Application of parameter-dependent robust control synthesis to turbofan engines

Recent results in multivariable robust control synthesis for linear parameter-varying (LPV) systems are applied to the control of a turbofan engine over a wide range of power codes. Seven linear, time-invariant models are used in the control design. The resulting LPV controller consists of seven linear controllers, gain scheduled via linear interpolation. This gain-scheduled controller is obtained directly as part of the described design process, as opposed to conventional processes, where the gain schedules are developed after the fact to connect point designs. A model matching approach is employed such that the resulting closed loop resembles a decoupled set of second-order systems with specified rise times and overshoots. The performance of linear H_∞ point designs are compared with the LPV controller at fixed operating points. A nonlinear simulation is performed with the turbofan engine and LPV controller schedules as a function of the power code. The LPV controller exhibits excellent tracking of reference commands as the power code varies in time.