Control of a laboratory helicopter using switched 2-step feedback linearization

A control structure based on feedback (input-output) linearization has been applied to the longitudinal subsystem of a laboratory double-rotor helicopter. This article focuses on the longitudinal subsystem which is underactuated in sense that the number of control variables is less than the number of degrees of freedom. A switching control law between exact and approximate input-output linearization is proposed. The feedback linearization has been applied in two steps, first to the nonlinear actuator, and then to the entire system. This law has been tested by simulated and experimental results.