Lego makes an incredible building system but its controls fall short if you want to make radio-controlled cars. Brian shows us a fairly simple upgrade that makes a huge difference.
Lego makes an amazingly cool building system. The simplicity of the blocks themselves are deceiving when you see the cool things people manage to construct from them. Mix a couple servos and motors into the equation and you've got some incredible potential. Brian saw this potential but found that the stock system was ultimately too limiting.
He really wanted to make radio-controlled cars out of Lego. Unfortunately, what he found were two main options for control, neither of which were able do the job he wanted. The first big strike was that both control systems were infrared, which means you have very limited range and it has to be line-of-sight. One of the systems has a horrid response time but more precise control. The other system has a quicker response time but simply offered "all or nothing" style control; full throttle or no throttle.
Brian decided that to really get what he wanted he was going to have to get his hands dirty. If he wanted to make radio-controlled cars from Lego, he was going to have to go all out and modify it to have proper control. He chose to use a 2.4Ghz transmitter and receiver as well as some custom electronics to translate that data for the Lego system. Keep in mind, the idea here was to use the Lego drives and servos so that everything meshes together well and is still backward compatible if he wishes to use the other Lego accessories.
To build this, Brian chose the Picaxe 14M2. He explains in his blog that it was chosen for the price as well as how easy it is to program since it uses BASIC. The Picaxe is doing the job of translating the the 2.4 Ghz transmitter's signal from standard servo control to the proper signal for the Lego drives. He notes that the Picaxe can't put out enough power to actually drive the motors though, so an H-bridge was required as well.
As you can see in the video above, the results appear to work quite well. I realy would have loved to have seen a few creations tooling around using this system, but I suspect those will be appearing soon. You can find the BASIC code as well as a full parts list and breakdown of the modification on his site.