Linearization and Identification of Helicopter Model for Hierarchical Control Design

This chapter presents an analytical modeling and model-based controller design for a small unmanned helicopter. Generally, it can be said that helicopter dynamics are nonlinear, with coupling of each axis. However, for low speed flights, i.e., speeds less than 5 m/s, the dynamics can be expressed by a set of linear equations of motion as a SISO (Single Input Single Output) system. The dynamics of the helicopter are divided into several components. We derive a model for each component from either the geometric relation or equation of motion. By combining all components, we derive two linear state equations that describe the helicopter’s lateral and longitudinal motion. The parameters of the model are decided by helicopter specs. Based on the derived models, we design A control system by using the linear quadratic integral (LQI). The validity of these approaches is then verified by flight tests.