A Test Bed for Measuring Commercial Component Reliability in Unmanned Aerial Systems
Non-military UAS are increasingly built from commercial off-the-shelf (COTS) components — servos, motors, and actuators sourced from the consumer market and integrated into flight-critical roles. Despite this, the reliability literature on these components under sustained operational loads is sparse. Stochastic component failure during flight operations is not just a maintenance problem; it is a safety hazard, and without empirical reliability data it is difficult to design maintenance schedules, redundancy systems, or safety cases that reflect actual field behavior.
This study designed and built a laboratory test bed to measure the operational reliability of a COTS servo unit under real-world load conditions. Rather than simulating representative inputs, the test bed was driven by actual flight data recorded from a Boeing Scan Eagle® aileron servo — one of the more demanding servo applications in small UAS, where the aileron must respond continuously to maintain roll control throughout a flight.
The test bed replayed this recorded command profile at baseline duration, then at double and triple the baseline period, measuring encoder output of commanded servo positions throughout. The research question was whether the servo's reliability — defined as the fidelity of its position response — would degrade measurably as accumulated operational time increased.
Results: The test bed performed within reliability criteria over the baseline period, but showed statistically significant degradation in mean position fidelity when operational cycles were doubled and tripled. The finding has direct implications for COTS component qualification and maintenance interval design in non-military UAS.
ElSaid A., Adjekum D., Nordlie J., ElJamiy F. — A test bed for measuring UAV servo reliability. MDPI Aerospace, 2019.