Computer Science 014
LEGO Robot Engineering

Lecture 5: Servos and Sonar
Date: Wednesday, January 10, 2007

Today's lecture location: TCL 206

Announcements
- Even more important than plugging in your robots: unplugging your soldering irons!
- Any group interested in using the Mindstorms NXT kit, please let me know soon
Demonstrate your bumpy and blind maze runners today, including corner detection and recovery
Line following continues
Debugging hints
- don't forget printf and the LCD displays!
- you may wish to have your robot beep or play music when it gets into certain situations if you are unsure why your robot is behaving as you observe
New toys
- Expansion boards for Handy Boards
- Servo motors
  - motors that move to a specified position
- Sonar
  - Sound Navigation and Ranging
  - use sound energy to locate objects and estimate their distance
  - the transmitter circuit causes an ultrasonic burst ("chirp") to be emitted from a speaker element
  - sound travels and is reflected back
  - the receiver circuit tuned to detect the specific frequency of sound emitted by the transmitter
  - at room temperature, sound travels approximately 1.1 ft/millisecond. (i.e., it takes .89 milliseconds to travel 1 foot)
  - problem: irregular objects may produce a collection of reflected sounds
  - problem: especially smooth surfaces at an angle, sound may reflect like light on a mirror and not return
New lab: finding a position, and back in the maze for a smoother run