Bond graph based dynamic characteristic modeling and simulation of planetary roller screw mechanism

Based on bond graph theory, a dynamic analysis model of planetary roller screw mechanism was presented, in which transmission clearances, contact deformations of threads, torsion and compression deformations of screw, machining errors, load distribution of threads, friction and inertias were taken into consideration. Meanwhile, the state equations of the model were derived. In the model, for describing the nonlinear and stepped properties of contact force and damping force caused by transmission clearances between thread surfaces, the concept of switched power junctions was introduced, and the influence of friction on dynamic characteristics of planetary roller screw mechanism was considered based on the LuGre model. Taking some planetary roller screw mechanism as an example, the calculated step response of velocity was compared with the result from Adams simulation to verify the effectiveness of the model. Then, the influences of rotating speed of screw and slide roll ratio on friction force response characteristics, and the influences of transmission clearances and machining errors on stiffness characteristics were investigated. The results can help to improve the dynamic accuracy and stability of planetary roller screw mechanisms.