Simultaneous identification of joint stiffness, kinematic and hand-eye parameters of measurement system integrated with serial robot and 3D camera

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jinlei Zhuang ◽  
Ruifeng Li ◽  
Chuqing Cao ◽  
Yunfeng Gao ◽  
Ke Wang ◽  
...  
Keyword(s):  
Measurement System ◽  
Measurement Accuracy ◽  
Joint Stiffness ◽  
Calibration Method ◽  
Identification Accuracy ◽  
Kinematic Calibration ◽  
Content Type ◽  
3D Camera ◽  
Serial Robot ◽  
Measurement Principle

Purpose This paper aims to propose a measurement principle and a calibration method of measurement system integrated with serial robot and 3D camera to identify its parameters conveniently and achieve high measurement accuracy. Design/methodology/approach A stiffness and kinematic measurement principle of the integrated system is proposed, which considers the influence of robot weight and load weight on measurement accuracy. Then an error model is derived based on the principle that the coordinate of sphere center is invariant, which can simultaneously identify the parameters of joint stiffness, kinematic and hand-eye relationship. Further, considering the errors of the parameters to be calibrated and the measurement error of 3D camera, a method to generate calibration observation data is proposed to validate both calibration accuracy and parameter identification accuracy of calibration method. Findings Comparative simulations and experiments of conventional kinematic calibration method and the stiffness and kinematic calibration method proposed in this paper are conducted. The results of the simulations show that the proposed method is more accurate, and the identified values of angle parameters in modified Denavit and Hartenberg model are closer to their real values. Compared with the conventional calibration method in experiments, the proposed method decreases the maximum and mean errors by 19.9% and 13.4%, respectively. Originality/value A new measurement principle and a novel calibration method are proposed. The proposed method can simultaneously identify joint stiffness, kinematic and hand-eye parameters and obtain not only higher measurement accuracy but also higher parameter identification accuracy, which is suitable for on-site calibration.

Kinematic calibration of serial robot using dual quaternions

2019 ◽  
Vol 46 (2) ◽  
pp. 247-258 ◽  
Author(s):  
Guozhi Li ◽  
Fuhai Zhang ◽  
Yili Fu ◽  
Shuguo Wang
Keyword(s):  
Kinematic Analysis ◽  
Quaternion Algebra ◽  
Error Model ◽  
Kinematic Calibration ◽  
Dual Quaternion ◽  
Robot Calibration ◽  
Geometrical Meaning ◽  
Content Type ◽  
Dual Quaternions ◽  
Serial Robot

Purpose The purpose of this paper is to propose an error model for serial robot kinematic calibration based on dual quaternions. Design/methodology/approach The dual quaternions are the combination of dual-number theory and quaternion algebra, which means that they can represent spatial transformation. The dual quaternions can represent the screw displacement in a compact and efficient way, so that they are used for the kinematic analysis of serial robot. The error model proposed in this paper is derived from the forward kinematic equations via using dual quaternion algebra. The full pose measurements are considered to apply the error model to the serial robot by using Leica Geosystems Absolute Tracker (AT960) and tracker machine control (T-MAC) probe. Findings Two kinematic-parameter identification algorithms are derived from the proposed error model based on dual quaternions, and they can be used for serial robot calibration. The error model uses Denavit–Hartenberg (DH) notation in the kinematic analysis, so that it gives the intuitive geometrical meaning of the kinematic parameters. The absolute tracker system can measure the position and orientation of the end-effector (EE) simultaneously via using T-MAC. Originality/value The error model formulated by dual quaternion algebra contains all the basic geometrical parameters of serial robot during the kinematic calibration process. The vector of dual quaternion error can be used as an indicator to represent the trend of error change of robot’s EE between the nominal value and the actual value. The accuracy of the EE is improved after nearly 20 measurements in the experiment conduct on robot SDA5F. The simulation and experiment verify the effectiveness of the error model and the calibration algorithms.

Research on the influence of background light on the accuracy of a three-dimensional coordinate measurement system based on dual-PSD

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xiaohong Lu ◽  
Yu Zhou ◽  
Jinhui Qiao ◽  
Yihan Luan ◽  
Yongquan Wang
Keyword(s):  
Neural Network ◽  
Measurement System ◽  
Bp Neural Network ◽  
Measurement Accuracy ◽  
Three Dimensional ◽  
Electrical Method ◽  
Content Type ◽  
Coordinate Measurement ◽  
Background Light ◽  
Three Dimensional Coordinate

Purpose The purpose of this paper is to analyze the measurement error of a three-dimensional coordinate measurement system based on dual-position-sensitive detector (PSD) under different background light. Design/methodology/approach The mind evolutionary algorithm (MEA)-back propagation (BP) neural network is used to predict the three-dimensional coordinates of the points, and the influence of the background light on the measurement accuracy of the three-dimensional coordinates based on PSD is obtained. Findings The influence of the background light on the measurement accuracy of the system is quantitatively calculated. The background light has a significant influence on the prediction accuracy of the three-dimensional coordinate measurement system. The optical method, electrical method and photoelectric compensation method are proposed to improve the measurement accuracy. Originality/value BP neural network based on MEA is applied to the coordinate prediction of the three-dimensional coordinate measurement system based on dual-PSD, and the influence of background light on the measurement accuracy is quantitatively analyzed.

The spectral calibration method for a crop nitrogen sensor

Sensor Review ◽  
2016 ◽  
Vol 36 (1) ◽  
pp. 48-56 ◽  
Author(s):  
Jun Ni ◽  
Jifei Dong ◽  
Jingchao Zhang ◽  
Fangrong Pang ◽  
Weixing Cao ◽  
...  
Keyword(s):  
Design Methodology ◽  
Measurement Accuracy ◽  
Signal To Noise Ratio ◽  
Calibration Method ◽  
Sensor Calibration ◽  
Content Type ◽  
Spectral Calibration ◽  
Calibration Methods ◽  
Detector Method ◽  
Standard Detector

Purpose – The purpose of this paper is to improve the accuracy and signal-to-noise ratio (SN) of a crop nitrogen sensor. Design/methodology/approach – The accuracy and wide adaptability of two spectral calibration methods for a crop nitrogen sensor based on standard reflectivity gray plates and standard detector, respectively, were compared. Findings – The calibration method based on standard detector could significantly improve the measurement accuracy and the SN of this crop nitrogen sensor. When compared with the method based on standard gray plates, the measurement accuracy and the SN of the crop nitrogen sensor calibrated based on the standard detector method improved by 50 and 10 per cent, respectively. Originality/value – This research analysed the calibration problems faced by the crop nitrogen sensor (type CGMD302) based on standard gray plates, and proposed a sensor calibration method based on a standard detector. Finally, the results of the two calibration methods were compared in terms of measurement accuracy and the SN of the crop nitrogen sensor.

A vision-based fully-automatic calibration method for hand-eye serial robot

2015 ◽  
Vol 42 (1) ◽  
pp. 64-73 ◽  
Author(s):  
Haixia Wang ◽  
Xiao Lu ◽  
Zhanyi Hu ◽  
Yuxia Li
Keyword(s):  
Design Methodology ◽  
Calibration Method ◽  
Automatic Calibration ◽  
Screw Axis ◽  
Robot System ◽  
Camera System ◽  
Content Type ◽  
Serial Robot ◽  
Fully Automatic ◽  
Robot Body

Purpose – The purpose of this paper is to present a fully automatic calibration method for hand-eye serial robot system is presented in this paper. The so-called “fully automatic” is meant to calibrate the robot body, the hand-eye relation, and the used measuring binocular system at the same time. Design/methodology/approach – The calibration is done by controlling the joints to rotate several times one by one in the reverse order (i.e. from the last one to the first one), and simultaneously take pictures of the checkerboard patterns by the stereo camera system attached on the end-effector, then the whole robot system can be calibrated automatically from these captured images. In addition, a nonlinear optimization step is used to further refine the calibration results. Findings – The proposed method is essentially based on an improved screw axis identification method, and it needs only a mirror and some paper checkerboard patterns without resorting to any additional costly measuring instrument. Originality/value – Simulations and real experiments on MOTOMAN-UP6 robot system demonstrate the feasibility and effectiveness of the proposed method.

Kinematic calibration of bracket type parallel posture alignment mechanism considering the gravity effect

2019 ◽  
Vol 46 (5) ◽  
pp. 581-598 ◽  
Author(s):  
Zhihao Wang ◽  
Wenliang Chen ◽  
Min Wang ◽  
Qinghe Xu ◽  
Can Huang
Keyword(s):  
Elastic Deformation ◽  
Great Influence ◽  
Target Position ◽  
Calibration Method ◽  
Geometric Errors ◽  
Kinematic Calibration ◽  
Error Identification ◽  
Content Type ◽  
Maximum Value ◽  
Alignment Mechanism

Purpose The purpose of this study is to improve the position and posture accuracy of posture alignment mechanism. The automatic drilling and riveting machine is an important equipment for aircraft assembly. The alignment accuracy of position and posture of the bracket type posture alignment mechanism has a great influence on the operation effect of the machine. Therefore, it is necessary to carry out the kinematic calibration. Design/methodology/approach Based on analysis of elastic deformation of the bracket and geometric errors of the posture alignment mechanism, an improved method of kinematic calibration was proposed. The position and posture errors of bracket caused by geometric errors were separated from those caused by gravity. The method of reduction of dimensions was applied to deal with the error coefficient matrix in error identification, and it did not change the coefficient of the error terms. The target position and its posture were corrected to improve the error compensation accuracy. Furthermore, numerical simulation and experimental verification were carried out. Findings The simulation and experimental results show that considering the influence of the elastic deformation of the bracket on the calibration effect, the error identification accuracy and compensation accuracy can be improved. The maximum value of position error is reduced from 5.33 mm to 1.60 × 10−1 mm and the maximum value of posture error is reduced from 1.07 × 10−3 rad to 6.02 × 10−4 rad, which is superior to the accuracy without considering the gravity factor. Originality/value This paper presents a calibration method considering the effects of geometric errors and gravity. By separating position and posture errors caused by different factors and correcting the target position and its posture, the results of the calibration method are greatly improved. The proposed method might be applied to any parallel mechanism based on the positioner.

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.

The Novel Calibration Method for 3-DOF Measurement System

2011 ◽  
Vol 120 ◽  
pp. 440-443
Author(s):  
Kwang Il Lee ◽  
Jin Seok Jang ◽  
Hyun Woo Lee ◽  
Suk Jin Kim ◽  
Sang Ryong Lee ◽  
...  
Keyword(s):  
Measurement System ◽  
Measurement Accuracy ◽  
Least Square Method ◽  
Calibration Method ◽  
Measured Data ◽  
Least Square ◽  
The Novel ◽  
Squareness Error ◽  
Misalignment Error ◽  
Calibration Parameters

In this paper, a novel calibration method is developed to improve the measurement accuracy of 3-DOF measurement system. The squareness error between three sensors and misalignment error with respect to reference coordinate of machine tool are calibration parameters. To estimate these parameters, reference ball is used and moved in the measuring ranges of 3-DOF measurement system. The relation between calibration parameters, position of reference ball, measured data of sensors are defined using geometric constraint and estimated using least square method. Finally, simulation is done to check the feasibility of developed calibration method. The result of simulation revealed the validation of developed method.

A kinematic calibration method based on the product of exponentials formula for serial robot using position measurements

Robotica ◽  
2014 ◽  
Vol 33 (6) ◽  
pp. 1295-1313 ◽  
Author(s):  
Ruibo He ◽  
Xiwen Li ◽  
Tielin Shi ◽  
Bo Wu ◽  
Yingjun Zhao ◽  
...  
Keyword(s):  
Calibration Method ◽  
Kinematic Parameter ◽  
Kinematic Calibration ◽  
Position Measurement ◽  
Error Models ◽  
Position Errors ◽  
Zero Position ◽  
Prismatic Joints ◽  
Serial Robot ◽  
Initial Transformation

SUMMARYBased on product of exponentials (POE) formula, three explicit error models are given in this paper for kinematic calibration of serial robot through measuring its end-effector positions. To obtain these error models, the tool frame should be chosen as reference frame at first, and then each position–error-related segment in the error models using pose measurement should be selected. And during kinematic parameter identification, all the errors in joint twists are identifiable, and the initial transformation errors and the joint zero-position errors can be identified conditionally. Namely, the initial transformation errors are identifiable if they do not contain orientation errors. And the joint zero-position errors are identifiable when a robot only consists of prismatic joints and the coordinates of its joint twists are linearly independent.The effectiveness of this calibration method has been validated by simulations and experiments. The results show that: (1) the identification algorithms are robust and practical. (2) The method of position measurement is superior to that of pose measurement.

An improved kinematic calibration method for serial manipulators based on POE formula

Robotica ◽  
2018 ◽  
Vol 36 (8) ◽  
pp. 1244-1262 ◽  
Author(s):  
Chenguang Chang ◽  
Jinguo Liu ◽  
Zhiyu Ni ◽  
Ruolong Qi
Keyword(s):  
High Precision ◽  
Least Square Method ◽  
Calibration Method ◽  
Error Model ◽  
Least Square ◽  
Identification Accuracy ◽  
Kinematic Calibration ◽  
Serial Manipulators ◽  
Serial Robots ◽  
Generic Modeling

SUMMARYExisting measurement equipments easily determine position with high precision. However, they evaluate orientation with low precision. It is necessary to minimize the effect of measurement error on identification accuracy. In this study, a method for kinematic calibration based on the product of exponentials (POE) is presented to improve the absolute positioning accuracy of a sliding manipulator. An error model with uniform and generic modeling rules is established in which the tool frame is selected as the reference frame. Furthermore, the redundant parameters of the error model are removed. Subsequently, the actual kinematic parameters are identified by using the least square method. Finally, the process of the improved method is discussed. Kinematic calibration simulations of a sliding manipulator are implemented. The results indicate that the proposed method significantly improves the precision of the sliding manipulator. The improved POE kinematic calibration method offers convenience, efficiency, and high precision. The proposed method can be applied to all types of serial robots with n-DOF

Kinematic calibration of parallel manipulator with full-circle rotation

2016 ◽  
Vol 43 (3) ◽  
pp. 296-307 ◽  
Author(s):  
Yanbing Ni ◽  
Biao Zhang ◽  
Wenxia Guo ◽  
Cuiyan Shao
Keyword(s):  
Error Compensation ◽  
Parallel Manipulator ◽  
Calibration Method ◽  
Kinematic Calibration ◽  
Error Sources ◽  
Content Type ◽  
Position Errors ◽  
Full Circle ◽  
Simulation And Experiment ◽  
Circle Rotation

Purpose The purpose of this paper is to develop a means of the kinematic calibration of a parallel manipulator with full-circle rotation. Design/methodology/approach An error-mapping model based on the space vector chain is formulated and parameter identification is proposed based on double ball-bar (DBB) measurements. The measurement trajectory is determined by the motion characteristics of this mechanism and whether the error sources can be identified. Error compensation is proposed by modifying the inputs, and a two-step kinematic calibration method is implemented. Findings The simulation and experiment results show that this kinematic calibration method is effective. The DBB length errors and the position errors in the end-effector of the parallel manipulator with full-circle rotation are greatly reduced after error compensation. Originality/value By establishing the mapping relationship between measured error data and geometric error sources, the error parameters of this mechanism are identified; thus, the pose errors are unnecessary to be measured directly. The effectiveness of the kinematic calibration method is verified by computer simulation and experiment. This proposed calibration method can help the novel parallel manipulator with full-circle rotation and other similar parallel mechanisms to improve their accuracy.

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