Chengjun Chen, Zhongke Tian, Dongnian Li, Lieyong Pang, Tiannuo Wang and Jun Hong
This study aims to monitor and guide the assembly process. The operators need to change the assembly process according to the products’ specifications during manual assembly of…
Abstract
Purpose
This study aims to monitor and guide the assembly process. The operators need to change the assembly process according to the products’ specifications during manual assembly of mass customized production. Traditional information inquiry and display methods, such as manual lookup of assembly drawings or electronic manuals, are inefficient and error-prone.
Design/methodology/approach
This paper proposes a projection-based augmented reality system (PBARS) for assembly guidance and monitoring. The system includes a projection method based on viewpoint tracking, in which the position of the operator’s head is tracked and the projection images are changed correspondingly. The assembly monitoring phase applies a method for parts recognition. First, the pixel local binary pattern (PX-LBP) operator is achieved by merging the classical LBP operator with the pixel classification process. Afterward, the PX-LBP features of the depth images are extracted and the randomized decision forests classifier is used to get the pixel classification prediction image (PCPI). Parts recognition and assembly monitoring is performed by PCPI analysis.
Findings
The projection image changes with the viewpoint of the human body, hence the operators always perceive the three-dimensional guiding scene from different viewpoints, improving the human-computer interaction. Part recognition and assembly monitoring were achieved by comparing the PCPIs, in which missing and erroneous assembly can be detected online.
Originality/value
This paper designed the PBARS to monitor and guide the assembly process simultaneously, with potential applications in mass customized production. The parts recognition and assembly monitoring based on pixels classification provides a novel method for assembly monitoring.
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The purpose of this paper is to use rapid prototyping (RP) technology to build physical models based on axisymmetric finite element (FE) simulation deformation results. To this…
Abstract
Purpose
The purpose of this paper is to use rapid prototyping (RP) technology to build physical models based on axisymmetric finite element (FE) simulation deformation results. To this end, an algorithm which extracts stereolithography (STL) model from axisymmetric ring element mesh is developed and realized by MATLAB programming.
Design/methodology/approach
The algorithm first identifies boundary element edges, which compose the contour(s) of an axisymmetric ring FE mesh. Then, the identified contour edges are around the symmetry axis revolved a specific angle, at certain intervals according to certain approximate criterion, to generate new nodes to form a group of oriented triangles whose normal vectors conform to the right-handed rule. Finally, a completely closed STL model is obtained by necessary triangulation processing and rotation mapping based on original mesh.
Findings
It is validated that the extracted STL model is sound and the proposed algorithm is feasible, right and characterized by linear time complexity for extracting STL model from either triangular, quadrilateral, or mixed triangular/quadrilateral axisymmetric mesh.
Research limitations/implications
Color is important for expressing FE simulation results, which is not involved in STL model. Among the alternative data file formats, VRML representation is an applicable one that is complimentary to existing RP processes and suitable for color 3D printing. Based on the current work, coloring VRML model could be extracted from axisymmetric FE simulation results conveniently.
Originality/value
The study of this paper provides a RP-based materialized mode to characterize axisymmetric FE simulation deformation results, which is more intuitive and visible than the computer graphics-based visualization.
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Tian Tian, Ruibo Zhao, Dongbo Wei, Kai Yang and Pingze Zhang
The purpose of this paper is to expound the relationship among microstructure, mechanical property, tribological behavior and deformation mechanism of carburized layer deposited…
Abstract
Purpose
The purpose of this paper is to expound the relationship among microstructure, mechanical property, tribological behavior and deformation mechanism of carburized layer deposited on Ti-6Al-4V alloy by double-glow plasma hydrogen-free carburizing surface technology.
Design/methodology/approach
Morphologies and phase compositions of the carburized layer were observed by scanning electron microscope and X-ray diffraction. The micro-hardness tests were used to evaluate the surface and cross-sectional hardness of carburized layer. The reciprocating friction and wear experiments under various load conditions were implemented to investigate the tribological behavior of carburized layer. Moreover, scratch test with ramped loading pattern was carried out to illuminate the deformation mechanism of carburized layer.
Findings
Compared to substrate, the hardness of surface improved to ∼1,100 HV0.1, while the hardness profile of carburized layer presented gradual decrease from ∼1,100 to ∼300 HV0.1 within the distance of the total carburizing-affected region about 30 µm. The coefficient of friction, wear rate and wear morphology of carburized layer were analyzed. Scratch test indicated that the deformation process of carburized layer could be classified into three mechanisms (elastic, changing elastic–plastic and stable elastic–plastic mechanisms), and the deformation transition of the carburizing-affected region was from changing elastic–plastic to elastic mechanisms. Both the elastic and changing elastic–plastic mechanisms are conducive to the wearing course.
Originality/value
Using this technology, hydrogen embrittlement was avoided and wear resistance property of titanium alloy was greatly improved. Simultaneously, the constitutive relation during the whole loading process was deduced in terms of scratch approach, and the deformation mechanism of carburized layer was discussed from a novel viewpoint.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2019-0489/
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Sijie Tong, Qingchen Liu, Qichao Ma and Jiahu Qin
This paper aims to address the safety concerns of path-planning algorithms in dynamic obstacle warehouse environments. It proposes a method that uses improved artificial potential…
Abstract
Purpose
This paper aims to address the safety concerns of path-planning algorithms in dynamic obstacle warehouse environments. It proposes a method that uses improved artificial potential fields (IAPF) as expert knowledge for an improved deep deterministic policy gradient (IDDPG) and designs a hierarchical strategy for robots through obstacle detection methods.
Design/methodology/approach
The IAPF algorithm is used as the expert experience of reinforcement learning (RL) to reduce the useless exploration in the early stage of RL training. A strategy-switching mechanism is introduced during training to adapt to various scenarios and overcome challenges related to sparse rewards. Sensor inputs, including light detection and ranging data, are integrated to detect obstacles around waypoints, guiding the robot toward the target point.
Findings
Simulation experiments demonstrate that the integrated use of IDDPG and the IAPF method significantly enhances the safety and training efficiency of path planning for mobile robots.
Originality/value
This method enhances safety by applying safety domain judgment rules to improve APF’s security and designing an obstacle detection method for better danger anticipation. It also boosts training efficiency through using IAPF as expert experience for DDPG and the classification storage and sampling design for the RL experience pool. Additionally, adjustments to the actor network’s update frequency expedite convergence.
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Zhiqing Tian, Bin Xu, Xiaobing Fan, Bingli Pan, Shuang Zhao, Bingchan Wang and Hongyu Liu
This paper aims to investigate the crucial roles of textured surfaces on oil-impregnated polytetrafluoroethylene (PTFE) created by a facile tattoo strategy in improving…
Abstract
Purpose
This paper aims to investigate the crucial roles of textured surfaces on oil-impregnated polytetrafluoroethylene (PTFE) created by a facile tattoo strategy in improving tribological properties.
Design/methodology/approach
Pored PTFE (PPTFE) was prepared by mixing powder PTFE and citric acid and experienced a cold-press sintering molding process. Subsequently, textured surfaces were obtained with using a tattoo strategy. Surface-textured PPTFE was thus impregnated with polyethylene glycol 200, yielding oil-impregnated and pore-connected PPTFE.
Findings
This study found that oil-impregnated and surface-textured PPTFE exhibited excellent tribological performances with an 82% reduction in coefficient of friction and a 72.5% lowering in wear rate comparing to PPTFE.
Originality/value
This study shows an efficient strategy to improve the tribological property of PTFE using a tattoo-inspired surface texturing method.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2024-0378/
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Wei Zhang, Jiali Weng, Shang Hao, Yuan Xie and Yonggui Li
Fabrics with photothermal conversion functions were developed based on the introduction of shape stable composite phase change materials (CPCMs).
Abstract
Purpose
Fabrics with photothermal conversion functions were developed based on the introduction of shape stable composite phase change materials (CPCMs).
Design/methodology/approach
Acidified single-walled carbon nanotubes (SWCNTs) were selected as support material to prepare CPCMs with n-octadecane to improve the thermal conductivity and shape stability. The CPCMs were finished onto the surface of cotton fabric through the coating and screen-printing method. The chemical properties of CPCMs were characterized by Fourier transform infrared spectrometer, XRD and differential scanning calorimetry (DSC). The shape stability and thermal conductivity were also evaluated. In addition, the photothermal conversion and temperature-regulating performance of the finished fabrics were analyzed.
Findings
When the addition amount of acidified SWCNTs are 14% to the mass of n-octadecane, the best shape stability of CPCMs is obtained. DSC analysis shows that the latent heat energy storage of CPCMs is as high as 183.1 J/g. The thermal conductivity is increased by 84.4% compared with that of n-octadecane. The temperature-regulating fabrics coated with CPCMs have good photothermal conversion properties.
Research limitations/implications
CPCMs with high latent heat properties are applied to the fabric surface through screen printing technology, which not only gives the fabric the photothermal conversion performance but also reflects the design of personalized patterns.
Practical implications
CPCMs and polydimethylsiloxane (PDMS) are mixed to make printing paste and printed cotton fabric with temperature-regulating functional is developed.
Originality/value
SWCNTs and n-octadecane are composited to prepare CPCMs with excellent thermal properties, which can be mixed with PDMS to make printing paste without adding other pastes. The fabric is screen-printed to obtain a personalized pattern and can be given a thermoregulatory function.