Calibration method for articulated industrial robots

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.

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A Kinematic Calibration Method for Industrial Robots Using Autonomous Visual Measurement

CIRP Annals ◽

10.1016/s0007-8506(07)60353-9 ◽

2006 ◽

Vol 55 (1) ◽

pp. 1-6 ◽

Cited By ~ 38

Author(s):

A. Watanabe ◽

S. Sakakibara ◽

K. Ban ◽

M. Yamada ◽

G. Shen ◽

...

Keyword(s):

Calibration Method ◽

Industrial Robots ◽

Kinematic Calibration ◽

Visual Measurement

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Self-Calibration of Eye-to-Hand and Workspace for Mobile Service Robot

Service Robots and Robotics ◽

10.4018/978-1-4666-0291-5.ch013 ◽

2012 ◽

pp. 229-246

Author(s):

Jwu-Sheng Hu ◽

Yung-Jung Chang

Keyword(s):

Visual Information ◽

Calibration Method ◽

Industrial Robots ◽

Service Robots ◽

Service Robot ◽

Mobile Service ◽

Robot Arm ◽

Self Calibration ◽

Laser Distance Sensor ◽

Distance Sensor

The geometrical relationships among robot arm, camera, and workspace are important to carry out visual servo tasks. For industrial robots, the relationships are usually fixed and well calibrated by experienced operators. However, for service robots, particularly in mobile applications, the relationships might be changed. For example, when a mobile robot attempts to use the visual information from environmental cameras to perform grasping, it is necessary to know the relationships before taking actions. Moreover, the calibration should be done automatically. This chapter proposes a self-calibration method using a laser distance sensor mounted on the robot arm. The advantage of the method, as compared with pattern-based one, is that the workspace coordinate is also obtained at the same time using the projected laser spot. Further, it is not necessary for the robot arm to enter the view scope of the camera for calibration. This increases the safety when the workspace is unknown initially.

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A Robotic Milling System Based on 3D Point Cloud

Machines ◽

10.3390/machines9120355 ◽

2021 ◽

Vol 9 (12) ◽

pp. 355

Author(s):

Yongzhuo Gao ◽

Haibo Gao ◽

Kunpeng Bai ◽

Mingyang Li ◽

Wei Dong

Keyword(s):

Large Scale ◽

Calibration Method ◽

Milling Process ◽

Processing Method ◽

Industrial Robots ◽

Cnc Machine Tools ◽

Cnc Machine ◽

Automatic Production ◽

Robotic Milling ◽

Measurement Planning

Industrial robots have advantages in the processing of large-scale components in the aerospace industry. Compared to CNC machine tools, robot arms are cheaper and easier to deploy. However, due to the poor consistency of incoming materials, large-scale and lightweight components make it difficult to automate robotic machining. In addition, the stiffness of the tandem structure is quite low. Therefore, the stability of the milling process is always a concern. In this paper, the robotic milling research is carried out for the welding pre-processing technology of large-scale components. In order to realize the automatic production of low-conformity parts, the on-site measurement–planning–processing method is adopted with the laser profiler. On the one hand, the laser profiler hand–eye calibration method is optimized to improve the measurement accuracy. On the other hand, the stiffness of the robot’s processing posture is optimized, combined with the angle of the fixture turntable. Finally, the experiment shows the feasibility of the on-site measurement–planning–processing method and verifies the correctness of the stiffness model.

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Tool Center Point Calibration Method for an Industrial Robots based on Spheres Fitting Method

10.1109/rose52750.2021.9611759 ◽

2021 ◽

Author(s):

Fakherddine Fares ◽

Haifa Souifi ◽

Yassine Bouslimani ◽

Mohsen Ghribi

Keyword(s):

Calibration Method ◽

Industrial Robots ◽

Center Point ◽

Fitting Method

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Auto-Calibration for Vision-Based 6-D Sensing System to Support Monitoring and Health Management for Industrial Robots

Volume 2: Manufacturing Processes; Manufacturing Systems; Nano/Micro/Meso Manufacturing; Quality and Reliability ◽

10.1115/msec2021-63892 ◽

2021 ◽

Author(s):

Guixiu Qiao ◽

Guangkun Li

Keyword(s):

High Precision ◽

Health Management ◽

Calibration Method ◽

Industrial Robots ◽

Smart Manufacturing ◽

Robot Arm ◽

Sensing System ◽

Robot Accuracy ◽

Robot Machining ◽

Machining Robot

Abstract Industrial robots play important roles in manufacturing automation for smart manufacturing. Some high-precision applications, for example, robot drilling, robot machining, robot high-precision assembly, and robot inspection, require higher robot accuracy compared with traditional part handling operations. The monitoring and assessment of robot accuracy degradation become critical for these applications. A novel vision-based sensing system for 6-D measurement (six-dimensional x, y, z, yaw, pitch, and roll) is developed at the National Institute of Standards and Technology (NIST) to measure the dynamic high accuracy movement of a robot arm. The measured 6-D information is used for robot accuracy degradation assessment and improvement. This paper presents an automatic calibration method for a vision-based 6-D sensing system. The stereo calibration is separated from the distortion calibration to speed up the on-site adjustment. Optimization algorithms are developed to achieve high calibration accuracy. The vision-based 6-D sensing system is used on a Universal Robots (UR5) to demonstrate the feasibility of using the system to assess the robot’s accuracy degradation.

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A calibration method of industrial robots based on ELM

2017 2nd International Conference on Advanced Robotics and Mechatronics (ICARM) ◽

10.1109/icarm.2017.8273137 ◽

2017 ◽

Cited By ~ 1

Author(s):

Ying Cai ◽

Peijiang Yuan ◽

Dongdong Chen ◽

Doudou Gao ◽

Xulei Wu ◽

...

Keyword(s):

Calibration Method ◽

Industrial Robots

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A calibration method of robot kinematic parameters by drawstring displacement sensor

International Journal of Advanced Robotic Systems ◽

10.1177/1729881419883072 ◽

2019 ◽

Vol 16 (5) ◽

pp. 172988141988307 ◽

Cited By ~ 1

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.

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A calibration method of kinematic parameters for serial industrial robots

Industrial Robot the international journal of robotics research and application ◽

10.1108/ir-06-2013-369 ◽

2014 ◽

Vol 41 (2) ◽

pp. 157-165 ◽

Cited By ~ 13

Author(s):

Wei Wang ◽

Gang Wang ◽

Chao Yun

Keyword(s):

Calibration Method ◽

Error Model ◽

Industrial Robots ◽

Reference Configuration ◽

Calibration Model ◽

Positioning Error ◽

Kinematic Parameters ◽

Rigid Displacement ◽

Content Type ◽

Zero Position

Purpose – Calibrating kinematic parameters is one of the efficient ways to improve the robot's positioning accuracy. A method based on the product-of-exponential (POE) formula to calibrate the kinematic parameters of serial industrial robots is proposed. The paper aims to discuss these issues. Design/methodology/approach – The forward kinematics is established, and the general positioning error model is deduced in an explicit expression. A simplified model of robot's positioning error is established as both the error of reference configuration and the error of rigid displacement of the base coordinating system with respect to the measuring coordinating system are equivalently transferred to the zero position errors of the robot's joints. A practical calibration model is forwarded only requiring 3D measuring based on least-squares algorithm. The calibration system and strategy for calibrating kinematic parameters are designed. Findings – By the two geometrical constrains between the twist coordinates, each joint twist only has four independent coordinates. Due to the equivalent error model, the zero position error of each joint can cover the error of reference configuration and rigid displacement of the robot base coordinating system with respect to the measuring coordinating system. The appropriate number of independent kinematic parameters of each joint to be calibrated is five. Originality/value – It is proved by a group of calibration experiments that the calibration method is well conditioned and can be used to promote the level of absolute error of end effector of industrial robot to 2.2 mm.

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