Control Systems - Chapter 2 Exam 2026 With A+ Graded Answers
Block Diagram answera shorthand, pictorial representation of the cause-and-effect relationship
between the input and output of a physical system.
provides a convenient and useful method for characterizing the functional relationships among the
various components of a control system. System components are alternatively called elements of the
system
Summing Point answerThe operations of addition and subtraction have a special representation.
block becomes a small circle, with the appropriate plus or minus sign associated with the arrows
entering the circle. An y number of inputs may enter a summing point. Some authors put a cross in the
circle
Takeoff Point answerIn order to have the same signal or variable be an input to more than one block or
summing point, a takeoff point is used. This permits the signal to proceed unaltered along several
different paths to several destinations.
SISO answerThe basic configuration of a simple closed-loop (feedback) control system with a single
input and a single output.
Closed Loop Diagram Terminology answerLowercase letters are used to represent the input and output
variables of each element as well as the symbols for the blocks. These quantities represent functions of
time, unless otherwise specified. r=r(t)
In subsequent chapters, we use capital letters to denote Laplace transformed or z-transformed
quantities, as functions of the complex variable s, or z, respectively, or Fourier transformed quantities
(frequency functions), as functions of the pure imaginary variable jcc. Functions of s or z are often
abbreviated to the capital letter appearing alone.
R(s) = R
Plant/Process/Controlled System answerthe system, subsystem, process, or object controlled by the
feedback control system.
, Controlled Output answeroutput variable of the plant, under the control of the feedback control
system.
Forward Path answerthe transmission path from the summing point to the controlled output
Feed forward (control) Elements answerthe components of the forward path that generate the control
signal u or m applied to the plant. Note: Feedforward elements typically include controller(s),
compensator(s) (or equalization elements), and/or amplifiers.
Control Signal answerthe output signal of the feedforward elements g1 applied as input to the plant g2
Feedback path answerthe transmission path from the controlled output c back to the summing point.
Feedback Elements answerh establish the functional relationship between the controlled output c and
the primary feedback signal b. Note: Feedback elements typically include sensors of the controlled
output c, compensators, and/or controller elements.
reference input answerr is an external signal applied to the feedback control system, usually at the first
summing point, in order to command a specified action of the plant. It usually represents ideal (or
desired) plant output behavior.
primary feedback signal answerb is a function of the controlled output c, algebraically summed with the
reference input r to obtain the actuating (error) signal e, that is, r ± b = e. Note: A n open-loop system
has no primary feedback signal.
actuating (error) signal answers the reference input signal r plus or minus the primary feedback signal b.
The control action is generated by the actuating (error) signal in a feedback control system Note: In an
open-loop system, which has no feedback, the actuating signal is equal to r
Negative Feedback answermeans the summing point is a subtractor, that is, e = r — b. Positive feedback
means the summing point is an adder, that is, e = r + b
Block Diagram answera shorthand, pictorial representation of the cause-and-effect relationship
between the input and output of a physical system.
provides a convenient and useful method for characterizing the functional relationships among the
various components of a control system. System components are alternatively called elements of the
system
Summing Point answerThe operations of addition and subtraction have a special representation.
block becomes a small circle, with the appropriate plus or minus sign associated with the arrows
entering the circle. An y number of inputs may enter a summing point. Some authors put a cross in the
circle
Takeoff Point answerIn order to have the same signal or variable be an input to more than one block or
summing point, a takeoff point is used. This permits the signal to proceed unaltered along several
different paths to several destinations.
SISO answerThe basic configuration of a simple closed-loop (feedback) control system with a single
input and a single output.
Closed Loop Diagram Terminology answerLowercase letters are used to represent the input and output
variables of each element as well as the symbols for the blocks. These quantities represent functions of
time, unless otherwise specified. r=r(t)
In subsequent chapters, we use capital letters to denote Laplace transformed or z-transformed
quantities, as functions of the complex variable s, or z, respectively, or Fourier transformed quantities
(frequency functions), as functions of the pure imaginary variable jcc. Functions of s or z are often
abbreviated to the capital letter appearing alone.
R(s) = R
Plant/Process/Controlled System answerthe system, subsystem, process, or object controlled by the
feedback control system.
, Controlled Output answeroutput variable of the plant, under the control of the feedback control
system.
Forward Path answerthe transmission path from the summing point to the controlled output
Feed forward (control) Elements answerthe components of the forward path that generate the control
signal u or m applied to the plant. Note: Feedforward elements typically include controller(s),
compensator(s) (or equalization elements), and/or amplifiers.
Control Signal answerthe output signal of the feedforward elements g1 applied as input to the plant g2
Feedback path answerthe transmission path from the controlled output c back to the summing point.
Feedback Elements answerh establish the functional relationship between the controlled output c and
the primary feedback signal b. Note: Feedback elements typically include sensors of the controlled
output c, compensators, and/or controller elements.
reference input answerr is an external signal applied to the feedback control system, usually at the first
summing point, in order to command a specified action of the plant. It usually represents ideal (or
desired) plant output behavior.
primary feedback signal answerb is a function of the controlled output c, algebraically summed with the
reference input r to obtain the actuating (error) signal e, that is, r ± b = e. Note: A n open-loop system
has no primary feedback signal.
actuating (error) signal answers the reference input signal r plus or minus the primary feedback signal b.
The control action is generated by the actuating (error) signal in a feedback control system Note: In an
open-loop system, which has no feedback, the actuating signal is equal to r
Negative Feedback answermeans the summing point is a subtractor, that is, e = r — b. Positive feedback
means the summing point is an adder, that is, e = r + b
