Investigation of Stability and Disturbance Rejection trade-offs for an e-VTOL Controller

Jean Pierre Theron, Joseph F. Horn, Daniel A. Wachspress, Jeffrey D. Keller, Abhinav Sharma

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The stability and disturbance rejection properties, and the associated design trade-off between these properties, of a Dynamic Inversion (DI) flight control system are investigated using advanced simulation models of an electric-VTOL aircraft. The simulation environment uses a conventional blade element / finite-state inflow simulator that can optionally couple to a higher fidelity aeromechanics model with free-vortex wake modeling. The DI control architecture allows for investigation of different rotor thrust control allocation schemes including variable collective pitch control and variable rotor speed control. The influence of the electric motor’s speed controller gains is also included in the investigation. A range of gain sets are evaluated using broken-loop and sensitivity loop frequency analyses. The acceptable design space was then investigated to identify designs that would meet the SAE International AS94900 standard’s requirements for stability margins, and the proposed revision of the ADS-33E-PRF standard’s requirements on disturbance rejection properties. The investigation showed that using larger gains sets for the flight controller generally reduced stability margins, while increasing the disturbance rejection properties. The higher fidelity models revealed that variable rotor speed thrust control could not yield any design that met the requirements of the standards in the roll axis. However, viable designs were found for the pitch axis. Variable collective pitch control yielded viable designs for both pitch and roll axes. No discernible trend was found with changing the electric motor speed controller gains.

Original languageEnglish (US)
Title of host publicationAeromechanics for Advanced Vertical Flight Technical Meeting 2022
PublisherVertical Flight Society
ISBN (Electronic)9781713859253
StatePublished - 2022
EventAeromechanics for Advanced Vertical Flight Technical Meeting 2022 - San Jose, United States
Duration: Jan 25 2022Jan 27 2022

Publication series

NameAeromechanics for Advanced Vertical Flight Technical Meeting 2022


ConferenceAeromechanics for Advanced Vertical Flight Technical Meeting 2022
Country/TerritoryUnited States
CitySan Jose

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering
  • Control and Systems Engineering
  • Electrical and Electronic Engineering


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