing angle, and used to compensate their impacts with linear state feedback thereafter. The control law is designed as a linear superimposition of two channels, one for reference response and another for suppression of payload swing angle. The weights of the superposition are dynamically adjusting according to the error in the response. Finally, the effectiveness of the proposed method is verified by simulation and system test. The accurate positioning of the trolley and significantly suppressing the payload swing has been achieved, with strong robustness to system parameters perturbation as well.