Taguchi defines quality loss as the loss imposed to the consumer for each unit of deviation from the target consumer requirements. In this thesis, the effects of inspection error and rework on quality loss are studied for a nominal-the-best type quality characteristic. The distribution of the quality characteristic in a production environment where there are inspection error and a separate rework facility is investigated. 100 % inspection policy is considered. After deriving the mean and variance of the resulting distribution of the quality characteristic, the true and simulated quality loss values for a number of scenarios are calculated. Furthermore, effects of deviation of the process mean from the target and variance of the rework are studied besides inspection error and process capability through a full factor factorial experimental design. Results are discussed for possible uses as quality improvement project selection criteria.

Les pièces mécaniques fabriquées tel que les feuilles de métal et les pièces à paroi mince, ont souvent des différences géométriques significatives par rapport à leurs modèles CAD nominaux car ils ont une forme considérablement différente dans une condition d’état libre en raison de la gravité et/ou la tension résiduelle. Par conséquence, les fixtures de conformation coûteux sont traditionnellement utilisés pendant les opérations d’inspection géométriques à la phase de contrôle de qualité. L’objective de cette étude est de développer les méthodes d’inspection géométriques automatisées des pièces flexibles qui ne nécessiteraient pas d’utilisation des fixtures. / In manufacturing, quality control (QC) is an essential phase of a product’s lifecycle management (PLM) as it ensures customers receive parts within permissible tolerance ranges and free from defects. Given that all manufactured parts often have geometrical differences compared to their nominal computer-aided design (CAD) models, performing geometrical inspections becomes critical during the QC phase. Nowadays, actual measurements and defect identification during geometrical inspections have been semi-automated through the use of computer-aided inspection (CAI) software. Such software can simplify the inspection into a data acquisition task (contact-based probing or non-contact scanning of the part) followed by semi-automated procedures in a software environment. Despite their growing popularity and practicality, currently available CAI software assume the input acquired data are from a rigid part. This assumption is a major limitation given that not all manufactured parts are rigid, and in some sectors such as the aeronautical industries a considerable percentage of all manufactured components (35 to 40 percent) possess some nonrigid behavior. In other words, CAI software can only be used when a part maintains its shape in both free-state and state-of-use positions. Free-state shape is that which a part has without inspection fixture support and/or before assembly, whilst state-of-use shape is that which is defined in the nominal CAD. Although free-state and state-of-use positions are the same for rigid parts, some mechanical parts such as sheet metals and skins (thin-wall featured parts) often have significantly large geometric deviations in a free-state position compared to their nominal CAD models due to the effects of gravity and residual stress. Referring to such parts as flexible, the aforementioned deviations force the QC technicians to traditionally use a variety of inspection fixtures and conformation jigs in order to maintain flexible parts in their state-of-use position before using conventional CAI software. Without fixation, the free-state elastic geometric deviation of flexible parts would be mistaken by CAI software as plastic deformations and as a result identified as defects. With fixation, the aforementioned free-state deviations are removed before data acquisition, and whatever deviations remain can be inspected as potential defects. However, multiple disadvantages exist in using fixtures including: time consuming set-up process (e.g. 60+ hours for a skin panel in the aerospace industry), considerable purchase and operating expenses, limitations of standard fixture kits in some scenarios, big errors in CAI analysis if fixation has not been conducted correctly, etc. Such disadvantages have recently led researchers to:1) try to circumvent use of fixtures by digitally deforming (or better called registering) the acquired free-state pointcloud/mesh data of a flexible part until it superimposes onto the part’s corresponding nominal CAD model, thereby elastically deforming the data to obtain an optimal state-of-use shape whilst avoiding neutralization of any existing manufacturing defects2) and to try to introduce dedicated defect identification modules with higher degrees of automation (compared to conventional semi-automated CAI tools)In this thesis the same two goals are pursued. A bi-criterion registration method (and two algorithms/demos based upon it) is proposed to achieve the first goal, thereby enabling defect identification of flexible parts in conventional CAI software without the use of fixtures. This is followed by introducing an automated method for fast approximation of defect amplitudes (and an algorithm/demo based upon it) to achieve the second goal. Validation was conducted against a number of virtual (simulated) and experimental industrial case studies. Obtained satisfactory results reflect the effectiveness and utility of the proposed methods.

The most common way to transport oil and natural gas in Canada is by using pipes. In the last years, population growth has led to an increase in the pipeline network. This increase will generate new areas of research such as the detection of leakages or cracks and the maintenance of the pipeline system as a whole. In this thesis, a novel hypermobile robot, capable of moving along pipes of different diameters, is proposed and developed. The robot is composed of three modules, two propulsive modules and one control module linked by passive joints. The propulsive module has eight actuators: four gearmotors to propel the robot along the pipe, and four servomotors to control the radial position of the robot in the pipe and to maintain the robot's balance. A Raspberry Pi is used to control the actuators, acquire sensor feedback, and receive commands from a remote wireless user-controlled GUI. An existing dynamic controller is adapted to the robot's architecture. Simulations and experimental tests in open-loop and closed-loop modes are performed to evaluate the effectiveness of the robot's design and controller. The results show the efficiency of the mechanical and electronic components of the robot since it is capable of following the generated paths. The outcome of this thesis can be used in trajectory tracking controllers and for in-pipe robot design.

This thesis describes the design of a robotic inspection tool which is based on a differential track-drive platform. The robotic inspection tool is a one man-portable UGV that has been developed for the purpose of non-destructive evaluation (NDE) and internal inspection of environments where human penetration may be difficult or hazardous. Various NDE and sensing techniques are described in this paper but the focus is on the mechanical and electrical design of the platform itself. The platform is a versatile device for mobile robotics research and development that supports a wide variety of instrumentation and payloads. Variable height control of the payload is achieved with a scissor lift assembly that provides accurate positioning of equipped sensors and instrumentation. The architecture of the platform was designed to support future autonomous implementations. / Master of Science

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published_or_final_version / Housing Management / Master / Master of Housing Management

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