Adaptive output feedback anti-swing control for underactuated 7-DOF rotary crane with gravitational estimation

Abstract

Rotary cranes with double spherical pendulums and variable cable lengths exhibit underactuation and high nonlinearity, resulting in an open control problem. The additional challenges posed by unknown system parameters and unmeasurable velocities further complicate the anti-swing control issues for the rotary cranes. This article proposes an adaptive output feedback anti-swing controller for the underactuated seven-degree of freedom (7-DOF) rotary crane with gravitational estimation. Firstly, we establish the dynamic model for a three-dimensional rotary crane system, which has seven degrees of freedom, including boom slewing, boom luffing, payload hoisting/lowering, as well as hook and payload spherical pendulum motion. Then, by designing auxiliary signals for velocity estimation and gravity compensation, an adaptive output feedback anti-swing controller is designed with a rigorous stability analysis. As far as we known, it is the first adaptive output feedback anti-swing control strategy for 7-DOF rotary crane without needing velocity signals. Ultimately, meticulous hardware experiments are designed to rigorously evaluate both the effectiveness and the robustness of the designed controller. The adaptive output feedback anti-swing controller outperforms current state-of-the-art control methods, achieving reductions of at least 53.99% and 35.11% in the actuated actuator positioning and unactuated swing angles, respectively.