MECH466 - Lecture14-LeadLagCompensatorDesign-2009W

We do not want to change cl pole location s1 so we

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Unformatted text preview: Control 19 2008/09 MECH466 : Automatic Control 20 5 Guidelines to choose z and p How to design lag compensator The zero and the pole of a lag compensator The should be close to each other, for other, For the desired CL pole For The pole of a lag compensator should be close The to the origin, to have a large ratio z/p, leading to origin, z/p, a large ramp-error constant Kv. rampKv. However, the pole of a lag compensator too However, close to the origin may be problematic: Slow settling (due to closed-loop pole near the origin) Slow closed- 2008/09 MECH466 : Automatic Control 21 Root locus With lead compensator 1.2 1 5 Imaginary Axis 22 1.4 10 0 MECH466 : Automatic Control Ro o t L o c u s Desired pole 5 Imaginary Axis 2008/09 Comparison of step responses 15 10 Lead-lag controller Lead- With lead-lag compensator lead- Ro o t L o c u s 15 Take a small p (by trial-and-error!) Take trial- and- 0.8 0 -5 -5 0.4 -10 -10 Uncompensated 0.6 0.2 With lead compensator With lead-lag compensator lead- -15 -6 -4 -2 0 -15 -6 R e a l A x i...
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