The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B3b. Beijing 2008 
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3. EXPERIMENT PROPOSAL 
Numerical simulation is as the test program to test the 
soundness, reliability and stability of the algorithm. If the 
condition ripens, the simulation for the semi-entities will be 
designed and tested. 
3.1 Numerical Simulation 
The simulation of numerical simulation, which is composed of 
mathematic models, simulation software and computers to 
complete relevant computer simulation and graphic and image 
simulation, researches the real system only by way of building 
the mathematic model of the system and needn’t any parts of 
real system. Building mathematic model and developing 
professional simulation module are the keys to the program, 
such as simulation generating and processing of CCD image 
symbols, astrodynamics and orbit model of relative motion 
between the target and the tracking spacecraft, resolution for 
relative navigation and so on. 
Based on Matlab/Simulink, which have high efficiency and 
great advantage in modeling in comparison with other general 
developing programs, the test platform of numerical simulation 
provides not only linear system modeling but also non-linear 
system modeling. In addition, the platform is a open simulation 
system which can be used to develop special simulation 
modules in order to realize special simulation tasks. The 
constitution of the platform is shown in Figure 4. 
Figure 4. The constitution of the numerical simulation test 
platform of relative navigation system 
3.2 Hard-in-loop Simulation 
After the above numerical simulation, only the test for real 
system can further judge whether the functions and capabilities 
meet the design demands, in which hard-in-loop simulation is 
the best method. In the hard-in-loop simulation, non- 
cooperative target is equipped in a platform owning 6 degrees 
of freedom, whose motion follows the pre-planned relative orbit 
and attitude-dynamics model designed by computers. Dual- 
CCD are controlled by the professional image-collection board 
and high-performance DSP module computer to complete the 
relevant image acquisition, target recognition, feature extraction, 
image matching and so on. Finally, all data will be conveyed in 
the master-control DSP module computer to realize the solution 
of relative navigation. The following hardware modules for 
simulation are indispensable: 6-DOF platform, CCD, parallel- 
image-collection board, DSP developing board, also called as 
module computer, D/A and A/D interfaces. The platform 
structure is shown in Figure 5. 
Figure 5. The constitution of the semi-entity simulation 
platform of relative navigation system 
4. CONCLUSION 
Relative navigation for space non-cooperative target has 
important practical value and wide practical prospect. Based on 
the relevant theories and methods in Digital Photogrammetry 
and Astrodynamics, the framework of relative navigation 
system rebuilds 3D geometric model of the target by way of the 
image matching algorithm based on features and the CSG 
method under analyzing the relative motion rules between space 
targets and researching the preprocessing methods for 3D 
sequence images of space targets deeply. And then the real-time 
solution for relative navigation is carried out by means of the 
photogrammetric location theory and Extended Kalman 
Filtering. Finally, the soundness, reliability and stability of the 
theory and algorithm for the relative navigation are tested by 
numerical and semi-entity simulation methods entirely. 
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