Ge X.,Beijing Information Science and Technical University |
Chen K.,Beijing Information Science and Technical University
Lixue Xuebao/Chinese Journal of Theoretical and Applied Mechanics | Year: 2016
Based on the Legendre pseudospectral method, the optimal control of free floating space robots path planning problems are studied. Free floating is the working status for the space robots in task and path planning is the foundation for them to fulfil a complex space task. Because the space robots have no fixed pedestal and there are nonholonomic constraints between the manipulator and the carrier, and it makes the path planning for free floating space robots different from those on the ground. In this paper, the Legendre pseudospectral method which can realize the optimal control of free floating space robots path planning problem is presented. Firstly, a dynamic model of free floating space robots is established by using multi-body dynamics theory. The path planning problem of Bolza with certain initial and terminal stance is then obtained. Here, we select the minimum joint dissipation as performance index and consider the actual control input saturation. Then, by applying the Legendre pseudospectral method, the state and control variables are discretized at Legendre-Gauss-Lobatto (LGL) point and Lagrange interpolation polynomials are constructed to approximate the state and control variables. The problem of continuous path optimization is discretized to solve a nonlinear programming problem. Finally, results of the numerical simulation show that using the application of Legendre pseudospectral method to solve the problem of free floating space robot path planning can get the optimal trajectory of manipulator and carrier. It can fit various constraint conditions well. And this method is with fast simulation calculation, high accuracy and good real-time performance. © 2016, Editorial Office of Chinese Journal of Theoretical and Applied Mechanics. All right reserved.
Ai H.,Beijing Information Science and Technical University |
Li T.,Beijing Information Science and Technical University
Intelligent Automation and Soft Computing | Year: 2016
A smart home module program is designed based on Linux, in the ARM11 embedded development environment, and by using the UP-Magic 6410 development board. A touch-screen graphical interface for human-computer interaction is designed using QT. The sensor module is integrated into the underlying QT program, and the actuator module program performs external calls via QT, thus a complete set of smart home terminal is constituted. The function of remote video monitoring and the function of displaying module statuses on webpage are realized through connecting video cameras to the development board as well as constructing GoAhead web server and Spcaserv video server. A face recognition program is designed using MATLAB, a database for storing the face information for different users is designed, and they are connected to the smart home terminal. Based on face recognition, the identity information for the current user and the desired temperature are displayed, and the speed of the DC motor is changed. This system can also realize sound and light alarm. Alarm for harmful gas can be raised under the help of smoke sensor. The photosensitive sound switch module is used for simulating the voice control device so as to facilitate the user’s control of the DC motor switch. Infrared irradiation sensor is used for simulating the identity-card identification equipment, so as to limit the system users. Through the coordination of the above parts, a complete smart home system which is composed of a computer, embedded development environment, sensors, actuators and ancillary devices is finally established. © 2016 TSI® Press
Zhang X.,Beijing Information Science and Technical University |
Jia Y.,Beijing Information Science and Technical University
Lecture Notes in Electrical Engineering | Year: 2016
A system of real-time monitoring and wireless transmission of illuminance, temperature and humidity parameters for a greenhouse environment is achieved in the framework of ZigBee protocol stack. It mainly includes two kinds of minimum systems with the cores of Texas Instruments CC2530 chip and ARM STM32F103 chip. CC2530 minimum system completes network nodes function of multipoint parameter monitoring. BPW34S sensors are used to construct the illuminance collection module and SHT10 sensors are used to construct the temperature and humidity collection module. Multipoint parameter data are sampled by CC2530 nodes. A node chip transmits measured data wirelessly to another node based on ZigBee technology. The STM32 minimum system contains a CC2530 which is used to receive data from other sensor node modules through serial port. After the system processes the data, the result is displayed on LCD12864 screen. Experiment shows that data loss rate of this system are zero within 15 m communication distance. This system is suitable for a greenhouse of about 20 m × 25 m area and it has several advantages of low cost, easy installation, and high efficiency. © Springer-Verlag Berlin Heidelberg 2016.
Zhang L.,Beijing Information Science and Technical University
Sheng wu yi xue gong cheng xue za zhi = Journal of biomedical engineering = Shengwu yixue gongchengxue zazhi | Year: 2012
EEG Synchronization is considered the conformity of the brain functional areas. Advanced brain function requires many nervous systems with a specific function in relevant brain regions (areas) to achieve integration and coordination at different levels. In this paper, a new method for phase synchronization analysis-Mutually Approximate Entropy is proposed to process different frequency band of EEG signal during audio-visual stimulation and get Similar results with the method of Synchronization Index and Mutual Information Entropy. This showed that the Mutually Approximate Entropy can lead to a good indication of the phase synchronization between two leads. The paper also explored the brain reaction zone by the results of the phase synchronization analysis. The research work lays the foundation for the brain-computer interface design.
Wang J.,Beijing Information Science and Technical University |
Mu X.,Beijing Jiaotong University
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2015
Aiming at that current control strategies of voltage source PWM rectifier under unbalanced voltage conditions at home and abroad exist complicated control structure and unsatisfactory control performances, hybrid passivity based control strategy by DC voltage loop(PI) and passivity based current controller is proposed in the paper. Based on EL model of the PWM rectifier, passivity based current controller is designed by damping injection method. According to passivity based current controller, switch function that can compensate unbalanced voltage conditions is obtained. All harmonics in input current of rectifier can be eliminated or restrained and DC output voltage of rectifier is kept constant by hybrid passivity based controller based on the real time value of voltage and current. Hybrid passivity based controller can make rectifier having good performances, and has simple control structure. Hybrid passivity based control of voltage source PWM rectifiers under unbalanced voltage conditions is proved feasible by simulation and experimental results. ©, 2015, Chinese Machine Press. All right reserved.
Ying W.,Beijing Information Science and Technical University
Open Cybernetics and Systemics Journal | Year: 2015
Knowledge transfer amid organizational units provides chances for shared learning and contributes to making innovation of organizational unit’s ability. Cooperative network offers a platform for knowledge transfer among organizational units. So to understand the process of knowledge transfer of several inter-organizations accurately and improve the effectiveness of knowledge transfer in the cooperative network is one of the most important problems that enterprises are confronted with commonly. In this article we investigate the critical influencing aspects of knowledge transfer amid member organizations in the cooperative network from the perspective of network structure. We analyze the relationship between the critical structure characteristics (including network density, network range, network tie strength and network centricity) and the efficiency of knowledge transfer and we get the conclusion that the four network structure characteristics are closely contacted with the easiness of knowledge transfer. © Wang Ying.
Beijing Information Science and Technical University | Date: 2014-10-08
A gas detection system with an inner ring cavity fiber laser using saturated absorption optical fiber is provided. The system comprising a ring fiber laser consisted of a pump source, a wavelength division multiplexer, a first active optical fiber, a first coupler, a fiber Bragg grating and a second coupler connected successively; an optical isolator coupled between said first active optical fiber and said first coupler; a second active grating connected between said fiber Bragg grating and said first coupler; a detection gas chamber connected between said first coupler and said second coupler; a first photoelectric detector for detecting the laser intensity outputted from said ring fiber laser to generate a first light intensity signal; a second photoelectric detector for receiving the intensity measuring beam passing through the detection gas chamber to generate a second light intensity signal; and a feedback control unit.
Beijing Information Science and Technical University | Date: 2013-10-09
A method for measuring the strain of material using a short cavity fiber laser, includes steps of: a) arranging the short cavity fiber laser, which laser comprises sequentially coupled laser diode pumping source, a wavelength division multiplexer, a fiber bragg grating, an active fiber and a loop mirror; b) fixing the short cavity fiber laser on the material whose strain will be measured, and matching the stretching direction of the fiber of the short cavity fiber laser with the direction of the strain produced by the material to be measured; c) measuring the drift amount of longitudinal mode output by the short cavity fiber laser; and d) calculating and obtaining the strain of the material to be measured.
Beijing Institute of Technology, Beijing Information Science and Technical University | Date: 2013-09-02
The present invention provides an angular rate gyro in which a bell-shaped vibrator having nonuniform thickness, axially symmetric and multi curved surface combined structural features is used as a sensitive element. The angular rate gyro is composed of the bell-shaped vibrator, a vibrator fixing shaft, a vibrator base, an airtight hood, a housing and a circuit system. The bell-shaped vibrator includes a bell shoulder having a hemispheric shell structure, a bell waist having a cylindrical shell structure and a bell lip having a hyperboloidal shell structure. The bell-shaped vibrator, the base and a central shaft are mechanically and fixedly connected together to be formed into an integral core having sensitive gyratory effect. A circuit system is used to control vibration forms of the bell-shaped vibrator, perform signal processing and solve the applied angular rate.
Beijing Information Science and Technical University | Date: 2014-10-01
The present invention provides a fiber laser gas detection system using active feedback compensation by a reference cavity, said system comprising: an optical fiber laser consists of a laser diode pump source, a wavelength division multiplexer, an active optical fiber and a fiber Bragg grating connected successively; an optical isolator coupled with said wavelength division multiplexer for blocking a reverse light transmission in said active fiber; a coupler connected with said optical isolator for dividing the laser light after being isolated by the optical isolator into a reference beam, a detecting beam and an intensity measuring beam according a certain ration power. The gas detection system according to the present invention can take advantages of the unique superiority of compact structure and narrow linewidth of the laser output of the fiber laser, and achieve a gas detection method with high sensitive and high precision by feedback controlling.