Dynamics And Application Of Flexible Tethered-net System

Flexible tethered-net system has important application value in active debris removal(ADR)and low-altitude unmanned aerial vehicle anti(anti-UAV)operations.But the existing dynamic model is not perfect enough and there is no clear guidance for the design of the tasks,which limit the application of the tethered-net system.Therefore,in view of the dynamics and application of the flexible tethered-net,the lumped mass model and the absolute node coordinate formula(ANCF)model with air forces are established.After a new folding and storage pattern is proposed,the corresponding dynamic model of the folding and the pulling-out process are carried out.On these basis,the tasks of using flexible tethered-net to capture space debris and UAV are optimized.In addition,in order to solve the problem of rapid spring-back after the space tethered-net is deployed to the maximum area,a new passive control method is proposed and optimized.The main contents are listed below.(1)Tethered-net system dynamic modeling.The Lumped mass model and the ANCF model with air forces are established.After the characteristic parameters are obtained by tests,the two models was compared and verified by the free fall test.(2)Detailed storage and pull-up dynamic modeling.A new initial folding pattern is proposed.And combined with the positional relationship between the tethers and the storage bag,the detailed dynamic model is carried out.Besides,the pseudo flexible element is applied to simulate the anti-deformation ability of the strengthen tethers caused by a long-term folding.(3)Multi-objective optimization of the space tethered-net system design.In order to maximize the acquisition capability and minimize the design risk,the maximum effective capture distance and the minimum internal force of the tethered-net are selected as the objective of the optimization design problem of the space tethered-net.After sensitivity analysis,the multi-objective optimization problem is carried out,and the optimal solution is auxiliarily selected by the criterion of minimum system mass.(4)Multi-objective optimization design of tethered-net system for UAV capture.A dynamic model of the UAV capture system,combined with the flight dynamic model of the capture platform,the dynamic model of the flexible tethered-net and the parachute dynamic model,is established and partially verified by experiments.Following this,a new criterion for the successful capture of the UAV with tethered-net is proposed,which takes the motion characteristics of the UAV into consideration.Based on this,the multiobjective optimization design of the tethered-net capture system is carried out.(5)Optimization design of the space tethered-net passive control.A new passive control method with energy dissipation bands(EDB)is proposed.After the detailed dynamic model of the EDB is studied and verified by tests,the global dynamic model of the tethered-net with the EDBs is built.Following this,the strengths of the EDBs are optimized to maximum the effective working distance.This paper aims to study and improve the dynamic model of the tethered-net system,as well as solve the problems faced by the application of ADR and anti-UAV.