Last Saturday was the warmest day of the year here so far. So we went to the park to do a outdoor test of my Qaudcopter. I had a sony bloggie video camera on board but unfortunately the camera lens was tilted downwards too much, so all it recorded was the ground with occasional brief horizon views during pitch/roll maneuver. However, the second camera did capture the flight quite well. Here is a short video of the flight..



The quadcopter controller is running on a homemade arduino board with Atmega328 (running at 16HMz) and the homemade sensor board mentioned in my last post. The sensor board has ITG3200 gyro & BMA180 accelerometer for stable flight mode and BMP085 barometric pressure sensors for altitute hold. I am using Hextronix 24 gram brushless motors and Super Simple 10A ESCs from hobbyking and a 4000mAh 2 cell lipo battery. The frame is made from round aluminium tubes and I am using a align t-rex 450 helicopter landing skids.

Here is a short video from the onboard camera:

Figure: 9 DOF Sensor board right after etching

When I started to gather interest in making a quad copter inspired from open source projects around the world, there was one problem. That is getting the gyro, accelorometer, magnetometer and barometric pressure sensors. All these sesnors are used to keep the quad copter stable in flight and for purposes like altitude hold, heading hold etc. The sensors very small package smd devices, are a bit hard to work with when it comes to DIY. Sparkfun electronics sells the sensors on breakout board, but those seem a bit over priced for me. For example, the ITG3200 gyro break out board was priced at $49.99 when the sensor chip can be purchased at $10 a piece. So I decied to give it a try after reading some tips about DIY smt/smd soldering on the web. I tried hot pan soldering couple of times but it partially burnt the pcb in process making it look very ugly but the sensors worked. Then I moved to toaster oven convection heat soldering and it seems to work much better. I got a cheap convection toaster oven for $29 on last black friday and I am quite happy with it. So here is my latest attempt of smt soldering, which involves making a all-in-one sensor board for my quad copter:

Figure: 9 DOF Sensor board after soldering

Although this process does not always go perfectly fine, I am happy to say that all my sensors worked perfectly fine. Here is it in action within MultiWii configuration tool:

Figure: 9 DOF IMU & Baro sensor reading in MultiWii config

I know my board does not look as good as the manufactured boards with silkscreen and things but it works and I am happy with it as it saves me money to buy more gadgets to play with.  The total cost to make the board included $10 for ITG3200, $8 for BMA180, $8 for BMP085, $3 for HMC5883, the I2C voltage level converter plus other passive parts cost were about $10, which brings the total to roughtly around $40. I spent around $10 for shipping for all the components. Still it is much cheaper then buying these sensors as breakout boards from Sparkfun or buying it from ebay for $99 which does not include the 3.3v regulator and I2C level converter.

This board has built-in 3.3v regulator and I2C level converter to use this board directly with a 5v powered arduino or any microcontroller board.

Here the schematic for anyone out there to give this a try, the schematic is based partially on Sparkfun breakout boards schematics, data sheets, and partially on the Free IMU project.

Figure: Second version of the board with corrected circuit for HMC5883L magnetic sensor and smaller board size.

I needed to make a little modification for the HMC5883L magnetic sensor, which has a little bit different application circuit than HMC5843 and HMC5883 version of this sensor.

Here is a short video of the sensor showing the output in MultWii config:

I have been working for a while on building RC quad copters. First I built a medium sized one following the Aeroquad hardware and software. But I was not very happy with the performance. Then I decided to build a small one which can be safely flown inside home for debugging and flight practice.  I tried aeroquad software on it first, but didn't get good result. Then, I was follwing the MultiWii threads and found they are expanding their code to support more hardware and that included Aeroquad hardwares as well. So I downloaded the latest MultiWii code and modified it to work with Aeroquad hardware (ITG3200 gyro, BMA180 accelerometer etc.). Here is how my mini quad prototype looks:

And here is short video of it in action: