Institute for Systems Research Technical Reports

Permanent URI for this collectionhttp://hdl.handle.net/1903/4376

This archive contains a collection of reports generated by the faculty and students of the Institute for Systems Research (ISR), a permanent, interdisciplinary research unit in the A. James Clark School of Engineering at the University of Maryland. ISR-based projects are conducted through partnerships with industry and government, bringing together faculty and students from multiple academic departments and colleges across the university.

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Author: search.filters.author.Dayawansa, Wijesuriya P.

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Now showing 1 - 10 of 14
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    The Hybrid Motor Prototype: Design Details and Demonstration Results
    (1998) Venkataraman, R.; Dayawansa, Wijesuriya P.; Krishnaprasad, Perinkulam S.; ISR; CDCSS
    A novel hybrid rotary motor incorporating piezoelectric and magnetostrictive actuators has been designed and demonstrated. The novelty of this motor was the creation of an electrical resonant circuit, whereby reactive power requirement on the power source is reduced. It was envisioned that the motor would be suitable for low output speed, high torque applications because of its design. This report presents the constructional details of this motor and the results of the demonstration.
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    A Wavelet Approach to Wafer Temperature Measurement via Diffuse Reflectance Spectroscopy
    (1996) Krishnaprasad, Perinkulam S.; Kugarajah, Tharmarajah; Dayawansa, Wijesuriya P.; ISR
    A methodology for the determination of wafer temperature in Molecular Beam Epitaxy via diffuse reflectance measurements is developed. Approximate physical principles are not used, instead, patterns in the data (reflectance versus wavelength) are exploited via wavelet decomposition and Principal Component Analysis.
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    Time-Varying simultaneous stabilization, Part II. Finite families of nonlinear systems
    (1996) Ho-Mock-Qai, Bertina; Dayawansa, Wijesuriya P.; ISR
    In this paper, we derive sufficient conditions for the existence of a continuous time-varying feedback law that simultaneously locally or globally asymptotically stabilizes a finite family of nonlinear systems. We then focus on a class of pairs of nonlinear homogeneous systems, and by using the previous sufficient conditions, we establish their asymptotic stabilizability by means of time-varying feedback.
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    Non-Smooth Simultaneous Stabilization of Nonlinear Systems: Interpolation of Feedback Laws
    (1996) Ho-Mock-Qai, Bertina; Dayawansa, Wijesuriya P.; ISR
    In this paper, we introduce a method that enables us to construct a continuous simultaneous stabilizer for pairs of systems in the plane that cannot be simultaneously stabilized by smooth feedback. We extend this method to higher dimensional systems and prove that any pair of asymptotically stabilizable nonlinear systems can be simultaneously stabilized (not asymptotically) by means of continuous feedback. The resulting simultaneous stabilizer depends on a partition of unity and we show how to circumvent the computation of this partition of unity by constructing an explicit simultaneous stabilizer.
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    Non-Smooth Robust Stabilization of a Family of Linear Systems in the Plane
    (1996) Ho-Mock-Qai, Bertina; Dayawansa, Wijesuriya P.; ISR
    In this paper, we use merely continuous feedback to robustly stabilize a class of parameterized family of linear systems in the plane. We introduce a new interpolation method that enables us to construct a robust stabilizer for the entire family of systems, by using two feedback laws that robustly stabilize two particular sub-families.
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    H∞ Control for Impulsive Disturbances: A State-Space Solution
    (1994) Wei, Q.F.; Dayawansa, Wijesuriya P.; Krishnaprasad, Perinkulam S.; ISR
    In this paper we formulate and study an interesting (sub) optimal H∞ control problem related to the attenuation of impulsive disturbances to a class of linear systems. Among the motivating factors is the need to study control problems related to mechanical systems subject to impulsive forces, e.g.active control of the suspension system of a vehicle, accurate pointing of guns, stabilization of an antenna on the space station subject to impact from space debris, or active damping of vibrations of flexible structures caused by impact forces [1,2]. A reasonable control objective in all these problems is to design a stabilizing controller to minimize the induced operator norm from the impulsive disturbances to the controlled outputs. We derive necessary and sufficient conditions for the existence of a (sub) optimal controller, and give a procedure to compute such a controller when one exists.
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    Modeling of Impact on a Flexible Beam
    (1993) Wei, Q.F.; Krishnaprasad, Perinkulam S.; Dayawansa, Wijesuriya P.; ISR
    We consider the problem of modeling dynamical effects of impact of an elastic body on a flexible beam. We derive a nonlinear integral equation by using the Hertz law of impact in conjunction with the beam equation. This equation does not admit a closed form solution. We demonstrate the existence of solutions, derive a reliable numerical method for computing solutions, and compare the numerical results with those obtained by others.
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    Optimal Control of a Rigid Body with Two Oscillators
    (1993) Yang, R.; Krishnaprasad, Perinkulam S.; Dayawansa, Wijesuriya P.; ISR
    This paper is concerned with the exploration of reduction and explicit solvability of optimal control problems on principal bundles with connections from a Hamiltonian point of view. The particular mechanical system we consider is a rigid body with two driven oscillators, for which the bundle structure is (SO (3) x 者, 者, SO (3)). The optimal control problem is posed by considering a special nonholonomic variational problem, in which the nonholonomic distribution is defined via a connection. The necessary conditions for the optimal control problem are determined intrinsically by a Hamiltonian formulation. The necessary conditions admit the structure group of the principal bundle as a symmetry group of the system. Thus the problem is amendable to Poisson reduction. Under suitable hypotheses and approximations, we find that the reduced system possesses additional symmetry which is isomorphic to S1. Applying Poisson reduction again, we obtain a further reduced system and corresponding first integral. These reductions imply explicit solvability for suitable values of parameters.
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    Stabilization of Globally Noninteractive Nonlinear Systems via Dynamic State-Feedback
    (1991) Battilotti, S.; Dayawansa, Wijesuriya P.; ISR
    We consider the problem of semiglobal asymptotic stabilization and noninteracting control via dynamic state-feedback for a class of nonlinear control systems. It is assumed that the plant has been already rendered noninteractive. A sufficient condition for the stabilization of the overall system, without destroying the noninteraction property, is given in terms of stabilizability of certain subsystems.
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    Noninteracting Control with Stability for a Class of Nonlinear Systems
    (1991) Battilotti, S.; Dayawansa, Wijesuriya P.; ISR
    In this paper we address the problem of noninteracting control with stability for the class of nonlinear square systems for which noninteraction can be achieved (without stability) by means of invertible static state-feedback. The use of both static state-feedback and dynamic state-feedback is investigated. We prove that in both cases the asymptotic stabilizability of certain subsystems is necessary to achieve noninteraction and stability. We use this and some recent results to state a complete set of necessary and sufficient conditions in order to solve the problem.