The failure mode of harmonic reducer under low-speed
light-load conditions in the space is the transmission error and backlash exceed the required accuracy due to thewear.Forthe failure mode
the modelsof calculating the transmission error and backlash considering the wear are established and thus establishingmodels of reliability of harmonic reducer.A case analysis is conducted by using the models of reliability and the reliabilities are calculated by MATLAB program.The results show that the models of reliability are consistentwith the actual situation.