Advanced Materials Research Vols. 383-390

Abstract: A new idea of multilevel leakage protective system is proposed in this paper in accordance with the deficiencies covered in present leakage protective system used in underground low voltage distribution networks. The leakage is especially analyzed, which occurred from transformer secondary to general switchgear or from general switchgear to branch switchgear. The new leakage protective equipments which based on the new idea are also introduced here. Finally equipments are tested. The measuring results show that equipments can form a leakage protective system, the selective leakage protection of which has no time difference. Consequently, the level of safety for underground LV distribution networks is greatly improved.

Abstract: The purpose of this paper is to model and study linear differential Hall sensor. A component for linear differential Hall sensor model was constructed, then a number of experiments were performed to check its output characteristics and temperature characteristics.Two Hall-components formed a linear differential Hall model,which had two independent outputs outputing differential voltage. The results show that the model significantly reduces quiescent output voltage, the signal amplitude increased 99.5%, sensitivity ≥ 40mV/mT, linearity error ≤ 0.5%, zero drift coefficient ≤0.023mV/°C.It is concluded that outputing differential voltage can prohibit common-mode interference and zero shift.The model will has self temperature compensation and nonlinear correctiion.In the future ,this model will practicaly in the current sensor.

Abstract: In order to improve the dynamical respond of the weighing system and to meet the demand of rapid weighing, a new method based on radial basis function neural network (RBFNN) is introduced in this paper. The dynamic system is described as a network and the output values of steady state are predicted by an on-line modeling before the platform has settled to the steady state. The sample weight is calculated according to weighted moving average. The experimental results proved that the neural network method in this paper can be used to effectively reduce the weighing time and to increase the accuracy simultaneously.

Abstract: A new method of rolling prediction for gas emission based on wavelet neural network is proposed in this paper. In the method, part of the sample data is selected, which length is constant, and the data is reselected as the next prediction step. Then a wavelet neutral network is adopted to prediction which input data is rolling, the sequence model of rolling prediction is thus constructed. Simulation results have proved that the method is valid and feasible.

Abstract: This paper details the design, production and programming methodology of a five degree of freedom robotic arm system. All the hardware and software of the robotic arm have been designed by author and manufactured successfully by CIMS & Robotics Center of Shanghai University. It is the arm of a service robot which is to present the following functions: Chinese calligraphy, carry something from one place to another exactly, and other accurate positioning motion in space. The robotic arm system is based on five orthotropic digital DC brushless servo motors in mechanism, five digital servoamplifier and other devices. Our communication mode is Can-bus, the control software is designed by vb.net2005 language under the .net framework and emulation based on matlab.

Abstract: Push-pull driving circuit is a type of commonly used driving circuit for ultrasonic motor. The symmetrical PWM signals are needed for the control of push-pull driver, and thus the motor. This paper introduces a novel 2-phase symmetrical PWM control signal generator that can be used with ultrasonic motor drive. The generator’s structure and operation is analyzed, and the actual realization using CPLD is also given out. The experimental results proved that, the design is correct.

Abstract: PWM technology has been widely used in motor drive systems today. To avoid the short-circuit condition, dead-time must be inserted to the PWM driving pulses. The addition of dead-time increases the harmonic of output voltage, makes the waveform of winding current more badly. The ripple of motor torque and speed is also increased by the addition of dead-time. The influence of dead-time is more remarkable while the motor speed is low, and so, greatly influence the low-speed working ability. This paper analyzes the influence of dead-time for low-speed motor drive in detail. The nonlinear phenomena in the motion of output voltage-vector, which affects the motor’s low-speed performance directly, is also indicate

Abstract: The Unmanned Aerial Vehicle (UAV) has special dynamical characteristics in ground motion different from that of flight in the airborne. The forces and moments on the ground to the UAV differ during taxiing, according to the different mechanical and aerodynamic characteristics. An all-states nonlinear model is established by studying on a sample UAV. Rotation speed and lift off speed is determined, finally a control law including longitudinal and lateral control for automatic take-off is designed. Results of simulation show that the model and control scheme can not only join the ground taxiing and flight in the airborne smoothly, but also has a high value in realizing engineering project.

Abstract: Electromagnetically inductive navigation system of the spraying robot is developed to meet the requirements of automatic spraying operation. The system is composed of the mechanical part, electromagnetic inductive sensor, SCM-based control system and DC electromotor PWM drive system. The mathematical model constituted by integral element and inertia element is founded with the DC servo-motor voltage as the input variable through the structural analysis of the navigation system. The increment digital PID algorithm is applied to achieve running path control of the spraying robot. Experimental results indicate that the spraying robot navigation system based on digital PID algorithm overcomes time-varying volatility, nonlinearity and strong coupling, thus has fast response speed and good robustness.

Abstract: According to the lack of simple, backward and low precision in fault diagnosis on hydraulic power cart for aircraft, an efficient vehicle fault diagnosis system on hydraulic power cart for aircraft is developed based on embedded technology. This system can identify the cause of the faults quickly and accurately according to the data collected in the spot and real-time analysis using expert system, the results show it greatly improves the efficiency and accuracy of fault diagnosis on hydraulic power cart for aircraft.