scholarly journals Kinematic Absolute Positioning with Quad-Constellation GNSS

2019 ◽  
Author(s):  
Lin Pan ◽  
Changsheng Cai ◽  
Jianjun Zhu ◽  
Xianqiang Cui
Keyword(s):  
Absolute Positioning

Đánh giá quan hệ giữa hàm lượng hơi nước khí quyển và độ chính xác định vị tuyệt đối bằng GPS ở Việt Nam

2008 ◽  
Vol 30 (2) ◽  
pp. 161-169
Author(s):  
Lê Huy Mình ◽  
Phạm Xuân Thành ◽  
Nguyễn Chiến Thắng ◽  
Trần Thị Lan ◽  
R. Fleury ◽  
...  
Keyword(s):  
Water Vapour ◽  
Viet Nam ◽  
Absolute Positioning ◽  
The Absolute

Estimatlon of the relatlon between the total tropospheric water vapour and the precision of the absolute positioning by GPS in Vietnam

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 Research on Absolute Positioning Sensor Based on Eddy Current Reflection for High-Speed Maglev Train

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5167
Author(s):  
Xiaobo Hong ◽  
Jun Wu ◽  
Yunzhou Zhang ◽  
Yongxiang He
Keyword(s):  
Eddy Current ◽  
High Speed ◽  
The Novel ◽  
Maglev Train ◽  
Compact Structure ◽  
Absolute Positioning ◽  
Eddy Current Effect ◽  
Speed Range ◽  
The Impact ◽  
Detection Coil

A novel absolute positioning sensor for high-speed maglev train based on eddy current effect is studied in this paper. The sensor is designed with photoelectric switch and four groups of unilateral coplanar code-reading detection coil combination. The photoelectric switch realizes the positioning of the marker plate, and the four groups of detection coils read the mileage code of the mileage sign plate to obtain the absolute mileage information of the vehicle, which effectively reduces the quality and volume of the sensor, and reduces the impact of ice and snow. At the same time, the code-reading reliability and speed adaptability index are proposed. The code-reading reliability of the sensor is analyzed and tested under the fluctuation of levitation guidance, and the positioning error under the speed range of 0–600 km/h is calculated and analyzed. The results show that the novel sensor has the advantages of simple and compact structure. It still satisfies the system’s requirements for absolute vehicle mileage information under the conditions of vehicle operating attitude fluctuations and changes in the full operating speed range.

A robot with improved absolute positioning accuracy for CT guided stereotactic brain surgery

1988 ◽  
Vol 35 (2) ◽  
pp. 153-160 ◽  
Author(s):  
Y.S. Kwoh ◽  
J. Hou ◽  
E.A. Jonckheere ◽  
S. Hayati
Keyword(s):  
Brain Surgery ◽  
Positioning Accuracy ◽  
Ct Guided ◽  
Absolute Positioning
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