# Shared Flashcard Set

## Details

3rd Exam
Chapter 8 and 9 exam
15
Mechanical Engineering
11/04/2012

Term
 1. What is a root locus? (8)
Definition
 The plot of a system's closed-loop poles as a function of gain
Term
 2.Do the zeros of a system change with a change in gain? Why or why not? (8)
Definition
 No because...
Term
 3.What are two ways to find where the root locus crosses the imaginary axis? (8)
Definition
 (1) Apply Routh-Hurwitz to the closed-loop transfer function's denominator. (2) Search along theimaginary axis for 180 degrees.
Term
 4.How can you tell from the root locus if a system is unstable? (8)
Definition
 7. If any branch of the root locus is in the rhp, the system is unstable.
Term
 5.How can you tell from the root locus if the settling time does not change over a region of gain? (8)
Definition
 If the branch of the root locus is vertical, the settling time remains constant for that range of gain on thevertical section.
Term
 6.How can you tell from the root locus that the natural frequency does not change over a region of gain? (8)
Definition
 If the root locus is circular with origin at the center
Term
 7.How would you determine whether or not a root locus plot crossed the real axis? (8)
Definition
 Determine if there are any break-in or breakaway points
Term
 8.Briefly describe how the zeros of the open-loop system affect the root locus and the transient response. (8)
Definition
 The zeros of the open loop system help determine the root locus. The root locus ends at the zeros. Thus,the zeros are the closed-loop poles for high gain.
Term
 1.Name two major advantages of the design techniques of Chapter 9 over the design techniques of Chapter 8.  (9)
Definition
 A. Permits design for transient responses not on original root locus and unattainable through simple gainadjustments. B. Transient response and steady-state error specifications can be met separately andindependently without the need for tradeoffs
Term
 2.What kind of compensation improves the steady-state error? (9)
Definition
 PI or lag compensation
Term
 3.What kind of compensation improves both steady-state error and transient response? (9)
Definition
Term
 4.Cascade compensation to improve the steady-state error is based upon what pole- zero placement of the compensator? Also, state the reasons for this placement. (9)
Definition
 A pole is placed on or near the origin to increase or nearly increase the system type, and the zero isplaced near the pole in order not to change the transient response.
Term