Robustness analysis of unmanned helicopter flight control law using μ-analysis techniques

This paper mainly describes a method based on structured singular value (μ) for analyzing the robustness of unmanned helicopter flight control system. The helicopter is a complex controlled system with static instability, non-linearity, multi-variables and strong coupling. In this paper, based on the introduction of basic theory of LFT and μ-analysis, the X-Unmanned Helicopter(X-UMH) is chosen as an example. In order to analyze the stability robustness in terms of the standard clearance criteria, a method to convert the classical simultaneous gain and phase margin requirements with a multiplicative uncertainty on the plant is studied. The Model-following control system (MFCS) was introduced to design the helicopter flight control law. The flight envelope could be cleared continuously in the condition with simultaneously varying uncertain parameters. The results of simulation results indicate the feasibility and effectiveness of the methods.