Research on Spatial Circle Fitting Algorithm Based on Radius Constraint and its Application in Spline Assembly

2018 ◽  
Author(s):  
Yongji Zhu ◽  
Hao Lan ◽  
Xi Zhang
Keyword(s):  
Circle Fitting ◽  
Fitting Algorithm ◽  
Radius Constraint

scholarly journals A High Precision Laser-Based Autofocus Method Using Biased Image Plane for Microscopy

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Chao-Chen Gu ◽  
Hao Cheng ◽  
Kai-Jie Wu ◽  
Liang-Jun Zhang ◽  
Xin-Ping Guan
Keyword(s):  
Laser Beam ◽  
High Precision ◽  
Low Cost ◽  
Image Plane ◽  
Circle Fitting ◽  
Essential Factor ◽  
Assembly Accuracy ◽  
Fitting Algorithm ◽  
Experiment Device ◽  
Study Designs

This study designs and accomplishes a high precision and robust laser-based autofocusing system, in which a biased image plane is applied. In accordance to the designed optics, a cluster-based circle fitting algorithm is proposed to calculate the radius of the detecting spot from the reflected laser beam as an essential factor to obtain the defocus value. The experiment conduct on the experiment device achieved novel performance of high precision and robustness. Furthermore, the low demand of assembly accuracy makes the proposed method a low-cost and realizable solution for autofocusing technique.

Automatic Calibration Method for Mounting Position of Protein Crystal Mounting Robot Based on Visual Positioning

2020 ◽  
Author(s):  
Jiangping Qin ◽  
Zhaolong Li ◽  
Bo Sun ◽  
Feng Yu ◽  
Yi Liu ◽  
...  
Keyword(s):  
Calibration Method ◽  
Image Features ◽  
Protein Crystal ◽  
External Parameter ◽  
Automatic Calibration ◽  
Relationship Matrix ◽  
Laser Sensor ◽  
Circle Fitting ◽  
Visual Positioning ◽  
Fitting Algorithm

Abstract With the popularization of automounting robots in protein crystal diffraction experiment beamline stations, the coordinate calibration of the robot sample mounting position has become an inevitable task in the daily maintenance of the beamline station. In this method, the image features of the laser sensor spot and goniometer are extracted by color extraction and edge detection, respectively, and the noise is eliminated by median filtering. Then, after locating the pixel coordinates of the center of the circle through the Hough circle detection and the minimum closed circle fitting algorithm, the coordinates in the base coordinate system are obtained using the camera internal and external parameter matrices and the hand-eye relationship matrix. Finally, according to the deviation of the laser spot and the visual positioning coordinate of the goniometer, the position of the robot is compensated to improve the positioning accuracy, and the automatic calibration of the sample point is realized.

Research on Measurement Method of Joint Angle for Underwater Manipulator

2014 ◽  
Vol 1039 ◽  
pp. 256-261
Author(s):  
Ding Hao Feng ◽  
Xi Zhang ◽  
Xu Zhang ◽  
Wei Qing Chu
Keyword(s):  
Measurement Method ◽  
Joint Angle ◽  
Vision System ◽  
Three Dimensional ◽  
Angle Measurement ◽  
Robot Arm ◽  
Circle Fitting ◽  
Fitting Algorithm ◽  
Stereo Reconstruction ◽  
Underwater Manipulator

Measurement method of joint angle for underwater manipulator is studied in this paper. The swing of a manipulator can be described as a circular motion in spatial. Therefore this paper proposes a spatial circle fitting algorithm. The points for spatial circle fitting come from multiple stereo vision system. At first, attach the designed target to the robot arm, then proposes algorithm to track the target in real time. Then three-dimensional coordinates of target’s movement in space at each location can be obtained by using stereo reconstruction techniques. At last, the center and radius of the circle can be calculated by spatial circle fitting. Through the theory of analytic geometry, the manipulator’s joint angle can be calculated. Experiments show that the algorithm proposed in this paper is well used in manipulator’s joint angle measurement.

Radius Constraint Least-Square Circle Fitting Method

2011 ◽  
Vol 411 ◽  
pp. 241-244
Author(s):  
Qiang Zhu ◽  
Guo Hui Zhang ◽  
Zhen Xu
Keyword(s):  
Circle Method ◽  
Least Square Method ◽  
Least Square ◽  
Circle Fitting ◽  
Excellent Performance ◽  
Testing Environment ◽  
Least Square Fitting ◽  
Fitting Method ◽  
Radius Constraint ◽  
Short Arc

Short arc usually lost the most part of information in measurement, therefore the fitting center can not be found accurately. The shortage of least-square method is analyzed in short arc fitting. The uncertainty of fitting center direction and fitting radius is illustrated. And we derived the solution to estimation of fitting center direction. Base on the testing environment, radius constraint least-square fitting circle method is proposed. Simulations demonstrated excellent performance of this algorithm.

Research on Roadbed Settlement Measurement with Laser Spot Detection Based on Ellipse Fitting

2014 ◽  
Vol 530-531 ◽  
pp. 113-116
Author(s):  
Jing Hong Xing ◽  
Xiang Wei Li ◽  
Lang Tao Zhao
Keyword(s):  
Curve Fitting ◽  
Optical Axis ◽  
Laser Spot ◽  
Ellipse Fitting ◽  
Edge Extraction ◽  
Circle Fitting ◽  
Spot Center ◽  
Spot Detection ◽  
Fitting Algorithm ◽  
Canny Edge

Detecting the location offset of laser spot center method to monitor roadbed settlement is a kind of portable, easy to layout method. Detection laser spot center offset, we can use gravity, circle fitting, ellipse fitting and Gaussian curve fitting, etc method. Gravity algorithm is only involves basic arithmetic and low precise, and ellipse fitting is higher precise. Because of the angle between the optical axis and the target, the laser spot is more approximate as a ellipse. Using the ellipse fitting algorithm, Sub-pixel precise threshold segmentation and Canny edge extraction we obtained an ideal monitoring precise of the roadbed settlement.

An Ellipse Fitting Algorithm Applied to the Construction of the Elliptic Arc-Shaped Leading Edge

2013 ◽  
Vol 744 ◽  
pp. 232-238
Author(s):  
Xiao Qiang Yu ◽  
Tao Ning ◽  
Yong Long Hou ◽  
Zhi Tong Chen
Keyword(s):  
Numerical Experiments ◽  
Leading Edge ◽  
Ellipse Fitting ◽  
Circle Fitting ◽  
Tangential Contact ◽  
Contact Constraint ◽  
Fitting Method ◽  
Fitting Algorithm ◽  
Strong Robustness ◽  
Precision And Accuracy

In this paper, we proposed a new ellipse fitting method converting the ellipse fitting into a circle fitting based on projection transformation. Numerical experiments demonstrate that our approach have good stability and strong robustness against noise in addition to excellent precision and accuracy. In our further research, we successfully extend our algorithm to the construction of the elliptic arc-shaped leading edge by using a tangential contact constraint. Keywords: Ellipse fitting; Projection; PSO; Leading edge

scholarly journals Accurate Detection Method of Aviation Bearing Based on Local Characteristics

Symmetry ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1069
Author(s):  
Xue ◽  
Jiang ◽  
Wang ◽  
He
Keyword(s):  
Detection Method ◽  
Circle Fitting ◽  
Lubricating Grease ◽  
Symmetrical Structure ◽  
Ball Size ◽  
Local Characteristics ◽  
Accurate Detection ◽  
Fitting Algorithm ◽  
Bearing Ball ◽  
Spatial Limitation

Aviation bearing assembled detection is the final barrier to quality and safety. Therefore, an accurate detection method of aviation bearing that is based on local characteristics is designed to solve the detection problem of mis-assembly and miss-assembly of balls in aviation bearing assembled. When considering the spatial limitation of aviation bearing assembled image acquisition, the dynamic distribution of balls and the interference of lubricating grease on the surface, a dynamic local ball segmentation model that is based on U-Net network with symmetrical structure is designed to achieve the accurate segmentation of the local ball region of aviation bearing. Subsequently, an incomplete circle fitting algorithm is designed based on the segmented local ball image and Hough transform principle. These two algorithms make the measurement error of aviation bearing ball size less than 100 μm. Using bearings validates the algorithm. The results show that the accuracy of dynamic local ball segmentation model that is based on U-Net network with symmetrical structure is over 99%. At the same time, on the basis of accurate segmentation in aviation bearing local ball, the designed Hough circle algorithm is used for circle detection. The experimental results show that the false detection rate of mis-assembly and miss-assembly of balls is less than 3%. Further, the goal of zero-missed detection of mis-assembly and miss-assembly of balls in aviation bearing is achieved. The accurate segmentation of aviation bearing local ball and the effective identification of mis-assembly and miss-assembly of balls are realized. This method can provide a theory for the improvement of mis-assembly and miss-assembly of balls detection in aviation bearing. Furthermore, it has high application value.

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