Automated RC Aircraft Rudder Control

PID ControlArduino C++MATLABPrototyping

Designed and built a closed loop automatic rudder prototype for an RC aircraft to counter adverse yaw without continuous pilot input. A mechanical inclinometer and position sensors measure lateral motion, while a PID controller converts the resulting error into servo driven rudder corrections, demonstrating the complete sensing to actuation loop on a physical test rig.

Coordinated turn correction

Uncoordinated turn

Slip presentPath deviationBody axis ≠ flight path

IMU detects yaw / slipController commands rudderAircraft returns to coordinated flight

Coordinated turn

Rudder correctionPath tracking restored → 0

01Problem

Develop an automatic rudder system that could reduce adverse yaw without requiring continuous manual rudder input from the pilot.

During a turn, adverse yaw can rotate the aircraft opposite the intended turn direction, requiring coordinated rudder input to keep the aircraft aligned with its flight path.
Making these corrections manually from the ground is difficult because the pilot must continuously judge the aircraft's yaw behavior from a remote viewpoint.
The goal was therefore to create a control system that could sense lateral attitude or yaw-related motion and automatically command corrective rudder deflection.

02Approach

Built a physical prototype that converts inclinometer feedback into closed loop rudder commands through a PID controlled servo system.

Created a mechanical inclinometer prototype in which a ball moves laterally through a constrained track as the system tilts, providing a physical representation of aircraft lateral motion.
Position sensors along the track detect the inclinometer's location and provide the feedback signal used to determine the magnitude and direction of the required correction.
Implemented PID control to convert the measured position error into servo motion, allowing the rudder to respond automatically rather than relying on direct pilot input.

03Result

Demonstrated a working benchtop feedback system that detected inclinometer motion and automatically repositioned an RC aircraft rudder in response.

The prototype continuously used inclinometer position feedback to command the servo and actively move the rudder toward the corrective direction.
Built and tested the sensing, control, and actuation architecture at prototype scale before attempting to package the mechanism into a smaller aircraft-compatible form.
The completed system demonstrated the full loop from mechanical sensing → position measurement → PID correction → physical rudder actuation.