Abstract: iththehighdemandforpointingaccuracyofthesatelliteantenna,thejointclearanceisinevitableduetotheexistenceofthekinematicpairinthetwoaxispositionmechanism.Soitisparticularlyimportanttostudytheinfluenceofthejointclearancetosatelliteantennamechanism.Thetwoaxispositionmechanismwastakenasresearchobject,thecontact dynamicsmodeloftheclearancejointwasestablishedbyapplyingthenonlinearspringdampmodel,andthefrictioneffectwasconsideredbyapplyingtheCoulombfrictionmodel.Thelawthatthedynamiccharacteristicoftwoaxisposition mechanismaffectedbythefactorswasanalyzedbythedynamicsimulationofthevirtualprototype,suchasthesizeofthejointclearanceandthedrivingtorqueintheclearance.Theresultsshowthatlargejointclearanceanddrivingtorquewillreducethepositioningaccuracyandmakethesystemunstable.Itisagoodwaytoincreasethepositioningaccuracythroughoptimizingthestructureofthesatelliteantennamechanism.

Key words: Two axis position mechanism, Joint clearance, Virtual prototype, Dynamic characteristics, Influence rule, Pointing accuracy, Satellite antenna