143,323 research outputs found

    Fast and reliable recognition of human motion from motion trajectories using wavelet analysis

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    Recognition of human motion provides hints to understand human activities and gives opportunities to the development of new human-computer interface. Recent studies, however, are limited to extracting motion history image and recognizing gesture or locomotion of human body parts. Although the approach employed, i.e. the transformation of the 3D space-time (x-y-t) analysis to the 2D image analysis, is faster than analyzing 3D motion feature, it is less accurate and less robust in nature. In this paper, a fast trajectory-classification algorithm for interpreting movement of human body parts using wavelet analysis is proposed to increase the accuracy and robustness of human motion recognition. By tracking human body in real time, the motion trajectory (x-y-t) can be extracted. The motion trajectory is then broken down into wavelets that form a set of wavelet features. Classification based on the wavelet features can then be done to interpret the human motion. An online hand drawing digit recognition system was built using the proposed algorithm. Experiments show that the proposed algorithm is able to recognize digits from human movement accurately in real time.postprintThe 2004 IFIP International Conference on Artificial Intelligence Applications and Innovation, Toulouse, France, 22-27 August 2004. In Proceedings of the IFIP International Conference on Artificial Intelligence Applications and Innovation, 2004, p. 1-1

    Real-Time Predictive Modeling and Robust Avoidance of Pedestrians with Uncertain, Changing Intentions

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    To plan safe trajectories in urban environments, autonomous vehicles must be able to quickly assess the future intentions of dynamic agents. Pedestrians are particularly challenging to model, as their motion patterns are often uncertain and/or unknown a priori. This paper presents a novel changepoint detection and clustering algorithm that, when coupled with offline unsupervised learning of a Gaussian process mixture model (DPGP), enables quick detection of changes in intent and online learning of motion patterns not seen in prior training data. The resulting long-term movement predictions demonstrate improved accuracy relative to offline learning alone, in terms of both intent and trajectory prediction. By embedding these predictions within a chance-constrained motion planner, trajectories which are probabilistically safe to pedestrian motions can be identified in real-time. Hardware experiments demonstrate that this approach can accurately predict pedestrian motion patterns from onboard sensor/perception data and facilitate robust navigation within a dynamic environment.Comment: Submitted to 2014 International Workshop on the Algorithmic Foundations of Robotic

    Autonomous real-time surveillance system with distributed IP cameras

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    An autonomous Internet Protocol (IP) camera based object tracking and behaviour identification system, capable of running in real-time on an embedded system with limited memory and processing power is presented in this paper. The main contribution of this work is the integration of processor intensive image processing algorithms on an embedded platform capable of running at real-time for monitoring the behaviour of pedestrians. The Algorithm Based Object Recognition and Tracking (ABORAT) system architecture presented here was developed on an Intel PXA270-based development board clocked at 520 MHz. The platform was connected to a commercial stationary IP-based camera in a remote monitoring station for intelligent image processing. The system is capable of detecting moving objects and their shadows in a complex environment with varying lighting intensity and moving foliage. Objects moving close to each other are also detected to extract their trajectories which are then fed into an unsupervised neural network for autonomous classification. The novel intelligent video system presented is also capable of performing simple analytic functions such as tracking and generating alerts when objects enter/leave regions or cross tripwires superimposed on live video by the operator

    Unravelling intermittent features in single particle trajectories by a local convex hull method

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    We propose a new model-free method to detect change points between distinct phases in a single random trajectory of an intermittent stochastic process. The local convex hull (LCH) is constructed for each trajectory point, while its geometric properties (e.g., the diameter or the volume) are used as discriminators between phases. The efficiency of the LCH method is validated for six models of intermittent motion, including Brownian motion with different diffusivities or drifts, fractional Brownian motion with different Hurst exponents, and surface-mediated diffusion. We discuss potential applications of the method for detection of active and passive phases in the intracellular transport, temporal trapping or binding of diffusing molecules, alternating bulk and surface diffusion, run and tumble (or search) phases in the motion of bacteria and foraging animals, and instantaneous firing rates in neurons

    Online Informative Path Planning for Active Classification on UAVs

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    We propose an informative path planning (IPP) algorithm for active classification using an unmanned aerial vehicle (UAV), focusing on weed detection in precision agriculture. We model the presence of weeds on farmland using an occupancy grid and generate plans according to information-theoretic objectives, enabling the UAV to gather data efficiently. We use a combination of global viewpoint selection and evolutionary optimization to refine the UAV's trajectory in continuous space while satisfying dynamic constraints. We validate our approach in simulation by comparing against standard "lawnmower" coverage, and study the effects of varying objectives and optimization strategies. We plan to evaluate our algorithm on a real platform in the immediate future.Comment: 7 pages, 4 figures, submission to International Symposium on Experimental Robotics 201
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