现代控制工程-第十二章.pptVIP

5-3 Typical Root Locus and 3. Effects of zeros and poles on root locus Example 5.9 OL transfer function is （typical system 8，9 ） example5.10 OL transfer function is 1.Location of CL poles and system response Root locus is very suitable for the allocation of desired CL poles. Where is the suitable location of CL poles? ------according to the design requirements A. quantitative understanding let the CL transfer function to be (simple roots) B qualitative understanding （1）To ascertain the system to be stable, all the poles should be located in the left half S plane. （2）To ascertain the system to be swift, the non-dominant poles should be located far from the imaginary axis, or have zeros nearby. （3）To ascertain the system to be smooth, the dominant complex poles should be located around the line in S plane. （4）To ascertain the system to be accurate, there ought to have poles located at origin. Example 5.11 OL transfer function is given as: * * Chapter 5 The Root Locus Method 5-1 The Root Locus Concept 5-2 The Root Locus Procedure 5-3 Typical Root Locus 5-4 Control System Analysis and Design Using Root Locus The Root Locus Concept and Procedure  5-3 Typical Root Locus 5-4 Control System Analysis and Design Using Root Locus OL transfer function CL root locus -1/T j 0 j 0 -1/T1 -1/T2 1. Typical Root Locus j 0 -1/T1 -1/T2 -1/T3 j 0 j 0 -1/T OL transfer function CL root locus j 0 -1/T1 -1/T2 j 0 j 0 -1/T OL transfer function CL root locus j 0 -1/T j 0 OL transfer function CL root locus OP zeros and poles have impact on root locus. 1. Effects of OL zeros Adding extra OL zeros will make the root locus move leftward, and improve the stability of the system. The nearer the zeros approach the imaginary axis, the more notable the effect is. j 0 -a -a/3 j 0 -a -z j 0 -j j -1 j 0 -z -1 -j j j 0 -2 j 0 -2 -4 2. Effects of OL poles A