Mathematical Modelling of the Limit Working Capacity of a Harmonic Drive

The limit torque is a characteristic of upmost importance as it determines the loading capacity of a harmonic drive. When designing harmonic drives, it is necessary to determine the limit torque as its value may happen to be less than nominal. In this case the drive becomes inoperative due to the slippage of the generator. The main reason for the slippage is the interference caused by the reduction of the backlash between the top of the teeth as they come into contact when the drive is loaded. The existing engineering methods of determining the limit torque of the harmonic drive are based on approximation and experimental data. They cannot be used to calculate the processes occurring when the generator slips. The article presents a mathematical model of harmonic drive that can be used to analyze its limit working capacity and determine the limit torque, after which slippage occurs. The developed model is based on the calculation of elastic interaction between the links of the drive that have spatial deformation. The validity of the proposed model is tested by comparing the results of calculations with experimental data. The results presented in the article broaden the knowledge about the limit working capacity of harmonic drives.

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