Abstract: The relative angle between pinwheel and cycloid disk is discussed after the equidistant modification and radial-moving modification, the concept of the inverse arch-shaped teeth profile is brought forward in order to improve the contacting state , reduce the contacting force and make fully use of the cycloid teethprofile. The formula of the existing condition are given and the inverse arch-shaped teeth profile can be obtained easily through plus equidistant + minus radial-moving combining modification if the modification meets the given conditions. The software is also made to find the optimum inverse arch-shaped teeth profile by means of optimization method. The results of calculation about the various modification methods show that the contacting force of the inverse arch-shaped teeth profile is obvious better than the other modification method.

Key words: Cycloid drive, Existing conditions, Inverse arch-shaped teeth profile, Optimization of modification