Transcript Behavior-Based Robotics

EE 1105: Introduction to EE
Freshman Seminar
Lecture 2: Signals, Systems and
Circuits
Credit: Dr. Bill Dillon, Dept. of Electrical Engineering, UTA
National Instruments MyDAQ and LABVIEW
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
EE Jargon
• Device: primitive element
– Passive (no power source needed), electric: ex: Resistor
vs:
- Active (need power source), electronic: ex: Transistor
• Analysis: Understand how a given circuit works
• Design (Synthesis): Understand how to build the
circuit from requirements
• Signals – inputs and outputs to devices, circuits,
and systems
– AC (time varying)
– DC (constant)
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Classifications of Systems By
Application Areas
•
•
•
•
•
•
•
Communications Systems
Computer Systems
Control Systems
Electromagnetics
Electronics
Power Systems
Signal Processing Systems
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Communications Systems
• Telephony
– Analog and Digital
– Switched Channels
• Radio
– Broadcast AM, FM, & SW
– Two-Way
• Television
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Computer Systems
• Programmable Microcircuits
• High-speed switching of logic circuits
• Used for
– Computation
– Control
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Control Systems
•
•
•
•
•
Automated
Adaptable
Faster Operation than Manual
More Reliable than Manual
Modern high-performance aircraft rely on
automated control systems
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Electromagnetics
• Antennas for Sending & Receiving
Information
– Cell Phones
– Satellite Dishes
• Magnetrons for generation of
Microwave Energy
• Induction Heating for Industrial
processes
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Electronics
•
•
•
•
Material Properties
Devices
Circuits
Used for Detecting, Amplifying and
Switching Electrical Signals
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Power Systems
• Large networks connected by low
frequency a-c transmission lines
• Small networks in aircraft and
spacecraft
• Electromechanical Energy Conversion
• Power Electronics
– High frequency switching converters
– High efficiency, high power density
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Signal Processing Systems
• Transform and manipulate signals and the
information they contain
• Image processing
– Data from weather satellites
– MRI scans of the human body
• Noise reduction
• Encryption
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
BSEE Degree Plan
Dr. Saibun Tjuatja, UG Advisor
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Intellectual Themes of EE
• Modularity (ex: device)
– Manage complexity by reusing simple components
(electrical, mechanical or code) nomenclature: devices
• Abstraction (ex: circuit, system)
– Represent complex systems by connecting modules
using interconnects
• Block diagrams, Data flow diagrams (state machines), signal
flow graphs, electric circuits
• Modeling (ex: electronic vs electric)
– Represent behavior of systems using mathematical
abstractions
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Signals and Systems
– Signal:
• Conventional Electrical or Optical signals
• Any time dependent physical quantity
• AC or DC
– System:
• Object in which input signals interact to
produce output signals.
• Linear vs Nonlinear systems
– Fundamental properties that make it
predictable:
» Sinusoid in, sinusoid out of same
frequency (when transients settle)
» Double the amplitude in, double the
amplitude out (when initial state
conditions are zero)
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
u(t)
?
x(t)
y(t)
Images Source: Internet
System Modeling
• Building mathematical models based on
observed data, or other insight for the system.
– Parametric models (analytical): ODE, PDE
– Non-parametric models: ex: graphical models - plots,
or look-up tables.
– Mental models – Ex. Driving a car and using the
cause-effect knowledge
– Simulation models – ex: Many interconnect
subroutines, objects in video game
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Types of Models
• White Box
– derived from first principles laws: physical,
chemical, biological, economical, etc.
– Examples: RLC circuits, MSD mechanical
models (electromechanical system models).
• Black Box
– model is entirely derived from measured data
– Example: regression (data fit)
• Gray Box – combination of the two
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Abstraction: Ideal Circuit
• A circuit model is usually two or more
circuit elements that are connected.
• A circuit model may have active
elements (sources) as well as passive
elements (such as resistors).
• By the assumption that electric signal
propagation is instantaneous in a circuit,
our circuit model has lumped
parameters.
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Example of a Circuit
1000 ft AWG 14
Copper Wire
100 W
Lamp
120 V Battery
0.25 
2.57 
144 
120 V
2.57 
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Model: Kirchhoff’s Voltage Law
• The sum of the voltage drops around a
closed path is zero.
• Example: -120 + V1 + V2 + V3 + V4 = 0
0.25 
+ V1 -
2.57 
+ V2 -
120 V
2.57 
- V4 +
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
+
V3
-
144 
MyDAQ
•
•
•
General Purpose Data Acquisition Device from National
Instruments (NI)
Multimeter, Oscillocope, Function Generator,
Spectrometer and much more
$50-$200
+
$200
=

$300-$10,000
+
$300-$5,000
+ much more
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
• LabVIEW programs are called:
– Virtual Instruments (VIs)
– because their appearance and operation
imitate actual instruments.
• However, they are analogous to main
programs, functions and subroutines from
popular language like C, Fortran, Pascal,
…
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Abstraction: LabVIEW Programs
Virtual Instruments (VIs)
• Front Panel
• Controls = Inputs
• Indicators = Outputs
• Block Diagram
• Accompanying “program”
for front panel
• Components “wired”
together
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Primitive Modules
• The basic primitive building blocks in LabVIEW include
–
–
–
–
Numbers – formatted according to type (e.g. integer, boolean, float, etc.)
Loops – While, For
Logical and Arithmetic Ops – Comparator, Summer, Adder
GUI Elements – Button, Knob, Dial
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
More Complex Modules
• More complex blocks in LabVIEW include
– Arrays, Clusters, Enums
– Signals and Transfer Functions
– Data statistics, Graphs
http://www.ni.com/gettingstarted/labviewbasics/datastructures.htm#enums
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Abstraction: Dataflow
Programming
• In this case, the block diagram executes from left to right, not
because the objects are placed in that order, but because the
Subtract function cannot execute until the Add function finishes
executing and passes the data to the Subtract function. Remember
that a node executes only when data are available at all of its input
terminals and supplies data to the output terminals only when the
node finishes execution.
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Basic Concepts: Charge
• Charge is measured by amounts of electrons or protons in
matter, measured in multiple of e=1.6 x 10^-19 C(oulombs)
• The charge density in materials depends on type of material
(conductor, semiconductor, insulator)
Images Source: Internet
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Voltage and Current
• Voltage is the energy per unit of charge.
dw
v
dq
• Current is the rate of flow of charge.
dq
i
dt
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Voltage and Current (continued)
• The relationship between voltage and
current in a circuit element defines that
circuit element.
• Both voltage and current have associated
polarities.
• These polarities determine the direction of
power flow.
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Ideal Basic Circuit Element
• Three attributes of an ideal circuit element:
– There are only two terminals
– Described mathematically in terms of current
and/or voltage
– Cannot be subdivided into smaller components
i
+
v
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
1
2
Five Fundamental Elements
• Ideal Voltage Sources
– Independent
– Dependent
• Ideal Current Sources
– Independent
– Dependent
• Resistors
• Inductors
• Capacitors
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Voltage Polarity Definitions
i
+
v
-
1
2
• Positive v
– voltage drop from 1 to 2 or
– voltage rise from 2 to 1
• Negative v
– voltage drop from 2 to 1 or
– voltage rise from 1 to 2
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Current Polarity Definitions
i
+
v
-
1
2
• Positive i
– Positive charge flowing from 1 to 2
– Negative charge flowing from 2 to 1
• Negative i
– Positive charge flowing from 2 to 1
– negative charge flowing from 1 to 2
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Passive Sign Convention
i
+
v
-
1
2
• Whenever the reference direction for the
current in an element is in the direction of the
reference voltage drop, use a positive sign in
any expression that relates voltage to current.
Otherwise, use a negative sign.
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Power and Energy
dw  dw   dq 
p

   vi

dt  dq   dt 
• Power associated with a circuit element
is consumed by that circuit element
when the value of power is positive.
• Conversely, power is generated, or
produced by the element if the value
consumed is negative.
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Expression of Power
i
i
1
+
v
-
2
1
+
v
-
2
p  vi
p  vi
i
v
+
i
1
2
p  vi
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
v
+
1
2
p  vi
Independent Voltage Source
• Voltage may be
constant or timedependent
• Delivers nominal
terminal voltage
under all conditions
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Positive Terminal
Vg
Negative Terminal
Independent Current Source
• Current may be
constant or timedependent
• Delivers nominal
terminal current
under all
conditions
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
Negative Node
Ig
Positive Node
Electrical Resistance
(Ohm’s Law)
• Electrical resistance
is the ratio of voltage
drop across a resistor
to current flow
through the resistor.
• Polarities are
governed by the
passive sign
convention.
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
R
i
+
v
v
R
i
-
Power Consumed by Resistors
• Resistors
consume power.
• v and i are both
positive or both
negative.
+
v
-
p  v i
v  R i
v
i
R
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
R
i
p i R
2
2
v
p
R
Conductance Defined
• Conductance is
the reciprocal of
resistance.
• The units of
conductance are
called siemens (S)
• The circuit symbol
is G
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
1
G
R
i  v G
i
v
G
p  v2  G
2
i
p
G
Homework 2 due next class!!
Available online at course website
Credit: Dr. Bill Dillon, Dept. of Electrical
Engineering.
Questions?
Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015
40