Study On The Control Of Inflatable Tube Deployment

The inflatable structure is a new type of space structure.Compared with traditional metal structures,it has the advantages of small volume and light weight,thus it has a broad application prospect.The key to the deployment of inflatable structures in space is the controllable,reliable and stable unfolding process.If the process is not effectively controlled,it could result in structural damage and ultimately degrade the stability of the entire system.The inflatable tube is the basic structural unit of an inflatable structure.Researches on inflatable tube control schemes can provide valuable references for engineering designs and practical application of inflatable tubes.They also promote future studies on complex inflatable structures.This paper introduces a new theoretical model for tube state estimation based on the nonlinear hinge model and the deformation theory.The new model incorporates multiple factors including inner pressure,tube radius and opening angle into the computation of the deployment moment.To verify the correctness of the model,thorough steady-state experiments were carried out to measure the deployment moments on different conditions and tube material.The good agreement between the experimental results and the theoretical model demonstrates the correctness of the theoretical model.Based on the aforementioned theoretical model and the pseudo-rigid-body model,this paper further proposes an inflatable tube control dynamics model to study the dynamics characteristics of the inflatable structures under different control schemes.A control scheme is abstracted as a time function of the control force and the control distance.Experiments on the transient dynamics characteristics of tube inflation processes were performed with hook and loop fasteners or springs as the control components.The experimental results reveal that the control dynamics model proposed in this paper achieves remarkable accuracy in simulating and predicting the deployment process of the inflatable tube.This work also performed numerical simulations using the control volume method based on the inflatable tube deployment model.The deformation characteristics of the inflatable tube were modeled in the simulation.Based on the numerical model,this work analyzed the influence of different peel strength of hook and loop fasteners,different elasticity coefficients and fracture strain of springs as well as the rate of inflation.Combining the analysis of this work and some previousresearch results,this paper presents a preliminary control scheme of inflatable tube.The simulation results show that the proposed control scheme can effectively unfold and deploy the inflatable tubes.