System Identification Guidance for Multirotor Aircraft: Dynamic Scaling and Test Techniques

• Published in: Journal of the American Helicopter Society Vol. 66; no. 2; pp. 1 - 16
• Main Authors: Ivler, Christina M., Rowe, Elizabeth S., Martin, James, Lopez, Mark J.S., Tischler, Mark B.
• Format: Journal Article
• Language: English
• Published: AHS International 01.04.2021
• ISSN: 2161-6027; 2161-6027
• DOI: 10.4050/JAHS.66.022006

State-space system identification was performed to extract flight dynamic models for hovering flight of a 55 cm, 1.56 kg hexacopter unmanned aerial vehicle. Different input excitation techniques were tested to determine which maneuvers provided high-quality system identification results for small-scale multirotor vehicles. These input excitation techniques included automated frequency sweeps, varying in amplitude, and multisine sweeps. Coherence, Cramer-Rao bounds, and insensitivities were used as metrics for comparing the system identification results. A parametric variation of frequency sweep amplitudes were performed in all axes (roll, yaw, pitch, and heave) to provide guidance on frequency sweep amplitude for small-scale multirotor unmanned aerial systems. The dynamics of the 55 cm hexacopter were used to estimate the dynamics of a larger 127-cm hexacopter via Froude scaling based on hub-to-hub distance as the characteristic length. The scaled results were compared to an actual system identification model of a 127-cm hexacopter.