Inthe'modifiedquasi-steady'approach,two-dimensional(2D)aerodynamicmodelsofflappingwingmotionsareana-lyzedwithfocusondifferenttypesofwingrotationanddifferentpositionsofrotationaxistoexplaintheforcepeakattheendofeachhalfstroke.Inthismodel,anadditionalvelocityofthemidchordpositionduetorotationissuperimposedonthetransla-tionalrelativevelocityofairwithrespecttothewing.Thismodificationproducesaugmentedforcesaroundtheendofeachstroke.Foreachcaseoftheflappingwingmotionswithvariouscombinationofcontrolledtranslationalandrotationalvelocitiesofthewingalonginclinedstrokeplaneswiththinfigure-of-eighttrajectory,discussionsfocusonlift-dragevolutionduringonestrokecycleandefficiencyoftypesofwingrotation.This'modifiedquasi-steady'approachprovidesasystematicanalysisofvariousparametersandtheireffectsonefficiencyofflappingwingmechanism.Flappingmechanismwithdelayedrotationaroundquarter-chordaxisisanefficientoneandcanbemadesimplebyapassiverotationmechanismsothatitcanbeusefulforroboticapplication.
