Determining position and orientation of a 3-wheel robot on a pipe using an accelerometer

Accurate positioning of robots on pipes is a challenge in automated industrial inspection. It is typically achieved using expensive and cumbersome external measurement equipment. This paper presents an Inverse Model method for determining the orientation angle (α ) and circumferential position angle (ω) of a 3 point of contact robot on a pipe where measurements are taken from a 3-axis accelerometer sensor. The advantage of this system is that it provides absolute positional measurements using only a robot mounted sensor. Two methods are presented which follow an analytical approximation to correct the estimated values. First, a correction factor found though a parametric study between the robot geometry and a given pipe radius, followed by an optimization solution which calculates the desired angles based on the system configuration, robot geometry and the output of a 3-axis accelerometer. The method is experimentally validated using photogrammetry measurements from a Vicon T160 positioning system to record the position of a three point of contact test rig in relation to a test pipe in a global reference frame. An accelerometer is attached to the 3 point of contact test rig which is placed at different orientation (α ) and circumferential position (ω) angles. This work uses a new method of processing data from an accelerometer sensor to obtain the α and ω angles. The experimental results show a maximum error of 3.40° in α and 4.17° in ω , where the ω circumferential positional error corresponds to ±18mm for the test pipe radius of 253mm

Recognizing People and Their Activities in Video from Security Cameras

Cieľom tejto práce je navrhnutie a implementovanie systému schopného rozpoznávať činností ľudí z bezpečnostných kamier. Hlavný dôraz je kladený na koncept komplexných situácií alebo udalostí, ktoré sú definované vzťahmi medzi rozpoznanými objektmi. Úvod tejto práce je venovaný oboznámeniu sa s jednotlivými časťami systému, kde sú objasnené využité techniky rozpoznávania objektov, sledovania objektov a rozpoznávania činností, ktoré sú použité v tejto práci. Druhá časť práce popisuje konečný návrh a implementáciu systému. Pre rozpoznávanie jednotlivých činností sú ďalej definované niektoré vzťahy medzi získanými informáciami popisujúce tieto činnosti, ako napríklad "vystupovanie z auta" alebo "kráčanie dvoch a viacerých ľudí spolu". Nakoniec je úspešnosť rozpoznávania vyhodnotená metrikou strednej priemernej presnosti (Mean Average Presicion).The aim of this thesis is to design and develop a system capable of recognizing the activities of people from surveillance cameras. Special attention is paid to the concept of complex situations or events that are defined by relations between identified objects. The first part surveys state-of-the-art techniques for object recognition, object tracking, and recognition of activities relevant to the realized solution. The second part describes the design and implementation of the devised system. It takes advantage of specific relations among two or more objects that are identified in video recordings, such as "person getting out of the car" or "one or more people met with a person of interest and they left together". Results are evaluated on video data extracted from available datasets and manually annotated. The mean average precision metric (MAP) on the data is reported.

Exploiting JavaScript Birthmarking Techniques for Code Theft Detection

Este relatório visa a análise de técnicas de birthmarking para detetar o roubo de código. Um birthmark de um software, como o próprio nome indica, é um conjunto de características únicas que permitem identificar esse mesmo software. Para a deteção do roubo de código são extraídos birthmarks de dois programas, o original e um suspeito, e são comparados um com o outro, permitindo assim detetar o roubo caso sejam muito semelhantes ou iguais. Como hoje em dia a internet é cada vez mais utilizada e o código JavaScript é usado para grande parte das aplicações web, o roubo de código nesta área é um grande problema da atualidade. Tendo isto em conta, a solução final tem como objetivo esta mesma linguagem.São analisadas, cronologicamente e tendo em conta a relevância para o tema, algumas das técnicas de birthmarking existentes. As técnicas são analisadas individualmente e no final é feito um resumo e comparação de todas as técnicas. Como a maior parte das técnicas existentes não foram pensadas para JavaScript, a sua aplicabilidade à linguagem é também analisada e são tiradas conclusões acerca de bons candidatos à solução final. O objetivo final é construir uma ferramenta que, usando uma técnica de birthmarking, determine se dois programas JavaScript foram copiados, de modo a suportar alegações de roubo de código.The purpose of this dissertation is to analyse birthmarking techniques in order to detect code theft. A birthmark of a software is, as the name suggests, the set of unique characteristics that allow to identify that software. In order to detect the theft, the birthmarks of two programs are extracted, the suspect and the original, and compared to each other to check if they are too similar or identical. Nowadays the web applications are growing and JavaScript code is the most used in this field, therefore the theft in this area is a current problem. Because of that, the theft detection of programs developed in that language is the focus of this dissertation.Some techniques of birthmarking are analysed in chronological order and accordingly to the relevance for the theme. Each technique is analysed individually and in the end a comparison between them is made. Given that most of the techniques were not created for JavaScript, their applicability to the language is analysed. With those analysis, some conclusions about the best candidates to the final solution are drawn.The final goal is to develop a tool, that uses a birthmarking technique, to determine if two JavaScript programs were copied, in order to support code theft allegations