Based on the harmonic drive kinematic feature

the interfence control model(ICM) is presented for calculating the theoretical meshing arcus length in this paper. Then

the theoretical meshing arcus length and the simutaneous meshing tooth numbers of Four-Tooth and two-tooth difference harmonic drive are analyzed . At last

the conclusion that the former transmission accuracy lever is more than ten percent of the latter is obtained under the condition of same reference diameter

same ratio

same radial deflection

same rim thickness and same manufacture accuracy.