14,107 research outputs found
Deep CNN-Based Automated Optical Inspection for Aerospace Components
ABSTRACT
The defect detection problem is of outmost importance in high-tech industries such as aerospace manufacturing and is widely employed using automated industrial quality control systems. In the aerospace manufacturing industry, composite materials are extensively applied as structural components in civilian and military aircraft. To ensure the quality of the product and high reliability, manual inspection and traditional automatic optical inspection have been employed to identify the defects throughout production and maintenance. These inspection techniques have several limitations such as tedious, time- consuming, inconsistent, subjective, labor intensive, expensive, etc. To make the operation effective and efficient, modern automated optical inspection needs to be preferred. In this dissertation work, automatic defect detection techniques are tested on three levels using a novel aerospace composite materials image dataset (ACMID). First, classical machine learning models, namely, Support Vector Machine and Random Forest, are employed for both datasets. Second, deep CNN-based models, such as improved ResNet50 and MobileNetV2 architectures are trained on ACMID datasets. Third, an efficient defect detection technique that combines the features of deep learning and classical machine learning model is proposed for ACMID dataset. To assess the aerospace composite components, all the models are trained and tested on ACMID datasets with distinct sizes. In addition, this work investigates the scenario when defective and non-defective samples are scarce and imbalanced. To overcome the problems of imbalanced and scarce datasets, oversampling techniques and data augmentation using improved deep convolutional generative adversarial networks (DCGAN) are considered. Furthermore, the proposed models are also validated using one of the benchmark steel surface defects (SSD) dataset
A ubiquitous service-oriented automatic optical inspection platform for textile industry
Within a highly competitive market context, quality standards are vital for the textile industry, in which related procedures to assess respective manufacture still mainly rely on human-based visual inspection. Thereby, factors such as ergonomics, analytical subjectivity, tiredness and error susceptibility affect the employee's performance and comfort in particular and impact the economic healthiness of each company operating in this industry, generally. In this paper, a defect detection-oriented platform for quality control in the textile industry is proposed to tackle these issues and respective impacts, combining computer vision, deep learning, geolocation and communication technologies. The system under development can integrate and improve the production ecosystem of a textile company through a properly adapted information technology setup and associated functionalities such as automatic defect detection and classification, real-time monitoring of operators, among others.This work was financed by the project “Smart Production Process” (No. POCI-01-0247-FEDER-045366),
supported under the Incentive System for Research and Technological Development - Business R&DT (Individual
Projects)
A convolutional neural network (CNN) for defect detection of additively manufactured parts
“Additive manufacturing (AM) is a layer-by-layer deposition process to fabricate parts with complex geometries. The formation of defects within AM components is a major concern for critical structural and cyclic loading applications. Understanding the mechanisms of defect formation and identifying the defects play an important role in improving the product lifecycle. The convolutional neural network (CNN) has been demonstrated to be an effective deep learning tool for automated detection of defects for both conventional and AM processes. A network with optimized parameters including proper data processing and sampling can improve the performance of the architecture. In this study, for the detection of good deposition quality and defects such as lack of fusion, gas porosity, and cracks in a fusion-based AM process, a CNN architecture is presented comparing the classification report and evaluation of different architectural settings and obtaining the optimized result from them. Since data set preparation, visualization, and balancing are very important aspects in deep learning to improve the performance and accuracy of neural network architectures, exploratory data analysis was performed for data visualization and the up-sampling method was implemented to balance the data set for each class. By comparing the results for different architectures, the optimal CNN network was chosen for further investigation. To tune the hyperparameters and to achieve an optimized parameter set, a design of experiments was implemented to improve the performance of the network. The performance of the network with optimized parameters was compared with the results from the previous study. The overall accuracy ( \u3e 97%) for both training and testing the CNN network presented in this work transcends the current state of the art (92%) for AM defect detection”--Abstract, page iv
BodyNet: Volumetric Inference of 3D Human Body Shapes
Human shape estimation is an important task for video editing, animation and
fashion industry. Predicting 3D human body shape from natural images, however,
is highly challenging due to factors such as variation in human bodies,
clothing and viewpoint. Prior methods addressing this problem typically attempt
to fit parametric body models with certain priors on pose and shape. In this
work we argue for an alternative representation and propose BodyNet, a neural
network for direct inference of volumetric body shape from a single image.
BodyNet is an end-to-end trainable network that benefits from (i) a volumetric
3D loss, (ii) a multi-view re-projection loss, and (iii) intermediate
supervision of 2D pose, 2D body part segmentation, and 3D pose. Each of them
results in performance improvement as demonstrated by our experiments. To
evaluate the method, we fit the SMPL model to our network output and show
state-of-the-art results on the SURREAL and Unite the People datasets,
outperforming recent approaches. Besides achieving state-of-the-art
performance, our method also enables volumetric body-part segmentation.Comment: Appears in: European Conference on Computer Vision 2018 (ECCV 2018).
27 page
Automatic vision based fault detection on electricity transmission components using very highresolution
Dissertation submitted in partial fulfilment of the requirements for the Degree of Master of Science in Geospatial TechnologiesElectricity is indispensable to modern-day governments and citizenry’s day-to-day operations.
Fault identification is one of the most significant bottlenecks faced by Electricity transmission and
distribution utilities in developing countries to deliver credible services to customers and ensure
proper asset audit and management for network optimization and load forecasting. This is due to
data scarcity, asset inaccessibility and insecurity, ground-surveys complexity, untimeliness, and
general human cost. In this context, we exploit the use of oblique drone imagery with a high spatial
resolution to monitor four major Electric power transmission network (EPTN) components
condition through a fine-tuned deep learning approach, i.e., Convolutional Neural Networks
(CNNs). This study explored the capability of the Single Shot Multibox Detector (SSD), a onestage
object detection model on the electric transmission power line imagery to localize, classify
and inspect faults present. The components fault considered include the broken insulator plate,
missing insulator plate, missing knob, and rusty clamp. The adopted network used a CNN based
on a multiscale layer feature pyramid network (FPN) using aerial image patches and ground truth
to localise and detect faults via a one-phase procedure. The SSD Rest50 architecture variation
performed the best with a mean Average Precision of 89.61%. All the developed SSD based
models achieve a high precision rate and low recall rate in detecting the faulty components, thus
achieving acceptable balance levels F1-score and representation. Finally, comparable to other
works of literature within this same domain, deep-learning will boost timeliness of EPTN inspection
and their component fault mapping in the long - run if these deep learning architectures are widely
understood, adequate training samples exist to represent multiple fault characteristics; and the
effects of augmenting available datasets, balancing intra-class heterogeneity, and small-scale
datasets are clearly understood
- …