Swing speed control for enhancing stability and reducing payload swing in a crawler crane

Abstract

This study proposes a combined approach of structural optimization and control system design to enhance slewing stability and suppress payload oscillation in crawler cranes. First, a parametric finite element model of the lattice boom was developed, and the thickness of the boom pipes was defined as the design variable for structural optimization. As a result, the boom weight was reduced by ∼10.1% while satisfying the maximum stress constraint, and the counterweight mass was reduced by 4.7% while maintaining moment equilibrium in the overall system. This led to a significant reduction in the overall system inertia, consequently reducing the required slewing torque. Subsequently, a flexible-body multibody dynamic model was used to evaluate the effectiveness of three different controller configurations in suppressing the pendulum motion of the payload during crane slewing. The control architecture consists of a slewing controller, a swing feedback controller, and a cable length controller. The control gains were optimized based on predefined objective functions and constraints. Notably, the cable length controller was designed to ensure a negative rate of change in the payload's kinetic energy, enabling active damping of pendulum motion. Simulation results demonstrated that the proposed control strategy effectively reduced the payload's swing angular velocity by up to 40% and suppressed the oscillation amplitude by as much as 37.6%. The reduced kinetic energy also contributed to lowering the dynamic load acting on the lattice boom, thereby improving the overall system stability. This integrated framework of structural design and control strategy provides a practical and effective solution for enhancing the dynamic stability of crane systems, with potential applications in intelligent construction machinery and large-scale mobile structures.