Block Approach with Sigmoidal Feedbacks for Twin Rotor MIMO System Control

The paper deals with the twin rotor MIMO system, which behavior is much similar to the behavior of a real technical device - a helicopter. The tracking problem of the generalized coordinates (yaw and pitch angles) for the given trajectories is posed in the conditions of the model's parametric uncertainties and in the action of unknown external disturbances. The decomposition synthesis of the control law is performed on the basis of the block approach using non-linear S-shaped sigmoidal feedbacks. The reduced order state observer with sigmoidal corrective action is constructed to obtain the estimates of the generalized velocities when generalized coordinates are measured. It is shown that the use of sigmoidal feedback allows us to reduce the possible overshoot at the beginning of transient responses, and to provide tracking of given signals with a given accuracy invariant with respect to parametric and external disturbances without using exogenous dynamic models of external influences.