Wednesday, January 2, 2013

Adding the Gyro...

After hundreds of tests, we are now convinced that this kind of helicopter just cannot fly without some software help (reading that on the internet was not enough, we had to try...). The stabilization system is really needed. So, we are going to start just with a gyro. We know the gyro has the drift issue, but we still think it could fly just with the gyro and the manual controls. So, this is the version 2.0 of our PCB board that includes the IGT-3200 triple-axis gyroscope:

Enhanced and a little bit smaller version:



Old version:



First version (without the gyro):



A 3.3v voltage regulator was needed to provide the 3.3v to the gyro.

Also, another correction was made, because the DJI ESC does not provide the 5v (like the Turnigy ESCs) to power the RC-Receiver and the ATMEGA328. So, now the board is prepared to either receive the power from the ESCs or from the RC Receiver battery. Just a minor wire change will be necessary to convert from one to another.

Another hundreds of tests will be made with this version. And later, maybe we are going to order the sparkfun 6 degrees of freedom (Gyro+Accelerometer) to implement the complementary filter or/and the Kalman Filter.

The LED is being used to indicate the gyro calibration on power up.
Futaba's channel 5 is being used to turn the gyro on/off, which is also indicated by this LED.

Friday, December 28, 2012

Back to the Begining, How it all started

So, somebody asked me the other day how all this started. My hobby was to fix smartphones, just for fun. I will get broken phones from my friends and I will open them up, see if I can learn something from them and try to figure out how to fix them, but after the 20th phone, I grew tired of it.

I was looking for a new hobby something fresh, something different, one day I just got a digital copy of Wired Magazine from a friend and I found a really interesting article titled "Here Comes the Drones", I think I read it like 5 times, kept thinking about it, and I start talking about it a lot, showing the article to a lot of people, I thought I found exactly what I wanted to do.

While I was talking about the idea to build one, a colleague from work , Roberto, asked me if he can be part of it, I thought it was a good idea, actually it was the best idea, honestly if it wasn't for him maybe I would it left the project in just that a project that I didn't finish, but Roberto's energy and enthusiasm kept us going, we talked about creating a log, a journal of everything that we do, and he came up with this blog.

I thought to make it all of plywood as some models I saw on the net. I got a clear idea of how I wanted to look like, but Roberto had a better idea as he researched the fiber carbon tubes, it made it lighter, we still used the center wheel made in wood.

Roberto has been doing all the electronics, I am really rusty in this part, the more we work on it, the more things we want to add and see if they work or not, I got some IR proximity sensors and we will see if we can add it to the project.

We hope this blog helps people who are interested in building an Hexacopter from scratch, the most important part is....Enjoy!

Wednesday, December 12, 2012

Research

We will post here all resources from the net that we got ideas from or that we learn from.

Balance Filters:
http://web.mit.edu/scolton/www/filter.pdf

Kalman Filter:
http://arduino.cc/forum/index.php/topic,58048.0.html
http://www.instructables.com/id/Guide-to-gyro-and-accelerometer-with-Arduino-inclu/
http://en.wikipedia.org/wiki/Kalman_filter

ESC Calibration:
http://code.google.com/p/arducopter/wiki/AC2_ESC

Stabilization System:
http://technicaladventure.blogspot.com/2012/09/quadcopter-stabilization-control-system.html
http://diydrones.com/forum/topics/quadcopter-control-function-layers

Some values for reference:


ITG-3200 Triple Axis Gyro:

ADXL345 Accelerometer:

Arduino - Adding more interrupts To Read More RC Channels:


DJI Flame Wheel:


Understanding how Accelerometers and Gyros work:


Eagle: Schematics
and libraries:

Burning the bootloader to the ATMEGA chip:

Controlling the ESCs using the Arduino Servo.h library:

Understanding PPM (in order to read the R/C channels and write to the ESCs):


Tuesday, December 11, 2012

HW and SW Tests

We are using a DJI F550 frame to test the electronics and our first version of software (actually, 2 frames are being used... :)

Once we have both working well, then it will be installed on the frame we are building.




Comparing the frames:



First test. Testing the PCB with the ATMEGA328 chip:



The electronics works! And apparently the first idea on how the microcontroller controls the hexa works too.
This test was made without calibrating any of the ESCs. We can notice that there is a small difference in the response between them. Next step will be calibrating the ESCs.

Tools List

Dremel 3000

Shopping List

(2) Carbon Fiber tubes 1cm by 1cm [cost USD / CLP]
(2) Plywood [cost USD / CLP]
(1) Balsa Block 3x3x12 [cost USD / CLP]
(12) screws [cost USD / CLP]
(12) nuts [cost USD / CLP]
(2) 12 gauge cable [cost USD / CLP]

(1) battery 3200mAh 11.1v 3 LI-PO [cost USD / 39000 CLP]
(6) ESC TURNIGY Plush 30amp Speed Controller [11.91 USD / CLP]
(6) Turnigy Park480 Brushless Outrunner 850kv [19.37 USD / CLP]
(3) CW Blades / Regular Blades [cost USD / 1200 CLP]
(3) CCW Blades / Reverse Blades [cost USD / 2000 CLP]

Customs Import Taxes

Monday, December 10, 2012

Day 2