Dynamics analysis of the six-body aircraft during the deployment and unfolding process via dynamic mode decomposition

Abstract

The dynamics of the multibody aircraft during the deployment and unfolding process is a time-varying process characterised by high degrees of freedom, non-equilibrium and nonlinearity. Existing linear small-disturbance theories and stability analysis methods are no longer applicable, making it imperative to explore and investigate how to analyse and characterise the dynamic behaviour of multibody aircraft during the deployment and unfolding process. Therefore, this paper adopts thedynamic mode decomposition (DMD) method to extract the characteristic modes of the six-body aircraft during the deployment and unfolding process and uses these modes to describe its dynamic behaviour. First, the multibody flight dynamics model suitable for analysing the dynamic behaviour of the multibody aircraft during the deployment and unfolding process is established. Based on this model, numerical simulations are conducted to obtain state-variable data for each flight unit during the deployment and unfolding process. DMD is employed to analyse the dynamic behaviour during the deployment process of the six-body aircraft and to extract its dominant modes. The eigenvectors associated with each mode are further analysed to interpret the physical significance of the corresponding DMD modes. Finally, the reconstruction model was established using the characteristic modes extracted by DMD. By comparing with the original simulation data, the mean absolute error (MAE) of the DMD reconstruction model was approximately 7.78%, thereby verifying the correctness of the reconstruction model. The impact of the number of DMD modes on the reconstruction error is evaluated using the MAE, and an appropriate set of characteristic modes is selected based on energy contribution to represent the deployment dynamics. Finally, aerial deployment experiments of the six-body aircraft were conducted to validate both the multibody flight dynamics model and the reconstruction model, thereby providing a theoretical foundation for analysing the dynamic characteristics of multibody aircraft during aerial deployment.