简介：Forintelligent/autonomoussubseavehicles,reliableshort-rangehorizontalpositioningisdifficulttoachieve,particularlyoverflatbottomtopography.Apotentialsolutionproposedinthispaperutilizedapassiveopticalsensingmethodtoestimatethevehicledisplacementusingthebottomsurfacetexture.Thesuggestedopticalflowmethoddoesnotrequireanyfeaturecorrespondencesinimagesanditisrobustinallowingbrightnesschangesbetweenimageframes.Fundamentally,thismethodissimilartocorrelationmethodsattemptingtomatchimagesandcomputethemotiondisparity.However,incorrelationmethods,searchinganeighborregionblindlyforbestmatchislengthy.Maincontributionsofthispapercomefromtheanalysisshowingthatopticalflowcomputationbasedonthegeneralmodelcannotavoiderrorsexceptfornullmotionalthoughthesignofopticalflowkeepscorrect,andfromthedevelopmentofaniterativeshiftingmethodbasedontheerrorcharacteristicstoaccuratelydeterminemotions.Advantagesoftheproposedmethodareverifiedbyrealimageexperiments.