This preview shows pages 1–10. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: K G(s) +  MECH 431 Design via Root Locus Slide 1 Control system design via Rootlocus method Chapter 7 K G(s) +  MECH 431 Design via Root Locus Slide 2 Performance specification • Control specifications include: 1) Transient response (overshoot and settling time) 2) Steadystate requirements (steady state error or accuracy to a particular input). • !!! Before any design of a control system is attempted, control specifications must by decided. K G(s) +  MECH 431 Design via Root Locus Slide 3 Design by RootLocus method • The design by the rootlocus method is based on reshaping the root locus of the system by adding poles and zeros to the system’s open loop transfer function and forcing the root loci to pass through desired closed loop poles in the s plane. • The characteristic of the rootlocus design method is its being based on the assumption that the closedloop system has a pair of dominant closedloop poles. K G(s) +  MECH 431 Design via Root Locus Slide 4 System compensation • In some cases, insuring satisfactory performance can be done by tuning the gain. • In many cases though, this adjustment may not provide sufficient alteration. • Increasing the gain will: – Improve the steadystate behavior, – Results in poor stability or even instability. K G(s) +  MECH 431 Design via Root Locus Slide 5 System compensation • At this point it is necessary to modify the structure so that the system will be have as desired. • Such a redesign by the addition of a suitable device is known as compensation . • A device inserted into the system for the purpose of compensating the deficit of the original system is called a compensator . K G(s) +  MECH 431 Design via Root Locus Slide 6 System compensation • Common used compensators are: 1) Lead compensator 2) Lag compensator 3) Laglead compensator K G(s) +  MECH 431 Design via Root Locus Slide 7 Lead & lag compensators • If a sinusoidal input is applied to the input of a network, and the steadystate output (which is also a sinusoid) has a phase lead, then the network is called a lead network and the compensator called a lead compensator . • If the steadystate output has a phase lag, then the network is called a lag network and the compensator called a lag compensator . K G(s) +  MECH 431 Design via Root Locus Slide 8 Laglead compensators • In a laglead network, both lag and lead occur in the output but in different frequency regions. • Phase lag occurs in the lowfrequency region and phaselead occurs in the highfrequency region. • The compensator is called a laglead compensator . K G(s) +  MECH 431 Design via Root Locus Slide 9 Series & parallel compensation • In series compensation the compensator is placed in series with the plant....
View
Full
Document
This note was uploaded on 02/07/2011 for the course MECH 433 taught by Professor Danielasmar during the Spring '09 term at American University of Beirut.
 Spring '09
 DanielAsmar

Click to edit the document details