Autonomous Quadcopter
I find small autonomous aerial vehicles incredibly interesting! The cost of sensors, microprocessors and high power brushless motors has fallen enough to make a small multicopter affordable to construct.
My basic design was influenced by some of the developments by other hobbyists at diydrones. I chose to develop a low weight compact quadcopter to keep component costs down. The basic system design consists of a controller board (in my case a low cost “KK” board combining an AVR ATMega 168p and 3 gyroscopes), 4 electronic speed controllers (ESCs) and 4 brushless motors. My chosen battery was a 610 mAh LiPolymer. A standard R/C receiver is used to give command inputs.
The board I chose provides an integrated solution for quadcopter control using conventional R/C inputs, but doesn’t have sufficient components for true stabilisation or autonomy. The board uses open source firmware, which I’m developing further to incorporate accelerometer data. My chosen accelerometers are from the Nintendo Wii Nunchuck. These communicate through i2c, which can be interfaced using 2 digital IO pins from the microcontroller.
This project is currently ongoing. Key areas of work are:
- Finish the construction of a lightweight frame
- Balance the motor and propellers
- Finalise the accelerometer/gyroscope fusion code
- Adjust gains through testing
Once the aircraft’s been constructed, I’ll have a better idea of the lifting capability available. There are a number of other sensor options I’d like to explore:
- Optical flow for position hold using a mouse sensor and a small lense
- Obstacle avoidance using infrared or ultrasonic distance sensors
Many of the core components involved are the same regardless of motor and ESC selection, and so a scaled up model could be built in a similar fashion.