Single-loop limited authority control: an architectural study

This paper summarises the main findings of a study of the architecture of limited authority control systems for helicopters. The paper has two objectives. The first is to develop systematic methods which enable a given full authority controller of arbitrary type to be implemented in a limited authority framework in which the small signal performance is preserved. The second objective is to demonstrate the effectiveness of a simple anti-windup method in limiting the deterioration of the large signal behaviour which arises due to the various sources of saturation intrinsic to the limited authority architecture. The effectiveness of the proposed method is illustrated in simulation using a simple model of the NRC Bell 205 helicopter.