Chapter 8 Flashcards
In an open loop system, the output does not _________.
Affect the input.
Yeckout Ch 8, Pg 422
Briefly describe closed-loop systems.
Closed-loop systems are systems where the output is measured and fed back to modify the input.
Yeckout Ch 8, Pg 425
For a “position” feedback system, the output variable ___________.
Is fed back as itself (not as a derivative of x).
Yeckout Ch 8, Pg 427
What is the equation for the feedback natural frequency for a position feedback system?
wn_position = wn*sqrt(1 - K1)
Yeckout Ch 8, Pg 428
What is the equation for the closed-loop damping ratio for a position feedback system?
z / sqrt(1 + K1)
Yeckout Ch 8, Pg 428
A closed-loop position feedback system provides the opportunity to change what aircraft characteristics?
The natural frequency and the damping ratio through an adjustable variable gain parameter.
Yeckout Ch 8, Pg 428
True or False
the closed-loop time constant remains unchanged from an open-loop time constant when a position feedback system is considered.
True
Yeckout Ch 8, Pg 428
What is the difference between a position feedback system and a rate feedback system?
In a rate feedback system, the derivative of the output variable is fed back.
Yeckout Ch 8, Pg 428
How is differentiation done in the Laplace domain?
Multiply by the Laplace variable s.
Ex: d/dL(s) = s^2
Yeckout Ch 8, Pg 428
What is the equation for the rate feedback system damping constant?
z = 2z + k2*wn *(1/2)
Yeckout Ch 8, Pg 429
True or False
The natural frequency of the open-loop and closed-loop system remain constant when considering a closed rate loop feedback system.
True
Yeckout Ch 8, Pg 429
What parameter can be changed with a rate feedback system?
The damping ratio.
Yeckout Ch 8, Pg 429
How does an acceleration feedback system differ from a position or rate feedback system?
The second derivative of the output is fed back.
Yeckout Ch 8, Pg 430
What are the equations for the feedback natural frequency and damping ratio for an acceleration feedback system?
wn = wn / sqrt(1+k3*wn^2) z = z / sqrt(1+k3*wn)
Yeckout Ch 8, Pg 430
What is the equation for the closed-loop transfer function?
CLTF = C/R = G/(1+GH)
Yeckout Ch 8, Pg 432
What is the utility of the closed-loop transfer function formula?
The equation allows the representation of a closed-loop system as one transfer function in an open-loop form.
Yeckout Ch 8, Pg 432
What is the closed-loop characteristic equation formula?
1 + GH = 0
Yeckout Ch 8, Pg 432
What is the time rise parameter?
The time required for a step input response to rise from 10 to 90% of its steady-state final value.
Yeckout Ch 8, Pg 435
What is the time delay parameter?
The time it takes for the response to reach 50% of its steady-state value.
Yeckout Ch 8, Pg 435
What is the settling time parameter?
The time required for the response to stay within a specified percentage, usually 2 to 5%.
Yeckout Ch 8, Pg 436
What is the maximum overshoot?
The maximum overshoot is the difference between the magnitude of the maximum overshoot and the steady-state value.
Yeckout Ch 8, Pg 436
The time to Max overshoot is approximately _____.
2pi/wd
Yeckout Ch 8, Pg 437
What is root locus analysis?
The root locus technique graphically presents how the roots of the closed-loop characteristic equation change on the complex plane as the adjustable gain is varied from zero to Infinity.
Yeckout Ch 8, Pg 437
True or False
The root locus will begin at the open-loop poles for a value of K = 0, and end at open-loop zeros for a value of K = infinity.
True
Yeckout Ch 8, Pg 440