检索结果-内蒙古大学图书馆

LANDING AN UNMANNED AIR VEHICLE: VISION BASED MOTION ESTIMATION AND NONLINEAR CONTROL

Asian Journal of Control 2008年第3期1卷

作者： Omid Shakernia Yi Ma T. John Koo Shankar Sastry Dept. of Electrical Engineering & Computer Science University of California at Berkeley Berkeley CA94720-1774 U.S.A. Tak-Kuen John Koo received the B.Eng. degree in 1992 in Electronic Engineering and the M.Phil. in 1994 in Information Engineering both from the Chinese University of Hong Kong. From 1994 to 1995 he was a graduate student in Signal and Image Processing Institute at the University of Southern California. He is currently a Ph.D. Candidate in Electrical Engineering and Computer Sciences at the University of California at Berkeley. His research interests include nonlinear control theory hybrid systems inertial navigation systems with applications to unmanned aerial vehicles. He received the Distinguished M.Phil. Thesis Award of the Faculty of Engineering The Chinese University of Hong Kong in 1994. He was a consultant of SRI International in 1998. Currently he is the team leader of the Berkeley AeRobot Team and a delegate of The Graduate Assembly University of California at Berkeley. He is a student member of IEEE and SIAM. S. Shankar Sastry received his Ph.D. degree in 1981 from the University of California Berkeley. He was on the faculty of MIT from 1980-82 and Harvard University as a Gordon McKay professor in 1994. He is currently a Professor of Electrical Engineering and Computer Sciences and Bioengineering and Director of the Electronics Research Laboratory at Berkeley. He has held visiting appointments at the Australian National University Canberra the University of Rome Scuola Normale and University of Pisa the CNRS laboratory LAAS in Toulouse (poste rouge) and as a Vinton Hayes Visiting fellow at the Center for Intelligent Control Systems at MIT. His areas of research are nonlinear and adaptive control robotic telesurgery control of hybrid systems and biological motor control. He is a coauthor (with M. Bodson) of “Adaptive Control: Stability Convergence and Robustness Prentice Hall 1989.” and (with R. Murray and Z. Li) of “A Mathematical Introduction to Robotic Manipulati

In this paper, we use computer vision as a feedback sensor in a control loop for landing an unmanned air vehicle (UAV) on a landing pad. The vision problem we address here is then a special case of the classic ego-motion estimation problem since all feature points lie on a planar surface (the landing pad). We study together the discrete and differential versions of the ego-motion estimation, in order to obtain both position and velocity of the UAV relative to the landing pad. After briefly reviewing existing algorithm for the discrete case, we present, in a unified geometric framework, a new estimation scheme for solving the differential case. We further show how the obtained algorithms enable the vision sensor to be placed in the feedback loop as a state observer for landing control. These algorithms are linear, numerically robust, and computationally inexpensive hence suitable for real-time implementation. We present a thorough performance evaluation of the motion estimation algorithms under varying levels of image measurement noise, altitudes of the camera above the landing pad, and different camera motions relative to the landing pad. A landing controller is then designed for a full dynamic model of the UAV. Using geometric nonlinear control theory, the dynamics of the UAV are decoupled into an inner system and outer system. The proposed control scheme is then based on the differential flatness of the outer system. For the overall closed-loop system, conditions are provided under which exponential stability can be guaranteed. In the closed-loop system, the controller is tightly coupled with the vision based state estimation and the only auxiliary sensor are accelerometers for measuring acceleration of the UAV. Finally, we show through simulation results that the designed vision-in-the-loop controller generates stable landing maneuvers even for large levels of image measurement noise. Experiments on a real UAV will be presented in future work.

关键词： Motion estimation computer vision based control unmanned air vehicle differential flatness

来源：评论

学校读者我要写书评

暂无评论

Iterative Detection of Linear Objects in GPR and Seismic images

Iterative Detection of Linear Objects in GPR and Seismic Ima...

引用

Sensor Array and Multichannel signal processing Workshop

作者： A.C. Gurbuz J.H. McClellan Center for Signal and Image Processing School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA USA

An iterative technique for detecting linear features in 2D images based on the Radon transform is developed. The algorithm is suitable for processing ground penetrating radar (GPR) and seismic images to find underground pipes and tunnels. Detection is performed in the Radon transform space. The length and width of the linear object area are estimated and the corresponding portion of the image is removed at each iteration. The algorithm has the advantage of detecting very weak linear objects, which are barely detected by existing detection algorithms, in Radon transform space. The proposed algorithm is tested on both simulated and experimental data measured from a laboratory scale model area. Results show successful detection of strong and weak linear objects

关键词： Object detection Ground penetrating radar Radar detection Space technology Iterative algorithms Detection algorithms Testing Laboratories signal processing image processing

来源：评论

学校读者我要写书评

暂无评论

Conjugate Distributed Arithmetic Adaptive FIR Filters and their Hardware Implementation

Conjugate Distributed Arithmetic Adaptive FIR Filters and th...

引用

Midwest Symposium on Circuits and Systems (MWSCAS)

作者： Walter Huang Venkatesh Krishnan David V. Anderson Center for Signal and Image Processing School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA USA

Adaptive filtering constitutes an important class of DSP algorithms employed in several hand held mobile devices for applications such as echo cancellation, signal de-noising, and channel equalization. In this paper, a new hardware architecture using conjugate distributed arithmetic (CDA) which is suitable for high throughput hardware implementations of LMS adaptive filters is presented. Unlike a traditional distributed arithmetic (DA) implementation where all possible combination sums of the filter coefficients are stored in a look-up-table (LUT), in the CDA architecture, all possible combination sums of the input signal samples are stored in the LUT and updated at the arrival of every sample using an efficient update procedure. We describe the design of CDA adaptive filters and show that practical implementations of CDA adaptive filters have very high throughput relative to multiply and accumulate architectures. We also show that CDA adaptive filters have a potential area and power consumption advantage over DSP microprocessor architectures for a given throughput.

关键词： Arithmetic Finite impulse response filter Hardware Adaptive filters Throughput Digital signal processing Table lookup Filtering algorithms Echo cancellers signal denoising

来源：评论

学校读者我要写书评

暂无评论

Noise Robust Aurora-2 Speech Recognition Employing a Codebook-Constrained Kalman Filter Preprocessor

Noise Robust Aurora-2 Speech Recognition Employing a Codeboo...

引用

International Conference on Acoustics, Speech, and signal processing (ICASSP)

作者： V. Krishnan S.M. Siniscalchi D.V. Anderson M.A. Clements Center for Signal and Image Processing School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA USA

In this paper, a speech signal estimation framework involving Kalman filters for use as a front-end to the Aurora-2 speech recognition task is presented. Kalman-filter based speech estimation algorithms assume autoregressive (AR) models for the speech and the noise signals. In this paper, the parameters of the AR models are estimated using a expectation-maximization approach. The key to the success of the proposed algorithm is the constraint on the AR model parameters corresponding to the speech signal to belong to a codebook trained on AR parameters obtained from clean speech signals. Aurora-2 noise-robust speech recognition experiments are performed to demonstrate the success of the codebook-constrained Kalman filter in improving speech recognition accuracy in noisy environments. Results with both clean and multi-conditional training are provided to show the improvements in the recognition accuracy compared to the base-line system where no pre-processing is employed

关键词： Noise robustness Speech recognition Speech enhancement Speech processing Automatic speech recognition signal processing State estimation Working environment noise Feature extraction Time measurement

来源：评论

学校读者我要写书评

暂无评论

Optimal Experiments With Seismic Sensors

Optimal Experiments With Seismic Sensors

引用

International Conference on Acoustics, Speech, and signal processing (ICASSP)

作者： M. Alam V. Cevher J.H. McClellan Center for Signal and Image Processing School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA USA

In this paper, we consider the problem of detecting and locating buried land mines and subsurface objects by using seismic waves. We demonstrate an adaptive seismic system that maneuvers an array of receivers, according to an optimal positioning algorithm based on the theory of optimal experiments, to minimize the number of distinct measurements to localize the mine. The adaptive localization algorithm is tested using numerical model data as well as laboratory measurements performed in a facility at Georgia Tech. It is envisioned that the future systems should be able to incorporate this new method into portable mobile mine-location systems

关键词： Landmine detection Seismic measurements Buried object detection Seismic waves Adaptive systems Adaptive arrays Position measurement Testing Numerical models Laboratories

来源：评论

学校读者我要写书评

暂无评论

Imaging and Detector Framework for Seismic Landmine Detection

Imaging and Detector Framework for Seismic Landmine Detectio...

引用

Sensor Array and Multichannel signal processing Workshop

作者： M. Alam J.H. McClellan Center for Signal and Image Processing Georgia Institute of Technology School of Electrical and Computer Engineering Atlanta GA USA

In this paper, we consider the problem of detecting and locating buried landmines and subsurface objects by using seismic waves measured with sources and receivers on the surface. An imaging algorithm is proposed which uses the separated forward and reflected waves obtained via a Prony-based spectrum analysis technique. The imaging algorithm is followed by an energy detector. The resulting algorithms will are verified by using the experimental data containing mines and clutter

关键词： Landmine detection Detectors Sensor arrays Seismic waves Surface waves Data mining Resonance Laboratories Testing image reconstruction

来源：评论

学校读者我要写书评

暂无评论

Low Complexity Inter-Mode Selection for H.264

Low Complexity Inter-Mode Selection for H.264

引用

IEEE International Conference on image processing

作者： Seydou-Nourou Ba Yucel Altunbasak Hasan Ates Center for Signal and Image Processing Georgia Institute of Technology Atlanta GA USA Department of Electronics Engineering Isik University Istanbul Turkey

The coding efficiency of the H.264/AVC standard enables the transmission of high quality video over bandwidth limited networks. Due to the use of multiple macroblock (MB) partitions, the motion estimation module has extremely high complexity that makes it unpractical for most real-time applications on resource-limited platforms such as hand held devices. In this paper we propose a novel algorithm that significantly reduces the encoding complexity while maintaining high rate distortion performance. The proposed method reduces the motion estimation (ME) computational complexity by accurately predicting the optimal MB partitions and restricting the number of candidate modes based on a-priori probabilities computed from spatio-temporal information. The experimental results show that the speed up of UmHexagonS (one of the most efficient ME algorithms) can be doubled while maintaining the coding efficiency of full search.

关键词： image coding Encoding Automatic voltage control Partitioning algorithms signal processing algorithms Computational complexity Bit rate Motion estimation Rate-distortion Lagrangian functions

来源：评论

学校读者我要写书评

暂无评论

Fast Computation of Centroids for Constant-Width Interval-Valued Fuzzy Sets

Fast Computation of Centroids for Constant-Width Interval-Va...

引用

Conference of the North American Fuzzy Information processing Society - NAFIPS

作者： Jerry M. Mendel Hongwei Wu Vladik Kreinovich Gang Xiang Signal and Image Processing Institute Department of Electrical Engineering University of Southern California Los Angeles CA USA Pan-American Center for Earth and Environmental Studies University of Texas El Paso El Paso TX USA

Interval-valued fuzzy sets provide a more adequate description of uncertainty than traditional fuzzy sets; it is therefore important to use interval-valued fuzzy sets in applications. One of the main applications of fuzzy sets is fuzzy control, and one of the most computationally intensive part of fuzzy control is defuzzification. Since a transition to interval-valued fuzzy sets usually increases the amount of computations, it is vitally important to design faster algorithms for the corresponding defuzzification. In this paper, we provide such an algorithm for a practically important case of constant-width interval-valued fuzzy sets

关键词： Fuzzy sets Fuzzy logic Fuzzy control Uncertainty Interpolation Medical diagnostic imaging signal processing image processing Earth Algorithm design and analysis

来源：评论

学校读者我要写书评

暂无评论

Multi-Modal Human Verification Using Face and Speech

Multi-Modal Human Verification Using Face and Speech

引用

IEEE International Conference on Computer Vision Systems (ICVS)

作者： Changhan Park Joonki Paik Taewoong Choi Soonhyob Kim Youngouk Kim J. Namkung Image Processing and Intelligent Systems Laboratory Department of Image Engineering Graduate School of Advanced Imaging Science Multimedia and Film Chung-Ang University Seoul South Korea Multimedia Signal Processing Laboratory Kwangwoon University Seoul South Korea Precision Machinery Center Korea Electronics and Technology Institute Puchon Gyeonggi South Korea Intelligent Image Communication Laboratory Department of Computer Engineering Kwangwoon University Seoul South Korea

In this paper, we propose a personal verification method using both face and speech to improve the rate of single biometric verification. False acceptance rate (FAR) and false rejection rate (FRR) have been a fundamental bottleneck of real-time personal verification. The proposed multimodal biometric method is to improve both verification rate and reliability in real-time by overcoming technical limitations of single biometric verification methods. The proposed method uses principal component analysis (PCA) for face recognition and hidden markov model (HMM) for speech recognition. It also uses fuzzy logic for the final decision of personal verification. Based on experimental results, the proposed system can reduce FAR down to 0.0001%, which provides that the proposed method overcomes the limitation of single biometric system and provides stable personal verification in real-time.

关键词： Humans Speech Face detection Face recognition Biometrics Principal component analysis Feature extraction Hidden Markov models image edge detection Laboratories

来源：评论

学校读者我要写书评

暂无评论

Multi-modal human verification using face and speech

Multi-modal human verification using face and speech

引用

Fourth IEEE International Conference on Computer Vision Systems, ICVS'06

作者： Park, Changhan Choi, Taewoong Kim, Youngouk Kim, Soonhyob Namkung, Jaechan Paik, Joonki Department of Image Engineering Graduate School of Advanced Imaging Science Multimedia and Film Chung-Ang University 221 Huksuk-dong Tongjak-Ku Seoul 156-756 Korea Republic of Multimedia Signal Processing Laboratory Department of Computer Engineering Kwangwoon University 447-1 Wolge-dong Nowon-Gu Seoul 139-701 Korea Republic of Intelligent Image Communication Laboratory Department of Computer Engineering Kwangwoon University 447-1 Wolge-dong Nowon-Gu Seoul 139-701 Korea Republic of Precision Machinery Center Korea Electronics Technology Institute 401-402 B/D 193 Yakdae-dong Wonmi-Gu Puchon Kyunggido 420-140 Korea Republic of

ISBN: (纸本)0769525067

关键词： Face recognition

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：