Abstract
Clearances caused by assemblage, manufacturing errors and wear, affect inevitably the dynamic responses of mechanisms such as robot manipulator. In this study, the effects of clearance on a robot manipulator system are investigated numerically. The contact behavior along normal and tangential direction of clearance joint is described by a nonlinear contact force model and a modified Coulomb friction model respectively. Then, the dynamics equations of the robot manipulator system are established considering joint clearance. In order to investigate the effects of clearance on dynamic performances of practical mechanism, a planar robot manipulator system on a spacecraft system with a revolute clearance joint is used as the apply example. Four case studies for various clearance sizes are implemented to investigate and discuss the effects of joint clearance. The simulation results indicate that clearance joints have severe effects on the dynamic performances of mechanism system and the impact in clearance joints represented by contact force models must be considered in dynamics analysis and design of mechanism system. The simulation results in this work can predict the effects of clearance on robot manipulator system preferably and it is the basis of precision analysis, robust control system design of robot manipulator system.
Highlights
The clearances in joints are always neglected in dynamics modeling and analysis of mechanisms, such as robot manipulator systems
The motion acceleration is obvious vibrated with higher peaks of value, which will lead to the decrease of dynamic performance as well as motion stability of the robot manipulator system
The results clearly show that the dynamic responses x 10-5 7 5
Summary
The clearances in joints are always neglected in dynamics modeling and analysis of mechanisms, such as robot manipulator systems. Muvengei et al [27] investigated the dynamics and motion modes of a slider-crank mechanism with two planar revolute clearance joints. Tan et al [33] investigated the effects of friction on dynamic behavior of a planar crank-slider mechanism considering revolute joint with radial clearance using the LuGre friction model. Pi and Zhang [37] presented a study of dynamic analysis of the classical planar slidercrank mechanism with multiple revolute clearance joints. Guo et al [40] presented a dynamic model to investigate the position secondary motion considering all associated joint clearances These works were limited to the linkage mechanism, such as slider-crank mechanism and son on.
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