Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
REMOTE CONTROL Overview
In this lesson you will learn:
• The relationship between (RF)
transmitters and receivers
• Resonance—the underlying
scientific factor that allows the
precise transmission
frequency of a signal
• Engineering notation
Vex CONTROLLER AND RADIO
IMAGES HERE
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
REMOTE CONTROL Introduction
The kettledrum
If a trumpet and a kettledrum tuned to the note of “E” were placed
in the same room, when the trumpet played the “E” note the
sound wave would leave the trumpet and travel through the air.
The air molecules would then vibrate against the surface of the
drum and the drum would vibrate with an audible sound.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
A dramatic example of resonance is
demonstrated by the Tacoma
Narrows Bridge disaster. Click
“Background/Slide Shows/Tacoma
Bridge: Example of Resonance” to
see the video.
REMOTE CONTROL Introduction
What is resonance?
Resonance is the induction on a physical object of vibrations by a
vibrating force having the same frequency.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
REMOTE CONTROL Introduction
Glossary
Crystal An electronic device, such as an oscillator or detector, using
such a material.
Oscillator To oscillate means to swing back and forth with a steady,
uninterrupted rhythm. An oscillator is a device or
mechanism for producing or controlling oscillations;
especially:one (as a radiofrequency or audio-frequency
generator) for producing an alternating current
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
REMOTE CONTROL Introduction
Resonance in electronic circuits
The induction on a physical object of vibrations by a vibrating force having
the same frequency.
The relationship between resonance and crystals is critical for this
exercise. The crystal placed in the transmitter is contained in a circuit
called an oscillator. The oscillator circuit then uses a concept called
feedback to send electrons to vibrate the crystal in the same manner
that the air molecules vibrated the kettledrum. This will cause the crystal to
vibrate at its resonance frequency and the oscillator circuit will send
a sinusoidal signal to an amplifier. The amplified signal will then travel
to an antenna where the electrical signal is changed to an electromagnetic
wave that will travel through the air.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
REMOTE CONTROL Introduction
Resonance in Vex
The Vex receiver circuit uses an antenna to receive all electromagnetic
waves in its vicinity changing these waves to an electrical signal. An
amplifier then amplifies the electric signal and is sent to a circuit
containing a crystal. If the amplified signal is at the same frequency of
the crystal, then the crystal circuit generates a large sinusoidal signal.
Upon the generation of this sinusoidal signal another circuit will be
initiated causing the motor to be activated.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Transmitter / Receiver Range
Horizontal Antenna Test
HORIZONTAL Antenna Test
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Materials needed
Constructed robotic system
Radio transmitter
Yard stick
Tape measure
Range Table 1 data sheet
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 1
Place robotic system at
stationary point. Turn on the Vex
Controller and Radio. Make sure
to have plenty of linear space for
this experiment.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 2
Place the radio in front of the
robotic system lying flat with the
back on the ground. Make sure
the antenna is extended 1 inch
for minimal reception.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 3
Start the experiment by pushing
the joystick of the radio forward.
With the radio on the ground
slowly slide it away from the test
assembly. Once the radio goes
out of range and the motor stops
slide it back until a consistent
connection is achieved.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 3 continued
When you find and maintain
a consistent signal, measure
the distance from the radio
to the antenna and record
it on Data Table 1.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 4
Using the yard stick,
extend the antenna 4” from the
radio and follow the same
procedure in step 3 to find a
consistent signal at maximum
distance, record the distance on
your data table.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 5
Next, extend the antenna
8” from the radio and follow the
same procedure as in Steps 3
and 4.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 6
Continue to extend the antenna
in 4” increments and measuring
the distance from antenna tip
to the receiver. Record the data
in the packet at each increment.
You will have 8 distances
recorded in Table 1.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 7
1. Complete graph comparison
data sheet, using the
“Example Data for Student
Exercises” as a guide.
2. Complete a reflection
worksheet.
ADD VISUALS FOR DATA SHEET AND
REFLECTION WORKSHEET
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
VERTICAL Antenna Test
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Materials needed
Constructed robotic system
Radio transmitter
Yard stick
Tape measure
Range Table 2 data sheet
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 1
Place robotic system at a
stationary point. Turn on Vex
controller and radio.IMAGE OF CONTROLLER AND RADIO BEING TURNED ON
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 2
Place radio in front of robotic
system upright and the antenna
pointing towards the ceiling.
Extend the antenna 1” to gain
minimal reception.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 3
Move the radio back slowly while
keeping it in a vertical position.
Once the motor stops slide it
back to find the farthest spot of
consistent connection. Measure
the distance back to the antenna
and record the data in table 2.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 4
Using the yard stick, extend the
antenna 4” from the radio and
follow the same procedure in
step 3. Once you find a
consistent signal at a maximum
distance, measure from the
antenna tip to the receiver
antenna. Record the data in
Table 2.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 5
Next, extend the antenna
8” from the radio and follow the
same procedure. Record the
data in Table 2.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 6
Continue to extend the antenna
in 4” increments and measuring
the distance from antenna tip to
the receiver. Record the data in
the packet at each increment.
You will have 8 distances
recorded in Table 2.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 7
1. Complete graph comparison
data sheet, using “Example
Data for Student Exercises”
as a guide.
2. Complete a reflection
worksheet.
ADD VISUALS FOR DATA SHEET AND
REFLECTION WORKSHEET
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
WAIST HIGH Test
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Materials needed
Constructed robotic system
Radio transmitter
Yard stick
Tape measure
Range Table 2 data sheet
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 1
Place the radio in front of robotic
system, waist high
(approximately 2’ -3’), and the
antenna between 45 degrees
and vertical. Extract the antenna
to 1” to gain minimal reception.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 2
Start by pushing down the
joystick to start the motor. Slowly
back up with the radio at your
waist tilted at 45 degrees. Once
you find the greatest distance of
consistent communication record
it in data table 3.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 3
Using the yard stick, extend the
antenna 4” from the radio and
follow the same procedure in
step 3 to find a consistent signal.
Once you find a consistent
signal at a maximum distance,
measure from the antenna tip to
the receiver antenna. Record the
data in Table 3.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 4
Next, extend the antenna
8” from the radio and follow the
same procedure in step 3 to find
a consistent signal. Once you
find a consistent signal at a
maximum distance, measure
from the antenna tip to the
receiver antenna. Record the
data in Table 3.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 5
Next, extend the antenna
8” from the radio and follow the
same procedure in step 3 to find
a consistent signal. Once you
find a consistent signal at a
maximum distance, measure
from the antenna tip to the
receiver antenna. Record the
data in Table 2.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 6
Continue to extend the antenna
in 4” increments and measuring
the distance from antenna tip to
the receiver. Record the data
in the packet at each increment.
You will have 8 distances
recorded in Table 3.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 7
1. Complete graph comparison
Data Sheet, using “Example
Data for Student Exercises”
as a guide.
2. Complete a reflection
worksheet.
ADD VISUALS FOR DATA SHEET AND
REFLECTION WORKSHEET
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
TEST with Obstacles
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Materials needed
Constructed robotic system
Radio transmitter
Tape measure
Sheet of paper
Wood
Sheet metal
Range Table 2 Data sheet
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 1
Place robotic system at a
stationary point. Turn on Vex
controller and radio.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 2
Place the radio in front of
robotic system, waist high
(approximately 2’ -3’),
and the antenna between 45
degrees and vertical. Make sure
antenna is fully extended from
the radio.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 3
Begin the experiment by placing
a piece of paper on top of the
receiver and the antenna. Make
sure the antenna wire is not in
the plastic tube and is wrapped
around the receiver. Push
forward on the joystick of the
radio to turn on the motor of the
robotic system.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 3 continued
Slowly walk backwards until the
motor stops. Find the maximum
distance of consistent
connection. Measure the
distance from the radio to the
antenna. Record the data in
Table 4.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 4
Next place a piece of wood over
the antenna where the paper
was previously. Repeat the
experiment and record the
results in data table 4.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 5
For the last test use a piece of
sheet metal in place of the wood
or paper. Repeat the experiment
as before and record the results
in data table 4.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Step 6
1. Complete graph comparison
Data Sheet, using “Example
Data for Student Exercises”
as a guide.
2. Complete a reflection
worksheet.
ADD VISUALS FOR DATA SHEET AND
REFLECTION WORKSHEET
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