N 9 0 2 ' : : an Y ( _ Experiments in Cooperative Manipulation : A System Perspective

Abstract This paper outlinesan experimentincooperativeroboticmanipulationconductedat Stanford'sAerospaceRoboticsLaboratory.Inadditiontocooperativedynamic control,thesystem incorporatesreal-time visionfeedback,a novelprogramming technique,and a graphicalhigh-level userinterface. By focusingon thevertical integration problem,we axeexaminingnot onlythesesubsystems,but alsotheirinterfaces and interactions. The controlsystem implements a multi-level hierarchical structure; the techniquesdevelopedforoperatorinput,strategicommand, and cooperativedynamic controlarepresented.At the highestlevel,a mouse-basedgraphicaluserinterface allowsan operatorto directthe activities of the system. Strategic command isprovidedby a table-driven finitestatemachine; thismethodology providesa powerfulyet flexible techniqueformanaging the concurrentsystem interactions. The dynamic controller implements "objectimpedance control'--anextensionofNevillHogan'simpedance controlconcepttocooperative-arm manipulationofs singleobject. Experimentalresults_e presented, showingthesystemlocatingand identifying amoving object,"catching"it,and performinga simplecooperativeassembly.Resultsfrom dynamic controlexperimentsare also presented,showingthe controller's excellent dynamic trajectory trackingperformance,whilealsopermittingcontrolofenvironmentalcontactforces.