Space detection
2017, 46(S1): 90-95.
doi: 10.3788/IRLA201746.S113001
In order to solve the problem of low accuracy in the calculation of space objective optical cross section(OCS), the improved Phong model based on the BRDF data of the space object was used, and the surface of the satellite model was folded. In the STK, the motion scene of the satellites in different precession states was designed. The OCS timing data of these satellites were calculated respectively. The influence of the precession angle on the optical scattering characteristics of the satellite was found by comparing the data periodically. Further research shows that when the precession angle of the satellite is small, the rotation speed of the satellite can be retrieved from the optical scattering characteristic data of the satellite. When the precession angle of the satellite is larger than the critical value(for the scenario designed in this paper, the value is 30), it becomes impossible to invert the periodicity of the satellite from the optical scattering characteristic data of the satellite.
2017, 46(S1): 96-103.
doi: 10.3788/IRLA201746.S113002
The problem of multi-sensor detecting and multi-target tracking was mainly studied. Firstly, the observability was analyzed according to the detecting geometry of double satellite, and the state equations and measurement equations were established according to the turning model based on gravity. Secondly, for the problem that fight path tracking abnormity exists in the situation of tracking multi-target, the SME filter algorithm based on binary polynomial was raised. Finally, in order to improve the tracking accuracy, the improved UKF algorithm based on the iteration was raised. The simulation indicates that all targets can be well tracked with the BPGM-SME algorithm. Compared with UKF algorithm, the improved UKF algorithm can get better convergence effect, and the tracking accuracy is better.
2017, 46(S1): 104-109.
doi: 10.3788/IRLA201746.S113003
Space-based two-dimensional turntable is the main load-bearing structure of space photoelectric detection equipment, and the collimation frame is the key support component of turntable, so its stiffness characteristics are vital for the performance of turntable. In order to decrease the mass and improve the stiffness performance, the structure of collimation frame was topologically optimized based on the variable density theory by finite element software-MSC. Patran/Nastran. Modal shape of collimation frame was regarded as the deformation of model under the thrust. The model was optimized with stiffness maximization as the objective function, the ratio of residual volume as the constraints. The results show that the model weight after optimization is lighten 1.32 kg and the first-order natural frequency increases 14.5 Hz compared with the model of experience design. The maximum deformation is relatively reduced by 22.4% and the maximum stress value is relatively reduced by 42.6% under the action of gravity in the Z direction and the statics characteristic of model are increased significantly in the other directions. The dynamic characteristics of the collimation frame are improved significantly with the weight reduction. Modal experiment was done for the optimization model and the results indicate that the finite element analysis is correct. Therefore, it is feasible to use the method of topology optimization to design the structure of collimation frame.
