Abstract: Anewreactionlessspacerobotdesignconceptwasputforwardtoovercometheshortcomingsofthecurrentdrivetypes.Controlmomentgyros(CMGs)weremountedoneachpartmechanicalarmandsystemplatformasmovementactuators.Mechanicalarmswereconnectedwithsphericalhinges.PlatformattitudeandangulardisplacementweremeasuredbytheRodriguesparameters(RPs).BasedonsystemdynamicsmodelbuiltwithKanemethod,agraduallystabletrajectorytrackingcontrollawwasdesignedtotracktheplatformattitudeand mechanicalarmangulardisplacement,andaCMGssteeringlawwasdesignedtooutputexactexpectedcontroltorque.Moreover,thedesigned controllawscanbefurtherextendedtotrackandcontroltheworkspacetrajectorybystudyingthetrajectoryplanningalgorithms betweenthemechanicalarmsworkspaceandjointsspace.Thesimulationresultsfromthethreejointssystemshaveverifiedthefeasibility ofdesignandeffectivenessoftheproposedtrajectoryalgorithms.

Key words: Sphericalhinge, Controlmomentgyros, Robotarm, Trajectorytracking, Spacerobot