Mesoscale Robotic Assembly With Orthogonal Optical Alignment for UV-LIGA Parts

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Xin Ye ◽  
Xiaofeng Zhang ◽  
Bile Wan ◽  
Zhijing Zhang ◽  
Pan Liu
Keyword(s):  
Vision System ◽  
Calibration Method ◽  
Robotic Assembly ◽  
Inertia Force ◽  
Success Rates ◽  
Time Consumption ◽  
Assembly Accuracy ◽  
Object Part ◽  
Optical Alignment ◽  
Causes Of Failure

This paper proposes an assembly system for ultraviolet-lithographie galvanik abformung (UV-LIGA) parts with a robotic manipulator. Both images of base part and object part could be obtained simultaneously from an in-house orthogonal optical alignment vision system. Two microgrippers were introduced to realize the reliable clamping. An initial calibration method was presented to ensure assembly accuracy. Assembly experiments were conducted with success rates of 80% and the time consumption of 20 min for all four parts assembly. Suspected causes of failure are motion mechanisms' uncertainty, part dislocation resulted from inertia force when microgripper is moving, and the error which is produced in the detection process because of random factors.

An improved vision calibration method for coaxial alignment microassembly

2014 ◽  
Vol 34 (3) ◽  
pp. 237-243 ◽  
Author(s):  
Xin Ye ◽  
Jun Gao ◽  
Zhijing Zhang ◽  
Chao Shao ◽  
Guangyuan Shao
Keyword(s):  
Degrees Of Freedom ◽  
Microelectromechanical Systems ◽  
Vision System ◽  
Image Plane ◽  
Calibration Method ◽  
Corner Detection ◽  
Objective Lens ◽  
Content Type ◽  
Assembly Accuracy ◽  
Methodological Guidelines

Purpose – The purpose of this paper is to propose a sub-pixel calibration method for a microassembly system with coaxial alignment function (MSCA) because traditional sub-pixel calibration approaches cannot be used in this system. Design/methodology/approach – The in-house microassembly system comprises a six degrees of freedom (6-DOF) large motion serial robot with microgrippers, a hexapod 6-DOF precision alignment worktable and a vision system whose optical axis of the microscope is parallel with the horizontal plane. A prism with special coating is fixed in front of the objective lens; thus, two parts’ Figures, namely the images of target and base part, can be acquired simultaneously. The relative discrepancy between the two parts can be calculated from image plane coordinate instead of calculating space transformation matrix. Therefore, the traditional calibration method cannot be applied in this microassembly system. An improved calibration method including the check corner detection solves the distortion coefficient conversely. This new way can detect the corner at sub-pixel accuracy. The experiment proves that the assembly accuracy of the coaxial microassembly system which has been calibrated by the new method can reach micrometer level. Findings – The calibration results indicate that solving the distortion conversely could improve the assembly accuracy of MSCA. Originality/value – The paper provides certain calibration methodological guidelines for devices with 2 dimensions or 2.5 dimensions, such as microelectromechanical systems devices, using MSCA.

scholarly journals Physician-Friendly Tool Center Point Calibration Method for Robot-Assisted Puncture Surgery

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 366
Author(s):  
Leifeng Zhang ◽  
Changle Li ◽  
Yilun Fan ◽  
Xuehe Zhang ◽  
Jie Zhao
Keyword(s):  
Vision System ◽  
Calibration Method ◽  
Robot Assisted ◽  
Precise Control ◽  
Time Consumption ◽  
Center Point ◽  
Calibration Methods ◽  
Key Factor ◽  
Tool Replacement ◽  
Robot Configuration

After each robot end tool replacement, tool center point (TCP) calibration must be performed to achieve precise control of the end tool. This process is also essential for robot-assisted puncture surgery. The purpose of this article is to solve the problems of poor accuracy stability and strong operational dependence in traditional TCP calibration methods and to propose a TCP calibration method that is more suitable for a physician. This paper designs a special binocular vision system and proposes a vision-based TCP calibration algorithm that simultaneously identifies tool center point position (TCPP) and tool center point frame (TCPF). An accuracy test experiment proves that the designed special binocular system has a positioning accuracy of ±0.05 mm. Experimental research shows that the magnitude of the robot configuration set is a key factor affecting the accuracy of TCPP. Accuracy of TCPF is not sensitive to the robot configuration set. Comparison experiments show that the proposed TCP calibration method reduces the time consumption by 82%, improves the accuracy of TCPP by 65% and improves the accuracy of TCPF by 52% compared to the traditional method. Therefore, the method proposed in this article has higher accuracy, better stability, less time consumption and less dependence on the operations than traditional methods, which has a positive effect on the clinical application of high-precision robot-assisted puncture surgery.

scholarly journals Towards Autonomous Robotic Assembly: Using Combined Visual and Tactile Sensing for Adaptive Task Execution

2021 ◽  
Vol 101 (3) ◽  
Author(s):  
Korbinian Nottensteiner ◽  
Arne Sachtler ◽  
Alin Albu-Schäffer
Keyword(s):  
Autonomous Robots ◽  
Vision System ◽  
Dynamic Environments ◽  
Bayesian Framework ◽  
Experimental Results ◽  
Robotic Assembly ◽  
Tactile Sensing ◽  
Task Execution ◽  
Industrial Assembly ◽  
Assembly Tasks

AbstractRobotic assembly tasks are typically implemented in static settings in which parts are kept at fixed locations by making use of part holders. Very few works deal with the problem of moving parts in industrial assembly applications. However, having autonomous robots that are able to execute assembly tasks in dynamic environments could lead to more flexible facilities with reduced implementation efforts for individual products. In this paper, we present a general approach towards autonomous robotic assembly that combines visual and intrinsic tactile sensing to continuously track parts within a single Bayesian framework. Based on this, it is possible to implement object-centric assembly skills that are guided by the estimated poses of the parts, including cases where occlusions block the vision system. In particular, we investigate the application of this approach for peg-in-hole assembly. A tilt-and-align strategy is implemented using a Cartesian impedance controller, and combined with an adaptive path executor. Experimental results with multiple part combinations are provided and analyzed in detail.

Easy calibration method of vision system for in-situ measurement of strain of thin films

2009 ◽  
Vol 19 ◽  
pp. s243-s249 ◽  
Author(s):  
Jun-Hyub PARK ◽  
Dong-Joong KANG ◽  
Myung-Soo SHIN ◽  
Sung-Jo LIM ◽  
Son-Cheol YU ◽  
...  
Keyword(s):  
Thin Films ◽  
Vision System ◽  
Calibration Method ◽  
In Situ Measurement

scholarly journals Stereo Camera Head-Eye Calibration Based on Minimum Variance Approach Using Surface Normal Vectors

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3706 ◽  
Author(s):  
Joong-Jae Lee ◽  
Mun-Ho Jeong
Keyword(s):  
Vision System ◽  
Real Data ◽  
Humanoid Robots ◽  
Calibration Method ◽  
Minimum Variance ◽  
Kinematic Data ◽  
Stereo Camera ◽  
Surface Normal ◽  
Normal Vectors ◽  
Variance Approach

This paper presents a stereo camera-based head-eye calibration method that aims to find the globally optimal transformation between a robot’s head and its eye. This method is highly intuitive and simple, so it can be used in a vision system for humanoid robots without any complex procedures. To achieve this, we introduce an extended minimum variance approach for head-eye calibration using surface normal vectors instead of 3D point sets. The presented method considers both positional and orientational error variances between visual measurements and kinematic data in head-eye calibration. Experiments using both synthetic and real data show the accuracy and efficiency of the proposed method.

scholarly journals Flexible method for accurate calibration of large-scale vision metrology system based on virtual 3-D targets and laser tracker

2019 ◽  
Vol 16 (6) ◽  
pp. 172988141989351
Author(s):  
Xi Zhang ◽  
Yuanzhi Xu ◽  
Haichao Li ◽  
Lijing Zhu ◽  
Xin Wang ◽  
...  
Keyword(s):  
High Precision ◽  
Stereo Vision ◽  
Large Scale ◽  
Vision System ◽  
Calibration Method ◽  
Field Of View ◽  
Large Field ◽  
Laser Tracker ◽  
Calibration Target ◽  
Pose Tracking

For the purpose of obtaining high-precision in stereo vision calibration, a large-size precise calibration target, which can cover more than half of the field of view is vital. However, large-scale calibration targets are very difficult to fabricate. Based on the idea of error tracing, a high-precision calibration method for vision system with large field of view by constructing a virtual 3-D calibration target with a laser tracker was proposed in this article. A virtual 3-D calibration target that covers the whole measurement space can be established flexibly and the measurement precision of the vision system can be traceable to the laser tracker. First, virtual 3-D targets by calculating rigid body transformation with unit quaternion method were constructed. Then, the high-order distortion camera model was taken into consideration. Besides, the calibration parameters were solved with Levenberg–Marquardt optimization algorithm. In the experiment, a binocular stereo vision system with the field of view of 4 × 3 × 2 m3 was built for verifying the validity and precision of the proposed calibration method. It is measured that the accuracy with the proposed method can be greatly improved comparing with traditional plane calibration method. The method can be widely used in industrial applications, such as in the field of calibrating large-scale vision-based coordinate metrology, and six-degrees of freedom pose tracking system for dimensional measurement of workpiece, as well as robotics geometrical accuracy detection and compensation.

Automatic press-fit assembly of small precision interference fitting parts: armature of electro-hydraulic servo valve

2019 ◽  
Vol 39 (5) ◽  
pp. 986-998
Author(s):  
Xingyuan Wang ◽  
Zhifeng Lou ◽  
Xiaodong Wang ◽  
Yue Wang ◽  
Xiupeng Hao ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Quality Assessment ◽  
Calibration Method ◽  
Technical Problems ◽  
Content Type ◽  
Press Fit ◽  
Automatic Press ◽  
Assembly Accuracy ◽  
The Press ◽  
Methodological Guidelines

Purpose The purpose of this paper is to design an automatic press-fit instrument to realize precision assembly and connection quality assessment of a small interference fitting parts, armature. Design/methodology/approach In this paper, an automatic press-fit instrument was developed for the technical problems of reliable clamping and positioning of the armature, automatic measurement and adjustment of the attitude and evaluation of the connection quality. To compensate for the installation error of the equipment, corresponding calibration method was proposed for each module of the instrument. Assembly strategies of axial displacement and perpendicularity were also proposed to ensure the assembly accuracy. A theoretical model was built to calculate the resistant force generated by the non-contact regions and then combined with the thick-walled cylinder theory to predict the press-fit curve. Findings The calibration method and assembly strategy proposed in this paper enable the press-fit instrument to achieve good alignment and assembly accuracy. A reasonable range of press-fit curve obtained from theoretical model can achieve the connection quality assessment. Practical implications This instrument has been used in an armature assembly project. The practical results show that this instrument can assemble the armature components with complex structures automatically, accurately, in high-efficiency and in high quality. Originality/value This paper provides a technical method to improve the assembly quality of small precision interference fitting parts and provides certain methodological guidelines for precision peg-in-hole assembly.

scholarly journals Computer Vision Tool-Setting System of Numerical Control Machine Tool

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5302
Author(s):  
Bo Hou ◽  
Congpeng Zhang ◽  
Shoubo Yang
Keyword(s):  
Computer Vision ◽  
Vision System ◽  
Performance Testing ◽  
Calibration Method ◽  
Numerical Control ◽  
Cnc Machine ◽  
Control Machine Tool ◽  
System Calibration ◽  
Tool Setting ◽  
Automatic Tool

An automatic tool-setting and workpiece online detecting system was proposed to study the key technologies of next-generation intelligent vision computerized numerical control (CNC) machines. A computer vision automatic tool-setting system for a CNC machine was set up on the basis of the vision tool-setting principle. A rapid vision calibration method based on the position feedback from the CNC machine was proposed on the basis of the theory of traditional vision system calibration. The coordinate mapping relationship of the image and the CNC machine, the tool-setting mark point on the workpiece, and the tool tip were calibrated. The vision system performance testing and system calibration experiments were performed. Experimental results indicated that the time consumption was 128 ms in image processing. The precision of tool setting and measuring was less than 1 μm. The workpiece positioning and processing online detection function of the system can completely meet the requirements of visual CNC machine application, and the system has wide application prospects.

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