中国开放科研知识云: 检索

High gain observer for drag tracking in mars entry longitudinal guidance (EI CONFERENCE) 会议论文
2012 International Conference on Measurement, Instrumentation and Automation, ICMIA 2012, September 15, 2012 - September 16, 2012, Guangzhou, China
Wu K.; Cui H.; Ma D.; Cui P.

收藏 | 浏览/下载：13/0 | 提交时间：2013/03/25

An extended high gain state and perturbation observer combined with feedback linearization was applied in drag tracking for Mars entry longitudinal guidance. The observer estimates the drag the drag rate and the perturbation due to model uncertainty and disturbance for drag tracking. Mars entry simulation was performed to assess the performance of the adaptive guidance law. The results demonstrate that the proposed guidance law is robust to model error and can recover the ideal performance of the feedback linearization control. Introduction In recent years the concept of pinpoint landing has been proposed (2013) Trans Tech Publications Switzerland.

Design of high speed and parallel compression system used in the big area CCD of high frame frequency (EI CONFERENCE) 会议论文
2011 International Conference on Precision Engineering and Non-Traditional Machining, PENTM 2011, December 9, 2011 - December 11, 2011, Xi'an, China
Liu Y.-Y.; Gao Y.-H.; Li G.-N.; Wang W.-H.; Zhang R.-F.; Jin L.-X.

收藏 | 浏览/下载：47/0 | 提交时间：2013/03/25

According to the area CCD camera of characteristics such as high resolution capacity and high frame frequency this paper puts forward a high speed and parallel image compression system of high integration degree. Firstly according to the work principle of the area CCD FPGA is adopted to realize the timing driving and multichannel and parallel analog signal handling to raise the export frame frequency of the area CCD. Secondly with an image compression scheme based on FPGA embedded processor MicroBlaze and ADV212 compression chip real time image compression and the high speed area CCD are realized. Finally by detecting the analog signal of the area CCD output the real time compression of the big area CCD image is carried out in different compression ratios and the compression performance is analyzed. Experiment result shows that this scheme can realize real time image compression with the biggest data rate of 520Mbps. When compression bit ratio is 0.15 the signal-to-noise ratio of peak value can reach 36 dB. Image collection and image compression are integrated which reduces the data transmission between them and improves systematic integration degree.

The technique of camera scan control based on current loop control (EI CONFERENCE) 会议论文
2011 International Conference on Electronics and Optoelectronics, ICEOE 2011, July 29, 2011 - July 31, 2011, Dalian, China
Li Q.; Liu Z.

收藏 | 浏览/下载：18/0 | 提交时间：2013/03/25

As the crucial structure of aerial camera sca reflector is always requested with high performance of control precision stable running and rapid responding. The paper introduces a kind of method about current loop control system which is based on position and velocity dual-closed loop control system. This method improves effectively the performance of velocity closed loop control system and amplifies the gain of low frequency. The results show applying these control methods the influence of the torque ripple has decrease 50% and the compensation rate precsion has promoted double. 2011 IEEE.

The stability design and realization of airborne platform based on TMS320F2812 (EI CONFERENCE) 会议论文
2011 International Conference on Mechatronic Science, Electric Engineering and Computer, MEC 2011, August 19, 2011 - August 22, 2011, Jilin, China
Li X.; Li Q.; Zhang X.

收藏 | 浏览/下载：29/0 | 提交时间：2013/03/25

Airborne electro-optical stable platform can isolate movement and vibration of the airframe stabilizes the optic axis of the photoelectic detector realize the observation and tracking for the object. It has comprehensive application value in army and cicil field. Most of present airborne platforms are analogic control system digital control system can improve the system general performance digital control is the development direction of platform systems. In view of the requirements of isolating disturbances and stabilizing optical axis of high-precision photoelectric guidance system a three-axis stabilized platform system centering on the rate gyro was designed. The disturbance-isolation theory of the stabilized platform was analyzed and the control structure including multiple closed-loops was designed. At last a controller of the servo system based on TMS320F2812 DSP has been designed. Experiment results meet the technical index and precision requirement and illustrate the practicability and effectiveness of the scheme. 2011 IEEE.

Design of driving circuit for binocular CCD image system (EI CONFERENCE) 会议论文
5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optoelectronic Materials and Devices for Detector, Imager, Display, and Energy Conversion Technology, April 26, 2010 - April 29, 2010, Dalian, China
Zhang M.; Ren J.; Zhang X.

收藏 | 浏览/下载：28/0 | 提交时间：2013/03/25

The paper designs a driving circuit of high sensitive wide dynamic and high signal-to-noise ratio for binocular CCD imaging system which adopts a Dalsa-made high resolution full-frame 33-mega pixels area CCD FTF5066M. Inner structure and driving timing of the FTF5066M sensor are presented. Field Programmable Gate Array (FPGA) is used as the main device to accomplish the timing design of the circuits and power driver control of the two sensors. By using the Correlated Double Sampling (CDS) technique the video noise is reduced and the SNR of the system is increased. A 12- bit A/D converter is used to improve the image quality. The output rate of the imaging system designed with integrated chip can reach to 1.3 frames per second through bi-channel. For its good performance low power consumption and small volume the driving system can be applied to aeronautics and astronautics field. With a further improvement a maximum data output rate of 2.7 frames per second can be reached through all the eight channels of the two CCDs. 2010 Copyright SPIE - The International Society for Optical Engineering.

Design of high-speed low-noise pre-amplifier for CCD camera (EI CONFERENCE) 会议论文
5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optoelectronic Materials and Devices for Detector, Imager, Display, and Energy Conversion Technology, April 26, 2010 - April 29, 2010, Dalian, China
Xue X.; Zhang S.; Li H.; Guo Y.

收藏 | 浏览/下载：18/0 | 提交时间：2013/03/25

Pre-amplifier circuit is critical for the noise performance of the high speed CCD camera. Its main functions are amplification and impedance transform. The high speed and low noise pre-amplifier of CCD camera is discussed and designed in this paper. The high speed and low noise operational amplifier OPA842 is adopted as the main part. The gain-set resistors for the amplifier are designed optimally. The different precision gain-set resistors are swept using Monte Carlo method. CCD video signal which has high DC offset voltage is AC coupled to the amplifier. The output signal of the amplifier is source terminated using 50 ohms matching resistor so as to transmit the video signal through coaxial cable. When the circuit works in high speed the PCB will have important effect to circuit performance and can even cause the amplifier unstable due to the parasitic problem of PCB. So the parasitic model of the PCB is established and the PCB layout design issues are also presented. The design result shows that the pre-amplifier can be used in the camera whose pixel rate could be up to 40 MHz and its input referred noise density is about 3 nV/Hz 1/2. 2010 Copyright SPIE - The International Society for Optical Engineering.

The design of high-speed optical fiber communication system based on PCI bus (EI CONFERENCE) 会议论文
2010 2nd IEEE International Conference on Advanced Management Science, ICAMS 2010, July 9, 2010 - July 11, 2010, Chengdu, China
Liang G.-L.; He X.; Wei Z.-H.; He J.-W.; Zhang L.-G.

收藏 | 浏览/下载：42/0 | 提交时间：2013/03/25

In order to increase the transmission distance and reduce noise effectively a communication system with the optical fiber interface is developed in this paper. In the system the PCI bus is adopted as the connection bus between the underlying optical fiber transceiver module circuitry and host computer using the WDM driver. The FPGA is the core logic of the whole system responsible for data transmission and timing logic control. The module structure and the design method of the PCI bus the principle and the design of optical interface module and the bottom-driven development are described in this paper. The experiment results show that the system has basically meet requirement targets. It can achieve the maximum transfer rate of 40MBps when running in the DMA mode. With long transmission distance strong antiinterference and high scalability this system has stable and reliable performance. 2010 IEEE.

Research on tracking approach to low-flying weak small target near the sea (EI CONFERENCE) 会议论文
ICO20: Optical Information Processing, August 21, 2005 - August 26, 2005, Changchun, China
Zhang S.-Y.; Liu W.-N.; Xue X.-C.

收藏 | 浏览/下载：24/0 | 提交时间：2013/03/25

Automatic target detection is very difficult in complicate background of sea and sky because of the clutter caused by waves and clouds nearby the sea-level line. In this paper in view of the low-flying target near the sea is always above the sea-level line we can first locate the sea-level line and neglect the image data beneath the sea-level line. Thus the noise under the sea-level line can be suppressed and the executive time of target segmentation is also much reduced. A new method is proposed which first uses neighborhood averaging method to suppress background and enhance targets so as to increase SNR and then uses the multi-point multi-layer vertical Sobel operator combined with linear least squares fitting to locate the sea-level line lastly uses the centroid tracking algorithm to detect and track the target. In the experiment high frame rate and high-resolution digital CCD camera and high performance DSP are applied. Experimental results show that this method can efficiently locate the sea-level line on various conditions of lower contrast and eliminate the negative impact of the clutter caused by waves and clouds and capture and track target real-timely and accurately.

Non-contact and on-line cone diameter measuring based on high speed linear CCD (EI CONFERENCE) 会议论文
2nd International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, November 2, 2005 - November 5, 2005, Zian, China
Guohui Z.; Jianhua W.

收藏 | 浏览/下载：20/0 | 提交时间：2013/03/25

The remarkable improvement of sensing and processing hardware performance makes the non-contact on-line high accuracy and high speed measuring possible by means of linear CCD. The goal of this pager is to describe the key questions on designing the cone diameter detecting system by linear CCD. This paper first describes the detecting scheme. In particular the factors affecting accuracy such as resolution voltage difference between neighbor pixels detecting rate and so on are analyzed and the quantitative estimation equations are provided. CCD takes on the photoelectric translation and measuring component double functions so the waveform of CCD output signal and the affecting factors merit deep discussion. On the basis of discussion several principles that can be used to improve the boundary recognition accuracy are presented.

Lossless wavelet compression on medical image (EI CONFERENCE) 会议论文
4th International Conference on Photonics and Imaging in Biology and Medicine, September 3, 2005 - September 6, 2005, Tianjin, China
Zhao X.; Wei J.; Zhai L.; Liu H.

收藏 | 浏览/下载：28/0 | 提交时间：2013/03/25

An increasing number of medical imagery is created directly in digital form. Such as Clinical image Archiving and Communication Systems (PACS). as well as telemedicine networks require the storage and transmission of this huge amount of medical image data. Efficient compression of these data is crucial. Several lossless and lossy techniques for the compression of the data have been proposed. Lossless techniques allow exact reconstruction of the original imagery while lossy techniques aim to achieve high compression ratios by allowing some acceptable degradation in the image. Lossless compression does not degrade the image thus facilitating accurate diagnosis of course at the expense of higher bit rates i.e. lower compression ratios. Various methods both for lossy (irreversible) and lossless (reversible) image compression are proposed in the literature. The recent advances in the lossy compression techniques include different methods such as vector quantization wavelet coding neural networks and fractal coding. Although these methods can achieve high compression ratios (of the order 50:1 or even more) they do not allow reconstructing exactly the original version of the input data. Lossless compression techniques permit the perfect reconstruction of the original image but the achievable compression ratios are only of the order 2:1 up to 4:1. In our paper we use a kind of lifting scheme to generate truly loss-less non-linear integer-to-integer wavelet transforms. At the same time we exploit the coding algorithm producing an embedded code has the property that the bits in the bit stream are generated in order of importance so that all the low rate codes are included at the beginning of the bit stream. Typically the encoding process stops when the target bit rate is met. Similarly the decoder can interrupt the decoding process at any point in the bil stream and still reconstruct the image. Therefore a compression scheme generating an embedded code can start sending over the network the coarser version of the image first and continues with the progressive transmission of the refinement details. Experimental results show that our method can get a perfect performance in compression ratio and reconstructive image.

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