scholarly journals Study on Telescope Gain Affected by a Multilevel Hybrid Mechanism in FAST

2014 ◽  
Vol 6 ◽  
pp. 841526 ◽  
Author(s):  
Xiaoming Chai ◽  
Jin Fan ◽  
Lanchuan Zhou ◽  
Bo Peng
Keyword(s):  
Radio Telescope ◽  
Physical Meaning ◽  
Error Model ◽  
Geometric Errors ◽  
Accuracy Analysis ◽  
Positioning Error ◽  
Error Sources ◽  
Positioning Accuracy ◽  
Hybrid Mechanism ◽  
Structural Deformations

This paper focuses on the telescope gain affected by a multilevel hybrid mechanism for the feed positioning in the five-hundred-meter aperture spherical radio telescope (FAST) project, which is based on the positioning accuracy analysis of the mechanism. First, error model for the whole mechanism is established and its physical meaning is clearly explained. Then two kinds of error sources are mainly considered: geometric errors and structural deformations. The positioning error over the mechanism's workspace is described by an efficient and intuitive approach. As the feed position error will lower the telescope gain, this influence is analyzed in detail. In the end, it is concluded that the design of the mechanism can meet the requirement of the telescope performance.

Identification and Compensation of Geometric and Elastic Errors in Large Manipulators: Application to a High Accuracy Medical Robot

1998 ◽  
Author(s):  
Marco A. Meggiolaro ◽  
Constantinos Mavroidis ◽  
Steven Dubowsky
Keyword(s):  
High Accuracy ◽  
Measured Data ◽  
Experimental Results ◽  
Geometric Errors ◽  
Medical Robot ◽  
Error Sources ◽  
End Effector ◽  
Positioning Errors ◽  
Structural Deformations ◽  
Manufacturing Tolerances

Abstract A method is presented to identify the source of end-effector positioning errors in large manipulators using experimentally measured data. Both errors due to manufacturing tolerances and other geometric errors and elastic structural deformations are identified. These error sources are used to predict, and compensate for, the end-point errors as a function of configuration and measured forces. The method is applied to a new large high accuracy medical robot. Experimental results show that the method is able to effectively correct for the errors in the system.

The Accuracy Analysis of Parallel Mechanism Assembly Robot

2013 ◽  
Vol 423-426 ◽  
pp. 2769-2775 ◽  
Author(s):  
Xin Rong Liu
Keyword(s):  
Parallel Mechanism ◽  
Joint Angle ◽  
Parallel Robot ◽  
Accuracy Analysis ◽  
Analysis Model ◽  
Error Sources ◽  
Positioning Accuracy ◽  
Moving Platform ◽  
Position And Orientation ◽  
High Repeatability

Parallel robot has the advantages of high rigidity,high bearing capacity and high repeatability of positioning accuracy,and make it more and more widely used in the field of industrial applications.In this paper,the 3-RRR parallel mechanism assembly robot was used as the research object;introduced the sources of error in the parallel mechanism operation platform's position and orientation,furthermore,analyzed the factors of the error sources;then built up that parallel robot's error analysis model,solved the error model with the differential equation,and analyzed the error of parallel robot's structural in rod length,joint angle,the moving platform and the base platform's radius of circle,then simulated with MATLAB.Research shows that All structure errors in parallel mechanism increased by the X axis monotone increasing.

Comparison of Relative Contributions of Process and Geometric Errors in Micro and Macro Scale Milling Using an Integrated Error Model

2009 ◽  
Author(s):  
George Mathai ◽  
Mukund Kumar ◽  
Shreyes Melkote ◽  
F. C. Hsu ◽  
C. C. Chiu ◽  
...  
Keyword(s):  
Machine Tool ◽  
Error Model ◽  
Geometric Errors ◽  
Relative Importance ◽  
Dimensional Error ◽  
Error Sources ◽  
Micro Scale ◽  
Relative Contribution ◽  
Thermal Growth ◽  
Macro Scale

Error models are available for individual error sources for specific components in a machine tool. However, proper error budgeting requires an understanding of the relative importance of various error sources. This paper presents an analysis of the relative contribution of process and geometric errors on the dimensional error produced in micro scale milling. The error contributions at the micro scale are compared and contrasted with those in macro scale milling. The analysis makes use of an error model that uses homogeneous transformation matrices (HTMs) to model the effect of each error source in each component of the machine tool on the final position of the tool with respect to the workpiece. The model is developed for a generic milling machine and used to compare the relative importance of errors due to misalignment, thermal growth, tool deflection and wear of the tool on the size of the machined feature at the micro and macro scale for slot milling using standard length tools.

Accuracy Analysis of Highly Kinematical Positioning of GPS

2014 ◽  
Vol 602-605 ◽  
pp. 1847-1850
Author(s):  
Jie Zhan ◽  
Lin Yuan ◽  
Yin Lin Wu
Keyword(s):  
Random Error ◽  
Carrier Phase ◽  
Processing Method ◽  
Error Characteristic ◽  
Accuracy Analysis ◽  
Positioning Error ◽  
Test Results ◽  
Characteristic Analysis ◽  
Positioning Accuracy ◽  
Data Processing Method

For the accuracy of highly kinematical positioning of GPS carrier phase is not easy to be obtained directly, a data processing method is presented based on the analysis of several common kinematical positioning accuracy analytical methods. The method firstly analyzes and models the state of motion carrier, and then conducts a statistics variable composed by multiple positioning data , Finally uses a determined relation between the variance of the statistics variable and the variance of the positioning error to gain the variance of positioning error by calculating the variance of the statistics variable. The test results show that the method is effective for random error characteristic analysis.

Dynamic and Positioning Performances of Linear Electromechanical Actuator

2015 ◽  
Vol 809-810 ◽  
pp. 682-687
Author(s):  
Vasile Nasui ◽  
Mihai Banica ◽  
Dinu Darabă
Keyword(s):  
Dynamic Characteristics ◽  
Practical Importance ◽  
Correct Identification ◽  
Positioning System ◽  
Positioning Error ◽  
Servo Motor ◽  
Positioning Accuracy ◽  
Electromechanical Actuator ◽  
Initial Errors ◽  
Selection For

This paper presents the dynamic characteristics and the proposed positioning performance of the system to them investigated experimentally. In this research, we developed the positioning system and we evaluated positioning accuracy. The developed system uses a servo motor for motion actuation. In this paper, we focused on studying the dependency of the positioning error – elementary errors – the position of the conducting element for the mechanism of the transformation of the rotation translation movement, representatively the mechanism screw – screwdriver and on emphasizing the practical consequences in the field of design, regulation and exploitation of the correct identification of all the initial errors in the structure of the mechanism, their character and the selection for an ultimate calculus of these which are of a real practical importance.

scholarly journals Research of Calibration Method for Industrial Robot Based on Error Model of Position

2021 ◽  
Vol 11 (3) ◽  
pp. 1287
Author(s):  
Tianyan Chen ◽  
Jinsong Lin ◽  
Deyu Wu ◽  
Haibin Wu
Keyword(s):  
Coordinate System ◽  
Industrial Robot ◽  
Calibration Method ◽  
Error Model ◽  
Position Error ◽  
Industrial Robots ◽  
Positioning Error ◽  
Robot Position ◽  
General Measurement ◽  
Parameter Error

Based on the current situation of high precision and comparatively low APA (absolute positioning accuracy) in industrial robots, a calibration method to enhance the APA of industrial robots is proposed. In view of the "hidden" characteristics of the RBCS (robot base coordinate system) and the FCS (flange coordinate system) in the measurement process, a comparatively general measurement and calibration method of the RBCS and the FCS is proposed, and the source of the robot terminal position error is classified into three aspects: positioning error of industrial RBCS, kinematics parameter error of manipulator, and positioning error of industrial robot end FCS. The robot position error model is established, and the relation equation of the robot end position error and the industrial robot model parameter error is deduced. By solving the equation, the parameter error identification and the supplementary results are obtained, and the method of compensating the error by using the robot joint angle is realized. The Leica laser tracker is used to verify the calibration method on ABB IRB120 industrial robot. The experimental results show that the calibration method can effectively enhance the APA of the robot.

scholarly journals Factor Graph-Assisted Distributed Cooperative Positioning Algorithm in the GNSS System

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3748 ◽  
Author(s):  
Chengkai Tang ◽  
Lingling Zhang ◽  
Yi Zhang ◽  
Houbing Song
Keyword(s):  
Smart Cities ◽  
Factor Graph ◽  
Positioning Error ◽  
Positioning Accuracy ◽  
Cooperative Positioning ◽  
Measured Range ◽  
Ranging Error ◽  
Positioning Algorithm ◽  
Range Error ◽  
Cooperative Nodes

The development of smart cities calls for improved accuracy in navigation and positioning services; due to the effects of satellite orbit error, ionospheric error, poor quality of navigation signals and so on, it is difficult for existing navigation technology to achieve further improvements in positioning accuracy. Distributed cooperative positioning technology can further improve the accuracy of navigation and positioning with existing GNSS (Global Navigation Satellite System) systems. However, the measured range error and the positioning error of the cooperative nodes exhibit larger reductions in positioning accuracy. In response to this question, this paper proposed a factor graph-aided distributed cooperative positioning algorithm. It establishes the confidence function of factor graphs theory with the ranging error and the positioning error of the coordinated nodes and then fuses the positioning information of the coordinated nodes by the confidence function. It can avoid the influence of positioning error and ranging error and improve the positioning accuracy of cooperative nodes. In the simulation part, the proposed algorithm is compared with a mainly coordinated positioning algorithm from four aspects: the measured range error, positioning error, convergence speed, and mutation error. The simulation results show that the proposed algorithm leads to a 30–60% improvement in positioning accuracy compared with other algorithms under the same measured range error and positioning error. The convergence rate and mutation error elimination times are only 1 / 5 to 1 / 3 of the other algorithms.

Pose Accuracy Analysis of Robot Manipulators Based on Kinematics

2011 ◽  
Vol 201-203 ◽  
pp. 1867-1872 ◽  
Author(s):  
Jian Ye Zhang ◽  
Chen Zhao ◽  
Da Wei Zhang
Keyword(s):  
Matrix Theory ◽  
Robot Manipulators ◽  
Error Model ◽  
Robot Kinematics ◽  
Accuracy Analysis ◽  
Serial Link ◽  
End Effector ◽  
Surface Graph ◽  
Position And Orientation ◽  
Kinematics Parameters

The pose accuracy of robot manipulators has long become a major issue to be considered in its advanced application. An efficient methodology to generate the end-effector position and orientation error model of robotic manipulator has been proposed based on the differential transformation matrix theory. According to this methodology, a linear error model that described the end-effector position and orientation errors due to robot kinematics parameters errors has been presented. A computer program to generate the error model and perform the accuracy analysis on any serial link manipulator has been developed in MATLAB. This methodology and software are applied to the accuracy analysis of a Phantom Desktop manipulator. The positioning error of the manipulator in its workspace cross section (XOZ) has been plotted as 3D surface graph and discussed.

scholarly journals A New Efficient Stiffness Evaluation Method to Improve Accuracy of Hexapods

2018 ◽  
Author(s):  
Vinayak J. Kalas ◽  
Alain Vissière ◽  
Thierry Roux ◽  
Olivier Company ◽  
Sébastien Krut ◽  
...  
Keyword(s):  
Evaluation Method ◽  
Positioning System ◽  
Positioning Error ◽  
Stiffness Parameter ◽  
Positioning Accuracy ◽  
Stiffness Evaluation ◽  
Improve Accuracy ◽  
Identification Technique ◽  
Six Degree Of Freedom ◽  
Structural Compliance

Structural compliance of hexapods limits their positioning accuracy. Taking a step towards solving this problem, this paper proposes a new efficient method to evaluate the stiffness of hexapods in order to predict and correct their positioning error due to compliance. The proposed method can be used to predict the six degree of freedom deflection of the platform under load. This method uses a simple lumped stiffness parameter model whose parameters can be estimated using the identification technique presented in this paper. An experimental study with micrometer level measurements performed on a hexapod based micro-positioning system is used to assess the efficiency of the presented method.

scholarly journals Assessing the quality of ionospheric models through GNSS positioning error: methodology and results

GPS Solutions ◽  
2019 ◽  
Vol 24 (1) ◽  
Author(s):  
Adrià Rovira-Garcia ◽  
Deimos Ibáñez-Segura ◽  
Raul Orús-Perez ◽  
José Miguel Juan ◽  
Jaume Sanz ◽  
...  
Keyword(s):  
Satellite System ◽  
Ionospheric Delay ◽  
Single Frequency ◽  
Positioning Error ◽  
Dual Frequency ◽  
Error Sources ◽  
Ionospheric Models ◽  
Evaluation Metric ◽  
Global Navigation Satellite

Abstract Single-frequency users of the global navigation satellite system (GNSS) must correct for the ionospheric delay. These corrections are available from global ionospheric models (GIMs). Therefore, the accuracy of the GIM is important because the unmodeled or incorrectly part of ionospheric delay contributes to the positioning error of GNSS-based positioning. However, the positioning error of receivers located at known coordinates can be used to infer the accuracy of GIMs in a simple manner. This is why assessment of GIMs by means of the position domain is often used as an alternative to assessments in the ionospheric delay domain. The latter method requires accurate reference ionospheric values obtained from a network solution and complex geodetic modeling. However, evaluations using the positioning error method present several difficulties, as evidenced in recent works, that can lead to inconsistent results compared to the tests using the ionospheric delay domain. We analyze the reasons why such inconsistencies occur, applying both methodologies. We have computed the position of 34 permanent stations for the entire year of 2014 within the last Solar Maximum. The positioning tests have been done using code pseudoranges and carrier-phase leveled (CCL) measurements. We identify the error sources that make it difficult to distinguish the part of the positioning error that is attributable to the ionospheric correction: the measurement noise, pseudorange multipath, evaluation metric, and outliers. Once these error sources are considered, we obtain equivalent results to those found in the ionospheric delay domain assessments. Accurate GIMs can provide single-frequency navigation positioning at the decimeter level using CCL measurements and better positions than those obtained using the dual-frequency ionospheric-free combination of pseudoranges. Finally, some recommendations are provided for further studies of ionospheric models using the position domain method.

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