Development of a Sensing System for Underground Optic Fiber Cable Conduit Mapping

The motivation of this research is to obtain an accurate three-dimensional (3D) layout of an underground conduit, which may be beneficial to optic fiber cable installers and engineers. A newly designed algorithm for 3D position tracking with the help of an inertial sensor and an encoder has been developed. Two types of representations (Euler angle and Quaternion) for orientation and rotation are also introduced, followed by several data pre-processing procedures. A sensing fusion method is utilized to overcome the accumulated errors introduced by the sensor drifting. Considering the application of 3D underground duct mapping in this research, a sensing system using the newly designed algorithm was designed and analyzed. Additional information, such as the orientation and position of the starting and ending points, are integrated into the algorithm to correct the sensing drifting and refine the position estimation. To verify and demonstrate the design of the algorithm and sensing system for 3D underground duct mapping, an experimental test-bed based on the sensing system design, which consists of an IMU, a duct rodder and a fiber blower, was developed. Experiments on three different layouts of the conduit were conducted and analyzed to demonstrate the feasibility and efficiency of the newly developed algorithm and the sensing system design

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

Optical Rotary Sensors for Avionic Applications

RÉSUMÉ Cette thèse concerne des nouveaux capteurs optiques dédiés aux systèmes de contrôle de vol d’avions «fly-by-wire (FBW)». Les capteurs de déplacement sont utilisés dans les systèmes de contrôle de vol pour détecter la distraction du pilote, les déplacements de l'actionneur et ceux de la surface de vol. Actuellement, les capteurs « Rotary variable displacement transducers - RVDTs» utilisés dans les systèmes de contrôle de vol d'avions FBW sont les capteurs basés sur des circuits magnétiques et électroniques analogiques. Donc, une interface électronique est nécessaire pour la démodulation et numérisation des signaux reçus. Par conséquent, des paires de fils longs torsadés sont utilisés pour connecter le RVDT à l’ordinateur installé à bord de l’avion. Les paires de fils torsadés sont lourds et sensibles aux interférences électromagnétiques (IEM) et aux coups de foudre qui peuvent se produire pendant le vol. Nous proposons des capteurs optiques intelligents pour réduire le poids de l’avion, la consommation du carburant pour un environnement vert, l’IEM et pour utiliser moins de pièces métalliques afin de protéger davantage l’avion contre les coups de foudre. La conception des encodeurs de capteurs optiques rotatifs (Optical rotation sensors - ORSs) est basée sur trois exigences importantes, soient la fiabilité, la linéarité, et l’exactitude de mesures. Ces capteurs intégrés dans le système de vol doivent être intelligents. Pour la fiabilité, la réponse du capteur est calculée à partir du ratio des deux puissances optiques ou celui de la différence divisée par la somme de ces deux puissances optiques. Cependant, pour la linéarité, la réponse du capteur consiste en une relation linéaire avec le paramètre à mesurer qui est l’angle de rotation. Quant à l’exactitude, l’erreur doit être moins de 1% sur toute la gamme de mesures. De plus, pour un capteur intelligent, le capteur basé sur des circuits analogiques, les convertisseurs au monde numérique et l’étape de démodulation doivent être emballés dans un boîtier commun. Dans un premier prototype, un capteur de déplacement ratio-métrique, auto-référant, analogique et optique a été proposé pour les applications avioniques. La position de rotation est déterminée par le ratio de deux puissances lumineuses réfléchie et transmise qui rendent le capteur indépendant de fluctuations de puissance. L’encodeur multi-gradient original proposé compense pour l’usage d’une source non-uniforme.----------ABSTRACT This thesis is on novel optical sensors for smart sensor system needed in flight control system (FCS) of fly-by-wire (FBW) aircraft. Displacement sensors are needed in FBW-FCS to detect pilot inceptors, actuator displacements, and flight control surface movement. Currently, the sensors used for rotary variable displacement transducers (RVDTs) are analog electronic sensors, hence an electronic interface is needed for demodulation and digitization of analog signals. As a result, long twisted wires are drawn from the sensor to the flight control computer (FCC) interface which are heavy and susceptible to electromagnetic interference (EMI) and lightning strike. By proposing smart optical sensors, we aim to reduce the aircraft weight to decrease the fuel usage towards a greener environment, reduce EMI, and protect the aircraft against a lightning strike by using fewer metallic parts. The encoders of the optical rotation sensors (ORS) are designed based on three important requirements of reliability, linearity, and accuracy. In addition, they must be smart sensors to be integrated into the smart sensor system needed in FBW aircraft. For reliability requirements, the designed sensor response is the ratio of two optical powers or the ratio of the difference to the sum of two optical powers. For linearity requirement, the sensor response must be a linear relation with the measurand which is the rotation angle. For accuracy requirement, the error should be less than 1% over the full range. In addition, for a smart sensor, the analog sensor and the electronics for digitization and demodulation have to be packaged into a single housing.In the first design, an optical, analog, self-referencing, ratio-metric, smart displacement sensor is proposed for avionic applications. The position of rotation is determined by an encoder by the ratio of the transmitted and reflected light powers, which makes the sensor independent of power fluctuations. A single multi-gradient encoder design compensates for the use of a non-uniform source. An anti-reflection coated glass window with the outer diameter of 27mm is used with an encoder pattern mapped on it using aluminum deposition. The experimental results show that the ratio of the transmitted and reflected powers has an accuracy of 0.53% over the full range, matching the specifications for avionic applications

Testing of MEMS gyroscopes

Tato diplomová práce se zabývá teoretickými poznatky o konstrukcích a parametrech MEMS gyroskopů. Dále je prezentován navržený měřicí řetězec pro testování MEMS gyroskopů ve společnosti Honeywell International s.r.o. a to zejména s použitím systémů: Polytec MSA-500, goniometrických plošin a kontroléru od firmy Standa a kontroléru pro řízení Peltierových článků. Praktická část diplomové práce obsahuje popis navrženého kontroléru pro řízení teploty testovaného zařízení a také popis aplikace v prostředí LabVIEW („Measurement systém“), která se používá pro řízení pozice dvou goniometrických plošin a pro řízení Peltierových článků. Tento systém je schopen plně řídit pozici goniometrických plošin, zarovnat povrch testovaného zařízení do ideálně kolmé pozice vůči optické hlavě analyzátoru Polytec MSA-500 a také kontrolovat teplotu testovaného zařízení. Závěrečná část diplomové práce je věnována testům základních parametrů MEMS gyroskopů se zaměřením na závislost tzv. Angle Random Walk a offsetu MEMS gyroskopu na kvalitě vakua v prostředí struktury.This diploma thesis presents theoretical information regarding MEMS gyroscopes their parameters and designs. The description of measurement chain be used for testing of MEMS gyroscopes in Honeywell International s.r.o. is presented. Special focus is devoted to: the Polytec MSA-500 system, the Standa goniometers and their controller, Peltier cell and its driver. The practical part of this thesis contains the description of the thermal control system and also the description of the developed “Measurement system” in the LabVIEW software which is used for controlling the goniometers position and the Peltier cell. The system is able to fully control two goniometer stages, align the surface of tested MEMS device to orthogonal position with respect to the Polytec MSA-500 measurement head and also control the temperature of the tested device. The last part of this thesis presents the tests of the MEMS gyroscope parameters with special focus to the MEMS gyroscope angle random walk and the bias dependence on the vacuum quality of the structure environment.

Vektorisuunnistukseen perustuva sisätilapaikannusjärjestelmä

In this thesis a positioning system, that can provide accurate reference coordinates for indoor usage is described and analysed. Those coordinates are needed in the development of various indoor positioning systems. Satellite navigation systems such as GPS can provide accurate positioning outdoors but their accuracy is poor when used indoors. Inertial navigation can provide accurate positioning indoors using accelerometers and gyroscopes but an accurate system is extremely expensive. Accurate indoor positioning is also achievable using a floor plan, a measuring tape or both but these methods are prone to human errors. The system presented in this thesis is designed to overcome the aforementioned problems using dead reckoning navigation. Dead reckoning is a positioning method, that starts always from a known location and attitude. In dead reckoning, gyroscope and odometer measurements are used to obtain position by updating the previous position. The dead reckoning system uses a micro electro mechanical (MEMS) gyroscope and two odometers to measure attitude and travelled distance, respectively. A data acquisition program was written to save their measurements to log files on a PC and position was computed by post processing those. The system has been mounted on a cart for easy transportation. Before testing accuracy of the system the gyro and odometers were calibrated. The gyro was attached to a turn table to calibrate its scale factor and bias. From the turn table study it became obvious that the gyro needs to be calibrated just before testing accuracy of the system. Odometers were calibrated by driving the cart in a known straight line distance several times. Based on the drives a scale factor was calculated to compensate the difference in odometer readings. The gyro scale factor was calibrated just before accuracy test of the system by turning the cart around several times. The accuracy of the system was tested in a test drive lasting 30 minutes. During the test the gyro bias was calibrated whenever the system was stopped at reference positions for positioning accuracy estimation. Positioning error of less than 30 cm was achieved in the test drive.Tässä työssä kehitettiin ja analysoitiin tarkka sisätilapaikannusjärjestelmä. Sitä voidaan käyttää tarkkojen koordinaattien määrittämiseen, joita tarvitaan kehitettäessä muita sisätilapaikannusjärjestelmiä. Satelliittipaikannusjärjestelmiä, kuten GPS:ää, voidaan käyttää ulkotiloissa tarkkojen koordinaattien määrittämiseksi, mutta sisällä niiden tarkkuus on heikko. Tarkkaan sisätilapaikannukseen soveltuvat esimerkiksi gyroskooppeja ja kiihtyvyysantureita käyttävät inertiapaikannusjärjestelmät, mutta ne ovat erittäin kalliita. Pohjapiirustusta, mittanauhaa tai molempia voidaan käyttää tarkkaan sisätilapaikannukseen, mutta niitä käytettäessä tulee tehtyä helposti virheitä. Työssä esitetty vektorisuunnistusjärjestelmä on suunniteltu ratkaisuksi edellä mainittuihin ongelmiin. Vektorisuunnistus on paikannusmenetelmä, joka alkaa aina tunnetusta sijainnista ja suunnasta. Siinä käytetään gyroskoopin ja matkamittarin mittauksia paikan määrittämiseksi päivittämällä edellinen sijainti. Työssä esitetty järjestelmä käyttää mikromekaanista (MEMS) gyroskooppia suunnan määrittämiseksi ja kahta matkamittaria kuljetun matkan mittaamiseksi. Mittausten lukemiseksi antureilta kirjoitettiin tietokoneohjelma, joka tallensi ne lokitiedostoihin. Järjestelmän sijainti määritettiin jälkikäteen käyttäen lokitiedostoihin tallennettuja mittauksia. Järjestelmä on kiinnitetty kärryyn, jotta sitä on helppo kuljettaa sisätiloissa. Järjestelmän gyroskooppi ja matkamittarit kalibroitiin ennen sen tarkkuuden tutkimista. Skaalauskertoimen ja biaksen määrittämiseksi gyroskooppi kiinnitettiin pyörityspöytään. Kalibrointituloksista kävi ilmi, että gyroskooppi täytyy kalibroida juuri ennen järjestelmän tarkkuuden tutkimista. Matkamittarit kalibroitiin työntämällä kärryä suoraan tunnetun pituinen matka, jonka mittaus toistettiin useampia kertoja. Mittausten perusteella määritettiin skaalauskerroin, jolla kompensoitiin matkamittareiden lukemissa havaittu ero. Gyroskoopin skaalauskerroin kalibroitiin juuri ennen järjestelmän tarkkuuden tutkimista pyörittämällä kärryä useampi kerta ympäri. Järjestelmän tarkkuutta tutkittiin koeajossa, joka kesti 30 minuuttia. Koeajon aikana gyroskoopin bias kalibroitiin aina pysähdyttäessä tunnetuissa sijainneissa paikannustarkkuuden tutkimiseksi. Paikannusvirhe koeajon aikana oli alle 30 cm

Machine learning-based method for linearization and error compensation of an absolute rotary encoder

The main objective of this work is to develop a miniaturized, high accuracy, single-turn absolute, rotary encoder called ASTRAS360. Its measurement principle is based on capturing an image that uniquely identifies the rotation angle. To evaluate this angle, the image first has to be classified into its sector based on its color, and only then can the angle be regressed. In-spired by machine learning, we built a calibration setup, able to generate labeled training data automatically. We used these training data to test, characterize, and compare several machine learning algorithms for the classification and the regression. In an additional experiment, we also characterized the tolerance of our rotary encoder to eccentric mounting. Our findings demonstrate that various algorithms can perform these tasks with high accuracy and reliability; furthermore, providing extra-inputs (e.g. rotation direction) allows the machine learning algorithms to compensate for the mechanical imperfections of the rotary encoder.Comment: This paper was submitted for publication to Measurement (Elsevier) on the 7th July 202

Design of Attitude Control Actuators for a Simulated Spacecraft

The Air Force Institute of Technology\u27s attitude dynamics simulator, SimSat, is used for hardware-in-the-loop validation of new satellite control algorithms. To provide the capability to test algorithms for control moment gyroscopes, SimSat needed a control moment gyroscope array. The goal of this research was to design, construct, test, and validate a control moment gyroscope array for SimSat. The array was required to interface with SimSat\u27s existing structure, power supply, and electronics. The array was also required to meet maneuver specifications and disturbance rejection specifications. First, the array was designed with initial sizing estimates based on requirements and vehicle size. Next, the vehicle and control dynamics were modeled to determine control moment gyroscope requirements and provide a baseline for validation. Control moment gyroscopes were then built, calibrated, and installed on the vehicle. The actuators were then validated against the dynamics model. Testing shows minor deviation from the expected behavior as a result of small misalignments from the theoretical design. Once validation was complete, the array was tested against the performance specifications. The performance tests indicated that the control moment gyroscope array is capable of meeting specification

Design and implementation of a sensor testing system with use of a cable drone

Abstract. This thesis aims to develop a testing method for various sensors by modifying a commercial cable cam system to drive with an automated process at constant speed. The goal is to find a way to lift the cables in the air securely without a need for humans to climb on ladders and place them afterwards. This is achieved with a hinged truss tower structure that keeps the cables stabile while the tower is lifted. Another goal was to achieve automated movement of the cable drone. This is done by connecting a tracking camera to a computer that is used to control the cable drone’s motor controller. This will have the drone behave in a certain way depending on the tracking camera’s position data. Third goal is to build a portable sensor system which collects and saves the data from the tested sensors. This goal is achieved with an aluminium profile frame which is equipped with all the necessary equipment, such as a powerful computer. Research included studying different sensors’ performance evaluation criteria and effect of the wind on magnitude of the force in this application. Research was done by studying written sources and consulting a cable camera company called Motion Compound GbR. Results of this master’s thesis are used to evaluate if the idea of using a cable cam is applicable for this kind of sensor testing system. As the conclusion the cable drone with automated driving is evaluated to be a practical method which can still be further developed to meet the requirements even better. Antureiden testausjärjestelmän suunnittelu ja toteuttaminen käyttäen vaijeridronea. Tiivistelmä. Tämän diplomityön tavoitteena on muokata kaupallisesta vaijerikamerajärjestelmästä vakionopeudella liikkuva testausmenetelmä eri antureille. Yhtenä työn tavoitteena on löytää tapa nostaa käytettävät vaijerit ylös turvallisesti siten, ettei niitä tarvitse asentaa jälkikäteen korkealla. Tämä toteutetaan saranoidulla, trusseista rakennetulla tornilla. Tornin huipulle asennetaan laakeroidut akselit sekä suoja, jotka yhdessä pitävät vaijerit paikoillaan myös tornin noston ajan. Toinen tavoite on saavuttaa vaijerilennokin automatisoitu liike. Tämä tapahtuu kytkemällä seurantakamera tietokoneeseen, jota käytetään ohjaamaan myös vaijeridronen moottoriohjainta. Näin vaijeridrone saadaan käyttäytymään halutulla tavalla riippuen seurantakameran sijaintitiedoista. Kolmas tavoite on rakentaa kannettava anturijärjestelmä, jolla kerätään ja tallennetaan testatuilla antureilla kerätty data. Tämä tavoite saavutetaan alumiiniprofiilirungolla, joka varustetaan tarvittavilla laitteilla, kuten esimerkiksi tehokkaalla tietokoneella. Tutkimukseen kuului myös antureiden suorituskyvyn arviointikriteereihin tutustuminen sekä työssä käytettävästä järjestelmästä koituvan voiman suuruuden laskeminen. Tutkimus tehtiin perehtymällä kirjallisuuteen ja konsultoimalla vaijerikamera-alalla toimivaa Motion Compound GbR -yritystä. Tämän diplomityön tuloksia voidaan hyödyntää arvioitaessa, onko vaijerikamerajärjestelmä sovellettavissa mainitun anturien testausjärjestelmän rakentamisessa. Lopputuloksena automatisoidulla ajolla varustetun vaijeridronen arvioidaan olevan tähän tarkoitukseen toimiva menetelmä, jota voidaan edelleen kehittää vastaamaan vaatimuksia vielä paremmin

High precision angle calibration for spherical measurement systems

The European Synchrotron Radiation Facility (ESRF) located in Grenoble, France is a joint facility supported and shared by 19 European countries. It operates the most powerful synchrotron radiation source in Europe. Synchrotron radiation sources address many important questions in modern science and technology. They can be compared to “super microscopes”, revealing invaluable information in numerous fields of diverse research such as physics, medicine, biology, geophysics and archaeology. For the ESRF accelerators and beam lines to work correctly, alignment is of critical importance. Alignment tolerances are typically much less than one millimetre and often in the order of several micrometers over the 844 m ESRF storage ring circumference. To help maintain these tolerances, the ESRF has, and continues to develop calibration techniques for high precision spherical measurement system (SMS) instruments. SMSs are a family of instruments comprising automated total stations (theodolites equipped with distance meters), referred to here as robotic total stations (RTSs); and laser trackers (LTs). The ESRF has a modern distance meter calibration bench (DCB) used for the calibration of SMS electronic distance meters. At the limit of distance meter precision, the only way to improve positional uncertainty in the ESRF alignment is to improve the angle measuring capacity of these instruments. To this end, the horizontal circle comparator (HCC) and the vertical circle comparator (VCC) have been developed. Specifically, the HCC and VCC are used to calibrate the horizontal and vertical circle readings of SMS instruments under their natural working conditions. Combined with the DCB, the HCC and VCC provide a full calibration suite for SMS instruments. This thesis presents their development, functionality and in depth uncertainty evaluation. Several unique challenges are addressed in this work. The first is the development and characterization of the linked encoders configuration (LEC). This system, based on two continuously rotating angle encoders, is designed improve performance by eliminating residual encoder errors. The LEC can measure angle displacements with an estimated uncertainty of at least 0.044 arc seconds. Its uncertainty is presently limited by the instrumentation used to evaluate it. Secondly, in depth investigation has lead to the discovery of previously undocumented error-motion effects in ultra-precision angle calibration. Finally, methods for rigorous characterisation and extraction of rotary table error motions and their uncertainty evaluation using techniques not previously discussed in the literature have been developed

Design and evaluation of an automated fiber optic untwisting machine

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1999.Includes bibliographical references (p. 103-104).by Pankaj B. Lad.S.M