Application of multivariable control to a turbofan engine

This paper describes the design of a multivariable control for an aeroplane turbofan engine based on working line control. The method starts with the identified engine. Controller performance is illustrated by means of engine test results. The emphasis is on the control structure, which must include the essential features of a complete flight-worthy system, such as all the necessary limiters and a pilot´s lever-driven range control, using scheduled gains capable of accommodating parameter variations across the flight envelope. Less importance is attached, at this stage, to the system response attributable to the design of the individual multivariable compensators. In the first instance they were designed as simple P+I controllers. Any changes in the design of the individual compensators can be accommodated within the overall scheme