Here is a build log that will be constantly updated as I progress. The project is to create an autonomous three-motored helicopter style UAV. An Axon will be used to process everything. In the beginning, I will be using Teleoperation (look under the RC tutorial) to allow me to test certain things at a time. As of 9/17/08, I have this:

The RC transmitter and the current test craft are shown. The transmitter is a Spektrum DX7 7-channel spread spectrum radio, currently the test craft is using a 6-channel half range receiver. Should the need arise, I can exchange receivers from one of my recreational helicopters, which uses a 7 channel full range receiver.

The test craft itself is manufactured by LaHeli in the Czech Republic. Before LaHeli began producing these a year ago, only a few tri-motored craft existed, and all were home built with varying sucess rates and flight characteristics. The main problem was the gyroscopic stabilization, which LaHeli solved by producing a small stabilizing unit that automatically mixed the 120 degree CCPM mixing for the motors, and has two small gyros to stabilize the craft.

I plan on removing the stabilizer, and replacing it with the Axon. The existing stabilizer does its job fairly well, but it wont be suitable for a UAV test platform, as the gyros are not accurate enough. However my first goal will be to insert the Axon in between the reciever and the stabilizer, to see how well the Axon can handle processing the signals from the receiver. The time between input and output should not exceed 100ms, or else the speed will be too low, and hinder flight ability. The current electronics have a delay of less than 40ms, and hopefully the Axon should not increase it by too much. I will post another update once I order and receive the Axon.

9/20/08

Ordered an Axon. Should arrive 9/24 or 9/25.

9/23/08

Axon came in early! I run a club at my high school, hopefully I can get some simple stuff working for tomorrow.

It's about 50 minutes since I got it, and it's working perfectly! The getting started and other tutorials on here are perfect, they can't make it any easier for you. Also programming in AVR is easy to learn. I have a little experience in Java using JGrasp, and with the prewritten code you download here on SoR, it's easy to figure it out. My first lines of code were to make two servos go foward, and it works great!

On a side note... the test craft crashed. I was flying it at a RC fun-fly, and I pitched it too far, and smacked it upside down into the ground... thank goodness it only restuled in some broken props and bent booms.

9/30/08

Lately I've been trying to get used to programming the Axon with AVR. I made a little robotic arm to actually see what the servos do...

Simple Robot Arm Video

I'm still a little rough on programming servo movements. I've been using for-loop style code to control the speed of the servos, but I just dont like doing it that way. Admin mentioned I can control servos using a timer, which I will have to try.

10/12/08 

I got a Sharp IR rangefinder, and was amazed how simple it is to get it to work. I will be using it on the UAV for autonomous landing purposes. The UAV will slowly descend (measured by DE accelerometer just ordered), and when the Sharp IR detects the ground, it will lower the descent rate for a nice landing.

On a side note, I crashed the test craft. I was flying at a RC fun fly, pitched it too far in a turn, and it flipped into the ground. Oops. Will have to replace some props and bend back some booms, nothing major.

11/4/08

Its been a while since my last update, but I've spent the time learning how to program the AVRs and other small robotic projects. Since the tri-motor system requires some complex mixing, I'll be making a mini-uav using my E-Flite Blade CX2 helicopter as the airframe.

Admin has a page about his Blade CX helicopter here. 

The only difference between the CX and the CX2 is that the CX uses an older 72mhz radio system, and that the CX2 uses a 2.4ghz radio system. On newer CX2s the receiver and 3-in-1 controller are separate, I bought my CX2 years ago so I have the older one where the receiver is integrated. However it still will be a fairly easy task of removing the receiver.

Here is a picture of an AR6100 receiver connected to the Axon

The receiver inside my CX2's 4-in-1 is the same as the AR6100, so any programming I do for the CX2 will work in other models (like the Y-Ufo) if I use the AR6100 receiver or the 7-channel AR7000 receiver. So now my next challenge is to read the pulses coming out of the receiver... the trick is to read the pulses in under 20ms, so after you read the pulses you can quickly adjust them according to the sensors (gyroscopic, accelerometer, etc) and output those signals to the servos and motor controller. I will probably use code people are developing in the Ardupilot project, where they are trying to make a UAV airplane with an Arduino.