A new approach of kinematic geometry for error identification and compensation of industrial robots

Author(s):  
Zhi Wang ◽  
Huimin Dong ◽  
Shaoping Bai ◽  
Delun Wang

A new approach for kinematic calibration of industrial robots, including the kinematic pair errors and the link errors, is developed in this paper based on the kinematic invariants. In most methods of kinematic calibration, the geometric errors of the robots are considered in forms of variations of the link parameters, while the kinematic pairs are assumed ideal. Due to the errors of mating surfaces in kinematic pairs, the fixed and moving axes of revolute pairs, or the fixed and moving guidelines of prismatic pairs, are separated, which can be concisely identified as the kinematic pair errors and the link errors by means of the kinematic pair errors model, including the self-adaption fitting of a ruled surface, or the spherical image curve fitting and the striction curve fitting. The approach is applied to the kinematic calibration of a SCARA robot. The discrete motion of each kinematic pair in the robot is completely measured by a coordinate measuring machine. Based on the global kinematic properties of the measured motion, the fixed and moving axes, or guidelines, of the kinematic pairs are identified, which are invariants unrelated to the positions of the measured reference points. The kinematic model of the robot is set up using the identified axes and guidelines. The results validate the approach developed has good efficiency and accuracy.

2013 ◽  
Vol 798-799 ◽  
pp. 464-467
Author(s):  
Jian Lu ◽  
Guan Bin Gao ◽  
Hui Ping Yang

The Articulated Arm Coordinate Measuring Machine (AACMM) is a new type of non-orthogonal system precision instrument with the advantages of large measuring range, small volume, low weight and portability. To improve the measurement accuracy of AACMMs, an error analysis and calibration method for AACMMs is proposed. The kinematic model of the AACMM was established with D-H model, and then the error model of the AACMM was established on the basis of kinematic model with total differential transforming method and the singular value decomposition of Jacobian matrix and the decomposition of orthogonal matrix elementary row transform. Finally, the error model was validated by position error residual calculation. The error model provides a theoretical foundation for calibration and compensation of the AACMM.


2006 ◽  
Vol 532-533 ◽  
pp. 313-316 ◽  
Author(s):  
De Jun Liu ◽  
Hua Qing Liang ◽  
Hong Dong Yin ◽  
Bu Ren Qian

First, the forward kinematic model, the inverse kinematic model and the error model of a kind of coordinate measuring machine (CMM) using 3-DOF parallel-link mechanism are established based on the spatial mechanics theory and the total differential method, and the error model is verified by computer simulation. Then, the influence of structural parameter errors on probe position errors is systematically considered. This research provides an essential theoretical basis for increasing the measuring accuracy of the parallel-link coordinate measuring machine. It is of particular importance to develop the prototype of the new measuring equipment.


2011 ◽  
Vol 105-107 ◽  
pp. 1899-1902 ◽  
Author(s):  
Xiao Wei Zhang ◽  
Xing Hua Li ◽  
Bo Chen

In this paper, the mathematical model with errors for parallel double-joint coordinate measuring machine (CMM) was proposed. The main factor of the impact of circular grating measurement error--radial install eccentric error--was analyzed. The error was measured and the data obtained from measurement was used to curve fitting and form the error compensation formula. Experiments show that the method of error compensation has good usability and accuracy.


2016 ◽  
Vol 6 (7) ◽  
pp. 181 ◽  
Author(s):  
Hui-Ning Zhao ◽  
Lian-Dong Yu ◽  
Hua-Kun Jia ◽  
Wei-Shi Li ◽  
Jing-Qi Sun

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yujia Wu ◽  
Zhewen Hu ◽  
Xinyue Zhang ◽  
Hefei Bai ◽  
Yuchun Sun ◽  
...  

Abstract Purpose The scanning of plaster models for three-dimensional (3D) construction requires their rigid fixation in the intercuspal position. Factors such as installation, motion, and scanning procedures influenced the accuracy of this method, which ultimately influence the results. Therefore, the present study attempted to provide an optimal and accurate method with less complex procedures and a more accessible equipment for determining the intercuspal relation in the 3D occlusal construction of dental models. Methods A pair of plastic mounting plates that could be directly attached to a mechanical articulator was designed and 3D printed. Nine axial hemispherical concaves were introduced on the axial surface of each plate. The rigidly fixed maxillary and mandibular dental models were scanned directly. The distances DR between nine pairs of concaves on both mounting plates adhered to the maxillary and mandibular sections of the articulator were measured using the three-coordinate measuring machine Faro Edge as the reference. The present study comprised seven test groups varying in number and location. Assessing the reference points from each of the seven groups performed the 3D construction. The Geomagic Studio software was used to construct the concaves of digital casts, and the distances DM between the pairs of concaves were measured as test values. Variable differences between DR and DM were analyzed. Results An optimum distribution scheme was obtained for reference point registration by quantitatively evaluating accuracy levels of the 3D constructions of different reference point distribution patterns. This scheme can serve as a reference for related studies and dental clinic operations. Conclusions Three-dimensional construction of the intercuspal relation during scanning of the maxillary and mandibular models with an accuracy of 0.046 mm ± 0.009 mm can be achieved using the improved design of mounting plates.


Author(s):  
S. Liu ◽  
Z. Dong

Abstract An ambiguous representation of design geometry and its allowed variation is essential to design and manufacturing analysis tools using geometric modeling. In this paper, a new approach for modeling and representing mechanical tolerances, using information embedded in the solid model, is introduced. The work focuses on mathematical mapping between the nominal and variant configurations of design geometry, using boundary face-based model variables. The method identifies the relation between the errors of part geometry, represented by a solid model and measured using a coordinate measuring machine, and the tolerances, specified by dimensioning and tolerancing standards. The work is of benefit in understanding of the fundamental nature of geometric errors and tolerances; it guides the specification of dimensional and geometric tolerances; and, contributes to automated mechanical tolerancing in a solid modeling based system.


Author(s):  
R M Hall ◽  
A Unsworth ◽  
P S Craig ◽  
C Hardaker ◽  
P Siney ◽  
...  

Twenty-eight standard Charnley sockets were retrieved at revision surgery. The penetration angle with respect to the cup coordinate system, β, and penetration depth, d, of the sockets were measured using both the traditional shadowgraph technique and by analysing data obtained from a coordinate measuring machine (CMM). In addition, d was deduced radiographically from pre-revision X-rays. Limits of agreement between the three methods of measuring d were of the order of ±0.5 mm. Using the data obtained from the CMM it was possible to deduce the wear volume Vmeas directly. It was found that, in general, values of the wear volume calculated from d and β using equations cited elsewhere (1, 2) were both imprecise and inaccurate. The direct measurement of the wear volume using the CMM depends on the location of reference points external to the wear surface. If such surfaces were damaged, then it was concluded that the shadowgraph technique provided the most suitable method for measuring the dimensional changes in the retrieved socket, due to its relative ease of use.


2003 ◽  
Vol 69 (6) ◽  
pp. 851-855 ◽  
Author(s):  
Kiyoshi TAKAMASU ◽  
Ryoshu FURUTANI ◽  
Ken SHIMOJIMA ◽  
Osamu SATO

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