Commercializedcapsule-typeendoscopesmovepassivelybyperistalticwaves(andgravity),whichmakesitdifficultfordoctorstodiagnosetheareasofinterestmorethoroughlyandactively.Toresolvethisproblemofpassivity,itisnecessarytofindaspeciallocomotionprinciple,whichfitsthegastrointestinal(GI)tract.Inthispaper,aleggedlocomotivemechanismwithshapememoryalloy(SMA)actuationbasedontheperistalticprincipleisproposed,andthenthestructureofthelocomotionmechanismisintroduced.Basedonthepreliminaryresults,thedesign,modeling,andfabricationofanSMAmicroactuationconceptforapplicationinanendoscopiccapsulearegiven,aswellastheSMAspringandleggedcomponentdesign,whichisthecoresectionofthesystemdesign.Weusedthepseudo-rigid-bodymodel(PRBM)toanalyzenonlinearandlargedeflectionsoftheSMAleggedcomponent.Thus,aprototypeendoscopewithanSMAspringandsixleggedcomponentswasdesignedandfabricated.Itis15mmindiameterand33mmintotallength,withahollowspacetohouseotherpartsneededforendoscopysuchasacamera,aradiofrequency(RF)module,andsensors.Duringtesting,thelocomotivemechanismwaseffectiveinaplastictubeenvironment.
