Map matching and heuristic elimination of gyro drift for personal navigation systems in GPS-denied conditions

This paper introduces a method for the substantial reduction of heading errors in inertial navigation systems used under GPS-denied conditions. Presumably, the method is applicable for both vehicle-based and personal navigation systems, but experiments were performed only with a personal navigation system called 'personal dead reckoning' (PDR). In order to work under GPS-denied conditions, the PDR system uses a foot-mounted inertial measurement unit (IMU). However, gyro drift in this IMU can cause large heading errors after just a few minutes of walking. To reduce these errors, the map-matched heuristic drift elimination (MAPHDE) method was developed, which estimates gyro drift errors by comparing IMU-derived heading to the direction of the nearest street segment in a database of street maps. A heuristic component in this method provides tolerance to short deviations from walking along the street, such as when crossing streets or intersections. MAPHDE keeps heading errors almost at zero, and, as a result, position errors are dramatically reduced. In this paper, MAPHDE was used in a variety of outdoor walks, without any use of GPS. This paper explains the MAPHDE method in detail and presents experimental results.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90785/1/0957-0233_22_2_025205.pd

AN EVALUATION PIPELINE FOR INDOOR LASER SCANNING POINT CLOUDS

The necessity for the modelling of building interiors has encouraged researchers in recent years to focus on improving the capturing and modelling techniques for such environments. State-of-the-art indoor mobile mapping systems use a combination of laser scanners and/or cameras mounted on movable platforms and allow for capturing 3D data of buildings’ interiors. As GNSS positioning does not work inside buildings, the extensively investigated Simultaneous Localisation and Mapping (SLAM) algorithms seem to offer a suitable solution for the problem. Because of the dead-reckoning nature of SLAM approaches, their results usually suffer from registration errors. Therefore, indoor data acquisition has remained a challenge and the accuracy of the captured data has to be analysed and investigated. In this paper, we propose to use architectural constraints to partly evaluate the quality of the acquired point cloud in the absence of any ground truth model. The internal consistency of walls is utilized to check the accuracy and correctness of indoor models. In addition, we use a floor plan (if available) as an external information source to check the quality of the generated indoor model. The proposed evaluation method provides an overall impression of the reconstruction accuracy. Our results show that perpendicularity, parallelism, and thickness of walls are important cues in buildings and can be used for an internal consistency check

Exploring the Use of Wearables to Enable Indoor Navigation for Blind Users

One of the challenges that people with visual impairments (VI) have to have to confront daily, is navigating independently through foreign or unfamiliar spaces.Navigating through unfamiliar spaces without assistance is very time consuming and leads to lower mobility. Especially in the case of indoor environments where the use of GPS is impossible, this task becomes even harder.However, advancements in mobile and wearable computing pave the path to new cheap assistive technologies that can make the lives of people with VI easier.Wearable devices have great potential for assistive applications for users who are blind as they typically feature a camera and support hands and eye free interaction. Smart watches and heads up displays (HUDs), in combination with smartphones, can provide a basis for development of advanced algorithms, capable of providing inexpensive solutions for navigation in indoor spaces. New interfaces are also introduced making the interaction between users who are blind and mo-bile devices more intuitive.This work presents a set of new systems and technologies created to help users with VI navigate indoor environments. The first system presented is an indoor navigation system for people with VI that operates by using sensors found in mo-bile devices and virtual maps of the environment. The second system presented helps users navigate large open spaces with minimum veering. Next a study is conducted to determine the accuracy of pedometry based on different body placements of the accelerometer sensors. Finally, a gesture detection system is introduced that helps communication between the user and mobile devices by using sensors in wearable devices

Depth Estimation Using 2D RGB Images

Single image depth estimation is an ill-posed problem. That is, it is not mathematically possible to uniquely estimate the 3rd dimension (or depth) from a single 2D image. Hence, additional constraints need to be incorporated in order to regulate the solution space. As a result, in the first part of this dissertation, the idea of constraining the model for more accurate depth estimation by taking advantage of the similarity between the RGB image and the corresponding depth map at the geometric edges of the 3D scene is explored. Although deep learning based methods are very successful in computer vision and handle noise very well, they suffer from poor generalization when the test and train distributions are not close. While, the geometric methods do not have the generalization problem since they benefit from temporal information in an unsupervised manner. They are sensitive to noise, though. At the same time, explicitly modeling of a dynamic scenes as well as flexible objects in traditional computer vision methods is a big challenge. Considering the advantages and disadvantages of each approach, a hybrid method, which benefits from both, is proposed here by extending traditional geometric models’ abilities to handle flexible and dynamic objects in the scene. This is made possible by relaxing geometric computer vision rules from one motion model for some areas of the scene into one for every pixel in the scene. This enables the model to detect even small, flexible, floating debris in a dynamic scene. However, it makes the optimization under-constrained. To change the optimization from under-constrained to over-constrained while maintaining the model’s flexibility, ”moving object detection loss” and ”synchrony loss” are designed. The algorithm is trained in an unsupervised fashion. The primary results are in no way comparable to the current state of the art. Because the training process is so slow, it is difficult to compare it to the current state of the art. Also, the algorithm lacks stability. In addition, the optical flow model is extremely noisy and naive. At the end, some solutions are suggested to address these issues

OPTIMIZATION OF TERMINAL LAYOUTS: AN ANALYTICAL AND SIMULATIVE APPROACH BASED ON GENETIC ALGORITHMS

2012/2013Every day millions of pedestrian move with different needs and objectives through spaces each of them with its functional specifications. An accurate design or revisiting of transport terminals, as for example railway stations, underway stations, airports, as well as complex buildings, open spaces and a deep analysis of public events with relevant pedestrian flows, would improve its usability at users benefit. To reach this goal is necessary a careful integration among architecture, engineering needs and transport disciplines, that, starting from the study of users behavior and pedestrian dynamics, provides the fundamental elements to be considered during design stage to ensure a major level of service. In literature nothing much is known about the optimal dimension of pedestrian transportation terminals. The aim of this study is to develop a methodology to size the functional terminal layouts, by the integration of analytical and simulative models submitted to generic algorithms, taking into account the dynamics and flows generated inside the terminals. In order to obviate the lack of requisite data for models calibration, validation and verification, as well as testing the process developed, an algorithm for data acquisition has been elaborated. It has a dedicated graphic interface, which allows to reveal the pedestrian dynamics and consequently to generate database; with these data is possible to obtain statistical and behavioral indicators about pedestrians detected. The use of analytical models, both to define the sizing of facilities inside the terminals and to model the user behavior during their paths, allows to define an objective function able to represent the performances of the terminal functional layout. Defined the dimensional ranges of each functional element inside the layout according a specific Level of Service, performed a design of experiments methodology and applied genetic algorithms to minimize the objective function, it is possible to obtain a set of optimal solutions for the terminal configuration sizing, in coherence with flows and dynamics generated inside the terminals itself. A further simulative approach, based on the application of the social force algorithm, allows, through quantitative and qualitative parameters, to identify the best solution(s) inside the domain previously identified with genetic algorithm application. Starting from the motivation that inspired this work, analyzed the existing literature and the main methods for data acquisition, it will be introduced the algorithm for the automatic acquisition of data and pedestrian database generation. The application of this tool will be illustrated in order to manifest the potentiality of the instrument same. Subsequently introduced the tool developed for the definition of the characteristic elements sizing and the model chosen for the correct estimation of pedestrian travel times, it will be explored the structure of the objective function aimed to identify the right trade-off between infrastructure and pedestrian costs. Finally, the application of genetic algorithms, resulting in the identification of Pareto front, generates the domain of optimal solutions to sift through the simulation approach. The developed methodology reveals a flexible and simple instruments, but, at the same time, accurate in the resolution of the problems for which has been structured. The potential of the developed methodology is highlighted in the course of the work thanks to a case of study.Ogni giorno milioni di pedoni si muovono con esigenze ed obbiettivi diversi in contesti differenti, ognuno dei quali con le sue caratteristiche tecniche funzionali. Un’attenta progettazione o rivisitazione dei terminali di trasporto, quali stazioni ferroviarie, metropolitane, aeroporti, così come degli edifici complessi, degli spazi aperti ed una corretta disamina degli eventi pubblici con flussi pedonali rilevanti, consentirebbe di migliorarne la fruibilità a beneficio dell’utenza. Per raggiungere tale obiettivo risulta necessaria un’attenta integrazione tra esigenze architettoniche, ingegneristiche e le discipline trasportistiche, le quali, partendo dallo studio comportamentale degli utenti e dalle dinamiche pedonali, forniscano gli elementi fondamentali da tenersi in considerazione nella fase di progettazione per garantire un maggiore livello di servizio. Riscontrata in letteratura una carenza di approcci finalizzata alla determinazione del miglior layout funzionale dei terminali, attraverso l’integrazione di modelli analitici e simulativi sottoposti ad algoritmi genetici, è stata sviluppata una metodologia che, coerentemente con le dinamiche e i flussi che all’interno dei terminali stessi si generano, mirasse al dimensionamento ottimo dei terminali di trasporto pedonale. Per ovviare alla mancanza di dati necessari per i processi di calibrazione, validazione e verifica dei modelli così come per testare il metodo sviluppato è stato innanzitutto elaborato un algoritmo per l’acquisizione di dati, con interfaccia grafica dedicata, che consente di rilevare le dinamiche pedonali, generare database e conseguentemente ricavare dati statistici e comportamentali dei pedoni. L’utilizzo di modelli analitici, sia per l’identificazione dei range dimensionali degli elementi caratteristici presenti all’interno dei terminali che per la modellizzazione del comportamento degli utenti, permette di definire una funzione obbiettivo che rappresenti le performances dei layout funzionali dei terminali. Attraverso design of experiments calibrati sui range dimensionali dei singoli elementi funzionali presenti all’interno dei terminali e la successiva applicazione degli algoritmi genetici finalizzati alla minimizzazione della funzione obiettivo, è possibile definire un insieme di soluzioni ottime per il dimensionamento dei terminali, in coerenza con i flussi e le dinamiche che in esso si generano. Un’ulteriore approccio simulativo, basato sull’applicazione dell’algoritmo delle forze sociali, consente, attraverso la valutazione di parametri quantitativi e qualitativi, di identificare la/e miglior soluzione/i all’interno del dominio di soluzioni precedentemente identificate con l’applicazione degli algoritmi genetici. A partire dall’esplicitazione delle motivazioni che hanno alimentato questo lavoro, analizzata la letteratura esistente e le principali metodologie per l’acquisizione dati, verrà introdotto l’algoritmo per l’acquisizione automatica dei dati pedonali e la generazione di database contenenti i profili degli utenti rilevati. A seguire troverà spazio l’applicazione di questo strumento per manifestarne le potenzialità. Successivamente, introdotto il tool sviluppato per la definizione dei range dimensionali degli elementi caratteristici e il modello scelto per la corretta stima dei tempi di percorrenza pedonali, verrà esplorata la strutturazione della funzione obiettivo finalizzata alla ricerca del giusto trade off tra costi infrastrutturali e pedonali. Infine, l’applicazione degli algoritmi genetici, risultanti nell’identificazione del fronte paretiano, genererà il dominio di soluzioni ottime da vagliare attraverso l’approccio simulativo. La metodologia sviluppata si è rivelata uno strumento flessibile ed agevole, ma, allo stesso tempo, puntuale nel risolvere i problemi per cui è stata ideata. Le potenzialità della metodologia sviluppata vengono messe in risalto nel corso dell’elaborato grazie ad un caso di studio condotto.XXVI Ciclo198