中国科学院机构知识库网格系统: 检索

Coordination of multiple rigid bodies under distance-induced interaction topologies 期刊论文 OAI收割
IET CONTROL THEORY AND APPLICATIONS, 2018, 卷号: 12, 期号: 15, 页码: 2067-2075
作者: Deng, Juan; Wang, Lin; Liu, Zhixin; Hu, Xiaoming

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收藏 | 浏览/下载：42/0 | 提交时间：2018/11/16

synchronisation control system synthesis graph theory attitude control distributed control multi-robot systems collision avoidance velocity control mobile robots multiple rigid bodies distance-induced interaction topologies coordination control problem distance-induced neighbour graphs nearby bodies angular velocity linear velocity attitude synchronisation

Effect of the secondary process on mass point vibration velocity propagation in magneto-acoustic tomography and magneto-acousto-electrical tomography 期刊论文 iSwitch采集
Technology and health care, 2016, 卷号: 24, 页码: S683-s689
作者: Sun, Zhishen; Liu, Guoqiang; Guo, Liang; Xia, Hui; Wang, Xinli

收藏 | 浏览/下载：27/0 | 提交时间：2019/05/09

Magneto-acoustic tomography Magneto-acousto-electrical tomography Wave equation of mass point vibration velocity Linear damping

Analytical solution of velocity distribution for flow through submerged large deflection flexible vegetation 期刊论文 OAI收割
Applied Mathematics and Mechanics, 2015, 卷号: 36, 期号: 1, 页码: 107-120
作者: Wang WJ; Huai WX; Zeng YH; Zhou JF(周济福)

收藏 | 浏览/下载：30/0 | 提交时间：2015/03/17

analytical velocity distribution linear drag force flexible vegetation large deflection mixing length theory

Reentry guidance based on feedback linearization (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Electronics, Communications and Control, ICECC 2011, September 9, 2011 - September 11, 2011, Ningbo, China
Li D.-W.

收藏 | 浏览/下载：28/0 | 提交时间：2013/03/25

This paper presents a new reentry guidance algorithm for RLV (Reusable Launching Vehicle). The algorithm consists of two integrated components: trajectory planning algorithm and tracking algorithm. The most striking feature of algorithm here lies in that both planning and tracking are executed directly in height-velocity space which is different from the methodology of configuration of drag in traditional shuttle guidance. In the session of trajectory planning all trajectory constraints can be expressed with upper bound and lower bound in height-velocity space then a linear interpolation is carried to search the nominal trajectory satisfying the requirement of downrange and target constraints. Then the tracking algorithm uses feedback linearization method to track this nominal profile and meet all constraints. Another typical feature of this algorithm is the strategy of downrange extension using FPA (flight path angle) controller to fulfill the requirement of large downrange. Proper combination of planning-tracking algorithm and FPA controller can bring great flexibility and adaptability to reentry guidance. The algorithm is proved to be robust enough to accommodate the model error and noises in the dynamics. 2011 IEEE.

Debris flows in Meigu county of Sichuan (SW China): Geomorphology and hazards 会议论文 OAI收割
Padua, 2011
作者: Liu, Xilin; Zhang, Dan

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收藏 | 浏览/下载：28/0 | 提交时间：2018/11/08

Channel evolution Coefficient of velocity Debris flows Discharge ratio Junction angles Linear relationships Model tests Wenchuan Earthquake

Method of improving the accuracy of image motion measurement for panoramic aerial cameras (EI CONFERENCE) 会议论文 OAI收割
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
作者: Jia P.

收藏 | 浏览/下载：24/0 | 提交时间：2013/03/25

To improve the accuracy of image motion measurement for panoramic aerial cameras the paper proposed a method of real-time image motion measurement based on 2D spatial correlation. An auxiliary area CCD is positioned paralleled to the main linear TDI CCD in the focal plane of the camera. For every frame of the image sequence taken by the auxiliary CCD a prediction on the displacement of the current image in the flight direction is made based on the forward image motion velocity. The current and the reference images are combined together for 2D-correlation which products an image motion vector. By decomposing the vector both the forward and pendulum-swing image motions can be determined. The demanding computational requirements for the real-time 2D-correlation are covered by a joint transform optical correlator. Simulation test results show that the accuracy is improved and the measurement error is within 0.2 pixels for input images with SNR=1 dB. 2010 Copyright SPIE - The International Society for Optical Engineering.

The analysis for the reason of limit cycle generated by friction in servo system (EI CONFERENCE) 会议论文 OAI收割
2010 International Conference on Computer, Mechatronics, Control and Electronic Engineering, CMCE 2010, August 24, 2010 - August 26, 2010, Changchun, China
作者: Li M.

收藏 | 浏览/下载：19/0 | 提交时间：2013/03/25

In this paper limit cycle which results from friction during low-velocity servo system has been discussed. First the piecewise linearization method has been applied to change nonlinear stribeck model to linear model. Second with analysis of equilibrium property it is proved the existence of limit cycle and its certain region. The analysis reveals that it is because of stability of equilibrium repeatedly changing results in the limit cycle during low-velocity state. In addition it also points that the key point to avoid this phenomenon is to keep robust stability of the close-loop system. 2010 IEEE.

Nonlinear control design for system with mechanical resonance based on two tracking-differentiators (EI CONFERENCE) 会议论文 OAI收割
2010 IEEE International Conference on Mechatronics and Automation, ICMA 2010, August 4, 2010 - August 7, 2010, Xi'an, China
作者: Li J.; Li Y.; Li Y.; Li Y.; Li Y.

收藏 | 浏览/下载：20/0 | 提交时间：2013/03/25

A nonlinear control strategy for controlling a motion system with mechanical resonance is presented in this paper. A mathematical model of the servo system is derived according to the parameters of an actual system. By using two Tracking-Differentiators reference input and system output are tracked and their differential signals are given simultaneously. A nonlinear PD control law in velocity loop is designed based on non-smooth feedback. The simulation results show that the control law is superior remarkably in performance to linear PD control law and the classical PID control law. Tracking-Differentiator resolves the contradiction between rapidity and overshoot of system response. The nonlinear PD control law improves system dynamic performance and intensifies the ability of disturbance rejection. The control design achieved in this paper makes the servo system more robust. 2010 IEEE.

Global smooth solutions of the quasi-linear wave equation with internal velocity feedback 期刊论文 OAI收割
SIAM JOURNAL ON CONTROL AND OPTIMIZATION, 2008, 卷号: 47, 期号: 4, 页码: 2044-2077
作者: Zhang, Zhi-Fei; Yao, Peng-Fei

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收藏 | 浏览/下载：19/0 | 提交时间：2018/07/30

quasi-linear wave equation Riemannian metric internal velocity feedback

Key techniques of laser direct writing of fine lines on the spherical surface (EI CONFERENCE) 会议论文 OAI收割
ICO20: Optical Design and Fabrication, August 21, 2005 - August 26, 2005, Changchun, China
Liang F.; Hu J.

收藏 | 浏览/下载：21/0 | 提交时间：2013/03/25

The main principles of laser direct writing (LDW) system for lines on the spherical surface (SS) are discussed. It is pointed out that line profile is determined by the exposure dose distribution which lies on the light intensity distribution of focus plane and the scanning speed. To improve the quality of line profile on the SS several key techniques as follows are introduced. Firstly the unique system configuration four axes mutually intersecting at the center of the SS is adopted which ensures the shape of the focus be maintained circular during the writing period. Secondly an automatic focus system (AFS) with the function of automatic focus in a certain range is introduced. Thirdly to guarantee the linear velocity to accord with the exposure character of the photoresist all the time an efficient arithmetic that controls motors run at appropriate angular velocity in different latitude is developed. Finally to achieve a stable and well-behaved system so as to compensate the velocity instability resulting from unavoidable errors of mechanical and electronics factor a powerful programmable multi-axis controller (PMAC) is utilized as the kernel element of the servocontrol system and the curves of step response and parabolic response achieved by feedforward and PID loop tuning indicate that the location precision and velocity stability have reached a high level. The experimental results of LDW of lines on the SS work piece with a diameter 30 mm and a radius equal to 100 mm are given. The section analysis of the lines on the photoresist by the atomic force microscope (AFM) after exposure and development is performed. The results show that line width is about 3.0 m and the steep sides of the lines are parallel to each other.