122 research outputs found
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High-speed multi-dimensional relative navigation for uncooperative space objects
This work proposes a high-speed Light Detection and Ranging (LIDAR) based navigation architecture that is appropriate for uncooperative relative space navigation applications. In contrast to current solutions that exploit 3D LIDAR data, our architecture transforms the odometry problem from the 3D space into multiple 2.5D ones and completes the odometry problem by utilizing a recursive filtering scheme. Trials evaluate several current state-of-the-art 2D keypoint detection and local feature description methods as well as recursive filtering techniques on a number of simulated but credible scenarios that involve a satellite model developed by Thales Alenia Space (France). Most appealing performance is attained by the 2D keypoint detector Good Features to Track (GFFT) combined with the feature descriptor KAZE, that are further combined with either the H∞ or the Kalman recursive filter. Experimental results demonstrate that compared to current algorithms, the GFTT/KAZE combination is highly appealing affording one order of magnitude more accurate odometry and a very low processing burden, which depending on the competitor method, may exceed one order of magnitude faster computation
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Person Classification Leveraging Convolutional Neural Network for Obstacle Avoidance via Unmanned Aerial Vehicles
Obstacle avoidance capability for Unmanned Aerial Vehicles (UAVs) remains an active research in order to provide a better sense-and-avoid technology. More severely, in an environment where it contains and involves humans, the capability required is of high reliability and robustness. Prior to avoiding obstacles during mission, having a high performance of obstacle detection is deemed important. We first tackled the detection problem by solving the classification task. In this work, humans were treated as a special type of obstacles in indoor environment by which they may potentially cooperate with UAVs in indoor setting. While existing works have long been focusing on using classical computer vision techniques that suffer from substantial disadvantages with respect to robustness, studies on the use of deep learning approach i.e. Convolutional Neural Network (CNN) to achieve this purpose are still scarce. Using this approach for binary person classification task has revealed improved performance of more than 99% both for True Positive Rate (TPR) and True Negative Rate (TNR), hence, is promising for realizing robust obstacle avoidance
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Fusing Deep Learning and Sparse Coding for SAR ATR
We propose a multimodal and multidiscipline data fusion strategy appropriate for automatic target recognition (ATR) on synthetic aperture radar imagery. Our architecture fuses a proposed clustered version of the AlexNet convolutional neural network with sparse coding theory that is extended to facilitate an adaptive elastic net optimization concept. Evaluation on the MSTAR dataset yields the highest ATR performance reported yet, which is 99.33% and 99.86% for the three- and ten-class problems, respectively
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A New Passive 3-D Automatic Target Recognition Architecture for Aerial Platforms
The 3-D automatic target recognition (ATR) has many advantages over its 2-D counterpart, but there are several constraints in the context of small low-cost unmanned aerial vehicles (UAVs). These limitations include the requirement for active rather than passive monitoring, high equipment costs, sensor packaging size, and processing burden. We, therefore, propose a new structure from motion (SfM) 3-D ATR architecture that exploits the UAV's onboard sensors, i.e., the visual band camera, gyroscope, and accelerometer, and meets the requirements of a small UAV system. We tested the proposed 3-D SfM ATR using simulated UAV reconnaissance scenarios and found that the performance was better than classic 3-D light detection and ranging (LIDAR) ATR, combining the advantages of 3-D LIDAR ATR and passive 2-D ATR. The main advantages of the proposed architecture include the rapid processing, target pose invariance, small template size, passive scene sensing, and inexpensive equipment. We implemented the SfM module under two keypoint detection, description and matching schemes, with the 3-D ATR module exploiting several current techniques. By comparing SfM 3-D ATR, 3-D LIDAR ATR, and 2-D ATR, we confirmed the superior performance of our new architecture
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Real-Time Setup with PD and Backstepping Control for a Pelican Quadrotor
In this paper, a real-time setup and an implementation of a Proportional Derivative (PD) controller for orientation and comparison between PD and BackStepping (BS) controllers for linear positioning are presented using a Pelican quadrotor from Ascending Technologies (AscTec). An onboard Inertial Measurement Unit (IMU) was used for orientation control and Optitrack Vision Tracking System for linear positioning control. A linear Kalman filter was implemented for linear velocity estimation. The software and hardware integration was achieved with the help of the Robot Operating System (ROS). Simulations and experiments with this drone platform are achieved in order to implement different controller algorithms and analyse them in order to achieve better aircraft performance
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Scale robust IMU-assisted KLT for stereo visual odometry solution
We propose a novel stereo visual IMU-assisted (Inertial Measurement Unit) technique that extends to large inter-frame motion the use of KLT tracker (Kanade–Lucas–Tomasi). The constrained and coherent inter-frame motion acquired from the IMU is applied to detected features through homogenous transform using 3D geometry and stereoscopy properties. This predicts efficiently the projection of the optical flow in subsequent images. Accurate adaptive tracking windows limit tracking areas resulting in a minimum of lost features and also prevent tracking of dynamic objects. This new feature tracking approach is adopted as part of a fast and robust visual odometry algorithm based on double dogleg trust region method. Comparisons with gyro-aided KLT and variants approaches show that our technique is able to maintain minimum loss of features and low computational cost even on image sequences presenting important scale change. Visual odometry solution based on this IMU-assisted KLT gives more accurate result than INS/GPS solution for trajectory generation in certain context
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3D Automatic Target Recognition for Future LIDAR Missiles
We present a real-time three-dimensional automatic target recognition approach appropriate for future light detection and ranging-based missiles. Our technique extends the speeded-up robust features method into the third dimension by solving multiple two-dimensional problems and performs template matching based on the extreme case of a single pose per target. Evaluation on military targets shows higher recognition rates under various transformations and perturbations at lower processing time compared to state-of-the-art approaches
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Multispectral Image Processing for Navigation Using Low Performance Computing
Space debris represents a growing threat for both current spacecraft and future launches. This is exceptionally alarming in the case of low Earth orbits, where chain impacts of existing debris generate even more fragments, increasing the probability of further collisions. The now defunct satellite Envisat represents one of the largest objects classified as space debris. The e.Deorbit mission will demonstrate active debris removal (ADR) technology to successfully decommission Envisat and other non-functional target spacecraft in orbit. Relative navigation solutions shall be achieved using image processing algorithms, which implies the detection and matching of two-dimensional regions of interest. In this work, multiple pattern recognition techniques are investigated for the detection and description of these features. This analysis of feature perception is achieved for the first time in the context of space non-cooperative rendezvous (NCRV) across two different modalities: the visible (0.39-0.70 µm) and the thermal infrared (8-14 µm). The assessed algorithms are implemented in a dedicated, space-appropriate hardware processor to benchmark their real-time capabilities
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B-HoD: A Lightweight and Fast Binary Descriptor for 3D Object Recognition and Registration
3D object recognition and registration in computer vision applications has lately drawn much attention as it is capable of superior performance compared to its 2D counterpart. Although a number of high performing solutions do exist, it is still challenging to further reduce processing time and memory requirements to meet the needs of time critical applications. In this paper we propose an extension of the 3D descriptor Histogram of Distances (HoD) into the binary domain named the Binary-HoD (B-HoD). Our binary quantization procedure along with the proposed preprocessing step reduce an order of magnitude both processing time and memory requirements compared to current state of the art 3D descriptors. Evaluation on two popular low quality datasets shows its promising performance
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