721 research outputs found

    Velocity field path-planning for single and multiple unmanned ariel vehicles

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    Unmanned aerial vehicles (UAV) have seen a rapid growth in utilisation for reconnaissance, mostly using single UAVs. However, future utilisation of UAVs for applications such as bistatic synthetic aperture radar and stereoscopic imaging, will require the use of multiple UAVs acting cooperatively to achieve mission goals. In addition, to de-skill the operation of UAVs for certain applications will require the migration of path-planning functions from the ground to the UAV. This paper details a computationally efficient algorithm to enable path-planning for single UAVs and to form and re-form UAV formations with active collision avoidance. The algorithm presented extends classical potential field methods used in other domains for the UAV path-planning problem. It is demonstrated that a range of tasks can be executed autonomously, allowing high level tasking of single and multiple UAVs in formation, with the formation commanded as a single entity

    Minimum-time trajectory generation for quadrotors in constrained environments

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    In this paper, we present a novel strategy to compute minimum-time trajectories for quadrotors in constrained environments. In particular, we consider the motion in a given flying region with obstacles and take into account the physical limitations of the vehicle. Instead of approaching the optimization problem in its standard time-parameterized formulation, the proposed strategy is based on an appealing re-formulation. Transverse coordinates, expressing the distance from a frame path, are used to parameterise the vehicle position and a spatial parameter is used as independent variable. This re-formulation allows us to (i) obtain a fixed horizon problem and (ii) easily formulate (fairly complex) position constraints. The effectiveness of the proposed strategy is proven by numerical computations on two different illustrative scenarios. Moreover, the optimal trajectory generated in the second scenario is experimentally executed with a real nano-quadrotor in order to show its feasibility.Comment: arXiv admin note: text overlap with arXiv:1702.0427

    Autonomous Navigation for Mobile Robots: Machine Learning-based Techniques for Obstacle Avoidance

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    Department of System Design and Control EngineeringAutonomous navigation of unmanned aerial vehicles (UAVs) has posed several challenges due to the limitations regarding the number and size of sensors that can be attached to the mobile robots. Although sensors such as LIDARs that directly obtain distance information of the surrounding environment have proven to be effective for obstacle avoidance, the weight and cost of the sensor contribute to the restrictions on usage for UAVs as recent trends require smaller sizes of UAVs. One practical option is the utilization of monocular vision sensors which tend to be lightweight and have a relatively low cost, yet still the main drawback is that it is difficult to draw a certain rule from the sensor data. Conventional methods regarding visual navigation makes use of features within the image data or estimate the depth of the image using various techniques such as optical flow. These features and methodologies however still rely on human-based rules and features, meaning that robustness can become an issue. A more recent approach to vision-based obstacle avoidance exploits heuristic methods based on artificial intelligence such as deep learning technologies, which have shown state-of-the-art performance in fields such as image processing or voice recognition. These technologies are capable of automatically selecting important features for classification or prediction tasks, hence allowing superior performance. Such heuristic methods have proven to be more efficient as the rules and features that are drawn from the image are automatically determined, unlike conventional methods where the rules and features are explicitly determined by humans. In this thesis, we propose an imitation learning framework based on deep learning technologies that can be applied to the obstacle avoidance of UAVs, where the neural networks in this framework are trained upon the flight data obtained from human experts, extracting the necessary features and rules to carry out designated tasks. The system introduced in this thesis mainly consists of three parts: the data acquisition and preprocessing phase, the model training phase, and the model application phase. A CNN (Convolutional Neural Network), 3D-CNN, and a DNN (Deep Neural Network) will each be applied to the framework and tested with respect to the collision ratios to validate the obstacle avoidance performance.ope

    Conception of control paradigms for teleoperated driving tasks in urban environments

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    Development of concepts and computationally efficient motion planning methods for teleoperated drivingEntwicklung von Konzepten und recheneffizienten Bewegungsplanungsmethoden fĂŒr teleoperiertes Fahre

    Vision-Based Autonomous Robotic Floor Cleaning in Domestic Environments

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    Fleer DR. Vision-Based Autonomous Robotic Floor Cleaning in Domestic Environments. Bielefeld: UniversitÀt Bielefeld; 2018

    Computational intelligence approaches to robotics, automation, and control [Volume guest editors]

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    Secure indoor navigation and operation of mobile robots

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    In future work environments, robots will navigate and work side by side to humans. This raises big challenges related to the safety of these robots. In this Dissertation, three tasks have been realized: 1) implementing a localization and navigation system based on StarGazer sensor and Kalman filter; 2) realizing a human-robot interaction system using Kinect sensor and BPNN and SVM models to define the gestures and 3) a new collision avoidance system is realized. The system works on generating the collision-free paths based on the interaction between the human and the robot.In zukĂŒnftigen Arbeitsumgebungen werden Roboter navigieren nebeneinander an Menschen. Das wirft Herausforderungen im Zusammenhang mit der Sicherheit dieser Roboter auf. In dieser Dissertation drei Aufgaben realisiert: 1. Implementierung eines Lokalisierungs und Navigationssystem basierend auf Kalman Filter: 2. Realisierung eines Mensch-Roboter-Interaktionssystem mit Kinect und AI zur Definition der Gesten und 3. ein neues Kollisionsvermeidungssystem wird realisiert. Das System arbeitet an der Erzeugung der kollisionsfreien Pfade, die auf der Wechselwirkung zwischen dem Menschen und dem Roboter basieren

    Segmentation of Floors in Corridor Images for Mobile Robot Navigation

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    This thesis presents a novel method of floor segmentation from a single image for mobile robot navigation. In contrast with previous approaches that rely upon homographies, our approach does not require multiple images (either stereo or optical flow). It also does not require the camera to be calibrated, even for lens distortion. The technique combines three visual cues for evaluating the likelihood of horizontal intensity edge line segments belonging to the wall-floor boundary. The combination of these cues yields a robust system that works even in the presence of severe specular reflections, which are common in indoor environments. The nearly real-time algorithm is tested on a large database of images collected in a wide variety of conditions, on which it achieves nearly 90% segmentation accuracy. Additionally, we apply the floor segmentation method to low-resolution images and propose a minimalistic corridor representation consisting of the orientation line (center) and the wall-floor boundaries (lateral limit). Our study investigates the impact of image resolution upon the accuracy of extracting such a geometry, showing that detection of wall-floor boundaries can be estimated even in texture-poor environments with images as small as 16x12. One of the advantages of working at such resolutions is that the algorithm operates at hundreds of frames per second, or equivalently requires only a small percentage of the CPU
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