Modeling and analysis of pure kinematic error in harmonic drive

Harmonic drives are widely used in the precision positioning systems due to their attractive attributes. However, kinematic error is the most fundamental problems in these drives. In this work, we present a method for analyzing the pure kinematic error of harmonic drive with machining and assembly errors. The pure kinematic error is decomposed into two parts including nonuniform motion component and lag component. The beat frequency phenomenon of the pure kinematic error is revealed. The explanation of the mechanism of pure kinematic error is verified by the experimental data from a specialized harmonic reducer test device. The influences of the wave generator structure (automatic alignment and integral structures) and shape on the pure kinematic error of harmonic drive are discussed and quantitatively evaluated, and the one possible new configuration of the wave generator is presented, which can improve the transmission performance of the drive. The results of this paper are believed to be useful for the design of harmonic drive. (C) 2020 Published by Elsevier Ltd.