Structure design and performance analysis of self-driving articulated arm coordinate measuring machine

2021 ◽  
Author(s):  
Hongtao Yang ◽  
Mei Shen ◽  
Mengyao Zhang ◽  
Jingjing Cheng ◽  
Tingting Hu ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Angular Acceleration ◽  
Coordinate Measuring Machine ◽  
Position Error ◽  
Static Deformation ◽  
Theoretical Research ◽  
Positioning Error ◽  
Instantaneous Position ◽  
Measuring Machine ◽  
Space Range

Abstract To solve the problem that the traditional articulated arm coordinate measuring machine cannot measure automatically, a self-driven articulated arm coordinate measuring machine (AACMM) is proposed. The length of the connecting rods of the AACMM was allocated according to the design indicators. The AACMM virtual prototype was assembled based on the joint module selection and joint component design, and its measurement space range was also verified. The AACMM ideal measurement model was established based on MDH methodology. The static deformation of the structure and the influence of the dynamic flexible deformation on the positioning error of the probe of the measuring machine was analyzed, respectively. The results show that the measurement space range of the AACMM designed in this paper can meet the design index of the measuring radius. The probe position error caused by static deformation of the measuring machine after structural optimization was reduced by an order of magnitude. The positioning error of the probe caused by the dynamic deformation of the AACMM structure meets the positioning accuracy index. In the constant-speed touch measurement stage, the instantaneous position error of the probe changes linearly with time, and the optimal touch speed (6.6 mm/s, 6.4 mm/s) exists to minimize the probe positioning error. During the variable-speed approach stage, the influence of angular acceleration and velocity of each joint on the positioning error of the probe can be negligible when AACMM in the typical posture. In the extreme posture, , the inertial force of the measuring machine structure and the instantaneous position error of the probe are the smallest with the optimal joint angular acceleration ( ) and angular velocity ( ). The structural design and positioning error performance analysis of self-driving AACMM can provide a theoretical research foundation for subsequent trajectory planning and error compensation modeling.

Measurement Method for the Symmetry Error of Double Keyway in a Wheel Hub Bore

2010 ◽  
Vol 139-141 ◽  
pp. 2087-2092
Author(s):  
Xiao Ming Zhao ◽  
Yun Feng
Keyword(s):  
Measurement Method ◽  
Geometric Analysis ◽  
Coordinate Measuring Machine ◽  
Position Error ◽  
Minimum Condition ◽  
Engineering Practice ◽  
Error Evaluation ◽  
Measurement Principle ◽  
Measuring Machine ◽  
Error Formulas

In this paper, a new measurement method is presented, This method is to use a three-coordinate measuring machine (CMM) to test the symmetry error of double keyway in a wheel hub bore. According to the minimum condition criterion of form and position error evaluation, and making use of the minimum tolerance zone of position error evaluation, two symmetry error formulas of double keyway in a wheel hub bore are deduced by geometric analysis. The problems may be encountered when using the formulas in the practical application are discussed. These formulas solve the measurement principle problem of double keyway in the engineering practice. In the end an example is put forward to verify this method and the formulas.

Study on Measuring Perpendicularity Based-On Non-Diffracting Beam as the References

2012 ◽  
Vol 586 ◽  
pp. 349-355
Author(s):  
Xin Bao Zhang ◽  
Kun Zhang ◽  
Hong Lu
Keyword(s):  
Coordinate Measuring Machine ◽  
Position Error ◽  
New Method ◽  
Straight Line ◽  
Pentagonal Prism ◽  
Measuring Machine ◽  
Working Distance

A new method for measuring perpendicularity is developed in this paper, in which the non-diffracting beam that illuminates a pentagonal prism to produce the vertical reference is used as the straight-line reference and CCD is used as the sensor to gauge the position error to the references. Three evaluation algorithms of the perpendicularity error are also given in the paper. And furthermore, perpendicularity of a Coordinate Measuring Machine was measured by this method, which is easy to be operated. The results and analysis indicate that its working distance can be more than 15m while the precision can be less than±5μm/m.

Measurement of Movement Error and its Compensation for 6-DOF Parallel Mechanism Worktable

2012 ◽  
Vol 523-524 ◽  
pp. 463-468 ◽  
Author(s):  
Yuan Rui Zhang ◽  
Jiang Zhu ◽  
Tomohisa Tanaka ◽  
Yoshio Saito
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Parallel Mechanism ◽  
Coordinate Measuring Machine ◽  
Geometric Error ◽  
Degree Of Freedom ◽  
Positioning Error ◽  
Uncertainty Factor ◽  
Movement Error ◽  
Measuring Machine

In this study, a small, 6-DOF (degree of freedom) parallel mechanism worktable for machine tool was developed. There are a lot of factors that affect the positioning error and the accuracy of the machine tools. The uncertainty in position is mainly due to the rigidity of the structure, the geometric error of parts and assembly errors. It is very difficult to estimate the assembly errors and the link parameter of each part. In this paper, the uncertainty factor in positioning of the worktable was investigated and compensated based on measurement of movement error by using coordinate measuring machine (CMM).

scholarly journals Evaluation of dimensional accuracy of dental bridges manufactured with conventional casting technique and CAD/CAM system with Ceramill Sintron blocks using CMM

2018 ◽  
Vol 12 (4) ◽  
pp. 264-271 ◽  
Author(s):  
Alireza Izadi ◽  
Fariborz Vafaee ◽  
Arash Shishehian ◽  
Ghodratollah Roshanaei ◽  
Behzad Fathi Afkari
Keyword(s):  
Reference Model ◽  
Coordinate Measuring Machine ◽  
Dimensional Accuracy ◽  
Three Dimensions ◽  
Casting Technique ◽  
Dimensional Changes ◽  
Conventional Casting ◽  
Cad Cam ◽  
Milling Method ◽  
Measuring Machine

Background. Recently, non-presintered chromium-cobalt (Cr-Co) blocks with the commercial name of Ceramill Sintron were introduced to the market. However, comprehensive studies on the dimensional accuracy and fit of multi-unit frameworks made of these blocks using the coordinate measuring machine (CMM) are lacking. This study aimed to assess and compare the dimensional changes and fit of conventional casting and milled frameworks using Ceramill Sintron. Methods. A metal model was designed and scanned and 5-unit frameworks were fabricated using two techniques: (I) the conventional casting method (n=20): the wax model was designed, milled in the CAD/CAM machine, flasked and invested; (II) the milling method using Ceramill Sintron blocks (n=20): the wax patterns of group 1 were used; Ceramill Sintron blocks were milled and sintered. Measurements were made on the original reference model and the fabricated frameworks using the CMM in all the three spatial dimensions, and dimensional changes were recorded in a checklist. Data were analyzed with descriptive statistics, and the two groups were compared using one-way ANOVA and Tukey test (α=0.05). Results. The fabricated frameworks in both groups showed significant dimensional changes in all the three dimensions. Comparison of dimensional changes between the two groups revealed no significant differences (P>0.05) except for transverse changes (arch) that were significantly greater in Ceramill Sintron frameworks (P<0.05). Conclusion. The two manufacturing processes were the same regarding dimensional changes and the magnitude of marginal gaps and both processes resulted in significant dimensional changes in frameworks. Ceramill Sintron frameworks showed significantly greater transverse changes than the conventional frameworks.

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