© 2006 Carnegie Mellon Robotics Academy Designed for use with the LEGO MINDSTORMS ® Education NXT Software and Base Set #9797 Mine Mapping Choose a Sensor See Teacher Guide for printing instructions

© 2006 Carnegie Mellon Robotics Academy Designed for use with the LEGO MINDSTORMS ® Education NXT Software and Base Set #9797 Opening Activity Look at an object in the room How far away is that object? How did you measure the distance? How might a robot do something similar?

© 2006 Carnegie Mellon Robotics Academy Designed for use with the LEGO MINDSTORMS ® Education NXT Software and Base Set #9797 Opening Activity Visual estimation Odometry (walk to the object and count steps) Measuring tools (meter stick) Humans measure distance by:

© 2006 Carnegie Mellon Robotics Academy Designed for use with the LEGO MINDSTORMS ® Education NXT Software and Base Set #9797 Opening Activity Touch Sensor Sound Sensor Light Sensor Ultrasonic Sensor Rotation Sensor (built into motors) Combinations of sensors! Robots can’t read meter sticks. Instead, they use sensors.

© 2006 Carnegie Mellon Robotics Academy Designed for use with the LEGO MINDSTORMS ® Education NXT Software and Base Set #9797 Choosing a Sensor How to choose a sensor –Identify what capabilities the sensor needs to have –Test each sensor to see whether it has those capabilities –Choose the best sensor or combination of sensors Sensors Which one (or maybe more than one) will work best?

© 2006 Carnegie Mellon Robotics Academy Designed for use with the LEGO MINDSTORMS ® Education NXT Software and Base Set #9797 Identify Capabilities The sensor needs to… –Detect walls –Detect objects –Give you some information about where those objects are detected –Can you think of more? Things to Look For In order to map the mine, you must be able to see the walls and any other important features

© 2006 Carnegie Mellon Robotics Academy Designed for use with the LEGO MINDSTORMS ® Education NXT Software and Base Set #9797 Testing and Evaluation In this investigation, you will test the different sensors and choose one What do you need to evaluate? –Functionality Does it work? –Reliability Is it going to work every time? –Accuracy Does it give good data? –Suitability to environment Will it work in a mine?

© 2006 Carnegie Mellon Robotics Academy Designed for use with the LEGO MINDSTORMS ® Education NXT Software and Base Set #9797 Choose Sensor: Technical Review The Sensors View Mode

© 2006 Carnegie Mellon Robotics Academy Designed for use with the LEGO MINDSTORMS ® Education NXT Software and Base Set #9797 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

© 2006 Carnegie Mellon Robotics Academy Designed for use with the LEGO MINDSTORMS ® Education NXT Software and Base Set #9797 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

© 2006 Carnegie Mellon Robotics Academy Designed for use with the LEGO MINDSTORMS ® Education NXT Software and Base Set #9797 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

© 2006 Carnegie Mellon Robotics Academy Designed for use with the LEGO MINDSTORMS ® Education NXT Software and Base Set #9797 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.

© 2006 Carnegie Mellon Robotics Academy Designed for use with the LEGO MINDSTORMS ® Education NXT Software and Base Set #9797 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

© 2006 Carnegie Mellon Robotics Academy Designed for use with the LEGO MINDSTORMS ® Education NXT Software and Base Set #9797 View Mode Displays a sensor value on the NXT’s LCD screen Updates continually View Mode The View Mode on the NXT allows you to read sensor values without having to write a program first

© 2006 Carnegie Mellon Robotics Academy Designed for use with the LEGO MINDSTORMS ® Education NXT Software and Base Set #9797 Your robot will need to use sensors to “see” important features inside the mine Detect walls Detect objects Report “where” things are Summary You must select an appropriate sensor or combination of sensors for the mine mapping task You will use the NXT’s View Mode to monitor sensor values while experimenting