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1 – 10 of 23Xiaohui Xie, Cui Ma, Qiang Sun and Ruxu Du
Bar‐tacking is a specialized sewing stitch designed to provide immense tensile strength to the garment which requires a high‐speed precision bar‐tacking sewing machine. This paper…
Abstract
Purpose
Bar‐tacking is a specialized sewing stitch designed to provide immense tensile strength to the garment which requires a high‐speed precision bar‐tacking sewing machine. This paper aims to present an event‐driven multi‐axis cooperative control method for a bar‐tacking sewing machine.
Design/methodology/approach
The control method consists of two parts: the multi‐axis cooperative control and the needle stop positioning control. The challenges include the high speed and the precision. For example, the needle must stop at a set position in milliseconds.
Findings
The presented multi‐axis cooperative control can ensure the high speed response and the precision of the cooperative control. The needle stop positioning control is based on a combination of the velocity control and the position control with velocity feed‐forward and limitation.
Research limitations/implications
The bar‐tacking sewing machine requires high‐speed start and stop response and coordination of displacement and velocity only at some given points. Therefore, the conventional multi‐axis cooperative control methods are not suitable. In addition, it requires high‐speed precision control under varying loading conditions.
Practical implications
While there are a number of commercial textile machines available in the market, designing a smart bar‐tacking sewing machine with good speed and precision performance remains a challenge.
Originality/value
The bar‐tacking sewing machine requires highly accurate multi‐axes cooperative control. The presented event‐driven multi‐axis control method is effective. It has not only the required high accuracy but also the fast time response.
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Zhengyu Huang, Lingyu Chen, Lianchao Zhang, Shixun Fan and Dapeng Fan
This paper aims to analyze the key factors influencing the synchronization performance of distributed motion control system and to improve the synchronization performance for…
Abstract
Purpose
This paper aims to analyze the key factors influencing the synchronization performance of distributed motion control system and to improve the synchronization performance for peripherals control of this system.
Design/methodology/approach
This paper deals with the software synchronization problems of distributed motion control system based on real-time Ethernet. First, combined with communication and control tasks, the key factors affecting synchronization performance of system are analyzed. Then, aiming at key factors and considering the synchronization of system bus, protocol conversion and task scheduling, a software synchronization method based on CANopen protocol and real-time Ethernet is proposed. Finally, the feasibility of this method is verified by establishing distributed motion control system and testing the synchronization performance of terminal control signals of slaves.
Findings
Based on this method, the results show that the synchronization accuracy for peripherals control of all slaves could be about 100 ns.
Practical implications
This research provides high-precision synchronization method, which could lay a foundation for the application of distributed motion control system in the field of assembly automation, such as multi-axis assembly robots control.
Originality/value
In distributed motion control system, many factors affect the synchronization performance. At present, there is no synchronization method that could comprehensively consider these factors. This paper not only analyzes the key factors influencing the synchronization performance of system but also proposes a synchronization method. Therefore, the method proposed in this paper has certain theoretical value and engineering significance.
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Joseph R. Kubalak, Alfred L. Wicks and Christopher B. Williams
Material extrusion (ME) suffers from anisotropic mechanical properties that stem from the three degree of freedom (DoF) toolpaths used for deposition. The formation of each layer…
Abstract
Purpose
Material extrusion (ME) suffers from anisotropic mechanical properties that stem from the three degree of freedom (DoF) toolpaths used for deposition. The formation of each layer is restricted to the XY-plane, which produces poorly bonded layer interfaces along the build direction. Multi-axis ME affords the opportunity to change the layering and deposition directions locally throughout a part, which could improve a part’s overall mechanical performance. The purpose of this paper is to evaluate the effects of changing the layering and deposition directions on the tensile mechanical properties of parts printed via multi-axis ME.
Design/methodology/approach
A multi-axis toolpath generation algorithm is presented and implemented on a 6-DoF robotic arm ME system to fabricate tensile specimens at different global orientations. Specifically, acrylonitrile butadiene styrene (ABS) tensile specimens are printed at various inclination angles using the multi-axis technique; the resulting tensile strengths of the multi-axis specimens are compared to similarly oriented specimens printed using a traditional 3-DoF method.
Findings
The multi-axis specimens had similar performances regardless of orientation and were equivalent to the 3-DoF specimens printed in the XYZ orientation (i.e. flat on the bed with roads aligned to the loading condition). This similarity is attributed to those sets of specimens having the same degree of road alignment.
Practical implications
Parts with out-of-plane loads currently require design compromises (e.g. additional material in critical areas). Multi-axis deposition strategies could enable local changes in layering and deposition directions to more optimally orient roads in critical areas of the part.
Originality/value
Though multi-axis ME systems have been demonstrated in literature, no prior work has been done to determine the effects of the deposition angle on the resulting mechanical properties. This work demonstrates that identical mechanical properties can be obtained irrespective of the build direction through multi-axis deposition. For ABS, the yield tensile strength of vertically oriented tensile bars was improved by 153 per cent using multi-axis deposition as compared to geometrically similar samples fabricated via 3-DoF deposition.
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Jace McPherson and Wenchao Zhou
The purpose of this research is to develop a new slicing scheme for the emerging cooperative three-dimensional (3D) printing platform that has multiple mobile 3D printers working…
Abstract
Purpose
The purpose of this research is to develop a new slicing scheme for the emerging cooperative three-dimensional (3D) printing platform that has multiple mobile 3D printers working together on one print job.
Design/methodology/approach
Because the traditional lay-based slicing scheme does not work for cooperative 3D printing, a chunk-based slicing scheme is proposed to split the print job into chunks so that different mobile printers can print different chunks simultaneously without interfering with each other.
Findings
A chunk-based slicer is developed for two mobile 3D printers to work together cooperatively. A simulator environment is developed to validate the developed slicer, which shows the chunk-based slicer working effectively, and demonstrates the promise of cooperative 3D printing.
Research limitations/implications
For simplicity, this research only considered the case of two mobile 3D printers working together. Future research is needed for a slicing and scheduling scheme that can work with thousands of mobile 3D printers.
Practical implications
The research findings in this work demonstrate a new approach to 3D printing. By enabling multiple mobile 3D printers working together, the printing speed can be significantly increased and the printing capability (for multiple materials and multiple components) can be greatly enhanced.
Social implications
The chunk-based slicing algorithm is critical to the success of cooperative 3D printing, which may enable an autonomous factory equipped with a swarm of autonomous mobile 3D printers and mobile robots for autonomous manufacturing and assembly.
Originality/value
This work presents a new approach to 3D printing. Instead of printing layer by layer, each mobile 3D printer will print one chunk at a time, which provides the much-needed scalability for 3D printing to print large-sized object and increase the printing speed. The chunk-based approach keeps the 3D printing local and avoids the large temperature gradient and associated internal stress as the size of the print increases.
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This paper, a “Q&A interview” conducted by Joanne Pransky of Industrial Robot Journal, aims to impart the combined technological, business and personal experience of a prominent…
Abstract
Purpose
This paper, a “Q&A interview” conducted by Joanne Pransky of Industrial Robot Journal, aims to impart the combined technological, business and personal experience of a prominent, robotic industry engineer-turned entrepreneur regarding the evolution, commercialization and challenges of bringing a technological invention to market.
Design/methodology/approach
The interviewee is Dr Esben H. Ostergaard, inventor, co-founder and chief technology officer of Universal Robots. From building his first robot to solve a local industrial problem at the age of four, to building the world’s first collaborative robot company, Dr Ostergaard shares his lifelong ventures as a robot scientist, inventor and entrepreneur.
Findings
Dr Ostergaard received degrees in computer science, physics and multimedia at Aarhus University in Denmark, and a PhD in robotics from the University of Southern Denmark. While at Aarhus, Dr Ostergaard pursued his hobby of robot football, and in 1998, his team STATIC became the world champion of the Federation of International Robot-soccer Association (FIRA). Dr Ostergaard held research positions at the University of Southern California (USC) Robotics Labs and at the Advanced Industrial Science and Technology (AIST) in Tsukuba/Tokyo. During the years 2001-2005 as a researcher and assistant professor in robotics and user interfaces at University of Southern Denmark, he created the foundation for a reinvention of the industrial robot. This led him to found Universal Robots in 2005 with two of his research colleagues.
Originality/value
From a young child who played with LEGOs until he got a Commodore 64, Dr Ostergaard has always been interested in robotics. His unique multidisciplinary education and multicultural research experiences helped him to pioneer a new multi-axis, lightweight industrial robot and launch the successful company, Universal Robots, which has grown from its three co-founders to nearly 150 employees, with more than 4,000 collaborative robot applications installed in over 50 countries worldwide. Dr Ostergaard has over 30 patents and has received many awards, including the 2012 IEEE-IFR Invention and Entrepreneurship Award (IERA), the 2013 Japanese Institute Good Design Award, the 2013 Robotics Business Review Game Changer Award and the Ernst & Young Entrepreneur of the Year 2012 in Region Funen.
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Zujin Jin, Zixin Yin, Siyang Peng and Yan Liu
Large optical mirror processing systems (LOMPSs) consist of multiple subrobots, and correlated disturbance terms between these robots often lead to reduced processing accuracy…
Abstract
Purpose
Large optical mirror processing systems (LOMPSs) consist of multiple subrobots, and correlated disturbance terms between these robots often lead to reduced processing accuracy. This abstract introduces a novel approach, the nonlinear subsystem adaptive dispersed fuzzy compensation control (ADFCC) method, aimed at enhancing the precision of LOMPSs.
Design/methodology/approach
The ADFCC model for LOMPS is developed through a nonlinear fuzzy adaptive algorithm. This model incorporates control parameters and disturbance terms (such as those arising from the external environment, friction and correlation) between subsystems to facilitate ADFCC. Error analysis is performed using the subsystem output parameters, and the resulting errors are used as feedback for compensation control.
Findings
Experimental analysis is conducted, specifically under the commonly used concentric circle processing trajectory in LOMPS. This analysis validates the effectiveness of the control model in enhancing processing accuracy.
Originality/value
The ADFCC strategy is demonstrated to significantly improve the accuracy of LOMPS output, offering a promising solution to the problem of correlated disturbances. This work holds the potential to benefit a wide range of practical applications.
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Feifei Bian, Danmei Ren, Ruifeng Li and Peidong Liang
The purpose of this paper is to eliminate instability which may occur when a human stiffens his arms in physical human–robot interaction by estimating the human hand stiffness and…
Abstract
Purpose
The purpose of this paper is to eliminate instability which may occur when a human stiffens his arms in physical human–robot interaction by estimating the human hand stiffness and presenting a modified vibration index.
Design/methodology/approach
Human hand stiffness is first estimated in real time as a prior indicator of instability by capturing the arm configuration and modeling the level of muscle co-contraction in the human’s arms. A time-domain vibration index based on the interaction force is then modified to reduce the delay in instability detection. The instability is confirmed when the vibration index exceeds a given threshold. The virtual damping coefficient in admittance controller is adjusted accordingly to ensure stability in physical human–robot interaction.
Findings
By estimating the human hand stiffness and modifying the vibration index, the instability which may occur in stiff environment in physical human–robot interaction is detected and eliminated, and the time delay is reduced. The experimental results demonstrate significant improvement in stabilizing the system when the human operator stiffens his arms.
Originality/value
The originality is in estimating the human hand stiffness online as a prior indicator of instability by capturing the arm configuration and modeling the level of muscle co-contraction in the human’s arms. A modification of the vibration index is also an originality to reduce the time delay of instability detection.
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The aim of this paper is to provide an update on the status of current fieldbuses and high‐speed Ethernet technologies for industrial automation.
Abstract
Purpose
The aim of this paper is to provide an update on the status of current fieldbuses and high‐speed Ethernet technologies for industrial automation.
Design/methodology/approach
The paper provides information on the various fieldbus technologies for industrial automation connectivity and examines high‐speed deterministic Ethernets for automated manufacturing and assembly plant.
Findings
The paper finds that the standards issue has still not been fully resolved, that Ethernets reduce manufacturing costs compared with conventional fieldbuses, that most effort has gone into making Ethernets work deterministically, rather than concentrating on IT and enterprise resource planning (ERP) integration, and that the internet will increasingly feed real‐time data to ERP levels.
Originality/value
The paper provides information on recent developments in Ethernet technologies.
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Abstract
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Wei Jiang, Yu Yan, An Zhang, Lianqing Yu, Gan Zuo, Hong Jun Li and Wei Chen
The purpose of this paper is to improve the operation and maintenance intelligence of power systems, and summarize the transmission line robots and their key technologies…
Abstract
Purpose
The purpose of this paper is to improve the operation and maintenance intelligence of power systems, and summarize the transmission line robots and their key technologies. High-voltage power cables are important channels for power transmission systems. Their special geographical environment and harsh natural environment can lead to many different faults. At present, such special operations in dangerous and harsh environments are performed manually, which have not only high labor intensity and low work efficiency but also great personal safety risks.
Design/methodology/approach
For maintenance works that are far away from the tower, power outages are required. With the increasing evaluation of transmission quality and operational safety, and the urgent need for automation and operation of modern power systems, the contradiction between this manual operation and modern high-quality power transmission has become increasingly prominent. An effective method to replace the manual maintenance work is to use the mobile robot to carry the operation manipulator and its end tool, that is, the live maintenance robot.
Findings
Some achievements have been made in the key technologies of live maintenance robots, the work to be done to meet the basic requirements of complex and changeable line environment and practical application. Based on the existing research results of live overhaul robot, the follow-up research will focus on the practical application needs and the frontier of scientific and technological development, and truly realize the human–machine integration between live overhaul robot–human working environment. Only in this way can the robot better serve the operation and maintenance of the power system.
Originality/value
This paper reviews the system platform, operation function, structural characteristics and key technologies involved in the power cable robot, and the combination of live maintenance robots and modern high-tech such as big data and cloud computing is also given, and finally, the future development direction of the special operation robot is pointed out.
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