Dynamic modeling and analysis for a differential modular robot joint with the friction model

The study of friction has long been popular with scientists. Considering the coupling characteristic of multi-input-multi-output (MIMO) system, the coupling friction model was established, which was based on Coulomb-Viscous friction model for the differential modular robot joint (DMRJ) according to the law of conservation of energy. Then, we identified the coefficients of the friction model through the experiment. In order to verify the accuracy of the established friction model, we regarded the DMRJ as a 2-DoF linkage and built the inertial dynamic model based on Lie theory, whose inertial parameters were estimated by computer aided design (CAD). Besides, we chose the trajectory based on the Fourier series, which has good performance in anti-interference ability, as the verification trajectory. From the generated trajectories, we used a trajectory that is able to change as much as possible in speed, position and acceleration to estimate the accuracy of the model comprehensively. Finally, the result indicated the model had good accuracy.