57 research outputs found

    Applications of Computer Vision Technologies of Automated Crack Detection and Quantification for the Inspection of Civil Infrastructure Systems

    Get PDF
    Many components of existing civil infrastructure systems, such as road pavement, bridges, and buildings, are suffered from rapid aging, which require enormous nation\u27s resources from federal and state agencies to inspect and maintain them. Crack is one of important material and structural defects, which must be inspected not only for good maintenance of civil infrastructure with a high quality of safety and serviceability, but also for the opportunity to provide early warning against failure. Conventional human visual inspection is still considered as the primary inspection method. However, it is well established that human visual inspection is subjective and often inaccurate. In order to improve current manual visual inspection for crack detection and evaluation of civil infrastructure, this study explores the application of computer vision techniques as a non-destructive evaluation and testing (NDE&T) method for automated crack detection and quantification for different civil infrastructures. In this study, computer vision-based algorithms were developed and evaluated to deal with different situations of field inspection that inspectors could face with in crack detection and quantification. The depth, the distance between camera and object, is a necessary extrinsic parameter that has to be measured to quantify crack size since other parameters, such as focal length, resolution, and camera sensor size are intrinsic, which are usually known by camera manufacturers. Thus, computer vision techniques were evaluated with different crack inspection applications with constant and variable depths. For the fixed-depth applications, computer vision techniques were applied to two field studies, including 1) automated crack detection and quantification for road pavement using the Laser Road Imaging System (LRIS), and 2) automated crack detection on bridge cables surfaces, using a cable inspection robot. For the various-depth applications, two field studies were conducted, including 3) automated crack recognition and width measurement of concrete bridges\u27 cracks using a high-magnification telescopic lens, and 4) automated crack quantification and depth estimation using wearable glasses with stereovision cameras. From the realistic field applications of computer vision techniques, a novel self-adaptive image-processing algorithm was developed using a series of morphological transformations to connect fragmented crack pixels in digital images. The crack-defragmentation algorithm was evaluated with road pavement images. The results showed that the accuracy of automated crack detection, associated with artificial neural network classifier, was significantly improved by reducing both false positive and false negative. Using up to six crack features, including area, length, orientation, texture, intensity, and wheel-path location, crack detection accuracy was evaluated to find the optimal sets of crack features. Lab and field test results of different inspection applications show that proposed compute vision-based crack detection and quantification algorithms can detect and quantify cracks from different structures\u27 surface and depth. Some guidelines of applying computer vision techniques are also suggested for each crack inspection application

    Development of a wall-climbing robot with biped-wheel hybrid locomotion mechanism

    Full text link

    Mobile Robot Navigation

    Get PDF

    Bio-Inspired Robotics

    Get PDF
    Modern robotic technologies have enabled robots to operate in a variety of unstructured and dynamically-changing environments, in addition to traditional structured environments. Robots have, thus, become an important element in our everyday lives. One key approach to develop such intelligent and autonomous robots is to draw inspiration from biological systems. Biological structure, mechanisms, and underlying principles have the potential to provide new ideas to support the improvement of conventional robotic designs and control. Such biological principles usually originate from animal or even plant models, for robots, which can sense, think, walk, swim, crawl, jump or even fly. Thus, it is believed that these bio-inspired methods are becoming increasingly important in the face of complex applications. Bio-inspired robotics is leading to the study of innovative structures and computing with sensory–motor coordination and learning to achieve intelligence, flexibility, stability, and adaptation for emergent robotic applications, such as manipulation, learning, and control. This Special Issue invites original papers of innovative ideas and concepts, new discoveries and improvements, and novel applications and business models relevant to the selected topics of ``Bio-Inspired Robotics''. Bio-Inspired Robotics is a broad topic and an ongoing expanding field. This Special Issue collates 30 papers that address some of the important challenges and opportunities in this broad and expanding field

    Egospace Motion Planning Representations for Micro Air Vehicles

    Get PDF
    Navigation of micro air vehicles (MAVs) in unknown environments is a complex sensing and trajectory generation task, particularly at high velocities. In this work, we introduce an efficient sense-and-avoid pipeline that compactly represents range measurements from multiple sensors, trajectory generation, and motion planning in a 2.5–dimensional projective data structure called an egospace representation. Egospace coordinates generalize depth image obstacle representations and are a particularly convenient choice for configuration flat mobile robots, which are differentially flat in their configuration variables and include a number of commonly used MAV plant models. After characterizing egospace obstacle avoidance for robots with trivial dynamics and establishing limits on applicability and performance, we generalize to motion planning over full configuration flat dynamics using motion primitives expressed directly in egospace coordinates. In comparison to approaches based on world coordinates, egospace uses the natural sensor geometry to combine the benefits of a multi-resolution and multi-sensor representation architecture into a single simple and efficient layer. We also present an experimental implementation, based on perception with stereo vision and an egocylinder obstacle representation, that demonstrates the specialization of our theoretical results to particular mission scenarios. The natural pixel parameterization of the egocylinder is used to quickly identify dynamically feasible maneuvers onto radial paths, expressed directly in egocylinder coordinates, that enable finely detailed planning at extreme ranges within milliseconds. We have implemented our obstacle avoidance pipeline with an Asctec Pelican quadcopter, and demonstrate the efficiency of our approach experimentally with a set of challenging field scenarios. The scalability potential of our system is discussed in terms of sensor horizon, actuation, and computational limitations and the speed limits that each imposes, and its generality to more challenging environments with multiple moving obstacles is developed as an immediate extension to the static framework

    Visually guided obstacle detection and avoidance for legged robot.

    Get PDF
    Chow Ying-ho.Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.Includes bibliographical references (leaves 78-83).Abstracts in English and Chinese.Chapter Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Objectives - Visual Navigation for Legged Robots --- p.1Chapter 1.2 --- Summary of Results --- p.3Chapter 1.3 --- Hardware Issues --- p.4Chapter 1.4 --- Contributions --- p.4Chapter 1.5 --- Organization of the Thesis --- p.4Chapter Chapter 2 --- Previous Work --- p.6Chapter 2.1 --- Vision Based Navigation --- p.6Chapter 2.1.1 --- Homography --- p.7Chapter 2.1.2 --- Ground Plane Obstacle Detection --- p.9Chapter 2.1.3 --- Regression --- p.12Chapter 2.2 --- Control Strategy --- p.13Chapter Chapter 3 --- System Overview --- p.16Chapter Chapter 4 --- Obstacle Detection by Fast Homography Estimation --- p.20Chapter 4.1 --- Ground Feature Extraction --- p.21Chapter 4.2 --- Ground Feature Correspondence --- p.21Chapter 4.3 --- Ground Homography Estimation --- p.24Chapter 4.3.1 --- Input point transformation --- p.24Chapter 4.3.2 --- Initial estimation --- p.26Chapter 4.3.3 --- Robust estimation --- p.27Chapter 4.4 --- Obstacle Detection --- p.29Chapter 4.5 --- Local Obstacle Map (LOM) on Ground --- p.33Chapter 4.5.1 --- Extraction from accumulative evidence --- p.34Chapter 4.5.2 --- Time-delay compensation --- p.34Chapter Chapter 5 --- Obstacle Avoidance by a Fuzzy Controller --- p.36Chapter 5.1 --- Gait Pattern --- p.38Chapter 5.2 --- Fuzzy Logic Controller --- p.42Chapter 5.2.1 --- Controller Inputs --- p.42Chapter 5.2.2 --- Controller Outputs --- p.43Chapter 5.2.3 --- Inference mechanism --- p.46Chapter Chapter 6 --- Implementation --- p.49Chapter 6.1 --- Hardware components --- p.49Chapter 6.1.1 --- VisionBug --- p.49Chapter 6.1.2 --- RF transmitter / receiver modules: --- p.52Chapter 6.2 --- Perception --- p.55Chapter 6.3 --- Image Calibration --- p.56Chapter 6.4 --- Motion Calibration: --- p.58Chapter 6.5 --- Software Programs --- p.66Chapter 6.5.1 --- Computational complexity --- p.68Chapter Chapter 7 --- Experimental Results --- p.69Chapter 7.1 --- Real Navigation Experiments --- p.70Chapter 7.2 --- Error Analysis of LOM --- p.73Chapter Chapter 8 --- Conclusion and future work --- p.7

    Mechatronic Systems

    Get PDF
    Mechatronics, the synergistic blend of mechanics, electronics, and computer science, has evolved over the past twenty five years, leading to a novel stage of engineering design. By integrating the best design practices with the most advanced technologies, mechatronics aims at realizing high-quality products, guaranteeing at the same time a substantial reduction of time and costs of manufacturing. Mechatronic systems are manifold and range from machine components, motion generators, and power producing machines to more complex devices, such as robotic systems and transportation vehicles. With its twenty chapters, which collect contributions from many researchers worldwide, this book provides an excellent survey of recent work in the field of mechatronics with applications in various fields, like robotics, medical and assistive technology, human-machine interaction, unmanned vehicles, manufacturing, and education. We would like to thank all the authors who have invested a great deal of time to write such interesting chapters, which we are sure will be valuable to the readers. Chapters 1 to 6 deal with applications of mechatronics for the development of robotic systems. Medical and assistive technologies and human-machine interaction systems are the topic of chapters 7 to 13.Chapters 14 and 15 concern mechatronic systems for autonomous vehicles. Chapters 16-19 deal with mechatronics in manufacturing contexts. Chapter 20 concludes the book, describing a method for the installation of mechatronics education in schools

    Use of Kinematics to Minimize Construction Workers' Risk of Musculoskeletal Injury

    Get PDF
    Construction work requires more repetitive and highly physical effort than, for example, office work. Despite technological advancements in construction, the human factor is still an essential part of the industry. Hence, the need to maintain a healthy work environment is a shared interest between workers and industry. This thesis addresses the problem of cumulative injuries among construction workers, with emphasis on masons, and examines ways to improve safety and productivity simultaneously. Vision-based motion capture and sensor-based joint angle measurement techniques were tested against a state-of-the-art Optotrak system. Results show that the overall error in joint angle measurements was 10 deg for vision-based approaches compared to 3 deg for optical encoders. Moreover, a noninvasive fatigue detection method was developed by applying time-delay embedding and phase-space warping (PSW) techniques to a single joint angle, exerted force, and electromyography (EMG) data. Results indicate that the method can detect a slowly changing variable, fatigue in a limb, from a single kinematic signal, limb exerted force, or its EMG signals. Furthermore, twenty one masons distributed in four experience categories, ranging from novice to expert, took part in a study to evaluate safety and productivity in masonry work using inertial measurement units (IMUs). The study hypothesized that masons adopt safer and more productive work techniques with experience and that these techniques can be identified and used to train novice workers. Results indicate that journeymen appear to develop more productive and safer work techniques compared to other groups. On the other hand, the three-years experience group was found to sustain the highest joint compression forces and moments. Results also show that a clear distinction exists between expert and inexpert mason motion patterns. Support Vector Machine (SVM) classifiers were able to identify these differences with an accuracy of %92.04 in 13 seconds using a linear kernel. The thesis findings justify exploration of sensor fusion techniques to combine direct and indirect motion capture systems. The findings also suggest that PSW can be used in applications such as rehabilitation to access information about patient status hidden in the full-chain kinematics using a single kinematic signal. Finally, findings show the potential for training apprentices to excel in all three aspects: proficiency, productivity, and ergonomic safety by following the example of experts

    Stereomatch

    Get PDF
    Import 04/07/2011Tato bakalářská práce si za hlavní cíl klade osvětlení základních metod, které se využívají při stereo korespondenci, nástinů možných řešení problémů, které se u těchto metod vyskytují a také optimalizaci algoritmů s využitím technologie CUDA. Základním cílem stereo korespondence je analyzovat 2 obrazy, zaznamenávající shodnou scénu, ovšem s odlišnými úhly pohledu a nalézt v nich stejné prvky. Tohoto lze poté dále využít při rekonstrukci 3D scény. Výpočetní nároky na takovéto analýzy jsou ovšem značně veliké, a tak je třeba hledat možnosti optimalizace, kterou přináší například právě CUDA technologie.Main goal of this bachelor work is explain main methods that are used for stereomatch, some basic solutions of problems that can appear during using of these methods and also propose optimization of these algorithm with help of CUDA technology. Stereomatch's basic purpose is to analyze 2 images that shows same scene but from different angles of view and find common elements. By means of this principle we can then reconstruct 3D scene. But basic problem is that the computation requirements required for this can be abnormal. Thus we can find and use some optimization, that in our case can be application of CUDA technology.460 - Katedra informatikyvelmi dobř

    Mobile Robots Navigation

    Get PDF
    Mobile robots navigation includes different interrelated activities: (i) perception, as obtaining and interpreting sensory information; (ii) exploration, as the strategy that guides the robot to select the next direction to go; (iii) mapping, involving the construction of a spatial representation by using the sensory information perceived; (iv) localization, as the strategy to estimate the robot position within the spatial map; (v) path planning, as the strategy to find a path towards a goal location being optimal or not; and (vi) path execution, where motor actions are determined and adapted to environmental changes. The book addresses those activities by integrating results from the research work of several authors all over the world. Research cases are documented in 32 chapters organized within 7 categories next described
    corecore