In order to minimize the mass of Long Slit Spectrometer (LSS)’s primary structure

and improve the structural response’s robustness

the primary structure was optimized. The effect of structure geometry tolerance and material property tolerance on the structure robustness was analyzed. Accordingly some structure geometry tolerance was altered. The robust optimization model of the LSS primary structure with the constrained conditions of the basic frequency and the objective function of total mass was established. The Monte Carlo simulation and Ant Colony algorithm was applied to solve the optimization model. The optimized structure has reduced about 17.5% in mass than the original design. Although the mass of the optimal robust design is more heavy than the mass obtained by deterministic based optimization

it is insensitive to variations on design variables within a feasible region.