SSSFD Manipulator Engineering Using Statistical Experiment Design Techniques

The Satellite Servicer System Flight Demonstration (SSSFD) program is a series of Shuttle flights designed to verify major on-orbit satellite servicing capabilities, such as rendezvous and docking of free-flyers, Orbital Replacement Unit (ORU) exchange, and fluid transfer. A major component of this system is the manipulator system that will perform the ORU exchange. The manipulator must possess adequate toolplate dexterity to maneuver a
variety of EVA-type tools into position to interface with ORU fasteners, connectors, latches, and handles on the satellite, and to move workpieces and ORUs through 6 degree-of-freedom (dof) space from the Target Vehicle (TV) to the Support Module (SM) and back.

Typical of study-phase contracts, a premium is placed on budget, time, and other resourqes to perform trade studies and investigations. Experiments requiring major laboratory hardware builds are almost precluded. Therefore, for this study, two cost efficient tools were combined to perform an investigation of robot manipulator design parameters. These tools are graphical computer simulations and Taguchi Design of Experiment methods. Using a high performance graphics platform, an off-the-shelf robot simulation software package, and an experiment designed with Taguchi's approach, the sensitivities of various manipulator kinematic design parameters to performance characteristics are determined with minimal cost.

Taguchi's methods have been applied to many research and manufacturing problems, but seldom to system design issues. To our knowledge, this is the first application of Taguchi's methods to a manipulator design problem.