Control of Systems With Periodic Coefficients, With Application To Active Rotor Control

摘要

The project focused on the analysis and synthesis of active rotor controls. The rotor was modeled as a periodic system. The key accomplishments are: (i) First systematic study of the effect of zeros in rotorcraft aeromechanics. The 'zeros' play a key role in the closed-loop behavior of the system. As rotor active controls become feasible, the calculation of zeros needs to become a routine design step. (ii) First study of the effects of closed-loop HHC/IBC on the aeroelastic stability of a helicopter rotor including, for example, the in-plane damping. This is especially important for configurations with inherently low in-plane damping such as bearingless rotors. (iii) Presentation to the rotorcraft community of techniques for the analysis of periodic systems developed in other areas of engineering, e.g., in the signal processing and control engineering communities. (iv) First study of the effects of closed-loop HHC/IBC on the aeroelastic stability of a helicopter, including the effects of the discrete elements, and of different sampling and update rates in the system. In all cases, a realistic mathematical model was used, with typically more than 35 degrees of freedom, including blade flexibility and nonlinear rigid body dynamics.