Research On Design, Analysis, And Optimization Of Separation Systems For Small Satellites

Modern small satellites feature high performance, low risk, short cycle, and lowinvestment, which represent an important developing trend of space technology. As oneof the key technologies of small satellites, satellite separation is a core technologyrelated to the successful launch and has an important effect on the overall performance.However, when applied in small satellites, traditional separation technology has suchproblems like huge separation impact, low reliability, large weight, etc. And traditionaldesign and analysis methods of separation systems are also not fully suitable for smallsatellites. Therefore, it is very significant to make special research on design, analysis,and optimization of small satellite separation systems.In this paper, the main problems of small satellite separation technology aresystematically studied. Based on the research on the fundamental issues, includingseparation system design, dynamic analysis, separation test, and optimization design, acomplete set of research system of small satellite separation is established. The mainresearch works are as follows:(1) The design of small satellite separation systems is studied. With regard to thepresent issues of huge separation impact, low reliability, and poor synchronization, thereare four unlocking and separating mechanisms proposed, including the low shockpyrotechnic, the hot knife, the shape memory alloy (SMA), and the QWKNUT. Thepyrotechnic with high reliability can significantly reduce the impact on the satellite,when equipped with a shock absorbing device; the hot knife can significantly improvereliability and synchronization with small impact, through the design of large-scalelevers and dual redundant knives; the SMA and QWKNUT have the advantages ofsmall impact, fast separation speed, low weight, and compact volume. With respect to atypical separation system using helical compression springs, a layout of foursymmetrical springs and a design of separation devices are confirmed considering therequirements of action range, separation attitude errors, and no instability. Finally, acalculating method of system preload and tightening torque is introduced.(2) The dynamic analysis of small satellite separation is studied. Based on theanalysis of disturbance factors during the separation process, transient perturbationanalysis is proposed for satellite separation, which can better solve the problem of largeerrors of separation parameters for small satellites (especially nano-satellites). Based onexperimental design and statistical analysis of perturbation factors, the approach canobviously improve the analysis precision of satellite separation dynamics. In addition,mathematical models of small satellite separation are established to make an accuratedescription of small satellite separation, considering mechanical properties of separationsprings and limit switches, and influence of eccentricity. Then, transient perturbation analysis approach is employed for a small satellite by combining ADAMS virtualprototype analysis and MATLAB program analysis. The influences of main disturbancefactors are concluded, which provides important references for optimization ofseparation systems and separation parameters.(3) The ground test of small satellite separation systems is studied. With regard tothe present issues of separation test systems, like fewer types, high cost, complexequipment, and limited measuring precision, a “single pendulum” test system isproposed for small satellite separation, which has advantages of low cost, goodadaptability, and simple equipment, and can simulate a variety of space separationconditions,. Also, detailed steps of separation tests are given. In order to improvemeasuring precision of separation parameters, both monocular measurement andbinocular measurement are studied and the optimal measuring method is obtained. Then,the whole separation test system and the data processing program are established. Andvarious pyrotechnic and non-pyrotechnic separation tests of a small satellite areconducted, in order to fully test the performance of separation system. Finally, the testresults are compared with the simulation results, which prove accuracy of the dynamicmodel and feasibility of the approach.(4) The optimization design of small satellite separation systems is studied. Inorder to cover the shortages of traditional design, optimization of separation systemsbased on multi-island genetic algorithm is proposed, and iSIGHT and ADAMS areintegrated as an optimization platform. The mass of separation system and separationangular velocities are regarded as the optimization objectives respectively. During theoptimization of minimum mass, the mathematical model is established, and the mass ofspring separation mechanism is decreased by30.7%, which shows that the multi-islandfully optimizes the performance of separation devices. During the optimization ofminimum angular velocity, angular velocities are significantly reduced through thedesign and configuration of spring parameters. Then, a series of separation tests arecarried out to prove the results of optimization design. The error of separation speed iscontrolled within1%and the angular velocity is reduced by nearly90%afteroptimization. Traditional techniques of precise separation have some limitations insmall satellites; however the proposed optimization approach obtains a betterapplication, and can significantly improve the precision of separation.To sum up, the design, dynamic analysis, test, and optimization approaches ofsmall satellite separation systems are systematically studied in this dissertation. Throughtheoretical analysis, simulations, and experiments, a series of conclusions andapproaches are proved, and some have been applied to “TianTuo-1” satellite, whichhave great significance to improve the design level of small satellite separation systems.The results in this dissertation can provide beneficial reference and technical support forfuture research in this field.