[UPDATE: after legal advice from LEGO, LatteBox has now changed its case design to remove the LEGO Technics holes, which you can see in these pictures. The new case is shown at the bottom of this post.
What got me into this whole UAV thing a couple years ago was the crazy idea that I could combine my love of LEGO Mindstorms robotics with my interest in RC planes. And thus was born the first Lego UAV
. But to be honest it's a bit a kludge, given the constraints of the huge Mindstorms motors, and the gearing apparatus I needed to get it to drive just one control surface, the rudder. (Everything else is controlled by the off-the-shelf FMA Co-Pilot).
That's a shame, because the Mindstorms NXT CPU module is a very capable ARM7 processor with Bluetooth, I2C ports, a display screen and a great set of programming tools, ranging from RobotC to LabView. And the available sensors include everything you'd need for a proper UAV, from 3-axis accelerometers to gyros, compasses, even pressure sensors. The only barrier to it being a real-world robotics platform is the motors, which basically only make sense in a Lego context. If only there were a way for NXT to drive regular RC servos....
Now there is. This week I received the new Lattebox NXT servo controller
, which was first discussed here
on DIYDrones a few weeks ago. It's a brand new product from a Taiwanese company, so it's still a little rough around the edges in terms of documentation (and I've got some doubts about whether the use of the Lego connecting holes is actually legal!), but the hardware build quality is excellent and it looks really powerful.
Here's what comes in the box:
That's an I2C multiplexer, which connects to the NXT CPU (and allows other I2C sensors to be connected) and a servo mulitplexer, with ports for up to ten servos. (You can add more of these boxes to a total of 160 servos--all independently driven by one NXT!). The I2C multiplexer costs $140 and the servo driver is $60. Both are quite small, around the size of a standard RC servo or RC receiver. The C code to run them is available here
I haven't had a chance to put it through its paces yet, but I'm pretty jazzed about what I've seen. But at this point I need to disclose that there is a competitor to this product that I've been beta testing for the past few months (but can't yet talk about). Indeed, I've built a whole new UAV around this other NXT-to-servo hardware, which I'll be showing at the FIRST Robotics Championships in Atlanta on April 16-18. The ability to use the Mindstorms controller, sensors and IDEs for proper aerial robotics is nothing short of mindblowing, and I can't wait to unveil my bird then.
In the meantime, here are some more shots of the LatteBox device.
The servo driver board, out of its case.
Back side of the servo driver board
[UPDATE: This is the new case, with the LEGO Technics holes removed. The case shown in the previous images are no longer available. If you order the product, you will get the case here, not the ones shown in the images above it!]