| Reducer for robot rotation joint has attracted more attention as its significant influence on accuracy and bearing capacity with the development of robotics. Generally, precise reducer for rotation joint can be categorized into RV reducer and harmonic reducer in the domestic research area, but often relies on import. Therefore, the research on precise reducer for robot rotation joint has great effect.The paper proposes a novel precise reducer for robot rotation joint based on planetary roller screw (PRS), the structure of reducer is designed and optimized, also, the performance is tested. Besides, the kinematics and dynamics of PRS are analysed respectively. The working principle of our reducer is that the reducer can translate the forward and reverse input rotation of the motor into the output rotation of the middle nut, whose acting scope is from0to180degree. The reducer has a high transmission precision, as well, inherits good performance of PRS, such as high bearing capacity.Kinematic analysis, structure design and optimization of reducer based on PRS theory. At first, the relevant theory of PRS is introduced. Then the inversion method of planetary gear train is applied to analyse the kinematics of PRS and the movement relationship between the screw by comparing the ball screw, so that the relationship of screw, roller and nut of PRS is obtained, based on which the transmission plan and the corresponding parts are developed. Moreover, the structure is optimized through modelling the total volμme of the transmission parts.A proper simplification for PRS is carried out, which means that transverse movement relation is regarded as the helical gear transmission, and the relationship between the contact normal force and the axial force, as well between the nut torque and the axial force is got by computing the stress of the screw, roller and nut.Thus laid the foundation for the analysis of the bearing capacity of the reducer.The theoretical model of the relationship between the axial contact deformation and the axial stiffness of PRS is built through analysing the stress and deformation of the roller considering the effect of the planetary roller screw spiral angle. Then the relationship between the stiffness and some related factors are shown; the friction torque which is generated by elastic hysteresis and roller spin sliding is calculated, and the effect rules of the contact angle, the helix angle and the nμmber of roller teeth on texture friction torque is checked. On this basis, a model for calculating the transmission efficiency of PRS is constructed, according to which the influence factors of the model are presented, such as contact angle and helix angle.The vadility of reducer design is given theoretically by simulation on the kinematics analysis and contact force analysis of the3D model built by SolidW orks under Adams framework. |
