Kinematic accuracy of the flexible space manipulator with harmonic drive

Space manipulator is an important tool of spacecraft to complete a variety of tasks, such as release and retracting of satellite, assembly and maintenance of space station in orbit. The trajectory precision of the end effector determines whether the mechanism performs normally or not. Nowadays the harmonic drive is widely used as the reducer in the space manipulator, which may lead to the kinematic hysteresis for application. The hysteresis of harmonic reducer is analyzed, and the dynamics equations with hysteretic characteristic for flexible space manipulator is shown based on Rayleigh-Ritz method. In order to describe the output error, the precision indices are proposed. The relation among the hysteresis angle, rigidity and the output accuracy is revealed. The results can be used in designing and optimizing the key dynamic parameters future space manipulators.