Sentry System
Integration and Action
See Teacher Guide for printing instructions
Designed for use with the LEGO
MINDSTORMS®
Education NXT Software and Base Set #9797
© 2006 Carnegie Mellon Robotics Academy
Opening Activity
What do you do when faced with the
following situations?
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•
•
Suspicious person in the hallway at school
Smell of gas in your home
Lights go out in your classroom
Students fighting in the locker room
Broken bottles found on the playground
Designed for use with the LEGO MINDSTORMS® Education NXT Software and Base Set #9797
© 2006 Carnegie Mellon Robotics Academy
Opening Activity
What do you do when faced with
dangerous situations?
• In some cases where the danger is immediate, you
should take steps to ensure your own safety first
• In all cases, the proper response includes alerting a
responsible authority figure as soon as possible
Designed for use with the LEGO MINDSTORMS® Education NXT Software and Base Set #9797
© 2006 Carnegie Mellon Robotics Academy
Reaction Action
How should your robot react to
situations it detects?
• What is your robot’s role and place in the security plan?
– This is up to your group to determine
– Consider the limitations of your robot
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•
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What you can detect
What you can actually tell based on what you detect
Physical limitations
Legal liability – even human security guards have very strict
limits on their legal authority!
• What are your robot’s priorities for keeping itself safe?
Designed for use with the LEGO MINDSTORMS® Education NXT Software and Base Set #9797
© 2006 Carnegie Mellon Robotics Academy
Investigation Path (b)
•
This version of Investigation 3
continues where the Two-Way
Communication Sentry System
Investigation left off
•
Groups that chose a One-Way
system should use Investigation
3a instead
Designed for use with the LEGO MINDSTORMS® Education NXT Software and Base Set #9797
© 2006 Carnegie Mellon Robotics Academy
Logistics
• The two cooperating groups
will continue to work together
for this project
• The two sentries must
perform their own lookout
duties, as well as
communicate with each other
Two of a… Kind Of
The two sentries must watch their
own posts, but also listen for alerts
from the other unit
Designed for use with the LEGO MINDSTORMS® Education NXT Software and Base Set #9797
© 2006 Carnegie Mellon Robotics Academy
Integration and Action:
Technical Review
The Sensors
Designed for use with the LEGO MINDSTORMS® Education NXT Software and Base Set #9797
© 2006 Carnegie Mellon Robotics Academy
Touch Sensor
• Detects physical
contact
• Tells you:
– 1 if touched
– 0 if not touched
Poke, Poke?
The cross axle probe inserted into
the end of the Touch Sensor contact
increases its effective range
Designed for use with the LEGO MINDSTORMS® Education NXT Software and Base Set #9797
© 2006 Carnegie Mellon Robotics Academy
Sound Sensor
• Detects Sound
• Tells you:
– Amplitude (volume) of sound
– Low numbers = quiet
– High numbers = loud
– Can be confused by sounds of
different frequencies (pitch)
Listen Carefully
The Sound Sensor can detect many sounds,
from gentle vibrations to jarring collisions
Designed for use with the LEGO MINDSTORMS® Education NXT Software and Base Set #9797
© 2006 Carnegie Mellon Robotics Academy
Light Sensor
• Detects light intensity
• Tells you:
– The intensity of light
detected
– Low numbers = dark
– High numbers = light
• Light on the front can
be turned on or off
Light the Way
The light sensor in Reflected Light mode
shines its own light out and measures
the amount that bounces back
Designed for use with the LEGO MINDSTORMS® Education NXT Software and Base Set #9797
© 2006 Carnegie Mellon Robotics Academy
Ultrasonic Sensor
• Detects distance
• Tells you:
– Distance to a surface or
object in front
– Indicates a distance in
cm or inches
Ro-Bat
The Ultrasonic Sensor uses the same
basic principle for detecting distance
as cave-dwelling bats do.
Designed for use with the LEGO MINDSTORMS® Education NXT Software and Base Set #9797
© 2006 Carnegie Mellon Robotics Academy
Rotation Sensor
• Detects rotation of
the motor axle
• Tells you:
– Amount the axle has
rotated in degrees or
full rotations
– Rotational position of
an attached piece*
– Linear position of an
attached piece*
Rotato Chips
The Rotation Sensor is built into the
Interactive Servo Motors
* If you also know the initial position and how
the piece is attached, you can calculate this
Designed for use with the LEGO MINDSTORMS® Education NXT Software and Base Set #9797
© 2006 Carnegie Mellon Robotics Academy
Summary
• Detection is not enough. Your robot must
also be programmed to respond
appropriately to anything it detects.
• Furthermore, it must respond to anything
the other robot detects!
• This investigation is a continuation of the
(b) path for two sentries; you will need your
previous Investigation 2b program for this
• See previous investigations or the
Advanced > Bluetooth section for
Bluetooth information
• The two sentries should work together
as partners, in a sensible way!
Designed for use with the LEGO MINDSTORMS® Education NXT Software and Base Set #9797
© 2006 Carnegie Mellon Robotics Academy