构架天线四面体桁架单元精度分析与多目标优化设计

为了减小加工装配误差对天线桁架精度的影响，解决含随机变量的优化问题，综合考虑了杆件加工装配误差正态分布特性对精度的影响，通过最小势能原理求解得到了含杆件误差的构架天线桁架单元的平衡状态，采用蒙特卡洛方法对杆件误差变化对型面精度的影响开展了分析，得到杆件随机误差下的平均精度。为提高计算效率，建立了以杆件长度公差为设计变量、以桁架型面精度和加工成本为目标函数的代理模型，通过多目标遗传优化算法进行了公差优化设计，得到了代理模型误差小于8%的多组公差设计方案。其中平均精度最小达到了0.013mm，并且分析结果显示腹杆影响显著大于底杆。

Multi-objective optimization design and precision analysis of truss antenna tetrahedron unit

In order to reduce the influence of machining and assembly errors on the accuracy of antenna truss，and solve the optimization problems with random variables，the influence of assembly error of the normal distribution on the accuracy was considered.And the equilibrium state of truss antenna unit was solved by the principle of minimum potential energy.The influence of the change of the bar on the surface accuracy was analyzed by the Monte Carlo method，and the average accuracy under the random error was obtained.For improving the computational efficiency，an approximate model of the truss antenna tetrahedron unit with the bar length tolerance as the design variable was established，with the truss surface accuracy and overall processing cost as the objective function.Tolerance optimization design was carried out through the multi objective optimization method，which obtained multi group tolerance design scheme with the approximate model error less than 8%.In addition，the minimum average accuracy is 0.013mm，and the analysis result shows that the influence of the web rod is significantly greater than that of the bottom rod.