MAXA Robotics 2011

1. MAXA Robotics 2011 Box NXT Adapted from Physics by Design, Second Edition, by Barbara Bratzel, College House Enterprises, 2007

2. TASK DESCRIPTION • The objective of this task is to help you become familiar with the beam-and-peg building system associated with the NXT robot, unlike the bricks-and-plates system used with the RCX robot and with most of the traditional LEGO projects. • In this robot task, you must build from scratch a box using the NXT brick as a base, using beams, pegs and some other related parts. • The box must completely contain two 2” diameter LEGO plastic balls (they can’t roll out of any side). • It must have a hinged lid that closes completely but does not touch the balls in the closed position.

3. TASK DESCRIPTION • You must also know the names of the parts you are using, which will be introduced in this lesson. • You must do this task individually when you pass it off, but may work with a partner when practicing. • To pass off this task, you will have 45 minutes in one sitting to completely assemble the Box NXT. • There is no programming required for this task.

4. BOX NXT Here is a possible solution for the Box NXT. In this picture the lid is closed and the ball is completely contained. Yours must contain two balls, but for a better view of the box, only one ball was used here.

5. BOX NXT Here the lid is in the open position.

6. BEAMS Here are several of the various beams available to use for this project. A straight beam is named by its size. If it has a bend or angle, describe it in those terms as well as the size. The size of each beam is always one less than the number of holes, the distance from end to end…think about it.

7. BEAMS From left to right: 5 hole straight beam (size 4) 7 hole straight beam 3 hole straight beam 13 hole straight beam 3X5 obtuse angle beam 3 hole straight beam with cross-hatch end 2X3X6 obtuse angle beam 2X4 right angle beam 1X3 right angle beam

8. PEGS Here are the most common pegs, or connectors in the LEGO system. The four pegs connect beams together in various ways. The two pegs in the middle connect two beams together, and are very similar, with one minor difference…the black peg is slightly thicker in diameter allowing for a snug fit. Use the grey peg if you want a loose fit, like a freely-rotating hinge. The longer black peg connects three beams together. The blue peg has two different connector patterns…round on one side, and crossed on the other.

9. PEGS The two parts in front are a bushing and a spacer, used on axles to keep other parts in place, or to create space between parts.

10. SAMPLE CONSTRUCTION Here are some examples of how you might connect beams and pegs together. Take careful notice of the two bottom pictures, two ways to create right angles. The first uses the 6-8-10 right angle pattern, based on the classic 3-4-5 Pythagorean triple studied in geometry. The second uses the curved beam shown earlier, which forms a right angle with the two end sections. These techniques are crucial to creating a rigid box structure.

11. AXLES Here are several axles that work very nicely with the beam and peg system. An axle is named by its length in relation to a standard brick or plate. Below is a size 10 axle.

12. PRACTICE AND PASS OFF • Now it is time to create your BOX NXT, to practice doing it until you have mastered it and can do it within the 45-minute time limit, in one sitting. • Remember, you can practice with a partner, but you must pass off this task by yourself. • You may also use this slide show to practice, but when you pass it off, you may not use it, or any other pictures or diagrams to help you. • When you are ready, tell a mentor first, then go for it! • Good luck!