Mode switching and gain scheduling of multivariable controllers applied to a combat rotorcraft

This paper describes the development of a full envelope, multivariable Lynx helicopter flight control system. The control law development has been completed and fully evaluated in off-line simulation and initial simulation trials have been performed on the RAE Bedford flight simulator. Full scale piloted simulation trials are scheduled to take place in April 1992. An important factor in choosing the loop-shaping design method was the robustness which this design method offers against modelling errors or variation in the plant dynamics: previous controller implementations have required several iterations in order to re-tune the controller to take account of differences between the model and the real helicopter. The main operational benefits, however, arise from the decoupled performance which a multivariable controller can provide: by employing a controller of this type the pilot workload is not only significantly reduced, but even more importantly in a combat situation, higher performance can be achieved