Arduino Mega and ArduPilot Mega(APM 2.5)

Hello everyone,

I am working on a project that will implement the Arduino Mega having sensors connected to it and send that data to an APM board. My question is, other than connecting the Arduino to the APM via the I2C, how can I make the connection??

Also, using any of the readily available code for sensing obstacles, how accurate would it be? Would there be lots of interfering? Is there a code to use digital data?

I would appreciate any other advice on this subject matter. The project is for both indoor and outdoor autonomous quadcopter.

Thanks