Effect of Attitude Control Jets on the performance of the Space Station Robotic Manipulator System (SSRMS) A Case Study on Flights 6A and 7A

The effect of Attitude Control System Jets (ACS) jets on the Space Station Robotic Manipulator System (SSRMS, “Canadarm2”) while in stationary, unloaded and loaded configurations define the flight rules that would inhibit the use of ACS during critical points of SSRMS operations. The objective of the analysis performed is to identify potential generic issues, using worst-case ACS magnitude and frequency inputs as forcing functions. The primary concern is that disturbances due to ACS may be large enough in magnitude to cause large motor slippage and joint deviation, which would result in large uncommanded Frame of Resolution (FOR) motion of the SSRMS while it is in Position Hold or in Brakes On mode. Furthermore, these ACS disturbances might induce high loads at the base or tip interfaces of the arm as well as at the joints. The screening identifies incidents where the use of a particular Attitude Control strategy may be potentially incompatible with flight specific arm configurations based on worst-case considerations. This would result in the more detailed review of available /optional attitude control strategies, mission design, and potentially the generation of generic, flight, or increment specific flight rules. Based on worst case considerations, this screening identifies viable and safe Attitude Control strategy candidates.