Comprehensive identification and parametric uncertainty assessment in the dynamic modelling of a 3D crane system

This paper presents a detailed study of the dynamic modeling and parametric uncertainty analysis of a 3D crane system, providing insights into its positional and angular responses across varying operational conditions. Using real-world experimental data, the study identifies and quantifies key parameters, including system gains, time constants, and damping ratios. These parameters form the basis of a validated mathematical model that accurately reflects the crane's dynamic behaviour under diverse Z-axis configurations and input conditions. The results demonstrate how payload height significantly affects both positional and angular dynamics, particularly revealing notable coupling effects between translational and rotational movements. Additionally, an asymmetric actuator dead-zone was experimentally observed and analysed to enhance the comprehensiveness of the system identification. A nonlinear state-space model and the manufacturer's nominal linear translational model are used for comparison with the identified linear model. To the best of the authors' knowledge, this is the first study to experimentally derive and quantify parametric uncertainties in a validated 3D crane system model, extending beyond existing literature, which often assumes fixed parameters or focuses on lower-dimensional models. The insights from this study establish a foundation for designing robust control strategies capable of handling the inherent variability and complexity of 3D crane systems. The findings have practical implications for industries requiring precise load handling and reliable operation under dynamic and uncertain conditions, such as construction, logistics, and automated systems.