ArduPilot home page

Chris Anderson
DIY Drones

June 23, 2008

ArduPilot is an inexpensive navigation-only autopilot based on the open-source Arduino [ http://arduino.cc/ ] platform. It is currently in beta. In fall 2008, it will be available as an easy-to-assemble kit (PCB with SMD parts already soldered, plus a few through-hold parts to solder yourself as required) for approximately $30. The software and hardware are all open source.

ArduPilot just controls the rudder (for navigation to GPS waypoints) and the throttle (for altitude hold). It requires a third-party stabilization unit (we recommend the FMA CPD4 CoPilot [ http://fmadirect.com/detail.htm?item=1489&section=20 ] ) to control the ailerons and elevator of the aircraft. If you want a more sophisticated autopilot that has the stabilization function built-in, you'll need to wait for ArduPilot Pro [ http://diydrones.com/profiles/blog/show?id=705844%3ABlogPost%3A44813 ], which is not as far along on the development path.

The entire electronics setup for a typical electric aircraft with an ArduPilot and FMA CoPilot looks like this:

ArduPilot features include:

Built-in hardware failsafe that uses a separate circuit (multiplexer chip and ATTiny processor) to transfer control from the RC system to the autopilot and back again.
Unlimited waypoints
Has eight spare analog inputs (with ADC on each) and two spare digital inputs to add additional sensors
Can be powered by either the RC receiver or a separate battery
Binary mode GPS parser with checksum error checking and high-speed (56k) throughput
Hardware-driven servo control (using the Arduino Servo Timer library), which means less processor overhead, tighter response and no jitters.
All four RC-in channels (plus the autopilot on/off channel) can be read by the CPU. This allows the autopilot to read the initial throttle and rudder position when you switch to autonomous mode, so it can maintain speed and heading. The other two channels can be used for whatever you want, such as triggering a camera sequence or dropping an object. (Remember that the aileron and elevator channels are seperately controlled by the FMA Co-Pilot)
Status LEDs for the failsafe (on/off) and the GPS (satellite lock).
A trim pot on the board so you can adjust the autopilot on/off position to suit your particular RC system.

4:30pm