Reducing weight

As told in my previous blogpost the weight of my new frame is currently the only negative factor. I bought some Carbon fiber plates to reduce weight.


-> Carbon Fiber Sheet 1.5mm*300mm*150mm

I just had to cut this sheet in half to get the exact size I needed to fit on my quad. The result looks really nice and it also feels strong.

I also threw away the aluminium battery holder underneath the quad and added a second carbon sheet on top to hold battery and electronics. This sheet is seperated by the same rubbers I use for my motormounts. I did this to hopefully reduce even more vibrations. But that is something I'll test later.

An other thing I did to reduce weight is by using just wires to connect my ecs to the battery. On my prevouis X-Frame I used the powerdistribution board I had created for my first + Frame equiped with arduino. But this board is currently not really needed. So in total I saved up to 130 grams (almost 10%). Current total weight 1270 grams.

Because of the bad weather. Just a little flight test in the garage to see if it still works.

The Motors that I'll use for my quadrocopter are the HobbyKing AX-2210N 1000kv.
(hobbyking productpage)

As I see, most quadrocopters use low kv motors. They just have to create a good static trust. Because these motors have a low kv they consume less power the high kv motors. Note that a large propellor should be used to get enough thrust.

These motors will be equiped with a 10 inch GWS 1060 prop. My quadrocopter will be around 1.1kg. I hope this will work :)


A good review/test of these motors with several props and voltages can be found on this link. peakeff.com AX-2210N benchmark As you can see on this page. At max power I should get a total thrust of 3kg. The total weigth of a quadrocopter should be maximal 1/2 of the maximal thrust.

practical advice: these motors perform well and are very cheap, but quality is medium. I bought a total of 6 motor. 2 motors had shaft that was not 100% straight. You can't see it with your eyes. But ones they turn with your prop. You will see them dance :). This gives a lot of unwanted vibrations on your quadroframe and noise to your imu. So if you buy these motors, order more than you need :)

Inertial measurement unit (IMU)

To get my quadrocopter stabelized I use the Razor 9 Degrees of Freedom inertial measurement unit. This 9DOF IMU is AHRS (Attitude and heading reference system) compatible. More info about this imu: Razor 9DOF

My first test with this board learned me that the data from the original firmeware is very sensitive for external noise.

A quadrocopter has 4 motors. And that is a lot of vibrations. The original firmeware for this board sends raw data comming from the sensors. When my motors are on > 60% power, this raw data can't be used and the need for a good software filter (algoritme) is essential.

The new AHRS firmeware for this board uses the DCM (Direction Cosine Matrix) algoritme. This should reduce error (noise) in data and eliminate drift. Test result for new firmeware will be posted in next blog. The AHRS firmeware can be downloaded here: Razor 9DOF IMU AHRS code

Mainboard

The Seeeduino Mega will be my choice as main controller. This board is 100% arduino platform compatible. So it's very easy to develop, program and test. The advantage above the original arduino mega is that the Seeeduino Mega is a bit smaller.

Weight: 25.3 grams
ATmega 1280 @ 16MHz
Selectable 5V/3.3V operation
70 Digital IO
16 Analog inputs
14 PWM outputs
4 Hardware serial ports (UART)
More info about the Seeeduino Mega

This litle mainboard will be the central control unit of the quadrocopter. All input sensors and all output control units will be attached to this board.

Blog Startup

Hi,

This is my first post on this blog. On this blog I will post all info about my current project: Building a homemade wifi controlled quadrocopter with gps autonavigation and onboard wifi IP camera. I hope this will work :)