I am working on a collective pitch quad, using a single motor to turn all 4 of the rotors, and servos to control the pitch of each individual rotor. I am using tail rotor components from helicopters for the rotors. The mechanical systems are coming together and now I am thinking about how to control it. I have an APM (without the GPS unit), and I have used arduinos before so I thought it would not be too bad to try to modify the ArduCopter code for this. But having looked at the code I do not even know where to start.
The changes that I know will be needed are:
Rather than changing the motor speed from 0-max (0 - 255 pwm value?) will be controlling a servo, and the servo is centered at the midway point (128 pwm?)
It will need to take into consideration negative pitch. Negative pitch will cause the thrust to be in the opposite direction, but the drag moment of the blade will be in the same direction.
I am looking for any advise, I’m not even sure where to start.