Learned graphical models for probabilistic planning provide a new class of movement primitives

Elmar A. Rückert, Gerhard Neumann, Marc Toussaint, Wolfgang Maass

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Biologicalmovementgenerationcombinesthreeinterestingaspects:itsmodularorganizationinmovementprimitives(MPs),itscharacteristicsofstochasticoptimalityunderperturbations,anditsefficiencyintermsoflearning.Acommonapproachtomotorskilllearningistoendowtheprimitiveswithdynamicalsystems.Here,theparametersoftheprimitiveindirectlydefinetheshapeofareferencetrajectory.WeproposeanalternativeMPrepresentationbasedonprobabilisticinferenceinlearnedgraphicalmodelswithnewandinterestingpropertiesthatcomplieswithsalientfeaturesofbiologicalmovementcontrol.Insteadofendowingtheprimitiveswithdynamicalsystems,weproposetoendowMPswithanintrinsicprobabilisticplanningsystem,integratingthepowerofstochasticoptimalcontrol(SOC)methodswithinaMP.Theparameterizationoftheprimitiveisagraphicalmodelthatrepresentsthedynamicsandintrinsiccostfunctionsuchthatinferenceinthisgraphicalmodelyieldsthecontrolpolicy.Weparameterizetheintrinsiccostfunctionusingtask-relevantfeatures,suchastheimportanceofpassingthroughcertainvia-points.Thesystemdynamicsaswellasintrinsiccostfunctionparametersarelearnedinareinforcementlearning(RL)setting.Weevaluateourapproachonacomplex4-linkbalancingtask.Ourexperimentsshowthatourmovementrepresentationfacilitateslearningsignificantlyandleadstobettergeneralizationtonewtasksettingswithoutre-learning.
Original languageEnglish
Article number97
Number of pages20
JournalFrontiers in computational neuroscience
Volume6.2013
Issue numberJanuary
DOIs
Publication statusE-pub ahead of print - 2 Jan 2013
Externally publishedYes

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