Structural Modeling Considerations for Dynamic Optical Space Structure Simulations

Boeing-SVS has developed an integrated modeling tool, Zelink, which effectively combines three commercial standard codes, Zemax, Simulink and Nastran, to predict the effect of quasistatic and dynamic disturbances on optical metrics of interest in optical space structures. Examples of optical metrics are time-varying wavefront error, point spread functions and predictions of image degradation. A simulation might involve specification of a slew angle and prediction of time-varying wavefront error. Different command shaping and attitude control techniques might be evaluated with respect to their ability to minimize wavefront error. Implementation of such simulations has shown significant dependence of simulation results on the structural modeling approach. In particular, one approach may introduce errors in the optical metric of interest, where another approach may avoid errors. The sensitivity of the optical metric is related to the necessity of maintaining the optical prescription when there is no structural deformation. A quasistatic rotation of the space structure should not significantly distort the optical prescription, since there is almost no structural deformation associated with this maneuver. This paper discusses structural modeling approaches and makes recommendations specific to optical space structure simulations.