Two time‐scale assignment with state extension for an autonomous helicopter

In this paper, a feedback control law based on two time‐scale assignment and state extension is implemented for the nonlinear non‐minimum phase dynamics of three degree‐of‐freedom autonomous unmanned helicopters (AUH). Unlike previous techniques, the design procedure does not require time‐scale decomposition between attitude angle and translational states. This reduces the requirements for the AUH model and makes the controller more reliable. Time‐scale assignment is implemented with partial internal dynamics. Exponential stability of the closed‐loop system is proved with the retained non‐minimum phase character, and simulation results are provided to demonstrate the effectiveness of the presented approach.