Control design of 3 DOF helicopter system

The helicopter system is highly complicated, non-linear, under-actuated with multiple inputs and multiple outputs (MIMO). To balance this system there lies an urgent requirement of stabilizing the states to the equilibrium. This is done by analysis of the parametric uncertainties or disturbances occuring at the time of operation of the system. The model referred in this paper has three degrees-of-freedom (DOF) with four inputs. Two different co-ordinate frames in translational motion are discussed. For regulation of the attitude dynamics, a linear back-stepping control theory is adopted with a combination of adaptive laws. The adaptive back-stepping allows the virtual control to be added in the backward direction of the physical model and evaluates the changing weight along with other parametric uncertainties. Experimental results show that the proposed control theory can be applied to two different definitions of translational motion and is helpful in finding out the uncertain moments. The Lift and static margin are well maintained in the presence of unhealthy condition.