Chen Shen, Youping Chen, Bing Chen and Yu Qiao
This paper aims to propose a novel robot kinematic calibration method based on the common perpendicular line (CPL) model to improve the absolute accuracy of industrial robots.
Abstract
Purpose
This paper aims to propose a novel robot kinematic calibration method based on the common perpendicular line (CPL) model to improve the absolute accuracy of industrial robots.
Design/methodology/approach
The deviation between the nominal and actual twists is considered the CPL transformation, which includes the rotation about the CPL and the translation along the CPL. By using the invariance of the reciprocal product of the two spatial lines, the previous deviation was analyzed in the neighbor space of the base frame origin. In this space, the line vector of the CPL contained only four independent parameters: two orientation elements and two moment elements. Thus, the CPL model has four independent parameters for the revolute joint and two parameters for the prismatic joint.
Findings
By simulations and experiment conducted on a SCARA robot and a 6-DOF PUMA robot, the effectiveness of the novel method for calibration of industrial robot is validated.
Originality/value
The CPL model avoided the normalization and orthogonalization in the iterative identification procedure. Therefore, identifying the CPL model was not only simpler but also more accurate than that of the traditional model. In addition, the results of the CPL transformation strictly conformed to the constraints of the twist.
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Keywords
Sifeng Liu, Hongyang Zhang and Yingjie Yang
The purpose of this paper is to present the terms of grey incidence analysis models.
Abstract
Purpose
The purpose of this paper is to present the terms of grey incidence analysis models.
Design/methodology/approach
The definitions of basic terms about various grey incidence analysis models are presented one by one.
Findings
The reader could know the basic explanation about the important terms about various grey incidence analysis models from this paper.
Practical implications
Many of the authors’ colleagues thought that unified definitions of key terms would be beneficial for both the readers and the authors.
Originality/value
It is a fundamental work to standardize all the definitions of terms for a new discipline. It is also propitious to spread and universal of grey system theory.
Details
Keywords
Sifeng Liu, Naiming Xie, Yingjie Yang and Jeffrey Forrest
The purpose of this paper is to present the terms of sequence operators and grey data mining.
Abstract
Purpose
The purpose of this paper is to present the terms of sequence operators and grey data mining.
Design/methodology/approach
The definitions of basic terms about sequence operators and grey data mining are presented one by one.
Findings
The reader could know the basic explanation about the important terms about sequence operators and grey data mining from this paper.
Practical implications
Many of the colleagues thought that unified definitions of key terms would be beneficial for both the readers and the authors.
Originality/value
It is a fundamental work to standardize all the definitions of terms for a new discipline. It is also propitious to spread the universal principles of grey system theory.
Details
Keywords
Baolei Wei, Naiming Xie and L.U. Yang
The cumulative sum (Cusum) operator, also referred to as accumulating generation operator, is the fundamental of grey system models and proves to be successful in various…
Abstract
Purpose
The cumulative sum (Cusum) operator, also referred to as accumulating generation operator, is the fundamental of grey system models and proves to be successful in various real-world applications. This paper aims to uncover the advantages of the Cusum operator from a parameter estimation perspective, i.e. comparing integral matching with classical gradient matching.
Design/methodology/approach
Grey system models are represented as a state space form to investigate the effect of measurement errors on estimation performance; subsequently, gradient matching and integral matching are respectively formulated to estimate parameters from noisy observations and, then, their quantitative relationships are established by using matrix computation tricks.
Findings
Extensive simulations, which are conducted on both linear and non-linear models under different sample size and noise level combinations, show that integral matching is superior to gradient matching, and, also the former is less sensitive to measurement error.
Originality/value
This paper explains why the Cusum operator is widely utilized in grey system models, thereby further solidifying the mathematical fundamentals of grey system models.
Details
Keywords
Abstract
Purpose
This papers aims to provide a fixed cutter axis control (F-CAC) industrial robot (IR) milling for NURBS surfaces with large fluctuation, which can avoid over-cut and interference during IR milling in contrast to variable cutter axis control (V-CAC) IR milling.
Design/methodology/approach
After the design of a target surface, the IR reciprocating milling trajectory can be obtained using NURBS mapping projection method. A set of interpolation points of the reciprocating trajectory can be calculated using the equi-chord interpolation method. Combining with F-CAC method and curvature estimation, the IR reciprocating trajectory of the tool center point (TCP) without over-cut can be obtained. The programs corresponding to posture control using F-CAC can be generated by IR kinematics.
Findings
In contrast to the V-CAC milling method, the F-CAC method can machine successfully the NURBS surfaces with large fluctuation. The simulation and machining proves that F-CAC is feasible and effective to machine NURBS surface with large fluctuation without over-cut phenomenon. The F-CAC has wide application in carving and woodworking industry at present.
Originality/value
The F-CAC method is very practical and effective for IR milling of complex NURBS surfaces with large fluctuation without over-cut and interference phenomenon.
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Keywords
Bingjun Li, Shuhua Zhang, Wenyan Li and Yifan Zhang
Grey modeling technique is an important element of grey system theory, and academic articles applied to agricultural science research have been published since 1985, proving the…
Abstract
Purpose
Grey modeling technique is an important element of grey system theory, and academic articles applied to agricultural science research have been published since 1985, proving the broad applicability and effectiveness of the technique from different aspects and providing a new means to solve agricultural science problems. The analysis of the connotation and trend of the application of grey modeling technique in agricultural science research contributes to the enrichment of grey technique and the development of agricultural science in multiple dimensions.
Design/methodology/approach
Based on the relevant literature selected from China National Knowledge Infrastructure, the Web of Science, SpiScholar and other databases in the past 37 years (1985–2021), this paper firstly applied the bibliometric method to quantitatively visualize and systematically analyze the trend of publication, productive author, productive institution, and highly cited literature. Then, the literature is combed by the application of different grey modeling techniques in agricultural science research, and the literature research progress is systematically analyzed.
Findings
The results show that grey model technology has broad prospects in the field of agricultural science research. Agricultural universities and research institutes are the main research forces in the application of grey model technology in agricultural science research, and have certain inheritance. The application of grey model technology in agricultural science research has wide applicability and precise practicability.
Originality/value
By analyzing and summarizing the application trend of grey model technology in agricultural science research, the research hotspot, research frontier and valuable research directions of grey model technology in agricultural science research can be more clearly grasped.
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Haixia Wang, Shuhan Shen and Xiao Lu
The purpose of this paper is to propose a screw axis identification (SAI) method based on the product of exponentials (POE) model, which is concerned with calibrating a serial…
Abstract
Purpose
The purpose of this paper is to propose a screw axis identification (SAI) method based on the product of exponentials (POE) model, which is concerned with calibrating a serial robot with m joints equipped with a stereo‐camera vision system.
Design/methodology/approach
Different from conventional approaches, like the circle point analysis (CPA) or the system theoretic method which must collect a great deal of data, the identification of the joint parameters for the proposed method only needs to measure m+1 times for n (n≥3) target points mounted on the manipulator end‐effector.
Findings
In this approach, the joint parameter, called a screw or twist, together with the actual value of joint angle can be obtained by linearly solving a closed‐form expression. Further, this method avoids calibrating the hand‐eye relationship and the exterior parameter of the robot.
Originality/value
Finally, the stability and accuracy of the SAI method are evaluated by simulation experiments, and it is also verified well in practical experiments.
Details
Keywords
The purpose of this paper is to present the terms of grey forecasting models and techniques.
Abstract
Purpose
The purpose of this paper is to present the terms of grey forecasting models and techniques.
Design/methodology/approach
The definitions of basic terms about grey forecasting models and techniques are presented one by one.
Findings
The reader could know the basic explanation about the important terms about various grey forecasting models and techniques from this paper.
Practical implications
Many of the authors’ colleagues thought that unified definitions of key terms would be beneficial for both the readers and the authors.
Originality/value
It is a fundamental work to standardise all the definitions of terms for a new discipline. It is also propitious to spread and universal of grey system theory.