Search

The present work investigates the physicochemical stability of spray paints when irradiated with artificial solar light (at spectral range 300–800 nm). This research highlights the importance of understanding the materials used in street art and public murals, recognising them as a significant component of contemporary cultural heritage. By examining the stability and degradation of spray paints toward solar light exposure, the study aims to contribute to the preservation of contemporary murals, which reflect current social and cultural narratives. A physicochemical approach was employed for the study of spray paints' physical and thermal properties, as well as the effect of specific photochemical ageing reactions/processes. The photochemical ageing results were compared with reference (unaged) samples. Specifically, a multi-technique approach was applied using stereo microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle measurement, colorimetry, glossimetry, differential scanning calorimetry (DSC), UV-Vis spectroscopy, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and pyrolysis-GC/MS (Py-GC/MS). The photodegradation of the spray paints occurred from the first 144 h of solar light irradiation, resulting in changes in morphology, colour, gloss, roughness, and wettability. Regarding photochemical stability, ageing seems to affect the binders more than the synthetic organic pigments and the inorganic fillers. In particular, acrylic binders showed small chemical changes, whereas the alkyd, nitrocellulose, and styrene binders underwent severe chemical modification. The results suggest that simulated daylight irradiation prompts the migration of additives toward the surface of the spray paint films. In addition, the results of the analyses on the white spray paints in comparison with the coloured paints (from the same manufacturer) showed that there seems to be an active distinct photoageing mechanism involving titanium dioxide, but the whole issue needs further investigation. [ABSTRACT FROM AUTHOR]

There has been considerable interest in piezoresistive nanocarbon-loaded polymer films for structural health monitoring, including damage detection and strain monitoring. While good performance has been demonstrated, issues related to practical implementation have received less attention. Here we present sensors made from exfoliated graphite nanoplatelets (xGnP) incorporated into a commercial paint that is applied to Sikorsky aircraft. A formulation and a fabrication method are developed that deliver high piezoresistive strain sensitivity alongside mechanical integrity. At approximately 7 wt% xGnP, the gauge factor in tension is in the range of 30–55, and the effectiveness of the sensors for damage monitoring is demonstrated by the detection of perforations. To obtain a paintable solution, key considerations in choosing the solvent employed for introducing the nanocarbon are compatibility and the ability to keep the nanocarbon suspended, which is achieved using ethyl acetate. The ability to form sensors in situ on aircraft structures requires an uncomplicated method of making robust electrical connections, which is demonstrated here using embedded copper mesh. The strong, often nonlinear, environmental sensitivity of polymer-nanocarbon materials must also be considered in applications; here, increasing temperature and humidity both raise sensor resistance. This work shows that a second, unstrained reference sensor would work well for automatic compensation. Lastly, a method for effecting a repair that employs standard processes and maintains the high gauge factor is demonstrated. With these advances, the paint-xGnP sensors are ready for in-the-field testing on aircraft. [ABSTRACT FROM AUTHOR]

The text describes a mural called The Dharma Mural, created by street artist "Crayone" Rigel Juratovac in San Francisco's Mission district. The mural, painted in 2018, features four internationally recognized humanitarians: Gandhi, Cesar Chavez, Martin Luther King Jr., and Mother Teresa. The mural represents principles of non-violence, compassion, and unity in diversity. It was created as a way to restore a sense of community after a fire destroyed nearby buildings and displaced residents. The mural is seen as a symbol of hope, promise, and peace, and it has the power to transform perspectives and inspire viewers. [Extracted from the article]

Coverage path planning for complex three-dimensional surfaces spray painting is one of the challenging problems in robotics. In this article, we propose a multiple chromosomes particle swarm optimization approach to address the coverage path planning problem for complex three-dimensional surfaces spray painting. Firstly, a layered segmentation method, which is composed of three-dimensional hole identification and region partition, is proposed to divide the complex surface into multiple simple regions with little curvature change and no holes. Secondly, a zigzag path is determined in each region by considering the practical aspects for spray painting. Thirdly, by taking short distance, few turns and high coverage rate into account, a multiple chromosomes particle swarm optimization algorithm is presented to connect the zigzag paths of the regions. Experimental tests are carried out on a complex surface, and the results validate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

Fabrication of waterproof decorative paintings has attracted a great deal of interest. In this work, in situ reaction using poly(glycidyl methacrylate) (PGMA) and polyhedral oligomeric silsesquioxane with amino group at end (amino-POSS) was utilized to fabricate coatings at surfaces of papery/cloth decorative paintings via spray, which endowed the decorative paintings with excellent hydrophobicity, transparency, and weather ability. Firstly, ring opening of epoxy groups in PGMA, cross-linking structure in coatings, and strong coating/painting interface adhesion were achieved. Then, surface morphology of coatings was observed, and high surface roughness was confirmed. Next, high transparency and thermal stability of coatings were confirmed. Finally, surface water-contact-angles (WCAs) of coatings with various substrates were tested as a function of POSS content. Weathering resistances of coating surface on cloth substrate were studied. Coatings exhibit excellent properties such as high light transmittance (over 80%), high glass-transition temperature (upper limit ~ 113 ℃), high hydrophobicity (maximum WCA ~ 149°), and strong weathering resistances (the aged WCAs over 140°). Work innovation lies in simultaneously gained high hydrophobicity, good transparency, and strong weather ability. This work might pave a road for fabricating excellent coatings for protecting decorative paintings. [ABSTRACT FROM AUTHOR]

In the intelligent transformation of spraying operations, the investigation into the robotic spraying process holds significant importance. The spraying process, however, falls within the realm of experience-driven technology, characterized by high complexity, diverse parameters, and coupling effects. Moreover, the quality of manual spraying processes relies entirely on manual experience. Thus, the crux of the intelligent transformation of spraying robots lies in establishing a mapping model between the spraying process and the resultant spraying quality. To address the challenge of intelligently transforming empirical spraying processes and achieving the mapping from the spraying process to spraying quality, an algorithm employing an enhanced extreme learning machine-based neural network is proposed for predicting spraying process parameters with respect to the evaluation index of spraying quality. In this approach, an algorithmic model based on the Extreme Learning Machine (ELM) neural network is initially constructed utilizing five spraying process parameters: spraying speed, spraying height, spraying width pressure, atomization pressure, and oil spraying pressure. Two spraying quality evaluation indexes, namely average film thickness at the center point and surface roughness, are also incorporated. Subsequently, the prediction neural network is optimized using the K-means improved predator optimization algorithm (KHPO) to enhance the model's prediction accuracy. This optimization step aims to improve the efficiency of the model in predicting spraying quality based on the specified process parameters. Finally, data collection and model validation for the spraying quality prediction algorithm are conducted using a designed robotic automated waterborne paint spraying experimental system. The experimental results demonstrate a significant reduction in the prediction error of the KHPO-ELM neural network model for the average film thickness center point, showcasing a decrease of 61.95% in comparison to the traditional ELM neural network and 50.81% in comparison to the BP neural network. Likewise, the improved neural network model yields a 2.31% decrease in surface roughness prediction error compared to the traditional ELM neural network and a substantial 54.0% reduction compared to the BP neural network. Consequently, the KHPO-ELM neural network, incorporating the prediction algorithm, effectively facilitates the prediction of multi-spraying process parameters for the center point of average film thickness and surface roughness in automated robot spraying. Notably, the prediction algorithm exhibits a commendable level of accuracy in these predictions. [ABSTRACT FROM AUTHOR]

Copyright of Grafica: Journal of Graphic Design / Documents de Disseny Gràfic is the property of Universitat Autonoma de Barcelona and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Using teach pendants or offline programming methods can generate tool paths for robot manipulators to carry out production activities, such as spray painting on objects of different geometries. This task, in which the complexity of painting the surface is one of the main challenges, requires highly skilled operators. In addition, the time spent setting up a robot task can be justified for the mass production of the same workpiece. However, it is inconvenient for low-production and high-variation production lines. In order to overcome these challenges, this study presents an algorithm to autonomously generate robot trajectories for a spray-painting process applied to objects with complex surfaces based on input 3D point cloud data. A predefined spherical mesh wraps the object, organizing the geometrical attributes into a structured data set. Subsequently, the region of interest is extracted and isolated from the model, which serves as the basis for the automatic path-planning operation. A user-friendly graphical user interface (GUI) is developed to define input parameters, visualize the point cloud model and the generated trajectory, simulate paint quality using a color map, and ultimately generate the robot's code. A 3D sensor is used to localize the pose of the workpiece ahead of the robot and adjust the robot's trajectory. The efficacy of the proposed approach is validated first by using various workpieces within a simulated environment and second by employing a real robot to execute the motion task. [ABSTRACT FROM AUTHOR]

Sensing skins and electrical impedance tomography constitute a convenient and inexpensive alternative to dense sensor networks for distributed sensing in civil structures. However, their performance can deteriorate with the aging of the sensing film. Guaranteeing high identification performance after minor lesions is crucial to improving their ability to identify structural damage. In this paper, electrical resistance tomography is used to identify the crack locations in nanocomposite paint sprayed onto structural components. The main novelty consists of using crack annotations collected during visual inspections to improve the crack identification performance of deep neural networks trained using simulated datasets through transfer learning. Transfer component analysis is employed for simulation‐to‐real information transfer and applied at a population level, extracting low‐dimensional domain‐invariant features shared by simulated models and structures with similar geometry. The results show that the proposed method outperforms traditional approaches for crack localization in complex damage patterns. [ABSTRACT FROM AUTHOR]

Robot-assisted spraying is a widespread manufacturing process for coating a multitude of mechanical components in an efficient and cost-effective way. However, process preparation is very time-consuming and relies heavily on the expertise of the robot programmer for generating the appropriate robot trajectory. For this reason, industry and academia investigate the possibility of supporting the end-user in the process by the use of appropriate algorithms. Mostly partial concepts can be found in the literature instead of a solution that solves this task end-to-end. This survey paper provides a summary of previous research in this field, listing the frameworks developed with the intention of fully automating the coating processes. First, the main inputs required for the trajectory calculation are described. The path-generating algorithm and its subprocesses are then classified and compared with alternative approaches. Finally, the required information for the executable output program is described, as well as the validation tools to keep track of program performance. The paper comes to the conclusion that there is a demand for an autonomous robot-assisted spraying system, and with a call-for-action for the implementation of the holistic framework. [ABSTRACT FROM AUTHOR]

In a compact B1B2 process, the inner surface of car body needs to be sprayed only with base coat and clear coat, which puts forward high demands to reasonable setting of spraying parameters and trajectory. The commissioning of a process for spraying inner surface of car body with pearl white paint was studied. The compatibility of different paints with spraying parameters, the setting of positions to start up and shut off the spray gun at different trajectory tracking speeds, and the relationship between the takt time of production line and robot spraying time were discussed. A set of improvements to the automation level of robotic spraying on inner surface of car body was proposed. [ABSTRACT FROM AUTHOR]

When a curved target surface is coated in an electrostatic spray-painting process, the paint film pattern on curved targets will deform, and the thickness will change compared with the planar target due to the curvature characteristics of the target, the inhomogeneous electric field, and the flow field. Therefore, directly using the planar deposition distribution for painting the trajectory planning of curved surfaces causes large errors and low paint transfer efficiency. A study investigating the curved surface paint film thickness distribution characteristics is presented in this research to understand the relations among the target surface curvature, the electrostatic field, and the flow field distribution. Spray-painting process simulations were performed for conical surfaces of different curvatures. Moreover, the paint particle' trajectories, electric potential, and film deposition distribution were computed using ANSYS Fluent. The paint transfer efficiencies of these targets were computed. The results show that when the generatrix curvature of the conical surface increases gradually, the electric field intensity near the wall increases, which enhances the deposition of charged droplets on the wall. Moreover, the airflow field velocity increases as the curvature increases, which leads to a large diffusions of the spray flow field, so the paint thickness decreases, and the transfer efficiency is low. [ABSTRACT FROM AUTHOR]

Laser material processing has diverse applications in the manufacturing industries. The efficiency of laser material processing depends on the interaction of the laser beam with workpiece material. This study investigates the effect of different coating conditions (graphite spray and black spray paint) on the mild steel worksheet surface during the laser bending process. The uncoated condition is compared with the coated conditions in terms of average maximum temperature at the top surface and bend angle. The average maximum temperature at the top surface and bend angle generated in all three coating conditions are analysed for single and multi-scan laser bending. The temperature and bend angle is increased by applying graphite coating than in the uncoated condition, whereas no significant variation is observed for black spray paint, during single scan laser bending. In multi-scan laser bending the temperature is increased steadily except for the graphite coating, and insignificant variation in bend angle is observed among different coating conditions. [ABSTRACT FROM AUTHOR]

Since the insulation performance of air is not as good as that of S F 6 and other gases, it is necessary to conduct an in-depth study on the insulation characteristics of the fuse tube in order to meet the requirements of normal breaking and to design a structural improvement scheme for a 12 kV environmental protection cabinet fuse tube that is suitable for using air as the insulating medium. In this study, the insulation performance of the fuse tube before improvement was studied, and the electric-field distribution of the 12 kV fuse tube placed in the air-insulated switchgear was analyzed. The results showed that the electric-field was heavily concentrated in the air gap of the fuse tube plug and around the ground rod. In this study, the structure of the fuse tube was specifically designed. By spraying conductive paint on the intersection surface of different media, equipotentiality was achieved, and a reasonable metal shielding structure was added to the site where the field intensity was concentrated so as to improve the distribution of the electric-field and avoid the breakdown caused by the concentration of field intensity. Through several improved designs, the maximum electric-field strength of the fuse tube of an environmental protection cabinet can be effectively reduced, and the insulation requirements of relevant standards can be met. A partial discharge test for the improved fuse tube was carried out, and the local discharge quantity of the improved fuse tube met the industry requirements, which verified the rationality of the fuse-tube-improvement scheme. [ABSTRACT FROM AUTHOR]

We investigated the removal of spray paint from heritage granite surfaces using a nanosecond pulse laser and compared the results, in terms of the effectiveness of treatment and preservation of the stone surface from potential damage, with results obtained using a femtosecond pulse laser. We show that, with the nanosecond laser, the ablation threshold of the stone was measured at 0.5 J·cm-2, but it was only possible to remove certain types of spray paints, such as blue and green paints, at a higher fluence of 0.9 J·cm-2. To remove other types of paints, such as red and yellow, it was necessary to increase even further the laser fluence to 1.5 J·cm-2, well above the ablation threshold of the stone. In this case, damage was induced in the minerals, such as melting of biotite, and a general roughening of the other minerals' surfaces was observed. Despite nanosecond pulse lasers being more widespread for cleaning purposes, we demonstrate that femtosecond pulse lasers allowed better effectiveness in removing various colours of paint, without leaving residues, while keeping the laser energy below the damage threshold of the underlying stone, allowing complete preservation of the substrate, and avoiding the melting of the most sensitive mineral grains (particularly biotite). We determined the ablation efficiency of spray paint using the femtosecond pulse laser and found a maximum ablation regime centered around 6.2 J·cm-2, at 8.36 mm3·(min·W)-1. This study highlights the benefits of using a laser with femtosecond pulses instead of longer pulse durations (nanosecond range) for the preservation and maintenance of heritage stone. [ABSTRACT FROM AUTHOR]

On 29 April 2022, a new mural called 'Home is Where We Make It', designed and installed by Amrisa Niranjan, an Indo-Guyanese artist was vandalized, just three days after completion. Black spray paint attempted to cover the artist's name, and the letters 'USA' were printed over the portrait of a hijabi woman. Other signs saying 'USA' were taped to the mural and removed by police. By that same evening, the Star of David had been added across the woman's face in an attempted erasure of her presence. Drawing on an interview with Amrisa Niranjan, I discuss the implications of being Indo-Caribbean migrants at the nexus of Islamophobic, xenophobic, and sexist rhetoric that mark us as 'unbelonging'. In this paper, I address this event as part of a continuum of white supremacist racist, sexist and xenophobic violence that gets played out at the national, institutional, and interpersonal levels. This incident highlights how border policing occurs in everyday spaces, from microaggressions to overt acts of violence and erasure, in communities, universities, and even in supposed sanctuary spaces, where hatred is hidden under banners of diversity and inclusion but resurfaces in these moments. [ABSTRACT FROM AUTHOR]

Currently, most of the robot path planning methods for spray painting are based on slicing the Computer-Aided Design model of the target surface to generate a series of path points. They usually neglect the geometric boundary of the model and the smoothness of the generated path, leading to a non-uniform coating thickness. To ameliorate it, an improved "boundary fitting approach" is proposed. In this method, the upper and lower boundaries of the target surface are firstly detected based on the topology of the stereolithography model. For each pass, several sample points are extracted with a uniform length interval from the intersection points generated by the basic slicing method. The path pass is then described by a fourth-order polynomial curve. It fits the boundary points and sample points for the $z$ - $t$ and $y$ - $t$ relationships, respectively. Based on the spray gun's motion direction and spray direction, the orientation of each path point is also defined. The parameters of the path pass are optimized by particle swarm optimization to get the optimal uniformity of the resulting coating thickness. Both of the global uniformity and the local uniformity between two adjacent passes are considered. The strength of the proposed approach is validated by comparing the simulation with the basic and other typical algorithms. The results denote that boundary fitting approach could improve the uniformity of coating thickness. It brings about a better performance for the painted workpiece. [ABSTRACT FROM AUTHOR]

Automotive paint sludge (PS) is the waste product generated in the painting process of vehicle bodies. Although automotive spray painting is an automated operation, its efficiency is still quite low, since approximately 40–50% of the employed paint does not reach the target and, after being mixed with the collecting water, becomes PS. PS is a very complex material that contains several organic and inorganic components, in addition to 90% water immediately after production. Italian automotive factories produce from 2.5 to 5.0 kg of PS per painted car. If that figure is related to the number of vehicles produced worldwide every year, in the order of 100 million, it determines an annual PS amount in the order of 200,000–500,000 t. Consequently, a proper final destination for PS must be found. The waste management hierarchy and the principles of the circular economy require that we privilege solutions that foresee the recovery of valuable products or energy. This paper first reviews the processes and the machines that have been recently developed to obtain an enhanced mechanical dewatering of PS. The pretreatment of PS dewatering is often crucial in order to obtain high efficiency in the subsequent recovery process. Afterwards, the paper presents and discusses the recovery options that have been proposed and tested, at different scales, by several authors in the last thirty years. The processes for PS management can be grouped as follows: (i) direct employment of physically/chemically treated PS in the production of primers and sealants; (ii) utilization of PS for the production of building materials, as supplementary components of cement concrete, mortar, or bituminous mixtures; (iii) extraction of valuable organic and inorganic products by using thermal processes (pyrolysis, gasification); (iv) biological processes for PS detoxification, metal recovery, and stabilization before landfilling. [ABSTRACT FROM AUTHOR]

The objectives of this study were to develop a novel analytical method for quantifying vinyl chloride (VC) emitted from aerosol products, to provide analytical data on VC in aerosol products, and to evaluate consumer VC exposure by aerosol products. Our quantitative method involves absorbing VC into dimethyl sulfoxide and analyzing it using headspace gas chromatography/mass spectrometry. The correlation coefficients of the VC calibration curves were ≥ 0.9994 in the range of 0.16–80 µg/mL VC standard gases, which were prepared under either nitrogen or emission gases containing dimethyl ether or liquid petroleum gas. VC concentrations in these emission gases were calculated using a VC calibration curve from standard gases prepared under nitrogen; they were within ± 10% of the actual concentrations. We analyzed 39 household aerosol products; VC concentrations of 0.095, 0.098, and 0.28 μg/L were detected in three polyvinyl chloride spray paints. Consumer VC inhalation exposure level was estimated through an exposure scenario, and the hazard quotient was confirmed to be very low when comparing the exposure level with a cancer risk level of 10−5 for inhaled VC. These results suggest that the human health risk from VC in spray paint was low. [ABSTRACT FROM AUTHOR]

Due to the limitation of model coloring process, 3D solid sand table cannot satisfactorily restore the color information of electronic sand table, which has become a technical bottleneck for the development of solid sand table model to higher accuracy and color restoration. This paper mainly studies the coating treatment of three - dimensional spray painting surface; independently prepares the coating solution, coating the three-dimensional surface, analyzes the physical properties and printing properties of the coating; solves the problems of ink absorption, ink color rendering and dot expansion of three -dimensional spray painting coating; and improves the color reduction of three-dimensional spray painting. The specific research conclusions are as follows: with the decrease of pigment particle size, the whiteness of the coating first increases and then decreases, the contact angle of the coating gradually decreases, and the color density of the coating gradually increases. When VAE-707 and SBR are used as adhesives, the whiteness of the coating is improved, with the decrease of the ratio of VAE-705 to PVA-1788, the whiteness decreased first and then increased. When the ratio of VAE-705 to PVA-1788 was 2:8, the whiteness was higher. VAE-707 as adhesive has the highest color density, followed by PVA-1799; When the ratio of VAE -705 to PVA-1788 is 6:4, the color density of the printing coating is higher and the ability of tone reproduction is better. [ABSTRACT FROM AUTHOR]

Taguchi L9 orthogonal array is used to conduct the IRB1410 robot spray painting experiments to investigate the surface characteristics of Cold Rolled close Annealed (CRCA) steel workpiece. The main parameter of spray painting is considered as Distance (D), Pressure (P) and Speed (S) of the Robot. The nanopaint is prepared through the ultra-sonication process for robot spray painting applications. To optimise the robot process parameters and to achieve the accuracy level, the fuzzy expert system is integrated with Taguchi analysis. The developed truth valued fuzzy logic model is assessed the surface roughness by robot nanopaint with Carbon Nanotube (CNT). ANOVA is used to identify the noteworthy factors influencing surface roughness in robot painting process and validated using the empirical regression model. Based on the model, the influence of Robot painting process parameters on surface roughness is analysed by using the sensitivity analysis method. Further, the Neural Network model is used to predict the thickness variation of Nano painted workpiece and compared the results with experimental values. [ABSTRACT FROM AUTHOR]

This paper deals with the design of an experimental circular channel model specially adapted for particle image velocimetry (PIV) measurements of airflow. The goal is to find a simple, fast, and functional approach for creating experimental models. The issue of the required PIV signal quality is defined, and the limits of acquiring relevant PIV data in the interior of circular channels are described, primarily as reflections of direct and scattered laser light caused by light passage through the cylindrical wall. As part of the experiment, measurements of reflections were made on differently coated surfaces of a plexiglass plate. Samples of various combinations of black matt spray, Rhodamine 6G coating, and roughened surface were created. From the presented results, a combination of black matt spray with a layer of Rhodamine 6G spray paint was chosen. The selected modification was further used for the internal modification of the experimental channel surface. Furthermore, a geometry modification to prevent light spread through the tube material is described. Data obtained from measurements before and after channel modification are presented and explained. [ABSTRACT FROM AUTHOR]

To understand the pollution characteristics of volatile organic compounds (VOCs) in the glass deep-processing industry, samples were collected using polyvinyl fluoride bags and quickly transferred to summa tanks for GC/MS/FID analysis. The emission characteristics of VOCs, the ozone formation potential and the secondary aerosol formation potential were studied. The results showed that the VOCs emitted by the six enterprises were mainly aromatics and OVOCs, accounting for 35% to 97% of the emissions, with high emission loads of alkanes and halocarbons from individual enterprises. The stack emissions from Enterprise 2 were as high as 38 mg/m3, while the emissions from the remaining five enterprises were all in the range of 1.7~4.1 mg/m3, probably because the terminal treatment facilities were not updated in a timely manner, resulting in excessive stack emissions from Enterprise 2. The characteristic pollutants, including OVOCs, aromatics and alkanes, which are mainly derived from spray painting and gluing, were screened in the six enterprises. Aromatics and OVOCs contributed the most to the ozone formation potential in the six enterprises, with some enterprises having a high contribution from alkanes and alkenes. On the basis of the secondary aerosol formation potential, toluene, benzene, ethylbenzene, o-xylene and m/p-xylene account for 98% of the six enterprises' emissions. Glass enterprises should prioritise the control of benzene and OVOCs emissions. The glass processing industry mainly emits aromatics, OVOCs and alkanes. Through a preliminary study on the emission characteristics of VOCs in the glass deep-processing industry, we provided basic data for the reduction and control of VOCs in the glass deep-processing industry in China. [ABSTRACT FROM AUTHOR]

Large-sized seven-degrees-of-freedom (7-DoF) hybrid spray-painting robots combine ample working space and high flexibility, making them lucrative for the spray painting of aircraft and rocket surfaces. However, their kinematic calibration is hindered by gravitational deformation, which problem is addressed in this study by introducing a rigid-flexible coupling error modeling method. The latter combines the finite element method (FEM) and stiffness matrix method to assess the spatial gravitational deformation of a hybrid robot, which is then introduced into a geometric error model to establish the rigid-flexible coupling error identification model. Given many redundant parameters in the identification model for 7-DoF robots, these parameters are classified and simplified using the nonlinear least-square regularization method for parameter identification. Combining the inverse solution of 7-DoF spray-painting robots with dynamic characteristics considered, an error compensation method for 7-DoF robots is proposed. The kinematic calibration test results strongly indicate that position errors are significantly reduced with gravity compensation taken into consideration, and error convergence speed increases, demonstrating that the kinematic calibration method is feasible and can effectively improve the accuracy of spray-painting robots. The mean errors in the X- and Y-directions are reduced by 20 and 17%, respectively, compared to the conventional method. The proposed method is instrumental in the accurate kinematic calibration of large-sized 7-DoF hybrid robots. [ABSTRACT FROM AUTHOR]

Using teach pendants or offline programming methods can generate tool paths for robot manipulators to carry out production activities, such as spray painting on objects of different geometries. This task, in which the complexity of painting the surface is one of the main challenges, requires highly skilled operators. In addition, the time spent setting up a robot task can be justified for the mass production of the same workpiece. However, it is inconvenient for low-production and high-variation production lines. In order to overcome these challenges, this study presents an algorithm to autonomously generate robot trajectories for a spray-painting process applied to objects with complex surfaces based on input 3D point cloud data. A predefined spherical mesh wraps the object, organizing the geometrical attributes into a structured data set. Subsequently, the region of interest is extracted and isolated from the model, which serves as the basis for the automatic path-planning operation. A user-friendly graphical user interface (GUI) is developed to define input parameters, visualize the point cloud model and the generated trajectory, simulate paint quality using a color map, and ultimately generate the robot’s code. A 3D sensor is used to localize the pose of the workpiece ahead of the robot and adjust the robot’s trajectory. The efficacy of the proposed approach is validated first by using various workpieces within a simulated environment and second by employing a real robot to execute the motion task.

Robot-assisted spraying is a widespread manufacturing process for coating a multitude of mechanical components in an efficient and cost-effective way. However, process preparation is very time-consuming and relies heavily on the expertise of the robot programmer for generating the appropriate robot trajectory. For this reason, industry and academia investigate the possibility of supporting the end-user in the process by the use of appropriate algorithms. Mostly partial concepts can be found in the literature instead of a solution that solves this task end-to-end. This survey paper provides a summary of previous research in this field, listing the frameworks developed with the intention of fully automating the coating processes. First, the main inputs required for the trajectory calculation are described. The path-generating algorithm and its subprocesses are then classified and compared with alternative approaches. Finally, the required information for the executable output program is described, as well as the validation tools to keep track of program performance. The paper comes to the conclusion that there is a demand for an autonomous robot-assisted spraying system, and with a call-for-action for the implementation of the holistic framework.

Microplastics are recently discovered contaminants, yet knowledge on their sources and analysis is limited. For instance, paint microplastics are poorly known because soil separation protocols using flotation solutions cannot separate paint microplastics due to the higher density of paint microplastic versus common microplastics. Here, we designed a new two-step density separation protocol for paint microplastics, allowing paint microplastics to be separated from the soil without digestion. Paint particles were separated from soil samples collected around the graffiti wall at the Mauerpark, Berlin, then quantified according to their shape and color characteristic. The presence of polymers as binders in the paint particles was verified by Fourier transform infrared spectroscopy. Results show concentrations from 1.1 × 105 to 2.9 × 105 microplastics per Kg of dry soil, representing the highest microplastic concentration ever reported in the literature. Particle concentrations decreased and the median size increased with soil depth. Our results provide first evidence that spray painting, a technique with a wide range of applications from industry to art, leaves a legacy of environmental microplastic in soils that has so far gone unnoticed. [ABSTRACT FROM AUTHOR]