共查询到20条相似文献,搜索用时 46 毫秒
1.
We address the problem of autonomous landing of a quadrotor onto a heaving (moving vertically) platform in this paper. A control architecture that consists of a motion estimation module, a trajectory generation module and a tracking control module is proposed. The motion estimation module estimates the absolute motion of the platform and the quadrotor with the measurements from an on‐board accelerometer and vision measurements. Based on these estimates, the trajectory generation module generates a time‐optimal reference trajectory. With the reference trajectory and motion estimation, the tracking control module synthesizes a control command that enables robust tracking of the reference trajectory. Experimental results and comparison with a state‐of‐the‐art landing controller demonstrate the effectiveness of the proposed control architecture. 相似文献
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Fabrice Urban Jean-François Nezan Mickaël Raulet 《Journal of Real-Time Image Processing》2009,4(1):23-31
H.264 AVC video compression standard achieves high compression rates at the cost of a high encoder complexity. The encoder performances are greatly linked to the motion estimation operation which requires high computation power and memory bandwidth. High definition context magnifies the difficulty of a real-time implementation. EPZS and HME are two well-known motion estimation algorithms. Both EPZS and HME are implemented in a DSP and their performances are compared in terms of both quality and complexity. Based on these results, a new algorithm called HDS for Hierarchical Diamond Search is proposed. HDS motion estimation is integrated in a AVC encoder to extract timings and resulting video qualities reached. A real-time DSP implementation of H.264 quarter-pixel accuracy motion estimation is proposed for SD and HD video format. Furthermore HDS characteristics make this algorithm well suited for H.264 SVC real-time encoding applications. 相似文献
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Gray W.S. Nabet B. 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》1999,29(2):190-197
The motion detection problem occurs frequently in many applications connected with computer vision. Researchers have studied motion detection based on naturally occurring biological circuits for over a century. In this paper, we propose and analyze a motion detection circuit which is based on nerve membrane conduction. It consists of two unidirectional neural networks connected in an opposing fashion. Volterra input-output (I-O) models are then derived for the network so that velocity estimation can be cast as a parameter estimation problem. The technique is demonstrated through simulation. 相似文献
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This contribution focuses on different topics that are covered by the special issue titled “Real-Time Motion Estimation for image and video processing applications” and which incorporate GPUS, FPGAs, VLSI systems, DSPs, and Multicores, among other platforms. The guest editors have solicited original contributions, which address a wide range of theoretical and practical issues related to high-performance motion estimation image processing including, but not limited to: real-time matching motion estimation systems, real-time energy-based motion estimation systems, gradient-based motion estimation systems, optical flow estimation systems, color motion estimation systems, multi-scale motion estimation systems, optical flow and motion estimation systems, analysis or comparison of specialized architectures for motion estimation systems and real-world applications. 相似文献
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An adaptive modification to the two-bit transform-based low-complexity block motion estimation approach is proposed. Initially, video frames are converted into two-bit representations using the two-bit transform (2BT), and binary block-based motion estimation is performed using these two bit-planes. Modification to the original 2BT-based motion estimation scheme is introduced by conditional local or full searches using the mean absolute difference criterion to improve the initial motion estimation accuracy. The condition threshold is adaptively varied according to block detail using the block variance already computed for the 2BT process. Experimental results show that the proposed adaptive modified 2BT-based motion estimation technique can significantly improve peak signal-to-noise ratio performance compared with 2BT only motion estimation, and outperforms modified one-bit transform (1BT)-based motion estimation as well as modified 2BT-based motion estimation without adaptation at the same motion estimation cost. The main contribution of this work is to provide an adaptive decision on whether a modified search should be carried out after the low-complexity motion estimation process. 相似文献
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一种基于新型遗传算法的块运动估计算法 总被引:1,自引:0,他引:1
提出了一种基于新型遗传算法的块匹配运动估计算法。该算法把块运动向量作为遗传染色体,经过选择变异等操作,将随机搜索与特定目标搜索相结合,解决了以往快速搜索算法易陷于局部最优的问题,同时该算法中所带的模糊评价函数使得对个体的评价更合理、客观,该算法还将运动矢量空间偏置特性用于初始种群的选取,进一步提高了算法性能。实验结果表明,该算法性能上接近于FSA,速度却接近于TSS。 相似文献
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基于分组误差的快速分数像素运动估计算法 总被引:1,自引:0,他引:1
H.264是最新一代的视频编码标准,它支持高精度分数像素运动估计。当在整数运动估计中采用快速算法后,分数像素的运动估计可能成为制约快速运动估计算法性能的瓶颈。根据匹配准则的目标函数在最优运动矢量的附近都是单调递增这一假设,提出一种基于分组误差的快速分数像素运动估计算法。实验结果表明该算法不但能够有效降低分数像素运动估计的计算量,而且还能保持较小的率失真性能损失。 相似文献
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电子稳像系统的核心是运动估计和运动补偿。为了提供运动估计的精度和降低时间开销,达到实时应用的要求,该文提出了基于宏块的步进全局运动估计算法,获得图像序列的全局运动矢量;给出了一个新的应用于电子稳像系统中运动估计与运动补偿模块的运动估计、运动补偿原理框图;采用两步补偿算法完成对图像序列的运动补偿,得到稳定的图像序列输出。仿真结果表明,采用的方法是高效、可行的。 相似文献
10.
Tomás Crivelli Patrick Bouthemy Bruno Cernuschi-Frías Jian-feng Yao 《International Journal of Computer Vision》2011,94(3):295-316
In this work we present a new way of simultaneously solving the problems of motion detection and background image reconstruction.
An accurate estimation of the background is only possible if we locate the moving objects. Meanwhile, a correct motion detection
is achieved if we have a good available background model. The key of our joint approach is to define a single random process
that can take two types of values, instead of defining two different processes, one symbolic (motion detection) and one numeric
(background intensity estimation). It thus allows to exploit the (spatio-temporal) interaction between a decision (motion
detection) and an estimation (intensity reconstruction) problem. Consequently, the meaning of solving both tasks jointly,
is to obtain a single optimal estimate of such a process. The intrinsic interaction and simultaneity between both problems
is shown to be better modeled within the so-called mixed-state statistical framework, which is extended here to account for
symbolic states and conditional random fields. Experiments on real sequences and comparisons with existing motion detection
methods support our proposal. Further implications for video sequence inpainting will be also discussed. 相似文献
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《Robotics & Automation Magazine, IEEE》2004,11(4):31-38
This article describes an imaging system that has been designed to facilitate robotic tasks of motion. The system consists of a number of cameras in a network, arranged so that they sample different parts of the visual sphere. This geometric configuration has provable advantages compared to small field of view cameras for the estimation of the system's own motion and, consequently, the estimation of shape models from the individual cameras. The reason is, inherent ambiguities of confusion between translation and rotation disappear. Pairs of cameras may also be arranged in multiple stereo configurations, which provide additional advantages for segmentation. Algorithms for the calibration of the system and the three-dimensional (3-D) motion estimation are provided. 相似文献
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Jinghong Zheng Lap-Pui Chau 《Multimedia, IEEE Transactions on》2005,7(3):507-513
In this paper, we propose an efficient motion vector recovery algorithm for the new coding standard H.264, which is based on a polynomial model. To achieve better coding efficiency, the motion estimation scheme used in H.264 is different from previous coding standards. In H.264, a 16/spl times/16 macroblock can be divided into different block shapes for motion estimation. Each macroblock contains more motion vectors than previous coding standards. For nature video, the blocks within a small area likely belong to the same object, hence the motion vectors of neighboring blocks are highly correlated. Based on the correlation of neighboring motion vectors, we can use the motion vectors that are adjacent to the lost motion vectors to constitute a polynomial model, which can describe the change tendency of motion vectors within a small area. Through this model, the lost motion vectors can be predicted and the lost macroblocks can be reconstructed. Different video sequences are used to test the performance of proposed method. The simulation results show that the quality of corrupted video can be obviously improved by proposed algorithm. 相似文献
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为了在甚低比特率下实现对数字视频的有效压缩和编码,提出了一种混合的多分辨运动补偿零树视频编码方案。在该编码方案中,运动矢量的获取采用了可变块大小的多分辨运动估计算法,运动估算在小波域中进行。编码器的核心部分是同基于内容的自适应量化方法相结合的预测误差帧的小波零树编码,它产生了一种具有嵌入特征的比特流,从而为精确的速率控制和基于内容的位流调节提供了可能。基于上述编码方案的实验表明:在甚低比特率下,所提出的编码方案在峰值信噪比和恢复视频的主观质量方面都具有较好的性能。 相似文献
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Genetic algorithm-based motion estimation schemes play a significant role in improving the results of H.264/AVC standardization efforts when addressing conversational and non-conversational video applications. In this paper, we present a robust motion estimation scheme that uses a noble genetic trail bounded approximation (GTBA) approach to speed up the encoding process of H.264/AVC video compression and to reduce the number of bits required to code frame. The proposed algorithm is utilized to enhance the fitness function strength by integrating trail information of motion vector and sum of absolute difference (SAD) information into a fitness function. Experimental results reveal that the proposed GTBA resolves conflict obstacles with respect to both the number of bits required to code frames and the execution time for estimation. 相似文献
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We develop a mathematical model for the angular motion dynamics of a large-scale space construction with a gyroforce engine, in which coordinates of the construction’s elastic oscillations are fully observable. This lets us design a joint estimation algorithm for angular motion coordinates and elastic oscillations for orientation control and angular stabilization of the construction in question. We show mathematical modeling results for the synthesized estimation algorithm that support its high accuracy, convergence, and stability. 相似文献
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Fan C.M. Namazi N.M. Penafiel P.B. 《IEEE transactions on pattern analysis and machine intelligence》1996,18(3):348-352
This paper focuses on the presentation and implementation of a new iterative algorithm for image motion coefficient estimation from noisy measurements based on the expectation-maximization (EM) technique. We also compare this algorithm with two other robust iterative algorithms. We represent the motion field by a (unitary) series expansion to obtain the motion coefficients, and show this characterization to have several virtues. First, an inherent property of motion, referred to as smoothness, is imposed. Second, the nonuniform motion estimation is reduced to the estimation of a few coefficients using the low-pass property of the motion. Finally, the motion estimation can be accomplished without the need for a motion model; in the events for which the motion model is completely unknown, the DCT representation is shown to be very effective in describing the true motion 相似文献
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A novel technique to estimate motion of the center of mass (COM) for a biped robot is proposed. A Kalman filter is synthesized where the time evolution of COM is predicted from the external force and corrected based on kinematic estimation and torque equilibrium. They complementarily work to compensate the initial estimation offset, the error accumulation, and errors in modeled mass properties. It makes use of the authors’ previous method to estimate the translational and rotational motion of the base body from inertial information and joint angle measurements. The information about torque equilibrium helps to reduce an uncertainty of the height of COM and to improve the estimation accuracy of it by utilizing an interference of the horizontal and vertical motion of COM. The parameters are tuned based on error analyses in mass properties and sensor signals. A comparative study showed a better performance of the proposed method than other methods through dynamics simulations. 相似文献