Multivariable robust control design of a turbofan engine for full flight envelope operation

In order to fulfill the full flight envelope aero-engine control, as one of the most effective solutions, gain scheduling control system was designed in this paper which could weaken the influence of the limited robust of traditional controller. Based on the previous works such as the engine modeling and the two degrees-of-freedom (2DOF) H∞ loop-shaping controller design, the full flight envelope was divided up into eight regions and the control system which was constituted by eight 2DOF controllers for each sub-regions was constructed in which the eight controllers of different sub-regions could be switched based on the engine altitude and Mach number. In order to decrease the disturbance in the process of switchover between the controllers of different sub-regions, as an innovation, the bumpless switch logic based on the technology called `inertia delayed to soften the switch´ was adopted in the control system. For the purpose of checking the effect of full envelope control system, the hardware in-the-loop simulations have been done on the real-time simulation platform based on rapid prototype. The excellent performance of the full envelope robust control system for the turbofan engine was shown, as well as the validity of flight envelope dividing method and the bumpless switch logic was verified.