PID ControllerThe AP50 features a low-power RISC controller with integrated gyroscopes, accelerometers, sensors, and a global positioning system. A proportional-integral-derivative (PID) controller with user-specifiable gain and flight control modes was used by this system to govern flight. The PID Control loops are as follows:
- Throttle position - derived from altitude error
- Aileron position - derived from roll error
- Elevator position - derived from pitch
- Elevator position - derived from airspeed error
- Rudder position - derived from turn rate error
- Desired roll - derived from bearing error
- Desired pitch - derived from altitude
- Desired pitch - derived from airspeed error
Therefore, a Kp or Kd value of 10 is an equivalent proportional or derivative gain coefficient of 1, while a Ki of 0 sets the integral gain to zero.
The multiple control loops for elevator position and desired pitch enabled adjustment of constant airspeed versus constant altitude. According to the documentation, the aileron, elevator, and rudder PID loops execute at the rate of 30 times per second, the calculation of desired roll, desired pitch, and elevator execute at a rate of 4 times per second, and throttle executes once per second.