Swing Angle Observation and Anti-swing Control of Quadrotor Suspended System with Variable Rope Length

Aiming at the problem of stable payload transport and payload swing suppression of the quadrotor suspended system with variable rope length under external disturbances, a compound control scheme based on extended state observer and anti-swing feedforward control is designed. Firstly, a separation modeling method is adopted to establish the mathematical model of the quadrotor suspended system with variable rope length, which is convenient to realize payload loading and unloading. Secondly, an extended state observer is constructed by using the statics equation of swing angle to estimate the swing angle in real time, and then the anti-swing feedforward controller is used to suppress the payload swing. PD control is adopted in both position and attitude control loops to realize trajectory tracking and attitude convergence of the quadrotor. Simulation results show that the designed control scheme can effectively suppress payload swing and the quadrotor can track the reference trajectory quickly and accurately.