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A multiple model gap-metric based approach to nonlinear quantitative feedback theory

IFAC-PapersOnLine 2016年第1期49卷 160-165页

作者： R. Jeyasenthil P.S.V. Nataraj Interdisciplinary Programme in Systems and Control Engineering IIT Bombay Mumbai-400 076 India

We propose a simple quantitative feedback theory (QFT) technique for designing robust nonlinear feedback systems. In the proposed approach, multiple linear models are obtained by linearization of the nonlinear plant model at each operating condition, and local QFT controller/filter obtained using standard QFT techniques. Then, global controller/filter effective over the entire operating range are constructed from the local ones by soft switching based on the gap-metric concept. The proposed approach is much simpler and easier than the existing NLQFT approaches where the so-called linear time invariant equivalent (LTIE) plants need to be constructed from the original nonlinear plant set. The proposed method is illustrated via a challenging nonlinear continuous stirred tank reactor (CSTR) example.

关键词： Multiple models Nonlinear control Quantitative feedback theory Robust control

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Steering laws of Single Gimbal control Moment Gyros applied to spacecraft manoeuvres and tracking — A comparison

Steering laws of Single Gimbal Control Moment Gyros applied ...

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Indian control Conference (ICC)

作者： Abhilash Mony Hari. B Hablani Srikant Sukumar Department of Aerospace Engineering IIT Bombay Mumbai India Department of Mechanical Engineering IIT Gandhinagar Ahmedabad India Systems and Control Engineering IIT Bombay Mumbai India

In this paper an attempt is made to compare four steering laws used for Single Gimbal control Moment Gyros (SG CMGs). The performance of a rigid spacecraft to execute multi-target acquisition and tracking with four SG CMGs in pyramid configuration is studied and steering law performance evaluated. The first steering law under consideration is the classic Moore-Penrose Pseudo Inverse(MPI). Subsequently, this is modified by adding null motion using inverse gain and null projection method. Then a steering law based on Preferred Gimbal Angles (PGA) is studied. The laws are compared based on the normalized singularity measure, gimbal rates, gimbal angles, output torque, attitude performance and angular momentum demand. The gimbal motor rates are restricted owing to hardware limits. This results in torque errors which affect the attitude of the spacecraft.

关键词： Torque Jacobian matrices Electronics packaging Wheels Space vehicles Attitude control Actuators

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Sliding Mode control of Uncertain Time Delay System using Lambert W Function

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IFAC-PapersOnLine 2016年第1期49卷 173-177页

作者： Kiran Kumari S. Janardhanan Systems and Control Engineering IIT Bombay Maharashtra 400076 India Dept. of Electrical Engineering IIT Delhi New Delhi 110016 India

This paper presents a robust sliding mode control law for time delay systems with parametric uncertainties and external disturbances. The uncertainties and disturbances are assumed to be matched. The method for designing a switching hyperplane using Lambert W function is proposed for generation of sliding motion in the system. This method includes desired eigenvalue placement for getting a stable sliding manifold. A controller is designed such that system trajectories reach sliding surface in finite time and remain there for all subsequent time. Simulation results are also shown on a numerical example to illustrate the effectiveness of the proposed method.

关键词： Time-delay systems Sliding Mode control Linear systems Lambert W Function

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Practical SOSM controller Design for Short-Circuit Mode of Transfer in GMAW using Two Sliding Surfaces

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IFAC-PapersOnLine 2016年第1期49卷 724-729页

作者： Arun Kumar Paul Manas Kumar Bera B. Bandyopadhyay Electronics Devices (W/W) Pvt. Ltd 22 Mistry Indl. Estate Andheri (E) Mumbai - 93 India Research Scholar Systems and Control Engineering IIT Bombay - 400076 India Professor Systems and Control Engineering IIT Bombay Mumbai - 400076 India

GMAW is a complete arc welding process of creating all types of metal joints of desirable quality involving virtually all metals of any thickness in any position. However, in doing so, there is continuous shift in operating point of arc and/or in arc characteristics leading to wide range parametric variations and disturbances injected into the system. Moreover, the process involves multiple dynamical events such as in arc characteristics, melting rate, dynamics of arc length and droplet transfer mechanism etc. for creating eventual welding joints where each event suffers from non-linearity as well as parametric variations. control of such process optimally, though complex, but is essentially required as welding joints are made through indirect control of operating point of arc where for certain events feedback signals are difficult to get. Sliding mode control (SMC) concepts are considered as robust and have the ability to reject external disturbances and generate parametric insensitive response characteristics. This article, using already established control laws, explores the ability of SOSM in GMAW with robust performance characteristics. Implementation along with results of popular short-circuit mode of transfer is presented here.

关键词： Second order sliding mode (SOSM) gas metal arc welding (GMAW) short-circuit transfer

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Call for papers: Special issue of international journal of robust and nonlinear control: "stochastic predictive control"

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International Journal of Robust and Nonlinear control 2016年第16期26卷 3670-3670页

作者： Quevedo, Daniel E. Chatterjee, Debasish Automatic Control Group Paderborn University EIM-E Warburgerstrasse 100 Germany Systems and Control Engineering IIT Bombay Powai Mumbai400076 India

September 2016 Special Issue of International Journal of Robust and Nonlinear control seeks to collect the current state-of-the-art directions in theoretical foundations and applications of stochastic model predictive control, with contributions from the finest researchers who are working in this area. With the steady growth in the availability of fast computing machines, control techniques based on algorithmic selection of actions derived from optimisation of a suitable performance index have gained prominence. Model predictive control, a framework that is based on such algorithmic selection procedures, has evolved over the years into one of the most useful and applicable control synthesis techniques currently available to a control engineer.

关键词： Model predictive control

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Stability of the integral control of stable nonlinear systems

Stability of the integral control of stable nonlinear system...

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IEEE International Conference on the Science of Electrical engineering (ICSEE)

作者： George Weiss Vivek Natarajan School of Electrical Engineering Tel Aviv University Ramat Aviv Israel Systems and Control Engineering Group Indian Institute of Technology (IIT) Bombay Mumbai India

ISBN: (纸本)9781509021536

PI controllers are the most widespread type of controllers and there is an intuitive understanding that if their gains are sufficiently small and of the correct sign, then they "always" work. In this paper we try to give some rigorous backing to this claim, under specific assumptions. Let P be a nonlinear system described by = f (x, u), y = g(x), where the state trajectory x takes values in R n , u and y are scalar and f, g are of class C 1 . We assume that there is a Lipschitz function Ξ : [u min , u max ] → R n such that for every constant input u 0 ϵ [u min, u max], Ξ(u 0 ) is an exponentially stable equilibrium point of P. We also assume that G(u) = gΞ(u)), which is the steady state input-output map of P, is strictly increasing. Denoting y min = G(u min ) and y max = G(u max ), we assume that the reference value r is in (y min , y max ). Our aim is that y should track r, i.e., y → r as t →∞ while the input of P is only allowed to be in [u min , u max ]. For this, we introduce a variation of the integrator, called the saturating integrator, and connect it in feedback with P in the standard way, with gain k > 0. We show that for any small enough k, the closed-loop system is (locally) exponentially stable around an equilibrium point (Ξ(u r ), u r ), with a "large" region of attraction X T ⊂ R n × [u min , u max ]. When the state (x(t),u(t)) of the closed-loop system converges to (Ξ(u r ),u r ), then the tracking error r - y tends to zero. The compact set X t can be made larger by choosing a larger parameter T > 0, resulting in smaller k.

关键词： Trajectory Closed loop systems Nonlinear systems Electrical engineering Lips Memoryless systems Lyapunov methods

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Guidance algorithm for the final translational phase of autonomous close range Rendezvous and Docking of spacecraft

Guidance algorithm for the final translational phase of auto...

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International Conference on control, Communication and Computing India, ICCC 2015

作者： Thomas, Maria Navin, M.S. Lal Priya, P.S. Systems and Control Engineering IIT Bombay Mumbai400076 India GDD/CGDG/CGSE VSSC Trivandrum India Dept. of Electrical and Electronics College of Engineering Trivandrum Trivandrum India

ISBN: (纸本)9781467373494

An orbital maneuver during which two spacecraft starting from a remote distance arrive at the same orbit and approach to a closer distance is often termed a space rendezvous. Rendezvous requires a precise match of the orbital velocities of the two spacecraft which would allow them to remain at a constant distance throughout the mission. This paper proposes a novel guidance algorithm for the final translational phase of an autonomous close range Rendezvous and Docking mission, to guarantee trajectory safety. It ensures that the final translational maneuver is through a predetermined approach corridor. The proposed algorithm employs the linearized Clohessy Wiltshire equations to compute the reference positions and velocities. The multiple impulse firing strategy is utilized to effect the transfer, due to the significant reduction in the maximum trajectory deviation from the docking axis achievable. The trajectory safety is accounted for by the Line of Sight constraint and the Rendezvous and Docking durations satisfying the Line of Sight constraint are computed through the algorithm. An analytical method to determine the maximum trajectory deviation is also proposed and serves as a safety check. The proposed strategies provide a safe trajectory in the final phase of an autonomous Rendezvous and Docking mission where mission safety is critical. © 2015 IEEE.

关键词： Space rendezvous

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Online thevenin equivalent parameter estimation using nonlinear and linear recursive least square algorithm

Online thevenin equivalent parameter estimation using nonlin...

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International Conference on Electronics, Communication and Computing Technologies (ICECCT)

作者： Umar Hashmi Rahul Choudhary Jayesh G. Priolkar Department of Energy Science & Engineering IIT Bombay Bombay Maharashtra Department of Systems and Control IIT Bombay Bombay Maharashtra Department of Electrical Engineering Goa College of Engineering Ponda Goa

This paper proposes method for detection, estimation of Thevenin equivalent parameters to describe power system behavior. Thevenin equivalent estimation is a challenge due to variation in system states caused by power flow in the network. Thevenin equivalent calculation based on changes in system with multiple sources integrated with grid, isolated distributed generator system is analysed and nonlinear least square fit estimation technique for algorithm is adopted. Linear least square fit is used with a linearized model. Performance evaluation of proposed method is carried out through mathematical model, nonlinear and linear least square fit based algorithm technique and simulation through MATLAB/SIMULINK package. Accurate grid and source side impedance estimation technique is applicable for distributed generation sources interfaced with grid to improve dynamic response, stability, reliability when subjected to faults or any other disturbances in network. Algorithm can accurately estimate Thevenin equivalent of multiple sources connected in parallel simultaneously with voltage and current phasor measurements at point of common coupling. Mathematical analysis and simulation results validate the effectiveness of proposed method.

关键词： Voltage measurement Impedance Electrical resistance measurement MATLAB Inductance Generators Inductance measurement

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Guidance algorithm for the final translational phase of autonomous close range Rendezvous and Docking of spacecraft

Guidance algorithm for the final translational phase of auto...

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International Conference on control Communication & Computing India (ICCC)

作者： Maria Thomas Navin M. S. Lal Priya P. S. Systems and Control Engineering IIT Bombay Mumbai GDD VSSC Trivandrum Dept. of Electrical and Electronics College of Engineering Trivandrum Trivandrum

关键词： Space vehicles Trajectory Mathematical model Orbits Safety Dynamics Electronic mail

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Constrained global optimization of non-polynomial problems using the Taylor-Bernstein form

Constrained global optimization of non-polynomial problems u...

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International Conference on Industrial Instrumentation and control (ICIC)

作者： Bhagyesh V. Patil P. S. V. Nataraj Laboratoire d'Informatique de Nantes Atlantique Université de Nantes Nantes France Systems and Control Engineering Group IIT Bombay Mumbai

In this paper, we propose a new constrained global optimization algorithm to solve non-polynomial problems. The proposed algorithm is of branch-and-bound type and use the Taylor-Bernstein form as a higher-order inclusion function for the global optimization. Several new ingredients are incorporated in the proposed algorithm to improve its efficiency, such as a improved range estimating technique along with a new simple method to generate the Taylor model of a give function. Further, different numerical experiments are conducted using the proposed algorithm on a set of 10 challenging test problems. The results of the numerical experiments are compared with the MATLAB fmincon solver and are found to be encouraging in terms of the chosen performance metrics.

关键词： Optimization Polynomials Mathematical model Computational modeling Radio frequency Numerical models Upper bound

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