Abstract-This paper addresses the problem of detecting people in two dimensional range scans. Previous approaches have mostly used pre-defined features for the detection and tracking of people. We propose an approach that utilizes a supervised learning technique to create a classifier that facilitates the detection of people. In particular, our approach applies AdaBoost to train a strong classifier from simple features of groups of neighboring beams corresponding to legs in range data. Experimental results carried out with laser range data illustrate the robustness of our approach even in cluttered office environments. I. INTRODUCTIONDetecting people is a key capacity for robots that operate in populated environments. Knowledge about presence, position, and motion state of people will enable robots to better understand and anticipate intentions and actions.In this paper, we consider the problem of people detection from data acquired with laser range finders. The application of such sensors for this task has been popular in the past as they provide a large field of view and, opposed to vision, are mainly independent from ambient conditions. However, laser range data contain little information about people, especially because they typically consist of twodimensional range information. Figure 1 shows an example scan from a cluttered office environment. While this scan was recorded, several people walked through the office. The scan suggests that in cluttered environments, people detection in 2D is difficult even for humans. However, at a closer look, range measurements that correspond to humans have certain geometrical properties such as size, circularity, convexity or compactness (see Figure 2). The key idea of this work is to determine a set of meaningful scalar features that quantify these properties and to use supervised learning to create a people detector with the most informative features. In particular, our approach uses AdaBoost as a method for selecting the best features and thresholds, while at the same time creating a classifier using the selected features.In the past, many researchers focused on the problem of tracking people in range scans. One of the most popular approach in this context is to extract legs by the detecting moving blobs that appear as local minima in the range image [1], [2], [3], [4]. To this end, two types of features have been quite popular: motion and geometry features. Motion in range data is typically identified by subtracting two subsequent scans. If the robot is moving itself, the scans have first to be aligned, e.g., using scan matching. The drawback of motion features is that only moving people can be found. Topp and Christensen [5] extend the method of Schulz et

This paper addresses the problem of classifying places in the environment of a mobile robot into semantic categories. We believe that semantic information about the type of place improves the capabilities of a mobile robot in various domains including localization, path-planning, or human-robot interaction. Our approach uses AdaBoost, a supervised learning algorithm, to train a set of classifiers for place recognition based on laser range data. In this paper we describe how this approach can be applied to distinguish between rooms, corridors, doorways, and hallways. Experimental results obtained in simulation and with real robots demonstrate the effectiveness of our approach in various environments.

We present an approach for creating conceptual representations of human-made indoor environments using mobile robots. The concepts refer to spatial and functional properties of typical indoor environments. Following findings in cognitive psychology, our model is composed of layers representing maps at different levels of abstraction. The complete system is integrated in a mobile robot endowed with laser and vision sensors for place and object recognition. The system also incorporates a linguistic framework that actively supports the map acquisition process, and which is used for situated dialogue. Finally, we discuss the capabilities of the integrated system.

In this paper we compare the behavior of different interest points detectors and descriptors under the conditions needed to be used as landmarks in visionbased simultaneous localization and mapping (SLAM). We evaluate the repeatability of the detectors, as well as the invariance and distinctiveness of the descriptors, under different perceptual conditions using sequences of images representing planar objects as well as 3D scenes. We believe that this information will be useful when selecting an appropriate landmark detector and descriptor for visual SLAM.

Abstract

2 Mozos et al.Stress remains a significant social problem for individuals in modern societies. This paper presents a machine learning approach for the automatic detection of stress of people in a social situation by combining two sensor systems that capture physiological and social responses. We compare the performance using different classifiers including support vector machine, AdaBoost, and k-nearest neighbour. Our experimental results show that by combining the measurements from both sensor systems, we could accurately discriminate between stressful and neutral situations during a controlled Trier social stress test (TSST). Moreover, this paper assesses the discriminative ability of each sensor modality individually and considers their suitability for real time stress detection. Finally, we present an study of the most discriminative features for stress detection.

Abstract-Indoor environments can typically be divided into places with different functionalities like corridors, kitchens, offices, or seminar rooms. The ability to learn such semantic categories from sensor data enables a mobile robot to extend the representation of the environment facilitating the interaction with humans. As an example, natural language terms like "corridor" or "room" can be used to communicate the position of the robot in a map in a more intuitive way. In this work, we first propose an approach based on supervised learning to classify the pose of a mobile robot into semantic classes. Our method uses AdaBoost to boost simple features extracted from range data and vision into a strong classifier. We present two main applications of this approach. Firstly, we show how our approach can be utilized by a moving robot for an online classification of the poses traversed along its path using a hidden Markov model. Secondly, we introduce an approach to learn topological maps from geometric maps by applying our semantic classification procedure in combination with a probabilistic relaxation procedure. We finally show how to apply associative Markov networks (AMNs) together with AdaBoost for classifying complete geometric maps. Experimental results obtained in simulation and with real robots demonstrate the effectiveness of our approach in various indoor environments.

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