Multivariate Turbofan Engine Control for Full Flight Envelope Operation

The design of a full flight envelope nonlinear multivariable controller is described for a single-bypass variable-cycle jet engine. The nonlinear controller is obtained by using appropriate engine corrected parameters to schedule multivariable linear compensator gains designed at selected operating points of the flight envelope. The KQ (K-matrix compensator, Q-desired response) multivariable control design technique is used to design the compensators using linear state-space models obtained from a detailed nonlinear aerothermo model. The controller is implemented in the detailed nonlinear aerothermo model. The paper describes an example KQ compensator design, the corrected-parameter gain scheduling approach, and controller performance validation by nonlinear simulation. Computer simulations for sea-level static, and supersonic operating points are included to show the closed-loop transient performance in the presence of an acceleration fuel schedule.