Error Analysis of 6-DOF Welding Robot

Wang, Caidong; Wang, Xin Jie; Chen, Xue Dong; Zhang, Zhao Hui

doi:10.4028/www.scientific.net/amm.220-223.1111

Cited by 1 publication

(1 citation statement)

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“…In previous years, there have been several studies undertaken on error modeling. The most extensive approach is to use a homogeneous transformation matrix or Denavit-Hartenberg (D-H) transformation matrix to describe the coordinate transformation between each rigid body frame and its reference coordinate system, 9,10 which is based on rigid body kinematics. The vector loop method, 11,12 product of exponentials (POE) method, 13,14 and screw method [15][16][17] are some other useful tools for such error modeling.…”

Section: Introductionmentioning

confidence: 99%

A Systematic Approach for Accuracy Design of Lower-Mobility Parallel Mechanism

Tian¹,

Shen²,

Lv³

et al. 2020

Robotica

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SUMMARY Geometric accuracy is a critical performance factor for parallel robots, and regardless of error compensation, accuracy design or tolerance allocation is another way to ensure the pose accuracy of a robot at design stage. A general method of both geometric error modeling and accuracy design of lower-mobility parallel mechanisms is presented. First, a general approach for error modeling of lower-mobility parallel mechanism is proposed based on screw theory, and then the geometric errors affecting the compensatable and uncompensatable accuracy of the end-effector are separated using the properties of dual vector space. The pose error aroused by compensatable geometric errors can be compensated via kinematic calibration, while the uncompensatable geometric errors should be minimized during the manufacturing and assembly processes. Based on that, the tolerance allocation method is presented, giving each uncompensatable geometric error a proper tolerance by the use of reliability theory. Compared with the traditional tolerance allocation method, the advantages of the proposed method are as follows: the number of geometric errors to be allocated is greatly reduced; the results of serialized tolerance allocation can be obtained according to different reliability indices of pose accuracy of end-effector for designers to choose; on the premise of guaranteeing the same pose accuracy of end-effector, the allocated tolerances are loose and easy to realize. Finally, the proposed methods are successfully applied to an R(2-RPS&RP)&UPS lower-mobility parallel robot, and the effectiveness and practicability of the proposed method are verified.

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