MECH 466 - Lecture21-LeadLagDesigninFrequencyDomain-2009W

We study the design of simple compensators we to use

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Unformatted text preview: =G(j desired shape. We study the design of simple compensators: We To use FR technique… To technique… C(s) C(s) G(s) G(s) Controller Gain compensator Gain Lag compensator Lag Lead compensator Lead MECH466 : Automatic Control 2 If G(s) has open RHP poles… Controller Plant without open RHP pole 2008/09 MECH466 : Automatic Control Unstable H(s) H(s) Stabilize first! 3 2008/09 MECH466 : Automatic Control 4 1 How to stabilize? An example Typical shaping goal (review) Steady-state accuracy SteadySensitivity Disturbance rejection An unstable plant An Characteristic eq. Characteristic eq. Case 1: Constant H Case Never be stable! Case 2: Case 1st Transient Response speed Relative stability Noise reduction order H Noise reduction G(s) G(s) Unstable Select controller parameters! 2008/09 MECH466 : Automatic Control Relative stability H(s) H(s) 5 2008/09 MECH466 : Automatic Control 6 An example Guideline of lead/lag design (review) Gain+lag Transient Overshoot Consider a system Consider C(s) C(s) G(s) G(s) Controller Lead Plant 50 Analysis for C(s)=1 Analysis C(s)=1 Lag Stable Stable PM at least 12 deg PM GM at least 3.5 dB GM 0 -50 -1...
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