NXT MindStorms Robot Racing Arena for Challenges 22, 26 

Arena for Challenge 22

Uses: Use for Robot Racing (Challenge 22). The image above is of a rather worn arena that has had three terms of use across three schools - but still seems to work OK!

Construction: I used a straw board [1] with taped start/finish lines. The start/finish lines were electrical tape [6]. In the centre of the race track I placed a piece of wood to give the students some experience of Robot behaviour when meeting a wall at a slight angle (the Robot will often try to climb up the wall, and may even fall over). The piece of wood was an off-cut about 17 inches (430mm) long, 4 inches(100 mm) high and 2 inches (50 mm) wide. None of these dimensions are critical, except that if the wood is much longer than 17 inches, there may be insufficient space for the Robots to navigate around it.

The race track shown above has silver sides, to allow it to also serve in a Challenge 26 - this is not necessary for Challenge 22.

To make this a dual purpose Arena (Challenge 26 as well as challenge 22), I sprayed the Arena with matt black paint [2] and rimmed it with silver tape [3]. This gave me light sensor calibration readings of about 70 in the silver area & 25 in the black area when new and about 35 when worn (the readings you will get in your arena will almost certainly be different). This gap between reading values is big enough for student’s robots to operate well even if the students are sloppy with their light sensor calibrations. The green/yellow electrical tape shown above gave a light reading of about 45, again sufficiently different for this to be used by students, if they so desired; (the tape positions are such that a Robot using a light sensor could use the green/yellow line as a signal to turn left.

If you decide to make an arena, also get a mask (see illustration above) from the chemist’s or similar shop to use when you spray-paint the strawboard, so that you do not breath in spray paint particles, (these particles can’t be good for your lungs).

Other options? The original suggestion from Carnegie-Mellon University (see link in the “About” section of this web site) was for a 3 feet by 3 feet arena. This size proved difficult to find in a form that was a reasonable price (that is, as dirt cheap as possible!) The strawboard was a the best substitute I could find, 1050 mm by 800 mm (3 feet 5 inches by 2 feet 7 inches). A hint- don’t use a gloss paint on this board – I tried a gloss red and it was absorbed very patchily - the board looked as if it had measles – ugh!

Regarding a substitute for the strawboard, if you have a tip shop near you, then it is worth a look as these recycling centres at the local refuse dump as they can be a rich source of really cheap material. Other centres that recycle building material could also be worth checking. If these do not prove successful, your next bet could be a building material supplier.

At a building material supplier an option is Masonite sold as a blackboard. This has a nice matt black surface, but I could not find any pieces available near the 3 feet by 3 feet size – you may have more luck.

If you have facilities for chopping up large sheets of building material (I haven’t) you could look at material like an MDF white backing sheet 2400 mm by 1200 mm (6 feet 10 inches by 3 feet 11 inches) [4]. In this case you would use black cloth tape [5] to edge the arena. An ordinary 3mm MDF board of the same size is about 2/3 the cost of the white-surfaced MDF board, but you would have to factor in the price of the paint to get a matt black or white surface for your arena. Which way to go? -  Up to you…

Good luck with your fossicking!

Obtainable Where?

The following information is included to provide an idea about price & availability - it is not intended to be a recommendation for any particular commercial institution. The prices were current at the end of 2008.

[1] The 102 cms x 76 cms x 2 mm (40 ins x 30 ins x 1/16 in) straw board was obtained from an Art supplies Store; (in my case “Artery”, Collins Street, Hobart, Tasmania $4.95).

[2] The matt black spray can paint was obtained from a "remainder" store; (in my case Chickenfeed, Hobart, Tasmania, $3:00; enough for blackening two strawboard sides). Revision: In 2010, Chickenfeed stopped selling spray cans of paint. However these are still available from hardware stores for prices in the range of $AU3:50 to $AU7:00.

[3] The 48 mm. wide (approx. 2 inches) self-adhesive CSR Bradford Insulation Aluminium Foil Tape was obtained from a hardware store, (in my case Kemp & Denning, Hobart, Tasmania, $14.99 for a roll long enough (20 metres) to last you for a really long time…) Subsequently I have also found a cheaper version at a remainder store (in my case Chickenfeed;  Aluminium tape 48 mm. wide by 10 meters long $2.99).

[4] The 3 mm MDF white backing sheet mentioned above can probably be obtained from a hardware store; (in my case I saw it in stock at Kemp & Denning, Hobart, Tasmania, for $19).

[5] This self-adhesive black cloth tape (48 mm by 4.5 meters, approx. 2 inches by 5 yards) was obtained from a hardware store; (in my case at Kemp & Denning, Hobart, Tasmania, $2.16).

[6] This electrical tape was obtained from a hardware store, I've forgotten the price, but think it was about $2.50. It need not be green/yellow, any colour that gives a light sensor reading that is more than 10 different from the light sensor reading in either the silver or black portions of the arena should be fine.

www.DrGraeme.net - LEGO NXT MindStorms - Tutorials - Robot Race (Challenge 22) arena construction.