Research on Flexible Joint Friction Identification of Space Lab Manipulator

In order to verify the flexible joint friction model with harmonic drive, the method of on orbit identification and the effect of joint friction on joint control, Chinese Space Laboratory Tiangong - 2 equipped with a Space Manipulator and Dexterous Hand System (SMDHS). Manipulator joint friction identification experiment was carried out on orbit. In this paper, a flexible joint model of manipulator is established. By using the experimental data obtained on orbit, the friction model of viscous friction plus coulomb friction, the cubic polynomial friction model and the Stribeck friction model are compared and analyzed. At the same time, the effect of gravity difference on joint friction is also analyzed. The on orbit experiment prove that the quasi-linear model of viscous friction plus coulomb friction can be used to predict the friction of unrecognized velocity range, the accuracy of joint position control can also tolerate the error of this quasi-linear friction model in engineering applications. The flexible joint model and on orbit identification method established in this paper are helpful to develop the follow up large scale space manipulator and recognize the joint friction characteristics more clearly in the orbital application, so as to further improve the fine operating performance of the manipulator.