Department of Electrical Engineering

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This paper introduces a robust non-overshooting tracking controller for descriptor systems based on an Integral Sliding Mode (ISM) technique. Non-overshooting controllers (NOS) are a class of controllers which provide good transient response while tracking without any overshoots. But, NOS controllers developed so far for the descriptor systems are not robust to disturbances. So, to provide robustness against matched disturbances, here an integral sliding mode based non-overshooting controller is proposed. Hence, good transient performance without any overshoot during tracking and robustness can be ensured at the same time. Simulation results are given towards the end, which confirms the efficacy of the proposed methodology. © 2018 European Control Association

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European Journal of Control

Robust nonovershooting tracking controller for descriptor systems

This paper introduces an Integral Sliding Mode (ISM) based Composite Nonlinear Feedback (CNF) controller for linear descriptor systems. CNF controllers are well known for guaranteeing good transient performance, while tracking. But, the CNF controllers developed so far for the descriptor systems are not robust to disturbances. Sliding mode controllers, on the other hand, are well known for its matched disturbance rejection capabilities. Hence, to improve the robustness of the CNF controllers for descriptor systems an ISM based approach is been used here so that robustness in presence of matched disturbances is guaranteed but at the same time inherent good transient performance capability of CNF controlled system is retained. Simulation results are also shown at the end to ascertain the effectiveness of the proposed method. © 2018

Integral Sliding Mode Based Composite Nonlinear Feedback Control For Descriptor Systems

This chapter briefly introduces the readers to the preliminary ideas on design and analysis of computer-controlled systems and then sliding mode control (SMC). In general, computer-controlled systems consist of both continuous and discrete-time systems that interact among themselves through the feedback channel to achieve certain objectives. Different available classical techniques, namely emulation, discrete-time and hybrid approaches, are summarized here with their own advantages and disadvantages. In almost all these techniques, the periodic sampling interval is often used to design and analyse the sampled-data systems for its simplicity and easier in design. On the other hand, aperiodic control implementation is desired in sampled-data systems to reduce the periodic computational burden and cost associated with the implementation. However, this introduces few difficulties in analysing closed loop system stability. © Springer International Publishing AG, part of Springer Nature 2018.

Studies in Systems, Decision and Control

Introduction

Segmentation of the phonocardiography (PCG) signal is of importance for diagnosis of heart health and the same is recently reported to be done with tunable quality Wavelet transform (TQWT). In the reported method, parameters of TQWT are tuned to vary the frequency range of the approximation level such that its kurtosis gets maximized. Kurtosis will be larger for the fundamental heart sounds (FHS) as compared to the murmur because probability distribution of FHS is super-Gaussian and murmur is sub-Gaussian. However, this is observed in some pathological cases with sharp peak murmurs, murmur and FHS are indistinguishable using kurtosis. Since Fano factor gives a measure of relative variability, we propose to use Fano-factor for selection of the sub-band, in place of Kurtosis. The proposed method decomposes the signal up to twenty levels only once as compared to approximately 55 times in the reported method and then selects a sub-band considering the detailed levels only. This result into 25 times reduction in computational cost. Moreover, exclusion of the approximation level also helps in reduction of the real-life noise. Another contribution of the paper is the adaptive thresholding method used to suppress the noise level from the selected level that improves the segmentation accuracy in the presence of noise. Experiments are performed on PCG signals of various normal and pathological cases, with and without simulated noise using white Gaussian, pink, and red noise models, separately. The obtained results show the efficiency of the proposed method to segment the PCG signal in the presence of noise, murmurs, and both. © 2017, Taiwanese Society of Biomedical Engineering.

Journal of Medical and Biological Engineering

A Robust Algorithm for Segmentation of Phonocardiography Signal Using Tunable Quality Wavelet Transform

The event-triggering strategy has become a popular control implementation technique in these days. To realize this technique, the continuous state measurements are needed to generate the possible triggering instant. This may not be economical in practical applications due to the need of sophisticated sensors and for the computational burden. © Springer International Publishing AG, part of Springer Nature 2018.

Discrete event-triggered sliding mode control for linear systems

In the previous chapters, the event-triggered SMC strategy is discussed for linear and nonlinear systems. The event-triggering strategy is a novel control implementation technique where the control signal is updated to the plant at some aperiodic time instants generated by executing a stabilizing triggering rule. The triggering scheme continuously monitors the state evolution of the system and generates possible triggering instants. © Springer International Publishing AG, part of Springer Nature 2018.

Self-triggered sliding mode control for linear systems

In more electric aircraft (MEA), three phase power factor correction (PFC) rectifiers of several kilowatts are required. In this paper, a three phase buck-boost derived PFC converter with inductors connected in delta configuration for aircraft application is presented. The proposed converter is operated in discontinuous conduction mode (DCM) to achieve PFC at ac input. This avoids the inner current control loop which further eliminates the current sensors. It requires only one output voltage sensor unlike five sensors in conventional PFC converter and uses a simple voltage control loop to regulate the output voltage. This makes the system cost effective, more reliable and robust. The steady state operation, design calculations and simulation results are presented. The experimental results from a 2kW laboratory prototype are also presented to confirm the operation of the proposed converter. © 2018 IEEE.

Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC

Discontinuous conduction mode three phase buck-boost derived PFC converter for more electric aircraft with reduced switching, sensing and control requirements

This paper proposes a novel notion of Adaptive Sliding mode based loss free resistor (ASLFR), to achieve the dual purpose of power factor correction and voltage regulation. The scheme serves itself as an efficient solution for single-stage PFC circuits applications. The work also provides a qualitative analysis to establish the expediency of the proposed ASLFR over the existing SLFR technique. A boost topology is chosen for implementation, to showcase the effectiveness of the scheme. Relevant results have been demonstrated to support the theoretical claims. © 2018 IEEE

2018 IEEE Industry Applications Society Annual Meeting, IAS 2018

Adaptive sliding mode based loss free resistor for power factor correction application

When exploring the charge transport in the MoS2/Si heterojunction, it is imperative to understand the contribution of different carrier interactions and scattering mechanisms in the conduction process. Here, we have demonstrated an ultrasensitive photodetector based on MoS2/Si (for both p-type and n-type Si) van der Walls (vdW) heterojunction, which provides a high photoresponsivity of greater than 103 A/W along with a large detectivity of ≈ 1012 Jones (Jones = cm · Hz1/2 · W-1). This high photoresponsivity is attributed to the high absorption rate of incident photons and large current carrying capacity of a few layer MoS2. The tuning of barrier height at the MoS2/n-Si interface with photoexcitation of different wavelengths was interpreted by using Bardeen's model. The increase in carrier density due to the photon energy results in a reduction of barrier height at the heterojunction. Because of increase in carrier density with wavelength, it was observed that the inverse Auger process prevails at higher wavelength for the relaxation of photoinduced charge carriers at the MoS2/Si interface over other scattering mechanisms. Our obtained results unveil the great potential of the MoS2/Si vdW heterojunction that may pave the way for new generation photodetectors. © 2018 IEEE.

IEEE Transactions on Electron Devices

Enhanced Carrier Density in a MoS2/Si Heterojunction-Based Photodetector by Inverse Auger Process

In this report, the hydrogen gas sensing properties based on Co doped ZnO nanostructures are explored. The undoped and Co doped nanostructures were grown by RF magnetron sputtering system, and its structural, morphological, and hydrogen sensing behavior are investigated. The maximum relative response was occurred by the 2.5% Co doped ZnO nanostructures among undoped and other doped sensors. The enhancement of relative response might be due to large chemisorbed sites formation on the ZnO surface for the reaction to hydrogen gas. © 2018 Author(s).