Abstract: This paper proposes a new H_∞/LTR method for control system design. By introducing appropriate weighting on the control signals, this method not only can achieve the target loop transfer function, but also can get a controller with relatively low gain and limited bandwidth. As a result, this controller rejects measuring noise effectively. On the contrary, the controller designed by LQG/LTR method inherently has very high gain and large bandwidth, and suffers greatly from measuring noise. This H_∞/LTR method has another merit: by carefully including an integrator in the weighting function, zero steady state error requirement is met without system augmentation. Results from simulation evaluation of the proposed method attest to its feasibility.

Key words: aeroengine, H∞/LTR, LQR, noise rejection