Statistical Characteriztion of Position Errors of an Ensemble of Robots and Its Applications

1989 ◽  
Vol 111 (2) ◽  
pp. 215-222 ◽  
Author(s):  
Chia-Hsiang Menq ◽  
Jin-Hwan Borm
Keyword(s):  
Reference Frames ◽  
Statistical Error ◽  
Position Error ◽  
Positioning Accuracy ◽  
Position Accuracy ◽  
Position Errors ◽  
Working Space ◽  
Absolute Positioning ◽  
Error Field ◽  
The Absolute

For the accurate control and implementation of a robot in an integrated manufacturing environment using off-line programming, a knowledge of the absolute positioning accuracy of the robot becomes important. This paper presents a framework which can be used to statistically represent the absolute positioning accuracy for a family of robots. Statistical error measure indices are proposed to represent the position error field over the working space for a family of robots. This error field provides statistical information for the position errors of the end-effector and can be a guide for the determination of the optimal design tolerances of the parts composing of a robot. The second objective of the paper is to introduce a simple interpolation scheme to improve the local position accuracy by teaching one or more task reference frames with which goal positions are mathematically expressed. It will be shown how the method shifts or alters the position error field in order to maintain the desired position accuracy within a desired working area.

scholarly journals Kinematic Modeling of Six-Axis Industrial Robot and its Parameter Identification: A Tutorial

2021 ◽  
Vol 15 (5) ◽  
pp. 599-610
Author(s):  
Md. Moktadir Alam ◽  
◽  
Soichi Ibaraki ◽  
Koki Fukuda
Keyword(s):  
Present Model ◽  
Industrial Robot ◽  
Local Coordinate System ◽  
Kinematic Model ◽  
Kinematic Modeling ◽  
Positioning Accuracy ◽  
Rotary Axis ◽  
Model Based ◽  
Absolute Positioning ◽  
The Absolute

In advanced industrial applications, like machining, the absolute positioning accuracy of a six-axis robot is indispensable. To improve the absolute positioning accuracy of an industrial robot, numerical compensation based on positioning error prediction by the Denavit and Hartenberg (D-H) model has been investigated extensively. The main objective of this study is to review the kinematic modeling theory for a six-axis industrial robot. In the form of a tutorial, this paper defines a local coordinate system based on the position and orientation of the rotary axis average lines, as well as the derivation of the kinematic model based on the coordinate transformation theory. Although the present model is equivalent to the classical D-H model, this study shows that a different kinematic model can be derived using a different definition of the local coordinate systems. Subsequently, an algorithm is presented to identify the error sources included in the kinematic model based on a set of measured end-effector positions. The identification of the classical D-H parameters indicates a practical engineering application of the kinematic model for improving a robot’s positioning accuracy. Furthermore, this paper presents an extension of the present model, including the angular positioning deviation of each rotary axis. The angular positioning deviation of each rotary axis is formed as a function of the axis’ command angles and the direction of its rotation to model the effect of the rotary axis backlash. The identification of the angular positioning deviation of each rotary axis and its numerical compensation are presented, along with their experimental demonstration. This paper provides an essential theoretical basis for the error source diagnosis and error compensation of a six-axis robot.

scholarly journals Improvement and Assessment of the Absolute Positioning Accuracy of Chinese High-Resolution SAR Satellites

2019 ◽  
Vol 11 (12) ◽  
pp. 1465
Author(s):  
Deng ◽  
Zhang ◽  
Cai ◽  
Xu ◽  
Zhao ◽  
...  
Keyword(s):  
High Resolution ◽  
Propagation Delay ◽  
Reference Points ◽  
Calibration Model ◽  
Land Resource ◽  
Positioning Accuracy ◽  
Geometric Calibration ◽  
Atmospheric Propagation ◽  
Absolute Positioning ◽  
The Absolute

In recent years, China has launched YaoGan-13 and GaoFen-3, high-resolution synthetic aperture radar (SAR) satellites that can acquire global high-resolution images. The absolute positioning accuracy of such satellites is important for mapping areas without ground reference points and for automated processing. However, satellites without geometric calibration have poor absolute positioning accuracy, greatly restricting their application (e.g., land resource surveys). Therefore, they cannot meet national demands for high-resolution SAR images with good geometric accuracy. Here, we propose a series of methods to improve the absolute positioning accuracy of YaoGan-13 and GaoFen-3, such as the multiple-image combined calibration strategy and geometric calibration model for a real continuously moving configuration, including consideration of atmospheric propagation delay. Using high-accuracy ground control data collected from different areas, the 2-D and 3-D absolute positioning accuracies of YaoGan-13 and GaoFen-3 were assessed after implementation of the improvement measures. Experimental results showed that, after calibration, the 2-D absolute positioning accuracy of YaoGan-13 and GaoFen-3 are improved from 43.86 m to 2.57 m and from 30.34 m to 4.29 m, respectively. In addition, the 3-D absolute positioning accuracies of YaoGan-13 in plane and elevation are 3.21 m and 2.22 m, respectively. Improving the absolute positioning accuracy of these satellites could broaden the scope of their potential applications in the future.

scholarly journals A calibration method of robot kinematic parameters by drawstring displacement sensor

2019 ◽  
Vol 16 (5) ◽  
pp. 172988141988307 ◽  
Author(s):  
Yahui Gan ◽  
Jinjun Duan ◽  
Xianzhong Dai
Keyword(s):  
Calibration Method ◽  
Industrial Robots ◽  
Displacement Sensor ◽  
Kinematic Parameters ◽  
Position Measurement ◽  
Positioning Accuracy ◽  
End Effector ◽  
Displacement Sensors ◽  
Absolute Positioning ◽  
The Absolute

Calibration of robot kinematic parameters can effectively improve the absolute positioning accuracy of the end-effector for industrial robots. This article proposes a calibration method for robot kinematic parameters based on the drawstring displacement sensor. Firstly, the kinematic error model for articulated robot is established. Based on such a model, the position measurement system consisting of four drawstring displacement sensors is used to measure the actual position of the robot end-effector. Then, the deviation of the kinematic parameters of the robot is identified by the least-squares method according to robot end-effector deviations. The Cartesian space compensation method is adopted to improve the absolute positioning accuracy of the robot end-effecter. By experiments on the EFORT ER3A robot, the absolute positioning accuracy of the robot is significantly improved after calibration, which shows the effectiveness of the proposed method.

A distance error based industrial robot kinematic calibration method

2014 ◽  
Vol 41 (5) ◽  
pp. 439-446 ◽  
Author(s):  
Wang Zhenhua ◽  
Xu Hui ◽  
Chen Guodong ◽  
Sun Rongchuan ◽  
Lining Sun
Keyword(s):  
Industrial Robot ◽  
Calibration Method ◽  
Calibration Model ◽  
Kinematic Calibration ◽  
Absolute Position ◽  
Positioning Accuracy ◽  
Content Type ◽  
Distance Error ◽  
Position Accuracy ◽  
The Absolute

Purpose – The purpose of this paper is to present a distance accuracy-based industrial robot kinematic calibration model. Nowadays, the repeatability of the industrial robot is high, while the absolute positioning accuracy and distance accuracy are low. Many factors affect the absolute positioning accuracy and distance accuracy, and the calibration method of the industrial robot is an important factor. When the traditional calibration methods are applied on the industrial robot, the accumulative error will be involved according to the transformation between the measurement coordinate and the robot base coordinate. Design/methodology/approach – In this manuscript, a distance accuracy-based industrial robot kinematic calibration model is proposed. First, a simplified kinematic model of the robot by using the modified Denavit–Hartenberg (MDH) method is introduced, then the proposed distance error-based calibration model is presented; the experiment is set up in the next section. Findings – The experimental results show that the proposed calibration model based on MDH and distance error can improve the distance accuracy and absolute position accuracy dramatically. Originality/value – The proposed calibration model based on MDH and distance error can improve the distance accuracy and absolute position accuracy dramatically.

Research on Absolute Positioning Error of Robot Based on Mapping Theory

2014 ◽  
Vol 494-495 ◽  
pp. 1156-1160
Author(s):  
Guan Hua Dong ◽  
Ying Yin ◽  
Xiao Bing Hu
Keyword(s):  
Industrial Robots ◽  
Positioning Error ◽  
Positioning Accuracy ◽  
Compensation Algorithm ◽  
Absolute Positioning ◽  
The Absolute ◽  
Mapping Theory

Joint-typical Industrial robots tend to have higher repetitive positioning accuracy and lower absolute positioning accuracy. In order to improve the absolute positioning accuracy of robots, this paper puts forward a compensation algorithm based on the mapping theory combining with the kinematics equation, which establish the connection between the space of off-line programming and teaching-programming, so as to approximate the repeat positioning accuracy. A experiment is implemented to confirm its correctness, and the result shows that the supposed method can improve the absolute positioning accuracy heavily, which the absolute positioning error reduces from 8.32mm to 1.08mm.

scholarly journals Performance Evaluation of Precise Point Positioning Using Dual Frequency Multi-GNSS Observations

2020 ◽  
Vol 55 (4) ◽  
pp. 150-170
Author(s):  
Jabir Shabbir Malik
Keyword(s):  
Root Mean Square ◽  
Precise Point Positioning ◽  
Convergence Time ◽  
Observation Data ◽  
Three Dimension ◽  
Mean Square ◽  
Positioning Accuracy ◽  
Position Accuracy ◽  
Position Errors ◽  
Point Positioning

AbstractIn addition to GPS and GLONASS constellation, the number of (Global Navigation Satellite System) GNSS satellites are increasing, it is now possible to evaluate and analyze the position accuracy with multi GNSS constellation. In this paper, statistical assessment of static Precise Point Positioning (PPP) using GPS, GLONASS, dual system GPS/GLONASS, three system GPS/GLONASS/Galileo, GPS/GLONASS/BeiDou and multi system GPS/GLONASS/Galileo/BeiDou PPP combinations is evaluated. Observation data of seven whole days from seven IGS multi GNSS experiment (MGEX) stations is used for analysis. Position accuracy and convergence time is analyzed. Results show that the GPS/GLONASS positioning accuracy increases over GPS PPP. Standard deviations (STDs) of position errors for GPS PPP are 4.63, 3.00 and 6.96 cm in east, north and up components while STDs for GPS/GLONASS PPP are 4.10, 3.42 and 6.50 cm respectively. Root mean square for three dimension (RMS3D) for GPS/GLONASS PPP solution is 8.96 cm. With the addition of Galileo and BeiDou to the combined GPS/GLONASS further enhances the positioning accuracy. Root mean square for horizontal component reach to 5.35 cm of GPS/GLONASS/Galileo/BeiDou PPP solutions. Results analysis of GPS/GLONASS/Galileo PPP solutions show an improvement of convergence time by only 3.81% to achieve accuracy level of 3.0 cm over GPS/GLONASS/BeiDou PPP mode. Results also demonstrate that position accuracy improvement after adding BeiDou observations to the GPS/GLONASS PPP mode is not significant.

scholarly journals A Novel Indirect Calibration Approach for Robot Positioning Error Compensation Based on Neural Network and Hand-Eye Vision

2019 ◽  
Vol 9 (9) ◽  
pp. 1940 ◽  
Author(s):  
Chi-Tho Cao ◽  
Van-Phu Do ◽  
Byung-Ryong Lee
Keyword(s):  
Neural Network ◽  
Position Error ◽  
Industrial Robots ◽  
Positional Error ◽  
Absolute Position ◽  
Position Errors ◽  
The Neural Network ◽  
Robot Positioning ◽  
The Absolute ◽  
Calibration Approach

It is well known that most of the industrial robots have excellent repeatability in positioning. However, the absolute position errors of industrial robots are relatively poor, and in some cases the error may reach even several millimeters, which make it difficult to apply the robot system to vehicle assembly lines that need small position errors. In this paper, we have studied a method to reduce the absolute position error of robots using machine vision and neural network. The position/orientation of robot tool-end is compensated using a vision-based approach combined with a neural network, where a novel indirect calibration approach is presented in order to gather information for training the neural network. In the simulation, the proposed compensation algorithm was found to reduce the positional error to 98%. On average, the absolute position error was 0.029 mm. The application of the proposed algorithm in the actual robot experiment reduced the error to 50.3%, averaging 1.79 mm.

scholarly journals Absolute Positioning Accuracy Improvement in an Industrial Robot

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4354 ◽  
Author(s):  
Yizhou Jiang ◽  
Liandong Yu ◽  
Huakun Jia ◽  
Huining Zhao ◽  
Haojie Xia
Keyword(s):  
Differential Evolution ◽  
Industrial Robot ◽  
Differential Evolution Algorithm ◽  
Substantial Improvement ◽  
Positioning Accuracy ◽  
Absolute Positioning ◽  
Calibration Methods ◽  
The Absolute ◽  
Six Degree Of Freedom ◽  
Kinematic Errors

The absolute positioning accuracy of a robot is an important specification that determines its performance, but it is affected by several error sources. Typical calibration methods only consider kinematic errors and neglect complex non-kinematic errors, thus limiting the absolute positioning accuracy. To further improve the absolute positioning accuracy, we propose an artificial neural network optimized by the differential evolution algorithm. Specifically, the structure and parameters of the network are iteratively updated by differential evolution to improve both accuracy and efficiency. Then, the absolute positioning deviation caused by kinematic and non-kinematic errors is compensated using the trained network. To verify the performance of the proposed network, the simulations and experiments are conducted using a six-degree-of-freedom robot and a laser tracker. The robot average positioning accuracy improved from 0.8497 mm before calibration to 0.0490 mm. The results demonstrate the substantial improvement in the absolute positioning accuracy achieved by the proposed network on an industrial robot.

scholarly journals A LiDAR-Aided Inertial Positioning Approach for a Longwall Shearer in Underground Coal Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Jiangtao Zheng ◽  
Sihai Li ◽  
Nan Li ◽  
Qiangwen Fu ◽  
Shiming Liu ◽  
...  
Keyword(s):  
Inertial Navigation System ◽  
Longwall Mining ◽  
Three Dimensional ◽  
Underground Coal Mining ◽  
Positioning Accuracy ◽  
Selection Scheme ◽  
Position Accuracy ◽  
Position Errors ◽  
Gyro Drift ◽  
Hydraulic Supports

The absolute three-dimensional position of a longwall shearer is fundamental to longwall mining automation. The positioning of the longwall shearer is usually realized by the inertial navigation system (INS) and odometer (OD). However, the position accuracy of this positioning approach gradually decreases over time due to the gyro drift. To further increase the positioning accuracy of the shearer, this paper proposes a positioning approach based on the INS and light detection and ranging (LiDAR). A Kalman filter (KF) model based on the observation provided by detecting hydraulic supports which are part of the longwall face, using the LiDAR, is established. The selection scheme of the point features is studied through a set of simulations. In addition, compared with that of the approach based on the INS and OD, the shearer positioning accuracy obtained using the proposed approach is higher. When the shearer moves along a 350 m track for 6 cutting cycles and lasts about 7.1 h, both east and north position errors can be maintained within 0.2 m and the height error within 0.1 m.

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