Transcription of Second Order Systems
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1 Second Order SystemsSecond Order Equations()1222++=ssKsG Standard Form 2d2ydt2+2 dydt+y=Kf(t)Corresponding Differential EquationK = Gain = Natural Period of Oscillation = Damping Factor (zeta)Note: this has to be !!!2 Origins of Second Order Equations1. Multiple Capacity Systems in SeriesK1 1s+1K2 2s+1becomeorK1K2 1s+1() 2s+1()K 2s2+2 s+12. Controlled Systems (to be discussed later)3. Inherently Second Order Systems Mechanical Systems and some sensors Not that common in chemical process controlExamination of the Characteristic Equation 2s2+2 s+1=0 Two complex conjugate rootsUnderdamped0 < < 1 Two equal real rootsCritically damped = 1 Two distinct real rootsOverdamped > 13 Response of 2ndOrder System to StepInputsFast, oscillations occurUnderdampedEq.
Critically damped Eq. 5-50 Overdamped Sluggish, no oscillations Eq. 5-48 or 5-49 Ways to describe underdamped responses: • Rise time • Time to first peak • Settling time • Overshoot • Decay ratio • Period of oscillation Response of 2nd Order Systems to Step Input ( 0 < ζ< 1) 1. Rise Time: tr is the time the process output takes to ...
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