مهندسی برق مجلسی
سال:1390 | دوره: | شماره: |تعداد مقالات:7

This paper presents a new approach to a robust fuzzy controller design for the bilateral teleportation system with varying time delays using linear matrix inequalities. Communication channels are considered with different forwarding and returning time delays. The time delays of communication channels are assumed to be unknown and randomly time varying, but the upper bounds of the delay interval and the derivative of the delay are assumed to be known. In order to design the controllers, first, an impedance controller is designed for the master system to achieve desired impedance behavior for the master. Then, nonlinear Euler-Lagrange equation of motion of the slave system is linearized in the neighborhood of some operating points. In the sequel, an open-loop scheme is considered for the slave system. The linear model of the slave system has two imaginary/unstable poles. The slave system is stabilized by a PD-controller to be used in the open-loop scheme. To design the slave controller, the tele-operator block diagram is rearranged such that the tele-operator block diagram converts to a standard representation of a feedback control system which helps us to design a robust H-infinity controller for the slave system. The local linear models of the system are combined to form a Takagi-Sugeno fuzzy model of the whole tele-operation system. A Lyapunov-Krasovskii function is defined to analyze the closed-loop system’s stability and derive a sufficient delay-dependent stability criterion. An H-infinity performance index is defined and the design criteria for the slave controller are expressed as a set of LMIs, which can be tested readily using standard numerical software.

Here, a self-oscillating mixer is experimentally demonstrated employing both the fundamental and harmonic signals generated by the oscillator sub-circuit in the mixing process. The resulting circuit is a dual-band down-converting mixer that can operate in the C-band, or in the X-band. The oscillator uses the active super harmonic coupling to enforce the quadrature relationship of the fundamental outputs. Either the fundamental outputs of the oscillator or the second harmonic oscillator output signals present at the common mode nodes are connected to the mixer via a set of complementary switches. The mixer achieves a conversion gain between 9-11.5 dB in both frequency bands. The third-order output intercept-point for the C-band and the X-band operations are 10.42 and 8.33 dBm, respectively. The circuit was designed and simulated in 0.18- CMOS technology by ADS2008.

This paper presents an investigation on the Hybrid Seven-Level (HSL) H–bridge inverter, which is used in a Distribution Static Compensator (DSTATCOM) in Power Systems (PS). Making use of HSLI has the benefits of low harmonics distortion, reduced number of switches required to achieve the seven- level inverter output over the conventional cascaded seven-level inverter, and also reduced switching losses. In order to compensate the reactive power and suppress the total harmonics distortion (THD) drawn from a Non-Liner Diode Rectifier Load (NLDRL) of DSTATCOM, we propose a Sub-Harmonics Pulse Width Modulation (SHPWM) technique to control the switches of HSL H-bridge inverter. The D-Q reference frame theory is used to generate the reference compensating currents for DSTATCOM and proportional and integral (PI) control is used for capacitors dc voltage regulation for DSTATCOM.An HSL H-bridge inverter is considered for the shunt compensation of a 4.5 kV distribution system. The results are validated by MatLab/Simulink simulation software.

This paper considers the problem of robust H¥ filter design in uncertain discrete-time singular systems with possible missing measurements due to unreliable network transmission channels. The stochastic variable satisfying Bernoulli random binary distribution is introduced to model the missing phenomena and the corresponding filtering error dynamics with delay is then induced. We provide a set of sufficient conditions for the existence of the desired filter, and propose a robust filter design method under a strict linear matrix inequality framework. A numerical example is given to illustrate the effectiveness of the proposed method.

In this paper, a control strategy for a non-holonomic robot based on an Adaptive Neural Fuzzy Inference System is proposed. The neuro-controller makes it possible for the robot to track a given reference trajectory. After a short introduction about Adaptive Neural Fuzzy Inference System, the control strategy which is used on our virtual non-holonomic robot is described. And finally, the simulations’ results where the robot has to pass into a narrow path and also the first validation results concerning the implementation of the proposed concepts on a real robot is given.

In this paper, the crosstalk in 32 nm UTB SOI MOSFET is examined by using a new structure, a high resistivity substrate, and a multilayer BOX (SiO2-Diamond). The electrical and thermal characteristics of the conventional SOI and a multilayer BOX SOI are compared, and it is concluded that parasitic capacitances and crosstalk are improved by incorporating multilayer BOX to a HR Substrate. In a conventional HR FD SOI, crosstalk is approximately -121dB, while by incorporating multilayer BOX substrate and increasing the thickness of the Diamond to 100nm, crosstalk can be reduced by 20%.

In this paper a license plate detection and recognition system for Iranian private cars is implemented. The proposed license plate localization algorithm is based on region elements analysis which works properly independent of distance (how far a vehicle is), rotation (angle between camera and vehicle), and contrast (being dirty, reflected, or deformed).In addition, more than one car may exist in the image. The proposed method extracts edges and then determines the candidate regions by applying window movement. The region elements analysis includes binarization, character analysis, character continuity analysis and character parallelism analysis. After detecting license plates, we estimate the rotation angle and try to compensate it. In order to identify a detected plate, every character should be recognized.For this purpose, we present 25 features and use them as the input to an artificial neural network classifier. The experimental results show that our proposed method achieves appropriate performance for both detection and recognition of the Iranian license plates.