Intelligent control of model helicopters - a building block approach

There is a growing interest in the modeling and control of model helicopters using nonlinear dynamic models and nonlinear control. A helicopter is an underactuated system with fewer independent control actuators than degrees of freedom to be controlled, making the control difficult. Further, most of the models and control are derived for separate flight conditions such as take-off or hovering because of the complexity involved. This simplification in fact seems to make the problem more difficult since the simplified model might not have the properties associated with the original physical system. Analytical techniques based on Lyapunov theory are then used to design the controller and the design can become extremely complex. In this paper, we present a new nonlinear and adaptive controller design. The design methodology basically involves making the combined dynamics of the helicopter and the controller to resemble the dynamics of a nonlinear time varying electrical circuit having the required properties, using a process similar to reverse engineering. This conceptually simple procedure leads to a new general class of complex nonlinear and adaptive controller algorithms without the use of or the necessity for complex analytical tools, and hence can be understood and applied easily. Even though the solution provided here is for a particular flight condition, this approach can easily be extended to multiflight conditions.