Person:
Sadegh, Nader

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Now showing 1 - 5 of 5
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    Test-Based Stabilizing Control of COVID-19 Transmission
    (Georgia Institute of Technology, 2020-03) Sadegh, Nader ; Sadegh, Payman
    The COVID-19 pandemic has confronted the world with a health and an economic crisis not seen since 1918. Appearing first in Wuhan, China, in late 2019, the virus has now spread to over 150 countries. At the time of this writing, hundreds of thousands have already been infected and tens of thousands have died as a result. Given the virus' high degree of contagion, a question that occupies everyone's mind is whether a strategy could be conceived to suppress or at least substantially slow the spread of the virus until a vaccine becomes widely available. Using an extended SEIR model with COVID-19's available epidemiological parameters, this paper studies a feedback control solution to stabilize the virus' transmission dynamic based on a test-and-isolate strategy. The derived theoretical results combined with simulation analyses are used to answer key questions around testing strategies that will be required for suppression of the virus.
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    Auto-Calibration Based Control for Independent Metering of Hydraulic Actuators
    (Georgia Institute of Technology, 2011-05) Opdenbosch, Patrick ; Sadegh, Nader ; Enes, Aaron R. ; Book, Wayne J.
    This paper describes a novel auto-calibration state-trajectory-based control method and its application to electronic flow control for independent metering systems. In this paper, the independent metering architecture that is considered uses five Electro-Hydraulic Poppet Valves (EHPV’s). The proposed control method is applied to four of these valves, arranged in a Wheatstone bridge configuration, to regulate the flow of hydraulic oil coming into and out of an actuator. For simplicity, the fifth valve is operated via open-loop to control the supply pressure. Experimental data presented herein demonstrate that the control method learns the valve’s conductance characteristics (i.e. the inverse input-state dynamic map of the valve) while simultaneously controlling the motion of the hydraulic actuator.
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    Combining a multirate repetitive learning controller with command shaping for improved flexible manipulator control
    (Georgia Institute of Technology, 1999-11) Rhim, Sungsoo ; Hu, Ai-Ping ; Sadegh, Nader ; Book, Wayne J.
    Command shaping, a feedforward approach used to control flexible manipulators, performs most effectively when applied to a linear system. In practice, various nonlinearities are present in a given system that will deteriorate the performance of command shaping. In this work, a multirate repetitive learning controller (MRLC) is used in conjunction with a command shaping method known as the optimal arbitrary time-delay filter (OATF) for discrete-time joint control of a single flexible link manipulator containing nonlinearities. With very little a priori knowledge of the given system, a MRLC is able to cancel the nonlinearities at select frequencies and achieve near-perfect tracking of a periodic desired trajectory. By doing this, a MRLC controls the joint to follow a given shaped command more closely, thus allowing the OATF to more effectively attenuate residual tip vibrations. It is shown both analytically and experimentally that this controller is more effective than a conventional PID and OATF controller at attenuating residual tip vibrations.
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    Application of learning control techniques to xerographic drive systems
    (Georgia Institute of Technology, 1997) Sadegh, Nader
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    Learning control of mechanical systems
    (Georgia Institute of Technology, 1992-01) Sadegh, Nader