DROW: Real-Time Deep Learning based Wheelchair Detection in 2D Range Data

We introduce the DROW detector, a deep learning based detector for 2D range data. Laser scanners are lighting invariant, provide accurate range data, and typically cover a large field of view, making them interesting sensors for robotics applications. So far, research on detection in laser range data has been dominated by hand-crafted features and boosted classifiers, potentially losing performance due to suboptimal design choices. We propose a Convolutional Neural Network (CNN) based detector for this task. We show how to effectively apply CNNs for detection in 2D range data, and propose a depth preprocessing step and voting scheme that significantly improve CNN performance. We demonstrate our approach on wheelchairs and walkers, obtaining state of the art detection results. Apart from the training data, none of our design choices limits the detector to these two classes, though. We provide a ROS node for our detector and release our dataset containing 464k laser scans, out of which 24k were annotated.Comment: Lucas Beyer and Alexander Hermans contributed equall

Aprendizagem automática aplicada à deteção de pessoas baseada em radar

The present dissertation describes the development and implementation of a radar-based system with the purpose of being able to detect people amidst other objects that are moving in an indoor scenario. The detection methods implemented exploit radar data that is processed by a system that includes the data acquisition, the pre-processing of the data, the feature extraction, and the application of these data to machine learning models specifically designed to attain the objective of target classification. Beyond the basic theoretical research necessary for its sucessful development, the work contamplates an important component of software development and experimental tests. Among others, the following topics were covered in this dissertation: the study of radar working principles and hardware; radar signal processing; techniques of clutter removal, feature exctraction, and data clustering applied to radar signals; implementation and hyperparameter tuning of machine learning classification systems; study of multi-target detection and tracking methods. The people detection application was tested in different indoor scenarios that include a static radar and a radar dynamically deployed by a mobile robot. This application can be executed in real time and perform multiple target detection and classification using basic clustering and tracking algorithms. A study of the effects of the detection of multiple targets in the performance of the application, as well as an assessment of the efficiency of the different classification methods is presented. The envisaged applications of the proposed detection system include intrusion detection in indoor environments and acquisition of anonymized data for people tracking and counting in public spaces such as hospitals and schools.A presente dissertação descreve o desenvolvimento e implementação de um sistema baseado em radar que tem como objetivo detetar e distinguir pessoas de outros objetos que se movem num ambiente interior. Os métodos de deteção e distinção exploram os dados de radar que são processados por um sistema que abrange a aquisição e pré-processamento dos dados, a extração de características, e a aplicação desses dados a modelos de aprendizagem automática especificamente desenhados para atingir o objetivo de classificação de alvos. Além do estudo da teoria básica de radar para o desenvolvimento bem sucedido desta dissertação, este trabalho contempla uma componente importante de desenvolvimento de software e testes experimentais. Entre outros, os seguintes tópicos foram abordados nesta dissertação: o estudo dos princípios básicos do funcionamento do radar e do seu equipamento; processamento de sinal do radar; técnicas de remoção de ruído, extração de características, e segmentação de dados aplicada ao sinal de radar; implementação e calibração de hiper-parâmetros dos modelos de aprendizagem automática para sistemas de classificação; estudo de métodos de deteção e seguimento de múltiplos alvos. A aplicação para deteção de pessoas foi testada em diferentes cenários interiores que incluem o radar estático ou transportado por um robot móvel. Esta aplicação pode ser executada em tempo real e realizar deteção e classificação de múltiplos alvos usando algoritmos básicos de segmentação e seguimento. O estudo do impacto da deteção de múltiplos alvos no funcionamento da aplicação é apresentado, bem como a avaliação da eficiência dos diferentes métodos de classificação usados. As possíveis aplicações do sistema de deteção proposto incluem a deteção de intrusão em ambientes interiores e aquisição de dados anónimos para seguimento e contagem de pessoas em espaços públicos tais como hospitais ou escolas.Mestrado em Engenharia de Computadores e Telemátic

A Brain-Controlled Exoskeleton with Cascaded Event-Related Desynchronization Classifiers

This paper describes a brain-machine interface for the online control of a powered lower-limb exoskeleton based on electroencephalogram (EEG) signals recorded over the user’s sensorimotor cortical areas. We train a binary decoder that can distinguish two different mental states, which is applied in a cascaded manner to efficiently control the exoskeleton in three different directions: walk front, turn left and turn right. This is realized by first classifying the user’s intention to walk front or change the direction. If the user decides to change the direction, a subsequent classification is performed to decide turn left or right. The user’s mental command is conditionally executed considering the possibility of obstacle collision. All five subjects were able to successfully complete the 3-way navigation task using brain signals while mounted in the exoskeleton. We observed on average 10.2% decrease in overall task completion time compared to the baseline protocol

Analysis of a Sorter Cascade Applied to Control a Wheelchair

The precise eye state detection is a fundamental stage for various activities that require human-machine interaction (HMI). This chapter presents an analysis of the implementation of a system for navigating a wheelchair with automation (CRA), based on facial expressions, especially eyes closed using a Haar cascade classifier (HCC). Aimed at people with locomotor disability of the upper and lower limbs, the state detection was based on two steps: the capture of the image, which concentrates on the detection actions and image optimization; actions of the chair, which interprets the data capture and sends the action to the chair. The results showed that the model has excellent accuracy in identification with robust performance in recognizing eyes closed, bypassing well occlusion issues and lighting with about 98% accuracy. The application of the model in the simulations opens the implementation and marriage opportunity with the chair sensor universe aiming a safe and efficient navigation to the user

Support vector machines to detect physiological patterns for EEG and EMG-based human-computer interaction:a review

Support vector machines (SVMs) are widely used classifiers for detecting physiological patterns in human-computer interaction (HCI). Their success is due to their versatility, robustness and large availability of free dedicated toolboxes. Frequently in the literature, insufficient details about the SVM implementation and/or parameters selection are reported, making it impossible to reproduce study analysis and results. In order to perform an optimized classification and report a proper description of the results, it is necessary to have a comprehensive critical overview of the applications of SVM. The aim of this paper is to provide a review of the usage of SVM in the determination of brain and muscle patterns for HCI, by focusing on electroencephalography (EEG) and electromyography (EMG) techniques. In particular, an overview of the basic principles of SVM theory is outlined, together with a description of several relevant literature implementations. Furthermore, details concerning reviewed papers are listed in tables and statistics of SVM use in the literature are presented. Suitability of SVM for HCI is discussed and critical comparisons with other classifiers are reported

Current state of digital signal processing in myoelectric interfaces and related applications

This review discusses the critical issues and recommended practices from the perspective of myoelectric interfaces. The major benefits and challenges of myoelectric interfaces are evaluated. The article aims to fill gaps left by previous reviews and identify avenues for future research. Recommendations are given, for example, for electrode placement, sampling rate, segmentation, and classifiers. Four groups of applications where myoelectric interfaces have been adopted are identified: assistive technology, rehabilitation technology, input devices, and silent speech interfaces. The state-of-the-art applications in each of these groups are presented.Peer reviewe

飛行ロボットにおける人間・ロボットインタラクションの実現に向けて : ユーザー同伴モデルとセンシングインターフェース

学位の種別: 課程博士審査委員会委員 : （主査）東京大学准教授 矢入 健久, 東京大学教授 堀 浩一, 東京大学教授 岩崎 晃, 東京大学教授 土屋 武司, 東京理科大学教授 溝口 博University of Tokyo(東京大学

Vision based system for detecting and counting mobility aids in surveillance videos

Automatic surveillance video analysis is popular among computer vision researchers due to its wide range of applications that require automated systems. Automated systems are to replace manual analysis of videos which is tiresome, expensive, and time-consuming. Image and video processing techniques are often used in the design of automatic detection and monitoring systems. Compared with normal indoor videos, outdoor surveillance videos are often difficult to process due to the uncontrolled environment, camera angle, and varying lighting and weather conditions. This research aims to contribute to the computer vision field by proposing an object detection and tracking algorithm that can handle multi-object and multi-class scenarios. The problem is solved by developing an application to count disabled pedestrians in surveillance videos by automatically detecting and tracking mobility aids and pedestrians. The application demonstrates that the proposed ideas achieve the desired outcomes. There are extensive studies on pedestrian detection and gait analysis in the computer vision field, but limited work is carried out on identifying disabled pedestrians or mobility aids. Detection of mobility aids in videos is challenging since the disabled person often occludes mobility aids and visibility of mobility aid depends on the direction of the walk with respect to the camera. For example, a walking stick is visible most times in front-on view while it is occluded when it happens to be on the walker's rear side. Furthermore, people use various mobility aids and their make and type changes with time as technology advances. The system should detect the majority of mobility aids to report reliable counting data. The literature review revealed that no system exists for detecting disabled pedestrians or mobility aids in surveillance videos. A lack of annotated image data containing mobility aids is also an obstacle to developing a machine-learning-based solution to detect mobility aids. In the first part of this thesis, we explored moving pedestrians' video data to extract the gait signals using manual and automated procedures. Manual extraction involved marking the pedestrians' head and leg locations and analysing those signals in the time domain. Analysis of stride length and velocity features indicate an abnormality if a walker is physically disabled. The automated system is built by combining the \acrshort{yolo} object detector, GMM based foreground modelling and star skeletonisation in a pipeline to extract the gait signal. The automated system failed to recognise a disabled person from its gait due to poor localisation by \acrshort{yolo}, incorrect segmentation and silhouette extraction due to moving backgrounds and shadows. The automated gait analysis approach failed due to various factors including environmental constraints, viewing angle, occlusions, shadows, imperfections in foreground modelling, object segmentation and silhouette extraction. In the later part of this thesis, we developed a CNN based approach to detect mobility aids and pedestrians. The task of identifying and counting disabled pedestrians in surveillance videos is divided into three sub-tasks: mobility aid and person detection, tracking and data association of detected objects, and counting healthy and disabled pedestrians. A modern object detector called YOLO, an improved data association algorithm (SORT), and a new pairing approach are applied to complete the three sub-tasks. Improvement of the SORT algorithm and introducing a pairing approach are notable contributions to the computer vision field. The SORT algorithm is strictly one class and without an object counting feature. SORT is enhanced to be multi-class and able to track accelerating or temporarily occluded objects. The pairing strategy associates a mobility aid with the nearest pedestrian and monitors them over time to see if the pair is reliable. A reliable pair represents a disabled pedestrian and counting reliable pairs calculates the number of disabled people in the video. The thesis also introduces an image database that was gathered as part of this study. The dataset comprises 5819 images belonging to eight different object classes, including five mobility aids, pedestrians, cars, and bicycles. The dataset was needed to train a CNN that can detect mobility aids in videos. The proposed mobility aid counting system is evaluated on a range of surveillance videos collected from outdoors with real-world scenarios. The results prove that the proposed solution offers a satisfactory performance in picking mobility aids from outdoor surveillance videos. The counting accuracy of 94% on test videos meets the design goals set by the advocacy group that need this application. Most test videos had objects from multiple classes in them. The system detected five mobility aids (wheelchair, crutch, walking stick, walking frame and mobility scooter), pedestrians and two distractors (car and bicycle). The training system on distractors' classes was to ensure the system can distinguish objects that are similar to mobility aids from mobility aids. In some cases, the convolutional neural network reports a mobility aid with an incorrect type. For example, the shape of crutch and stick are very much alike, and therefore, the system confuses one with the other. However, it does not affect the final counts as the aim was to get the overall counts of mobility aids (of any type) and determining the exact type of mobility aid is optional

Statistical Review of Health Monitoring Models for Real-Time Hospital Scenarios

Health Monitoring System Models (HMSMs) need speed, efficiency, and security to work. Cascading components ensure data collection, storage, communication, retrieval, and privacy in these models. Researchers propose many methods to design such models, varying in scalability, multidomain efficiency, flexibility, usage and deployment, computational complexity, cost of deployment, security level, feature usability, and other performance metrics. Thus, HMSM designers struggle to find the best models for their application-specific deployments. They must test and validate different models, which increases design time and cost, affecting deployment feasibility. This article discusses secure HMSMs' application-specific advantages, feature-specific limitations, context-specific nuances, and deployment-specific future research scopes to reduce model selection ambiguity. The models based on the Internet of Things (IoT), Machine Learning Models (MLMs), Blockchain Models, Hashing Methods, Encryption Methods, Distributed Computing Configurations, and Bioinspired Models have better Quality of Service (QoS) and security than their counterparts. Researchers can find application-specific models. This article compares the above models in deployment cost, attack mitigation performance, scalability, computational complexity, and monitoring applicability. This comparative analysis helps readers choose HMSMs for context-specific application deployments. This article also devises performance measuring metrics called Health Monitoring Model Metrics (HM3) to compare the performance of various models based on accuracy, precision, delay, scalability, computational complexity, energy consumption, and security