MECH466 - Lecture19-FrequencyDomainSpecifications-2009W

on closed loop performance closedsensitivity

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Unformatted text preview: troller Wind turbulence in airplane altitude control Wind Wave in ship direction control Wave Sudden temperature change outside the temperatureSudden temperaturecontrolled room Air pressure brake to DC motor Air Bumpy road in cruise control Bumpy Plant y(t) y(t) For disturbance rejection, L should have large gain at low frequencies. Often, disturbance is neither measurable nor Often, predictable. (Use feedback to compensate it!) MECH466 : Automatic Control 26 Disturbance rejection Unwanted signal Unwanted Examples Examples 2008/09 MECH466 : Automatic Control y(t) is not affected by d(t) y(t) d(t) composed of low frequencies. 27 2008/09 MECH466 : Automatic Control 28 7 Typical shaping goal (Summary) Modeling Steady-state accuracy SteadySensitivity Disturbance rejection Transient Response speed Noise reduction Relative stability Transient Overshoot Transfer function Models for systems • electrical • mechanical • electromechanical Linearization Next, frequency shaping (loop shaping) design Next, frequency 2008/09 MECH466 : Automatic Control Analysis Laplace transform Noise reduction Relative stability Course roadmap Time response • Transient • Steady state Frequency response • Bode plot Stability • Routh-Hurwitz Routh• Nyquist Design Design specs Root locus Frequency domain PID & Lead-lag LeadDesign examples Matlab simulations & laboratories 29 Frequency shaping (Loop shaping) 2008/09 MECH466 : Automatic Control 30 An advantage of Bode plot (revi...
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