Position and orientation correction for pipe profiling robots

Sewer pipelines are prevalent, important, valuable, unnoticed, and often in a state of disrepair. Pipeline inspection is essential for effective management of wastewater systems and is now mandated for many municipalities complying with the Governmental Accounting Standards Board Statement 34 and EPA regulations. Pipe inspection robots are routinely used to inspect underground pipelines for cracks, deformations, leaks, blockages and other anomalies to prevent catastrophic failure and to ensure cost effective maintenance and renewal. Most existing pipe inspection robots only collect video footage of pipe condition. Pipe profiling technology has recently been introduced to allow for measurement of the internal coordinate geometry of pipelines. Accurate radial measurements permit the calculation of several important pipe parameters which aid in the determination of pipe condition and prediction of time to failure. Significant research work has been completed in North America, Europe, Asia and Australia aimed at improving the accuracy and automation of the pipe inspection process. However, standard calibration, verification, reporting and analysis practices must be developed for pipe profilers if coordinate profiling data is to be effectively included in the long term management of pipeline assets. The objective of this research is to quantify the measurement error incurred by a pipe profiler\u27s misalignment with the pipe axis, present a new methodology to correct the measurement error, develop a prototype profiler to verify the equations derived herein, and to further the development of pipe profiler technology at the Trenchless Technology Center at Louisiana Tech University. Equations are derived for pipe ovality as a function of the robot\u27s position and orientation with respect to a pipe to demonstrate the magnitude of the error which is introduced by a robot\u27s misalignment with the pipe axis. A new technique is presented to estimate the position and orientation of a profiler using radial measurement devices at each of its ends. This technique is demonstrated by applying homogeneous coordinate transformations to simulated radial measurements based on mathematically generated data that would be obtained by incrementally rotating two parallel radial measuring devices in a perfectly cylindrical pipe. A prototype pipe profiling robot was developed to demonstrate the new position and orientation technique and to experimentally verify the measurement error caused by a robot\u27s misalignment with the pipe axis. This work improves the accuracy and automation of pipe profiling technology and makes a case for the development of industry standard calibration, verification, reporting and analysis practices

Feasibility of active vision for inspection of continuous concrete pipes.

This thesis describes work to establish the feasibility of using active vision on a mobile robot to improve survey techniques for concrete and clay sewers of less than 1m diameter. Software and hardware components of a prototype mobile remote visual sensing system have been designed and developed. The active vision system (AVS) operates within smooth-walled small-bore pipes (0.5m < d < 1.0m). The AVS consists of two distinct, but related hardware components, a controllable (pan and tilt) camera head mounted on a remote control tractor and a system control unit which interfaces this remote system to a PC-based system supporting image capture and analysis.The software associated with the AVS comprises modules to control the camera orientation and supplement existing Artificial Intelligence vision analysis tools. The latter modules estimate the vanishing point (VP) of a sewer pipe (as a reference feature) and detect coaxial cracks in the periphery of the image (nearest the camera). Control software for the camera head has also been developed.The VP detection and crack detection modules have been evaluated on images captured from library videos of sewer surveys. The results show that the routines successfully locate the VP and can successfully detect coaxial cracks in a predefined region of interest in an image. The AVS as a whole has been tested in a laboratory setting using a short section of concrete pipe and simulated cracks in its wall. The AVS successfully implements a control cycle which determines and fixes the pipe VP, detects coaxial cracks in the pipe wall, orients the camera to attend to those cracks, and then re-fixes the VP

Automated Sewer Inspection Analysis and Condition Assessment

Underground infrastructure serves an essential need for the society. Huge number of facilities is dedicated to facilitate the well-being’s needs. Sewer infrastructure, one of the facilities, plays a major role in maintaining healthier environment. Its main duty is to transfer sewage material to treatment plants or any designated disposal area. Therefore, providing well performing sewer systems is essential to avoid any breakdown. Nevertheless, sewer pipelines’ condition in North America is deteriorating. In fact, studies have shown that 30% of municipal infrastructure in Canada is in either fair or very poor condition. As a result, there is a significant requirement for inspection and rehabilitation. Many municipalities utilize Closed Circuit Television (CCTV) inspection technique in inspecting sewer pipelines. However, this technique suffers from significant subjective and imprecise conclusions. Hence, studying, analyzing and applying different sewer inspection technologies and designing a condition assessment model are necessary to reduce subjectivity and errors and produce accurate and reliable results. This research aims to develop an automated tool to quantify: deformation, settled deposits, infiltration and surface damage sewer defects. The automated approach is dependent upon using image processing techniques and several models to analyze output data from 2D laser profiler, sonar and electroscan. Other than using ASTM F1216 formula, the research suggests applying the roundness factor in quantifying the deformation defect. The research develops a condition assessment model, based on the aforementioned defects, to arrive to an aggregated index suggesting the condition of sewer pipelines. Multi Attribute Utility Theory (MAUT) approach is used for each defect. The research also suggests a methodology to evaluate the surface damage defect of sewer pipelines for reinforced concrete, vitrified clay and ductile iron sewer pipeline materials. An interface, using MATLAB, was developed to implement the designed quantification algorithms and the MAUT model on real case studies. After implementing and validating the two deformation quantification methods, the Mean Absolute Error (MAE) utilizing the ASTM F1216 was 4.27%, while the MAE using the roundness factor was 4.83%. The maximum difference percentage was found to be 40.06%; however, the minimum difference percentage was 0.59%. The average difference percentage for all the cases was calculated as 16.67%. Later, the MAUT model was validated with actual case studies. Three rounding types (rounding to nearest number, rounding up and down) were tested to change the aggregated index, containing decimals, to a whole number. Mean Absolute Error (MAE) was utilized to compare the rounding types. In all case studies, rounding up type produced the lowest MAE values. When rounding up the computed index in case study 1, the MAE for Concordia Sewer Protocol (CSP), Water Research Centre (WRc) and New Zealand were 0.33, 0.33 and 0.42, respectively. This research shall encourage subject matters to utilize technologies, other than or beside CCTV, to conclude sound results. The developed automated user interface shall reduce inaccuracy and subjectivity through the application of robust image processing algorithms. After extending this research in including several sewer’s components and defects, the condition assessment model shall aid asset managers to allocate their maintenance and rehabilitation budgets

Catalytic steam reformer tubes non-destructive inspection technology investigation and advancement : a dissertation presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Engineering at Massey University, Manawatu Campus, New Zealand

Catalytic Steam reforming is a chemical synthesis process used in the production of hydrogen by mixing hydrocarbon with steam in the presence of a metal-based catalyst. This is achieved in a steam reformer plant where the mixture of gases is elevated to high pressure and temperature through a continuous process for efficient mass production of syngas to meet the global hydrogen demand. One of the challenges in operating a steam reformer plant is monitoring and maintaining the tubular reactors (Reformer tube). Under the severe service conditions the tubes a subjected to various degradation mechanism which ultimately determine the service life. With the tubes accounting to over 20% of the capital cost of a reformer plant, it is of great significance to maximise the service life of each tubes, which has been the motivation to the advancement in metallurgy and NDT technology around reformer tubes from the introduction of Catalytic Steam reforming in the early 20th century. Under the influence of long-term exposure of mechanical stressing and elevated temperature, reformer tube is subjected to a material degrading phenomenon call creep deformation. In 1952, F.R. Larson and J. Miller devised the Larson-Miller Parameter which predicts the lifetime of a material based on service temperature and stress-rupture time and for decades this method was used design and managed reformer tubes on a time-based strategy of 10,000 service hour. However, case studies have time and time shown premature rupture of reformer tube causing unexpected downtime resulting in significant loss in production and asset. Hence engineers and researchers have worked on a more direct method of assessing the remaining service life of reformer tubes. Inline pipe inspection is a hot area of research in robotics and automation. Eddy current, laser profilometry, ultrasonic and infrared thermography is the four technology that is currently dominating the Reformer industry, of which laser profilometry assessment being the only method capable of early stage creep detection. While other fields of pipe inspection have advanced and industrially applied over past decades, it is the author's opinion that NDT technology for reformer tube is outdated with areas of innovation. The aim of this research is to investigate an alternative solution to overcome the challenges and limited faced in modern systems and contribute to the advancement of NDT of Catalytic Steam reformer tubes. Presented in this dissertation is a new framework for an autonomous Reformer Tube inspection system, which incorporates a number of innovative elements for improved creep damage assessment. The program for this work is comprised of three studies. In the first study, the challenges around process profilometry dataset is demonstrated, the limitation in the available methods is discussed, and the impacts in regards to detection creep deformation is identified. Based on the finding, a three-stage creep detection algorithm (CDA) is derived, offering a dynamic solution to distinguish two modes of isotropic and anisotropic creep deformation. The system is experimentally assessed using a set of profilometry measurements collected from retire reformer tube. In the second study, a novel method for tracking a motion of an object moving inside a reformer tube is devised. Literature study showed that conventional profilometry system suffers from measurement uncertainty cause from an uncontrolled rotation of measurement instruction during an inspection. Because location information gives valuable insight as to the performance of the plant, the long-range optic solution is conceptualised, based on polarising filters and Malus Law, to overcome these limitations. In this research, a proof of concept experiment is conducted to evaluate and justify the conceptual method through the development of a working prototype. This novel technique is named Optical Position Tracking (OPT) system. Presented in the final study is an autonomous reformer tube inspection system developed on the basis of the results and finding in the first portion of the research. The contribution of this research is demonstrated with a working prototype justifying the practicality of CDA and the OPT system. The design incorporates wireless communication, modular design, and modern semiconductor sensing technology. In conclusion, this research met the first milestone for an ongoing research to progress the NTD industry