An exact and approximation conjugate principle based on envelope theory and modified kinematic method was presented,respectively,by using the double-circular-arc common tangent tooth profile (DCTP) and considering the effect of the tooth profile and elastic deformation of harmonic drive (HD).The results showed that there exists two conjugate existent domains(CEDs) and dual conjugated phenomenon.The CED and conjugate tooth profile (CTP)calculated based on envelope theory and modified kinematic method perform the similar property.The CTP,the locus of the conjugate completion phase,and the backlash that is near the major axis of wave generator (WG) are slightly influenced while using the approximation conjugate principle.Meanwhile,the CED,the movement trails of the conjugate initial state and the backlash that far from the major axis of (WG) are evidently influenced.
