| With the flourishing of industrial robots and the continuous expansion of its application,modern technic and manufacturing have put more stringent requirements on the performance of robots.Accuracy is one of the important indexes to measure the performance of industrial robots and the object which researchers attach great importance to.Nowadays,the welding robot in the market is mainly traditional series robot which has advantages of large workspace and small size.However,its open-chain structure and the drive motor at the corner of joint not only increase the force of mechanical arm,but also affecting rotational inertia.Extemal load,inertial force and operation posture of the robot are the main factors that cause the accumulative deformation of the members and joints,and they affect the stability of the robot and the accuracy of the end positioning seriously.In order to improve the dynamic performance of the robot and improve the operation accuracy,we combine the advantages of parallel mechanism,and controlled organization theory with the traditional serial robot phase structure,developed a new type of six degrees of freedom of controlled welding robot.This paper used the laboratory prototype as the research object.Then modeled the robot mechanism in elastodynamics methods,solved the dynamic equation of the mechanism.Selected reasonable size to limit the elastic displacement at the end of the robot and ensured the rigidity of the robot,to limit the elastic error within a certain range and lay a good basis for calibration.Besides,error analysis on the robot was studied.we analyzed the key factors affecting the end positioning in parameter error,provided economic and practical reference for us to achieve reasonable distribution of machining accuracy and the assembly order.Through the calibration,the real parameters of the robot can be identified and give feedback in the kinematics model of the robot to improve the absolute positioning accuracy of the robot. |
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