Department of Electrical Engineering

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IIT Jodhpur

An adaptive neuro fuzzy based three phase four wire Shunt Active Power Filter is presented in this paper. The active power filter composed of asymmetric cascaded transformer multilevel converter and DC link capacitor. Under dynamic load conditions harmonic compensation and reactive power compensation can be achieved effectively. An ANFIS controller is designed to regulate voltage across DC link capacitor. The proposed method generates the compensation current reference which can handle reactive power requirement of non linear load and DC voltage regulation. Simulation results show fuzzy and ANFIS controller gives better harmonic compensation and DC link voltage regulation.

World University root node

IET Conference Publications

Shunt active power filter based on cascaded multilevel converters using ANFIS

Gas metal arc welding (GMAW) is the most popular industrial welding process today, preferred for its versatility, speed and relative ease of adapting to robotic automation. This process has been used extensively by many industrial environments especially, the automobile industry. The advantages of automated welding process with feedback controllers include increased productivity, consistency in welding quality, as well as health and safety benefits for the welder. This paper proposes a discrete time sliding mode controller, a highly robust controller, to control the welding current and arc voltage of a GMAW system using output feedback. The concept of multirate output feedback technique, with infrequent output measurements has been employed to design the robust controller. A linear multi input multi output (MIMO) system model has been considered here for the design. Since the proposed algorithm is based on output feedback, it is more practical in comparison to any state feedback based control algorithms. The performance of the controller is analyzed in the presence of model parameter uncertainties and the simulation results prove the efficiency of the controller proposed. © 2013 EUCA.

2013 European Control Conference, ECC 2013

Discrete-time sliding mode control of GMAW systems using infrequent output measurements

The practical implementation of a state feedback controller demands a state observer of large order. In this context, an attractive alternative to the state feedback would be an output feedback controller. In the recent past, Fast Output Sampling (FOS) control technique, a method which utilizes only the system output for feedback, has emerged as a promising candidate for control of sampled data control systems[36, 109, 123]. Major advantage of this technique is its ability to guarantee arbitrary symmetric pole placement, thereby yielding a closed-loop stable system. Large number of applications of FOS control technique can be found especially in the areas of simultaneous stabilization, robust control, sliding mode control, nuclear reactor control etc. [9, 85, 121, 122]. © 2013, Springer-Verlag Berlin Heidelberg.

Lecture Notes in Control and Information Sciences

Design of Fast Output Sampling controller for three-time-scale systems

The paper presents some new results on digital implementation of sliding mode control when designed from a continuous time system. When a continuous sliding mode control is digitally implemented, it cannot bring the sliding variable to the surface in finite time and stay there, but the sliding variable remains within an ultimate band around the surface. Analysis is done which relates such an ultimate band with the continuous controller parameters. If the controller parameters are chosen accordingly, one can be sure that the sliding motion will remain inside the specified ultimate band, and hence stability can be assured for such a digital implementation of the continuous sliding mode control. © 2013 IEEE.

IECON Proceedings (Industrial Electronics Conference)

On digital implementation of continuous sliding mode control

A novel technique based on dynamic stochastic resonance (DSR) in discrete cosine transform (DCT) domain has been proposed in this paper for the enhancement of dark as well as low-contrast images. In conventional DSR-based techniques, the performance of a systemcan be improved by addition of external noise. However, in the proposedDSR-based work, the intrinsic noise of an image has been utilized to create a noise-induced transition of a dark image to a state of good contrast. The proposed technique significantly enhances the image contrast and color information without losing any image or color data by optimization of bistable system parameters. The performance of the proposed methodology has been measured in terms of relative contrast enhancement factor, perceptual quality measure, and color enhancement factor. When compared with the existing enhancement techniques, such as adaptive histogram equalization, gamma correction, single-scale retinex, multi-scale retinex, modified high-pass filtering,multicontrast enhancement with dynamic range compression, color enhancement by scaling, edge-preserving multi-scale decomposition, automatic control of imaging tool, and various spatial/frequency-domain SR-based techniques, the proposed technique gives remarkable performance in terms of contrast and color enhancement while ascertaining good perceptual quality. © The Authors, 2013.

Fulltext

APSIPA Transactions on Signal and Information Processing

Dark and low-contrast image enhancement using dynamic stochastic resonance in discrete cosine transform domain

In this paper, we discuss the recent enhancements made in the BSIM6 bulk MOSFET model. BSIM6 is the latest compact model of bulk MOSFET from BSIM group which have body referenced charge based core. Junction capacitance model is improved over BSIM4 and is infinitely continuous around Vbs=V bd=0V. Symmetry of the model is successfully validated by performing Gummel Symmetry Test (GST) in DC and symmetry test for capacitances in AC. Self heating model is also included in BSIM6 and test results are reported. Model capabilities are compared against an advanced 40nm CMOS technology and it is observed that simulated results are in excellent agreement with the measured data. © 2013 IEEE.

International Conference on Simulation of Semiconductor Processes and Devices, SISPAD

Recent enhancements in BSIM6 bulk MOSFET model

In applications such as telesurgery, it is required to transmit haptic signals to a remote location with a delay of at most few milliseconds. To reduce the packet rate and yet retain perceptual quality, adaptive sampling has been explored in the literature. In particular, in earlier work we proposed and analyzed an adaptive sampling scheme based on Weber's law of perception. In this paper, we explore other possible adaptive sampling candidates. We describe an experimental setup where users are subjected to piecewise constant haptic stimuli to which they can respond with a click. We record the clicks and ask the question: can we identify signal features and classiers to predict the clicks? The answer suggests adaptive sampling schemes that improve over Weber sampling. © 2013 IEEE.

2013 Information Theory and Applications Workshop, ITA 2013 - Conference Proceedings

Can we improve over Weber sampling of haptic signals?

This paper presents a technique to control the Stewart platform using a Smooth Second Order sliding Mode (SSOSM) Controller based on modified 'twisting' algorithm for relative degree two systems. For a given position of the platform, the leg lengths and leg velocities are estimated using inverse kinematics. The desired position of the platform has been achieved with a smooth control using a Smooth Second Order Sliding Mode Controller. The results show that control input is free from chattering. The effectiveness of this control technique has been proved with simulation results. © 2013 IEEE.

IEEE International Symposium on Industrial Electronics

Stabilization of stewart platform using Smooth Second Order Sliding Mode Controller

This report focuses on the structural and optical properties of the GaN films grown on p-Si (100) substrates along with photovoltaic characteristics of GaN/p-Si heterojunctions fabricated with substrate nitridation and in absence of substrate nitridation. The high resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), Raman and photoluminescence (PL) spectroscopic studies reveal that the significant enhancement in the structural as well as in the optical properties of GaN epifilms grown with silicon nitride buffer layer when compared with the sample grown without silicon nitride buffer layer. The low temperature PL shows a free excitonic (FX) emission peak at 3.51 eV at the temperature of 5 K with a very narrow line width of 35 meV. Temperature dependent PL spectra follow the Varshni equation well and peak energy blue shifts by ∼63 meV from 300 to 5 K. Raman data confirms the strain free nature and reasonably good crystallinity of the films. The GaN/p-Si heterojunctions fabricated without substrate nitridation show a superior photovoltaic performance compared to the devices fabricated in presence of substrate nitridation. The discussions have been carried out on the junction properties. Such single junction devices exhibit a promising fill factor and conversion efficiency of 23.36 and 0.12 %, respectively, under concentrated AM1.5 illumination. © 2013 Springer Science+Business Media New York.