The influence of actuator nonlinearities in advanced flight control system design

Two multivariable control system design methodologies with appropriate conditioning are proposed to handle actuator saturation and rate limiting. The first methodology results in error-actuated multivariable proportional-plus-integral (PI) controllers implemented in a velocity form to avoid integrator wind-up. An alternative controller, a robust inverse dynamics (RID) controller, is developed which retains the robustness properties of the original method but is conditioned by a different approach to handle multiple actuator saturation and rate limiting. The presentation of simulation results for a VSTOL aircraft has shown that the multivariable RID controller offers significant performance improvements over the multivariable PI controller when facing multiple actuator saturation and rate limiting