Dynamics modelling and system identification of small unmanned helicopters

This chapter describes a control-oriented modelling and system identification procedure based on a Trex-250 miniature helicopter. This can be extended to other small helicopters with Bell-Hiller stabilizer bar mechanism. The system identification approach naturally focuses on input-output data, trying to specify a model that can interpret such experimental phenomena. This method is more direct and more effective since it integrates validation into the modelling process. The chapter introduces the identification procedure including the design of flight experiments, identification algorithm, model breakdown and parameter estimation. It also describes the controller design to support the non-aggressive flight of a small helicopter. Around the hover mode, helicopter dynamics can be considered as a linear system with multiple inputs and multiple outputs. Then, by decoupling the helicopter dynamics into several subsystems, a cascaded PID controller can be developed. The chapter discusses the development of a highly simplified tip-path-plane (TPP) rotor model for system identification and later for control design.