International Space Station assembly and operation control challenges

For the International Space Station program to be successful mission requirements must be robustly met in the presence of uncertainties. Changing Station characteristics during assembly such as variability in structural flexibility and mass properties pose unique control challenges. Three examples of control challenges are reviewed in this paper, the first two arising out of variability in flex structure and the last one due to mass property variation. Controller/flex structure interaction issues and their origins are reviewed as well as representative examples. CMG momentum desaturation issues during robotic operations are addressed and an operational solution is reviewed. Finally, CMG attitude control issues during payload robotic operations are presented as well as an issue resolution technique.