Adaptive finite time extended state observer for varying rope length tower cranes

This paper proposes a new control algorithm, the second-order sliding mode control (SO-SMC) based on adaptive finite time extended state observer (AFT-ESO) for a threedimensional tower crane (3DTC) system. The 3DTC system is an un-actuated and nonlinear system, the motion of the load depends on the movement of the trolley, the turntable, and the length of the rope. Furthermore, the 3DTC system working in an outdoor environment is heavily influenced by external disturbance, affecting the control performance and the ability to measure the system states. Therefore, an adaptive finite time extended state observer is proposed to solve these problems. The AFT-ESO estimates the state variables and the total disturbance (including the external disturbances and the uncertainty component) accurately, which creates the premise to build a second-order sliding mode control based on AFT-ESO that ensures a globally stable closed-loop system and controls the load to follow the reference trajectory to the desired position. Finally, simulation results are provided to confirm the effectiveness and sustainability of the proposed algorithm. © 2023 IEEE.