Inspection of Large Guide Rail Precision Based on Bistatic Measurement Method

2013 ◽  
Vol 791-793 ◽  
pp. 945-948 ◽  
Author(s):  
Yue Liu ◽  
Zhi Wei Hao ◽  
Tian Tian Ren
Keyword(s):  
Coordinate System ◽  
High Precision ◽  
Measurement Method ◽  
Least Square Method ◽  
Least Square ◽  
Guide Rail ◽  
Total Station ◽  
Measuring Tool

Use two total stations cooperating with each other to measure the straightness of the guide rail. The straightness can test the accuracy of a large rail. Put the coordinates measuring with the two total station instruments to the same user coordinate system, take a key point between some distance with the auxiliary measuring tool of high precision, measure and record the key point s coordinate values. According to them, it can calculate the straightness of guide rail by using the least square method. The straightness accuracy of bistatic measurement can reach below 0.05mm, so it can meet the accuracy requirements.

Software Development and Data Processing of Tool Wear Based on Mapping Measurement

2011 ◽  
Vol 383-390 ◽  
pp. 4971-4976 ◽  
Author(s):  
Song Guo ◽  
Chen Zhang ◽  
Xi Hui Liu
Keyword(s):  
Tool Wear ◽  
Data Processing ◽  
Measurement Method ◽  
Flank Wear ◽  
Great Influence ◽  
Least Square Method ◽  
Milling Process ◽  
Processing Method ◽  
Least Square ◽  
Data Processing Method

In NC milling process, tool wear has great influence on the machining quality of product. In this paper, a mapping measurement method is used to obtain tool wear and a data processing method is proposed to deal with the data getting from the measurement. First, tool wear along radius of tool’s cross-section, which is called radial wear, can be obtained by mapping measurement method. Then tool flank wear can be easily calculated based on the established relationship between radial wear and flank wear. In order to get radial wear, we process those measured data that are obtained from mapping measurement. In this process, least square method is adopted to fit these data to get the radius of section circle at a certain position. So the radial wear can be obtained by comparing the radius of the fitting circle and the original radius of tool at a certain section. Finally, the data processing software is realized by using Visual C++ development tool according to the designed data processing method of tool wear.

An improved kinematic calibration method for serial manipulators based on POE formula

Robotica ◽  
2018 ◽  
Vol 36 (8) ◽  
pp. 1244-1262 ◽  
Author(s):  
Chenguang Chang ◽  
Jinguo Liu ◽  
Zhiyu Ni ◽  
Ruolong Qi
Keyword(s):  
High Precision ◽  
Least Square Method ◽  
Calibration Method ◽  
Error Model ◽  
Least Square ◽  
Identification Accuracy ◽  
Kinematic Calibration ◽  
Serial Manipulators ◽  
Serial Robots ◽  
Generic Modeling

SUMMARYExisting measurement equipments easily determine position with high precision. However, they evaluate orientation with low precision. It is necessary to minimize the effect of measurement error on identification accuracy. In this study, a method for kinematic calibration based on the product of exponentials (POE) is presented to improve the absolute positioning accuracy of a sliding manipulator. An error model with uniform and generic modeling rules is established in which the tool frame is selected as the reference frame. Furthermore, the redundant parameters of the error model are removed. Subsequently, the actual kinematic parameters are identified by using the least square method. Finally, the process of the improved method is discussed. Kinematic calibration simulations of a sliding manipulator are implemented. The results indicate that the proposed method significantly improves the precision of the sliding manipulator. The improved POE kinematic calibration method offers convenience, efficiency, and high precision. The proposed method can be applied to all types of serial robots with n-DOF

A Method for Enhancing the Accuracy of On-Machine Inspection for Five-Axis CNC Machines

2012 ◽  
Vol 426 ◽  
pp. 351-354
Author(s):  
Sheng Bao ◽  
Xi Zhang ◽  
Ping Fa Feng
Keyword(s):  
Coordinate System ◽  
Reference Frame ◽  
Least Square Method ◽  
Practical Method ◽  
Least Square ◽  
Inspection System ◽  
Cnc Machines ◽  
Structural Parts ◽  
Five Axis ◽  
Valid Information

The efficiency of manufacturing structural parts can be improved by using on-machine inspection system. It is difficult to separate the valid information from hundreds of points and correct the errors by rotating and translating the workpiece coordinate system directly, especially for five-axis CNC machines. In this paper, a practical method is designed to correct errors easily. By using the least square method, an error reference frame is constructed, and the relation between the compensation values and coordinates of the theoretical points is derived. An example of aircraft structural parts is presented to validate the design.

Research on Course Radius Measurement for Vertical Petroleum Tank Volume Metrology Based on 3D Laser Scan Principle

2010 ◽  
Vol 439-440 ◽  
pp. 983-988
Author(s):  
Jin Tao Wang ◽  
Zi Yong Liu ◽  
Long Zhang ◽  
Li Gong Guo ◽  
Xue Song Bao ◽  
...  
Keyword(s):  
Phase Shift ◽  
Measurement Method ◽  
Least Square Method ◽  
Measured Data ◽  
Least Square ◽  
Point Location ◽  
Equivalent Radius ◽  
Optical Grating ◽  
Maximal Deviation ◽  
Mandatory Standard

One course radius measurement method for vertical petroleum tank volume metrology based on 3D laser scan principle was researched. Method of distance measurement by laser phase-shift technology and angular measurement by optical grating was applied to acquire coordinates of points in each course under the control of servo system. The permitted error of measured point location is 2mm. Fitting algorithms base on direct iterative method (DIM) and least square method (LSM) were used to process measured data and deduce equivalent radius of each course. In comparison experiment, one 1000m3 vertical tank was used as test object. Compared to strapping method (international mandatory standard), the maximal deviation radius value of method discussed is 2.8mm. The maximal difference of radius value calculated by DIM and LSM is 0.1mm. The experimental results verified the method discussed in this paper.

scholarly journals Multi-Camera-Based Universal Measurement Method for 6-DOF of Rigid Bodies in World Coordinate System

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5547 ◽  
Author(s):  
Zuoxi Zhao ◽  
Yuchang Zhu ◽  
Yuanhong Li ◽  
Zhi Qiu ◽  
Yangfan Luo ◽  
...  
Keyword(s):  
Rigid Body ◽  
Coordinate System ◽  
High Speed ◽  
Measurement Method ◽  
Degrees Of Freedom ◽  
Rigid Bodies ◽  
Least Square ◽  
Matrix Analysis ◽  
Average Error ◽  
World Coordinate System

The measurement of six-degrees-of-freedom (6-DOF) of rigid bodies plays an important role in many industries, but it often requires the use of professional instruments and software, or has limitations on the shape of measured objects. In this paper, a 6-DOF measurement method based on multi-camera is proposed, which is accomplished using at least two ordinary cameras and is made available for most morphological rigid bodies. First, multi-camera calibration based on Zhang Zhengyou’s calibration method is introduced. In addition to the intrinsic and extrinsic parameters of cameras, the pose relationship between the camera coordinate system and the world coordinate system can also be obtained. Secondly, the 6-DOF calculation model of proposed method is gradually analyzed by the matrix analysis method. With the help of control points arranged on the rigid body, the 6-DOF of the rigid body can be calculated by the least square method. Finally, the Phantom 3D high-speed photogrammetry system (P3HPS) with an accuracy of 0.1 mm/m was used to evaluate this method. The experiment results show that the average error of the rotational degrees of freedom (DOF) measurement is less than 1.1 deg, and the average error of the movement DOF measurement is less than 0.007 m. In conclusion, the accuracy of the proposed method meets the requirements.

Study on the Virtual Instrument for Coaxiality Error

2012 ◽  
Vol 220-223 ◽  
pp. 45-48
Author(s):  
Li Jie Chen ◽  
Ping Zou
Keyword(s):  
High Precision ◽  
Virtual Instrument ◽  
Least Square Method ◽  
Least Square ◽  
Manufacturing Cost ◽  
Zone Method ◽  
Hardware Platform ◽  
Experimental Teaching ◽  
Data Acquisition Card ◽  
Minimum Zone

Used LabWindows/CVI as software platform, existing apparatus in laboratory and a data acquisition card as hardware platform, the virtual instrument for coaxiality error was developed. It combines the theory to measure form and position error with technology about virtual instrument. Coaxiality error by least square method and the minimum zone method is measured. The image of coaxiality error can be displayed on the screen to analyse the causes of error, so as to control the manufacturing error. The virtual instrument has the advantages of high precision, stablity, low manufacturing cost, especially the excellent function expandability. It can be used for experimental teaching and the actual production.

A New Method to Measure the Radial Flexibility of Ship Pressure Hull

2012 ◽  
Vol 468-471 ◽  
pp. 694-698
Author(s):  
Xiao Jun Zhu ◽  
Fu Yu Yan ◽  
Peng Wang ◽  
Zhi Jie Zhu
Keyword(s):  
Coordinate System ◽  
Least Squares ◽  
High Precision ◽  
Measurement Method ◽  
High Efficiency ◽  
New Method ◽  
Precision Control ◽  
Transfer Station ◽  
Projection Point

The radial flexibility of ship pressure hull directly effects the structure tension of pressure hull, so it must be measured and controlled. At present, stay bar method is mainly used to measure it in shipyards and the method has low precision and efficiency, many artificial errors. Electronic total stations (ETS) are the main equipments of precision control now and they have high precision, but are seldom used in shipbuilding. So the paper presented a new method to measure the radial flexibility of ship pressure hull with ETS and transfer station measurement method. The data measured in different stations could be transformed and dealt with. Then the plane and the projection point on the plane could be calculated in the same coordinate system. Finally the radial flexibility of ship pressure hull could be worked out according to the theory of least squares. The new method is very easy to operate and have high efficiency. Experiments showed that the method has high precision.

Research on Course Radius Measurement for Vertical Petroleum Tank Volume Metrology Based on 3D Laser Scan Principle

2010 ◽  
Vol 439-440 ◽  
pp. 1105-1110
Author(s):  
Jin Tao Wang ◽  
Zi Yong Liu ◽  
Long Zhang ◽  
Li Gong Guo ◽  
Xue Song Bao ◽  
...  
Keyword(s):  
Phase Shift ◽  
Measurement Method ◽  
Least Square Method ◽  
Measured Data ◽  
Least Square ◽  
Point Location ◽  
Equivalent Radius ◽  
Optical Grating ◽  
Maximal Deviation ◽  
Mandatory Standard

One course radius measurement method for vertical petroleum tank volume metrology based on 3D laser scan principle was researched. Method of distance measurement by laser phase-shift technology and angular measurement by optical grating was applied to acquire coordinates of points in each course under the control of servo system. The permitted error of measured point location is 2mm. Fitting algorithms base on direct iterative method (DIM) and least square method (LSM) were used to process measured data and deduce equivalent radius of each course. In comparison experiment, one 1000m3 vertical tank was used as test object. Compared to strapping method (international mandatory standard), the maximal deviation radius value of method discussed is 2.8mm. The maximal difference of radius value calculated by DIM and LSM is 0.1mm. The experimental results verified the method discussed in this paper.

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