Abstract:  In practical applications of tower cranes, due to the change of rope length, the swing of the load was aggravated, making it difficult to transport the goods to the designated position quickly and accurately. In order to achieve accurate load positioning and anti-swing control of tower crane, a novel anti-swing control method based on sliding mode active disturbance rejection control (SM-ADRC) for variable rope tower crane was proposed. Firstly, the dynamical equation of the system was derived from Lagrange equation. According to the dynamic equation, the system was divided into three subsystems: luffing, turning and lifting. A linear extended state observer (LESO) was designed for each subsystem to observe and compensate for the unknown total disturbance caused by parameter changes, system coupling and external factors in the corresponding loop. Then, the nonlinear error feedback control law with disturbance compensation was designed in combination with sliding mode control (SMC). Finally, in MATLAB/Simulink, the control performance of sliding mode control method and sliding mode auto disturbance rejection control method was compared and analyzed in terms of rapidity and robustness. The research results show that the SM-ADRC method reduces the time of the tower crane anti-swing control by 25.5 % compared with the sliding mode control. Comparing with the sliding mode control, not only the fast performance is improved, but also the robustness and adaptability are stronger, and the load of tower crane can be accurately positioned and effectively controlled against swing.
Key words:  tower crane; sliding mode active disturbance rejection control (SM-ADRC); sliding mode control (SMC); linear extended state observer (LESO); nonlinear error feedback control law; robustness