Flying with Arduino!

I like to build stuff with my hands and I like programming and I like things that fly, so for me the tricopter project was really three things coming together. The project was seeded about a year ago after seeing the amazing videos on Youtube made by David WindestĂĄl. I soon ordered the hardware needed for the build from Hong Kong, but my order ended up in the customs and I didn’t get the stuff until late autumn. Finally, with a box full of cheep Chinese RC electronics in my possession, I started out making the wooden frame on which I fitted motors and electronics; a rather crude and simple construction. The only moving part (apart from the three rotating propellers, hence its name ”tricopter”) is the tail rotor that controls the machine’s yaw direction (the ”rudder”). This makes a tricopter a much simpler construction than a helicopter. When almost done with the fittings I discovered that my transmitter did not support the mixing needed to make David’s build work.

While hesitating to buy a new transmitter I stumbled upon the multiwii.com project, a project devoted to make multicopters (tricopters, quadcopters, hexacopters) fly with the help of Arduino (programmable microprocessor), Nintendo Wii Motion Plus (gyro), and Nintendo Nunchuck (accelerometer). It turns out that the gyro and accelerometer used in the Nintendo Wii hand controls are pretty competent. The Arduino is like a very small computer with enough processing power to make real time decisions based on the inputs from the Nintendo PCBs and the user. A tricopter is an inherently instable flying machine, and without the help of electronics (configured correctly) it will flip in a matter of milliseconds. The combination of the three main components makes for a very stable flying platform. Since these units are mass produced they come with a relatively low price tag.

Being a happy Arduino hobbyist I immediately fell in love with the idea to use Arduino as the tricopter’s brain, and as a bonus I could use my old transmitter. The mutilwii project comes with a two programs; an Arduino program that needs to be configured with your multicopters specific settings, such as number of rotors, min and max rpm, yaw direction and a few other parameters; and the MultiWiiConf program used to configure and calibrate the multicopter. Even though I followed the assembly instructions as close as I could, it took a while to sort things out. The soldering of the tiny Nintendo components and connecting all the wires to the Arduino proved to be quite a challenge. Finally when I had found the correct positions for the gyro (Wii Motion Plus) and the accelerometer (Nintendo Nunchuck), I could calibrate the thing and spin up the motors for the first time.

Equipped with three brushless motors, each capable of producining almost 1 kilo of thrust and mounted on the tip of long arms, the tricopter has enough punch to break lose from your hand if not  gripped firmly. With safety goggles on I did a lot of test runs, first holding the thing in my hand, and later on the tarmac outside my maker shed. Luckily nothing vital broke and no one got injured. After a few iterations of weeding out vibrations, trims, and other configurations; it finally took off!

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