Last Saturday, I had the opportunity to participate in a local RoboCup Junior (RCJ) training session at Georgia Tech University. One of the competitions of RCJ is 1-vs-1 soccer and 2-vs-2 soccer. Robots detect a ball giving off an infrared signal and try to score points.
I must thank HiTechnic for sending me a prototype of their new IRSeeker to play with and show off at the session. With it, I was able to build a robot that could participate in the 1-on-1 or 2-on-2 soccer challenge, but it was tricky! In the 1-on-1, the robot has specific limitations - it must fit inside an 18cm diameter cylinder (with all arms and moving parts fully extended) and can be no taller than 22 cm.
I started by printing out a gray circle with a diameter of 18cm and began to build. Try it - try keeping your Brick, wheels, and any sensors or other tools inside that circle... very challenging. Well, you're looking at my solution. In the photo, the IRSeeker is on the left and the Compass sensor is on the right. I'm also including a top-view photo, but the circle is difficult to see. Trust me that it does all fit inside that circle!
To give you an idea of how the IRSeeker works, imagine dividing the IRSeeker's surroundings into 30 degree sections. The rear-most sections are not readable (about 90 degrees worth), so numbering the accessible sections from left to right gives the IRSeeker 9 sections to monitor. (This image is taken from HiTechnic documentation.)
I take the value that the IRSeeker obtains (1-9) and (because I lacked time) using a rather unsophisticated string of COMPARE blocks, I have the robot turn the proper number of degrees so it is facing the correct segment where the IRBall is located. Not very fancy, but it'll work in a pinch...
Also provided to me by HiTechnic were some prototype boards (solderless and solderable) that you can use to create your own sensors and such... all able to be connected to the Brick via the standard NXT cable.
All in all, HiTechnic is developing a nice range of add-ons for your NXT. I highly encourage you to visit their website and they love feedback! If you've got something you'd like to see developed (sensor-ish, that is), drop them an email and see what they have to say...
Thanks you, HiTechnic team, for the loans and help in getting the stuff to work.