Search results

1 – 10 of over 3000
To view the access options for this content please click here
Article

Dan Zhao, Yunbo Bi and Yinglin Ke

This paper aims to propose a united kinematic calibration method for a dual-machine system in automatic drilling and riveting. The method takes both absolute and relative…

Abstract

Purpose

This paper aims to propose a united kinematic calibration method for a dual-machine system in automatic drilling and riveting. The method takes both absolute and relative pose accuracy into account, which will largely influence the machining accuracy of the dual-machine system and assembly quality.

Design/methodology/approach

A comprehensive kinematic model of the dual-machine system is established by the superposition of sub-models with pose constraints, which involves base frame parameters, kinematic parameters and tool frame parameters. Based on the kinematic model and the actual pose error data measured by a laser tracker, the parameters of coordinated machines are identified by the Levenberg–Marquardt method as a multi-objective nonlinear optimization problem. The identified parameters of the coordinated machines will be used in the control system.

Findings

A new calibration method for the dual-machine system is developed, including a comprehensive kinematic model and an efficient parameter identification method. The experiment results show that with the proposed method, the pose accuracy of the dual-machine system was remarkably improved, especially the relative position and orientation errors.

Practical implications

This method has been used in an aircraft assembly project. The calibrated dual-machine system shows a good performance on system coordination and machining accuracy.

Originality/value

This paper proposes a new method with high accuracy and efficiency for the dual-machine system calibration. The research can be extended to multi-machine and multi-robot fields to improve the system precision.

To view the access options for this content please click here
Article

Hua Liu, Weidong Zhu, Huiyue Dong and Yinglin Ke

This paper aims to propose a calibration model for kinematic parameters identification of serial robot to improve its positioning accuracy, which only requires position…

Abstract

Purpose

This paper aims to propose a calibration model for kinematic parameters identification of serial robot to improve its positioning accuracy, which only requires position measurement of the end-effector.

Design/methodology/approach

The proposed model is established based on local frame representation of the product of exponentials (local POE) formula, which integrates all kinematic errors into the twist coordinates errors; then they are identified with the tool frame’ position deviations simultaneously by an iterative least squares algorithm.

Findings

To verify the effectiveness of the proposed method, extensive simulations and calibration experiments have been conducted on a 4DOF SCARA robot and a 5DOF drilling machine, respectively. The results indicate that the proposed model outperforms the existing model in convergence, accuracy, robustness and efficiency; fewer measurements are needed to gain an acceptable identification result.

Practical implications

This calibration method has been applied to a variable-radius circumferential drilling machine. The machine’s positioning accuracy can be significantly improved from 11.153 initially to 0.301 mm, which is well in the tolerance (±0.5 mm) for fastener hole drilling in aircraft assembly.

Originality/value

An accurate and efficient kinematic calibration model has been proposed, which satisfies the completeness, continuity and minimality requirements. Due to generality, this model can be widely used for serial robot kinematic calibration with any combination of revolute and prismatic joints.

Details

Industrial Robot: An International Journal, vol. 45 no. 5
Type: Research Article
ISSN: 0143-991X

Keywords

To view the access options for this content please click here
Article

Guozhi Li, Fuhai Zhang, Yili Fu and Shuguo Wang

The purpose of this paper is to propose an error model for serial robot kinematic calibration based on dual quaternions.

Abstract

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.

Details

Industrial Robot: the international journal of robotics research and application, vol. 46 no. 2
Type: Research Article
ISSN: 0143-991X

Keywords

To view the access options for this content please click here
Article

Wei Wang, Gang Wang and Chao Yun

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…

Abstract

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.

Details

Industrial Robot: An International Journal, vol. 41 no. 2
Type: Research Article
ISSN: 0143-991X

Keywords

To view the access options for this content please click here
Article

Nicolas Andreff, Pierre Renaud, Philippe Martinet and Franc¸ois Pierrot

Presents the kinematic calibration of an H4 parallel prototype robot using a vision‐based measuring device. Calibration is performed according to the inverse kinematic

Abstract

Presents the kinematic calibration of an H4 parallel prototype robot using a vision‐based measuring device. Calibration is performed according to the inverse kinematic model method, using first the design model then a model developed for calibration purpose. To do so, the end‐effector pose (i.e. position and orientation) has to be measured with the utmost accuracy. Thus, first the practical accuracy of the low‐cost vision‐based measuring system is evaluated to have a precision in the order of magnitude of 10μ_it;m and 10−3° for a 1,024×768 pixel CCD camera. Second, the prototype is calibrated using the easy‐to‐install vision system, yielding a final positioning accuracy of the end‐effector reduced from more than 1cm down to less than 0.5mm. Also provides a discussion on the use of such a method on commercial systems.

Details

Industrial Robot: An International Journal, vol. 31 no. 3
Type: Research Article
ISSN: 0143-991X

Keywords

To view the access options for this content please click here
Article

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.

Details

Industrial Robot: An International Journal, vol. 45 no. 6
Type: Research Article
ISSN: 0143-991X

Keywords

To view the access options for this content please click here
Article

Fayong Guo, Hao Cai, Marco Ceccarelli, Tao Li and Butang Yao

Robot kinematic modeling needs to be based on clear physical concepts. The widely used Denavit–Hartenberg (D–H) convention requires the coordinate system to be established…

Abstract

Purpose

Robot kinematic modeling needs to be based on clear physical concepts. The widely used Denavit–Hartenberg (D–H) convention requires the coordinate system to be established on an extension of the axis. This leads to non-trivial problems which this study seeks to address by developing an improved convention.

Design/methodology/approach

First, the problems associated with the traditional D–H convention are systematically analyzed. Then, pursuant of solving these problems, an enhanced Denavit–Hartenberg (ED–H) convention is proposed, and a procedure is delineated for establishing the coordinate frame and obtaining the associated parameters. The transformation equations are derived based on a homogeneous matrix. The characteristics of traditional D–H and ED–H with regard to kinematics and dynamics are comprehensively compared. Finally, an application of dynamics for lead-through programming and collision protection is undertaken to validate the proposed ED–H method. Simulations and experiments are carried out using the Tiansui-One cooperative robot platform with the aim of exploring the merits of the proposed convention.

Findings

The proposed convention is compatible with traditional methods and can solve the problems inherent in these methods. The main characteristic of ED–H is that the coordinate system is fixed on the joint, which is a general modeling method.

Originality/value

An enhanced D–H convention is proposed to establish a unified, intuitive and accurate link model that exhibits stronger adaptability than traditional D–H and can be used effectively in kinematic and dynamic modeling of mechanical arms.

Details

Industrial Robot: the international journal of robotics research and application, vol. 47 no. 2
Type: Research Article
ISSN: 0143-991X

Keywords

To view the access options for this content please click here
Article

Kanika Jolly, Sybille Krzywinski, PVM Rao and Deepti Gupta

Whilst motorcycling is an activity of pleasure in most parts of the world, in India, it is a regular mode of commuting. The number of registered motorized two wheelers…

Abstract

Purpose

Whilst motorcycling is an activity of pleasure in most parts of the world, in India, it is a regular mode of commuting. The number of registered motorized two wheelers increased at the rate of 14.7 percent during the year 2016-2017 to reach the figure of 20.19m in 2018. But, with this increase, the number of motorcycle road accidents is also increasing. Uncomfortable riding clothing is one of the major factors for motorcycle rider’s muscular fatigue, which might at times lead to serious accidents. No kinematic human models have been, so far, used for the design of protective, functional and aesthetic looking products, and the result is, hence, a compromised fit that is not protective or comfortable. The purpose of this paper is to develop virtual 3D human body models for specific postures of a motorcycle rider.

Design/methodology/approach

Kinematic analysis of a motorcycle rider was conducted to identify typical body postures obtained by the motorcycle rider while mounting and riding a motorcycle. The identified body postures were mapped on a virtual parametric human model to obtain digital model of a motorcycle rider. 3D garment patterns for jacket and trouser were developed on all the four body postures. 3D patterns were flattened out to get 2D flat patterns that were compared and analyzed, and appropriate pattern shapes from each of the four postures were selected. Virtual fit analysis was conducted for the finally garment.

Findings

It is well established that a static 2D anthropometry fails to accurately capture the dimensions of complex 3D human form, yielding poor garment fit. Therefore, in this study, virtual, 3D human body models were developed in selected dynamic poses. Garment patterns developed in 3D have the typical movement inbuilt in them; hence, they offer more comfort and ease of motion to the wearer.

Originality/value

The identification of typical body postures of motorcycle rider has not been done before. The CAD models developed in the study can be used for the generation of ergonomic garment patterns for the motorcycle riders.

Details

International Journal of Clothing Science and Technology, vol. 31 no. 6
Type: Research Article
ISSN: 0955-6222

Keywords

To view the access options for this content please click here
Article

Jun Zhong and Ruqi Ma

Jumping robots with coordinated multiple legs have been a hot research subject during the past years because of their excellent abilities in fast moving and…

Abstract

Purpose

Jumping robots with coordinated multiple legs have been a hot research subject during the past years because of their excellent abilities in fast moving and obstacle-climbing. However, dynamics of jumping process of these coordinated legged robots are complex because of collisions between coordinated legs and the ground. This paper aims to analyze features of jumping process and to present the kinematic and dynamic models of a novel sole-type quadruped jumping robot with variable coordinated joints.

Design/methodology/approach

A complete jumping period of is divided into several subphases according to contact status of different coordinated legs to the ground. Continuous dynamics and discrete dynamics are established in different subphases. Simulations are performed in MATLAB software and ADAMS environment.

Findings

Comparison between two-set simulated results acquired from ADAMS and MATLAB demonstrates the validity of kinematic and dynamic equations.

Originality/value

The established dynamics establish the foundation of further research in motion planning and controller design of coordinated multiple legs.

Details

Assembly Automation, vol. 40 no. 1
Type: Research Article
ISSN: 0144-5154

Keywords

To view the access options for this content please click here
Article

Yuzhe Liu, Jun Wu, Liping Wang, Jinsong Wang, Dong Wang and Guang Yu

The purpose of this study is to develop a modified parameter identification method and a novel measurement method to calibrate a 3 degrees-of-freedom (3-DOF) parallel tool…

Abstract

Purpose

The purpose of this study is to develop a modified parameter identification method and a novel measurement method to calibrate a 3 degrees-of-freedom (3-DOF) parallel tool head. This parallel tool head is a parallel mechanism module in a five-axes hybrid machine tool. The proposed parameter identification method is named as the Modified Singular Value Decomposition (MSVD) method. It aims to overcome the difficulty of choosing the algorithm parameter in the regularization identification method. The novel measurement method is named as the vector projection (VP) method which is developed to expand the measurement range of self-made measurement implements.

Design/methodology/approach

Newton Iterative Algorithm based on Least Square Method is analyzed by using the Singular Value Decomposition method. Based on the analysis result, the MSVD method is proposed. The VP method transforms the angle measurement into the displacement measurement by taking full advantage of the ability that the 3-DOF parallel tool head can move in the X – Y plane.

Findings

The kinematic calibration approach is verified by calibration simulations, a Rotation Tool Center Point accuracy test and an experiment of machining an “S”-shaped test specimen.

Originality/value

The kinematic calibration approach with the MSVD method and VP method could be successfully applied to the 3-DOF parallel tool head and other 3-DOF parallel mechanisms.

Details

Industrial Robot: An International Journal, vol. 44 no. 2
Type: Research Article
ISSN: 0143-991X

Keywords

1 – 10 of over 3000