Lawrence Technological University
College of Arts and Science
Department of Mathematics and Computer Sciences

Handouts

LEGO Mindstorms, what comes in the box and what does not

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In the box

  1. A good platform for teaching mathematics and geometry
  2. A good platform for teaching mechanics
  3. A good platform for teaching robotics
  4. A simple icon based programming language for Windows suitable for getting started quickly.
Appreciating the power of the LEGO Mindstorms kit requires understanding a little about its organization. This LEGO robotics kit continues the tradition of easy construction from standardized blocks that snap together without tools. In traditional LEGO sets the fundamental piece was the LEGO brick. In the technical sets like the Mindstorms set, the fundamental piece is the LEGO beam (beams are bricks with holes in them). Each LEGO beam is 1 vertical LEGO unit high, 1 horizontal LEGO unit thick and as many horizontal LEGO units long as there are studs along the top of the beam. The important thing to remember is that the horizontal LEGO unit is only 5 / 6 of the vertical LEGO unit. A second important fact is that a plate (a thin brick) is 1/3 of a LEGO vertical unit. With these two facts you can construct stable rectangles and right triangles from beams and pegs (in the holes of the beams). The gears also fit nicely into this scheme of LEGO horizontal units.
Gear TeethGear Radius
in LEGO units
80.5
121.0
241.5
402.5
So with their axles 3 units apart, two 24 tooth gears should mesh nicely. What about meshing a 12 tooth and a 24 tooth gear? The LEGO folks have provided those odd little 2-unit-2-hole and 1-unit-1-hole beams that, when abutted to a regular beam make a 0.5 unit spacing easy! In the picture below, notice examples of proper and improper gear meshing, and of the smallest stable locked rectangle.
The LEGO unit, gear meshing and beam locking

Not in the box, but easily available

  1. A platform for teaching the fundamentals of good programming. Relax, I won't duplicate Donald Knuth's Literate Programming here. Just remember that long term institutional associations are history and "institutional memory" seldom resides in people anymore. A clearly documented programming application is a vital communication skill today more than ever before.
  2. Batteries. The Yellow Brick continues to eat batteries even after you press the off button. The memory is not the Flash memory you may be used to with a digital camera. This brick uses a small amount of power all the time to remember your programs and its firmware! Over vacations, remove your batteries; and then, re-insert them and re-install the firmware when classes resume. Keep plenty of spare batteries on hand. Batteries seem most likely to run down in the middle a class session. If you delay replacing the batteries you will also have to reload the firmware. (Then after you insert new batteries, your laptop, which is running without its power cord, will perversely die in the middle of reloading the firmware.)
  3. Updates. The LEGO company has struggled a bit in recent years. Hobbyists have continued to improve the Mindstorms kit as a learning platform. (This is not so unusual. Much of what we take for granted as the Internet today came from a bunch of model railroad hobbyists.) As it happens, many of the major contributers to this learning resource use something other than Windows as their favorite development platform.
The analogy of easy assembly from basic building beams and blocks, without tools, continues imperfectly into programming the RCX brick. Because of a lot of interested Open Source developers, it is easy to extend both your LEGO robot's hardware and software.

About the box that the LEGO Mindstorms kit comes in

  1. The boxtop is good for putting over the IR tower and the robot while firmware or new programs are being loaded. This prevents interference from other towers that may be sending data at the same time.
  2. The big clear plastic box insert with the deep wells wastes storage space in a classroom. If you are looking for a small part it often helps to lift up the whole insert so you can look up at the bottom of the wells.
  3. For storing the larger parts, I use plastic microwave boxes: 1 for my robot, 1 for wheels and 1 for motors, sensors and wires. I prefer the ones from the Hiller's Market Deli counter. Your taste may vary.
  4. All of the small parts from a kit fit, nicely organized, in an Art Bin plastic box. Their "900 Infinite Divider System" boxes are available at craft stores like the Michaels chain.

      Revised June 19, 2005