MECH466 - Lecture20-FrequencyResponseShaping-2009@

5 db gm 20 60 2 10 gs gs mech466 automatic control 26

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Unformatted text preview: fter Step 2 Phase-lag C(s) design 3. Set z and p as 50 deg 0 -50 For small phase lag at ωg -100 10 -2 10 -1 0 10 10 1 10 -45 2 -100 dB PM=55 -150 For setting new gain crossover at ωg -200 -20 -250 10 -2 10 -1 2008/09 10 0 10 1 10 MECH466 : Automatic Control 2 29 2008/09 After Step 3 MECH466 : Automatic Control 30 Step responses 50 2 C(s)=1 C(s)=1 -50 (PM=12deg, ωg=1.1) C(s)=0.286 C(s)=0.286 0 (PM=50deg, ωg=0.5) C(s)=CLag(s) (PM=52.3deg, ωg=0.4) C(s)=C (s) 1.5 -100 -2 10 -1 10 10 0 10 1 2 10 1 -100 PM=50 -150 0.5 Small overshoot is due to larger PM. Slower response is due to smaller wg. -200 -250 -2 10 2008/09 -1 10 0 10 MECH466 : Automatic Control 10 1 0 0 2 10 31 2008/09 5 10 MECH466 : Automatic Control 15 32 8 Ramp responses Summary and exercises Gain controller design in Bode plot Gain Gain changes uniformly over frequencies. Gain Phase does not change. Phase 70 69 68 67 C(s)=0.286 C(s)=0.286 66 Lag compensator design in Bode plot Lag Ramp reference C(s)=1 (Kv=2) C(s)=1 Kv=2) C(s)=CLag(s) (Kv=2) C(s)=C (s) (Kv=2) Low freq. gain determines steady state error, Low disturbance rejection, while PM does overshoot. Read Sections 11.1, 11.2, and 11.3. Read 65 64 67 67.5 68 68.5 69 69.5 70 Smaller steady-state error is due to larger Kv. steadyKv. 2008/09 Lag compensator can be used for Lag • Improving PM by maintaining low freq. gain, or • Improving low freq. gain by maintaining PM (Kv=0.572) (Kv=0.572) MECH466 : Automatic Control 33 2008/09 MECH466 : Automatic Control 34 Lab report hand-in policy The last lab report must be handed-in in person The handedto TA Mr. Roland Lang (ICICS 065), or the instructor (Kaiser 3104), by 5pm April 9 (Thursday). Late hand-in will not be accepted! Late hand- 2008/09 MECH466 : Automatic Control 35 9...
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