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Application of Rayleigh wave-based nonlinearity parameter to estimate the remnant useful life of fatigued thick aluminum plates

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ISSS Journal of Micro and Smart systems 2021年第2期10卷 161-178页

作者： Yelve, Nitesh P. Masurkar, Faeez Tse, Peter Department of Mechanical Engineering Indian Institute of Technology Bombay Mumbai India Adaptive Intelligent Materials & Systems (AIMS) Center School for Engineering of Matter Transport and Energy Arizona State University Tempe USA SEAM and CNDT Laboratories Department of Systems Engineering and Engineering Management City University of Hong Kong Hong Kong SAR China

In the present study, Rayleigh waves are propagated through a thick Aluminum (Al) plate to evaluate its material nonlinearity based on the second harmonic produced in the response. The experiments and numerical simulations are carried out on the pristine and fatigued thick Al specimens, and an amplitude-based Rayleigh wave nonlinear parameter is used to characterize the material nonlinearity. In addition, a physics-based nonlinear parameter that depends on the sub-structural evolution parameters, and higher-order plastic and elastic constants are also used to characterize the nonlinearity of the pristine and fatigued Al material. They found to be in good agreement for the predefined conditions of tone burst cycles in the actuation signal and propagation distance. The knowledge of material nonlinearity parameters evaluated for the pristine and fatigued thick plate specimens using Rayleigh waves is shown in the present study to be crucial to evaluate the remnant useful life (RUL) of the fatigued specimen with fair accuracy.

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Optimal Landmark Selection for Bearing-Only Navigation 19

Optimal Landmark Selection for Bearing-Only Navigation

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Proceedings of the 2019 4th International Conference on Advances in Robotics

作者： Pranav Thakkar Leena Vachhani Department of Aerospace Engineering Indian Institute of Technology Bombay Powai Mumbai India Systems & Controls Engineering Group Indian Institute of Technology Bombay Powai Mumbai India

ISBN: (纸本)9781450366502

Bearing-only navigation, using landmark information, is a well-researched area, with applications ranging from mapping an environment to reaching a known target position. Robot pose localization using bearing-only measurements is highly affected by the locations of surrounding landmarks, from which angular readings can be obtained via feature extraction. This paper develops landmark selection algorithms for pose localization, observed in the context of visual navigation towards a familiar target position (i.e. visual homing). An augmented state approach is used and four landmark selection criteria are developed and utilized to select landmarks to be measured from, from a landmark set. This paper abstracts out the feature recognition issues associated with vision. The effect of choice of selection algorithm and number of landmarks measured from, on pose uncertainty, is observed. Suitable inferences regarding the best choice of algorithm and thereafter number of landmarks to be measured, are drawn.

关键词： Bearing-Only Localization

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Position control of Solar Powered Aerostat for Reliable Power Generation in the Presence of Clouds

Position Control of Solar Powered Aerostat for Reliable Powe...

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2019 International Conference on Nascent Technologies in engineering, ICNTE 2019

作者： Gupta, Sowmya Mitra, Mira Vachhani, Leena Duttagupta, Siddhartha P. Centre for Research in Nanotechnology Science Indian Institute of Technology Bombay Powai Mumbai400076 India Indian Institute of Technology Kharagpur Department of Aerospace Engineering Kharagpur West Bengal721302 India Systems and Control Engineering Indian Institute of Technology Bombay Powai Mumbai400076 India Indian Institute of Technology Bombay Department of Electrical Engineering Powai Mumbai400076 India

ISBN: (纸本)9781538691663

This paper presents single tethered and bi-tethered position control of a solar-powered aerostat. The objective is to station the aerostat at a desired position anywhere into and on a hemisphere of an allocated radius with constraints applied on tether lengths and controller gains. Optimization is performed to find an optimal set of PID controller gains in order to minimize the total error over the entire trajectory. Two schemes for integral error calculation are proposed in this work. The first scheme implements historical values of the error resulting in adding an unnecessary bias to the output. This is overcome by the use of an error history over a finite horizon when calculating the integral error. Improved performance of the controller with faster convergence for position tracking is achieved by the implementation of the second scheme. In the first scheme, a settling time of approximately 72 s is achieved which is improved to approximately 40 s with the implementation of the second scheme. The conditions for position change of the aerostat are discussed. The results depict a three- dimensional space trajectory of the solar-powered aerostat being relocated to a cloudless new position for reliable solar power generation. © 2019 IEEE.

关键词： Errors

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Observation of non-Hermitian topological disclination states and charge fractionalization

arXiv

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arXiv 2025年

作者： Li, Ruifeng Banerjee, Rimi Mandal, Subhaskar Li, Da Long, Yang Ma, Tianchi Liu, Jianwei Liu, Gui-Geng Chong, Yidong Zhang, Baile Li, Er-Ping College of Information Science & Electronic Engineering Zhejiang Key Laboratory of Intelligent Electromagnetic Control and Advanced Electronic Integration Zhejiang University Hangzhou310027 China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore Singapore Department of Physics Indian Institute of Technology Bombay Mumbai400076 India Centre for Disruptive Photonic Technologies Nanyang Technological University Singapore Singapore Research Center for Industries of The Future Westlake University Hangzhou310030 China Department of Electronic and Information Engineering School of Engineering Westlake University Hangzhou310030 China

There has been significant interest in exploring topological disclination states, which effectively probe the band topology of the host material beyond the conventional bulk-edge correspondence. While most studies in this area have primarily focused on Hermitian systems, recent theoretical work predicts that non-Hermiticity can drive topological phase transitions and host topological disclination states associated with fractional charge. However, no experimental observations have been reported to date. Here, we report the first experimental observation of topological disclination states in electric circuits, induced solely by gain and loss. Through admittance matrix measurements and eigenstate analysis, we confirm their emergence and compute the corresponding fractional charge. Moreover, the disclination mode profile and localization effect can be directly visualized via monochromatic field excitation. Additionally, we demonstrate the emergence of degenerate zero-energy topological disclination states, devoid of fractional charge, in distinct non-Hermitian geometries. Our findings open the possibility of non-Hermiticity-induced fractional charges in two-dimensional non-Hermitian lattices, which may pave the way for advancements in active topological photonic devices. © 2025, CC BY.

关键词： Electric network topology

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ASYMPTOTICALLY STABLE OPTIMAL MULTI-RATE RIGID BODY ATTITUDE ESTIMATION BASED ON LAGRANGE-D’ALEMBERT PRINCIPLE

arXiv

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arXiv 2020年

作者： Bhatt, Maulik Sanyal, Amit K. Sukumar, Srikant Systems and Control Engineering Indian Institute of Technology Bombay400076 India Mechanical and Aerospace Engineering Syracuse University SyracuseNY United States

The rigid body attitude estimation problem is treated using the discrete-time Lagrange-d’Alembert principle. Three different possibilities are considered for the multi-rate relation between angular velocity measurements and direction vector measurements for attitude: 1) integer relation between sampling rates, 2) time-varying sampling rates, 3) non-integer relation between sampling rates. In all cases, it is assumed that angular velocity measurements are sampled at a higher rate compared to the inertial vectors. The attitude determination problem from two or more vector measurements in the body-fixed frame is formulated as Wahba’s problem. At instants when direction vector measurements are absent, a discrete-time model for attitude kinematics is used to propagate past measurements. A discrete-time Lagrangian is constructed as the difference between a kinetic energy-like term that is quadratic in the angular velocity estimation error and an artificial potential energy-like term obtained from Wahba’s cost function. An additional dissipation term is introduced and the discrete-time Lagrange-d’Alembert principle is applied to the Lagrangian with this dissipation to obtain an optimal filtering scheme. A discrete-time Lyapunov analysis is carried out to show that the optimal filtering scheme is asymptotically stable in the absence of measurement noise and the domain of convergence is almost global. For a realistic evaluation of the scheme, numerical experiments are conducted with inputs corrupted by bounded measurement noise. These numerical simulations exhibit convergence of the estimated states to a bounded neighborhood of the actual states. Copyright © 2020, The Authors. All rights reserved.

关键词： Kinetic energy

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Optimal landmark selection for bearing-only navigation

Optimal landmark selection for bearing-only navigation

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2019 Conference on Advances in Robotics, AIR 2019

作者： Thakkar, Pranav Vachhani, Leena Department of Aerospace Engineering Indian Institute of Technology Bombay Powai Mumbai400076 India Systems and Controls Engineering Group Indian Institute of Technology Bombay Powai Mumbai400076 India

ISBN: (纸本)9781450366502

关键词： Navigation

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Event-triggered Discrete-time Sliding Mode control for High-order systems via Reduced-order Model Approach

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IFAC-PapersOnLine 2020年第2期53卷 6207-6212页

作者： Kiran Kumari Bijnan Bandyopadhyay Johann Reger Abhisek K. Behera Systems and Control Engineering Indian Institute of Technology Bombay India Control Engineering Group Technische Universität Ilmenau 98684 Ilmenau Germany Faculty of Mechanical Engineering Technion-Israel Institute of Technology Haifa 32000 Israel Department of Statistics University of Haifa Haifa 31905 Israel

We propose the design of event-triggered (ET) discrete-time sliding mode (DTSM) control for a high-order discrete-time system via a reduced-order model-based approach. This design includes a triggering mechanism using a reduced-order state vector and a controller based on the modified Bartoszewicz’ reaching law for a reduced-order model of the system, to stabilize the uncertain high-order system. The main advantages of using a reduced-order vector in the event condition are the low-order synthesis of the controller and the sampling pattern, which may be sparser than the full vector-based design. This motivation arises from the fact that relaxing a few components of the state vector in the triggering mechanism may decrease its rate of violation. An added advantage of the proposal is that the transmission of the reduced-order vector, particularly in a network-based implementation, can outperform the full-order based design due to the severe challenges that exist in the data network. The robust performance for the closed-loop system is achieved using the DTSM control. We show that our proposal guarantees the stability of the full-order plant with the reduced-order triggering mechanism. The control execution is Zeno-free because of the inherent discrete nature of the control. The efficiency of the proposed method is shown using the simulation results of a numerical example.

关键词： Event-triggered control Discrete-time sliding mode Model-order reduction

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Connecting the Unconnected

Connecting the Unconnected

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IEEE Future Networks World Forum (FNWF)

作者： Sudhir Dixit Ashutosh Dutta Sandeep Agrawal Marvin Arias Olivas Vimal Bhatia Carlos Daniel Altamirano Carrillo Pranav Jha Matogoro Jabhera Amit Karna Sanjram Premjit Khanganba Catherine Kimambo Roman Lara-Cueva Marja Martinmikko-Blue Fisseha Mekuria Apurva Mody Nelson Wasilwa Brad Kloza Craig Polk Matt Borst Basic Internet Foundation Norway University of Oulu Finland Wireless World Research Forum Applied Physics Labs Johns Hopkins University USA C-DoT India National University of Engineering Nicaragua Indian Institute of Technology Indore India Universidad de las Fuerzas Armadas - ESPE Ecuador Indian Institute of Technology Bombay India University of Dodoma Tanzania African Childs Project Tanzania Universidad de las Fuerzas Armadas ESPE Ecuador Council of Scientific and Industrial Research (CSIR) South Africa A5 Systems LLC Communications Authority of Kenya

Connecting the Unconnected or under-connected (CTU) is the holy grail of transforming the lives of over 3 billion people around the globe with wireless internet who are yet to experience its value in multiple ways. If this could be accomplished, its impact on the society would be enormous as everyone would have access to information and an opportunity to improve their quality of life and income. This chapter from the IEEE Future Networks CTU Working Group endeavors to highlight the need to consider the CTU requirements in 5G and B5G networks in the standardization process and in the development of the use cases and affordable solutions. In its Vision 2030 SDG (Sustainability Development Goals) the United Nations has proclaimed access to internet as basic human right and has said these goals cannot be achieved without affordable access to internet by everyone on this planet[65]. While there are numerous projects and initiatives ongoing around the world, these are fragmented and lack the critical mass and coordination to be able to impact the future standards, product development, and cost of deployment otherwise achievable by economy of scale. Although difficult to pin down, to define a threshold for basic connectivity for all is important. But it would need to be flexible to adapt to changing times. It is the goal of the CTU group to create an open platform where the experts can bring their ideas, solutions, and potentially collaborate to create large global projects and influence the network service providers, manufacturers and their governments. This paper defines the CTU working group's charter, scope, and provides a brief overview of the relevant stakeholders and linkages between them. Then the paper goes into the current status of the CTU landscape and where we want to reach to accomplish the vision of connecting everybody, especially those living in rural and remote areas. We present the various standards and industry fora and how they are interlinked. While t

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control of systems Exhibiting Input Multiplicities using Dual Nonlinear MPC

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IFAC-PapersOnLine 2018年第20期51卷 110-115页

作者： Kumar, Kunal Patwardhan, Sachin C. Noronha, Santosh Systems and Control Engineering Indian Institute of Technology Bombay Mumbai India Department of Chemical Engineering Indian Institute of Technology Bombay Mumbai India

control of a system exhibiting input multiplicity at an optimum (singular) operating point poses a challenging control problem due to loss of invertibility and change in the sign of the steady state gain in the neighbourhood of the optimum. In this work, for controlling systems exhibiting input multiplicities, we develop a novel adaptive dual NMPC (ADNMPC) formulation based on a Wiener model which is parameterized using orthonormal basis filters (OBF). The static nonlinear output map in the Wiener model is constructed using multidimensional quadratic polynomials. The OBF poles are chosen through an off-line identification exercise and the parameters of the static nonlinear map are updated on-line using recursive least squares algorithm. Similar to Kumar et al. (2017), by introducing concept of excitation horizon, the objective function in the NMPC formulation is modified to include terms that are sensitive to the parameter covariance. The proposed formulation provides su¢cient degrees of freedom to shape the probing signals. E¢cacy of the proposed approach is demonstrated by simulating problem of controlling a continuously operated fermenter system at its optimum operating point. Analysis of the simulation results shows that the proposed ADNMPC scheme judiciously injects perturbations into the process as and when required. The probing perturbations subside when the parameter estimates stabilize. In particular, it is observed that the intensity of the perturbation increase as the excitation horizon increases. The proposed on-line model adaptation also ensures better control performance with reference to a non-adaptive NMPC controller. © 2018

关键词： Model reference adaptive control Degrees of freedom (mechanics) Parameter estimation Adaptive control Dual control Line identifications Nonlinear MPC Orthogonal basis filters Parameter covariance Quadratic polynomial Recursive least squares algorithms

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Reference tracking stochastic model predictive control over unreliable channels and bounded control actions

arXiv

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arXiv 2020年

作者： Mishra, Prabhat K. Diwale, Sanket S. Jones, Colin N. Chatterjee, Debasish Coordinated Science Laboratory University of Illinois at Urbana-Champaign United States Switzerland Systems & Control Engineering Indian Institute of Technology Bombay India

A stochastic model predictive control framework over unreliable Bernoulli communication channels, in the presence of unbounded process noise and under bounded control inputs, is presented for tracking a reference signal. The data losses in the control channel are compensated by a carefully designed transmission protocol, and that of the sensor channel by a dropout compensator. Our proposed class of feedback policies is parametrized in terms of the disturbances appearing in the dynamics of the dropout compensator. A reference governor is employed to generate a trackable reference trajectory and mean-square boundedness of the error between the states of the system and that of the reference governor is achieved with help of stability constraints. The overall approach yields a computationally tractable quadratic program, which is solved iteratively online. Copyright © 2020, The Authors. All rights reserved.

关键词： Stochastic systems

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