Nonlinear modelling and control of helicopters
This paper presents the development of a nonlinear helicopter model in vertical flight (takeoff, climbing, hover, decent and landing). Such a mathematical model is much simpler than the ``free-flying'' case and may be limited only to 3-DOF. In control design the authors assume that the operation is split into two main phases: 1. start up and takeoff and 2. vertical flight. In the first phase, the feedback control has to guarantee asymptotic stability of the tracking errors when the helicopter is at rest on the ground and at takeoff. In the second phase the helicopter takes off, and the controller guarantees the asymptotic tracking of the preceding errors. The robustness properties are studied by computing a quadratic criterion which includes all main coordinates. The experimental model was mounted on a platform, thereby avoiding the ground effect. So the effects of compressed air in takeoff and landing are neglected. The authors state that because the generalized forces are nonlinear, the resulting control problem is different than the one usually considered in the literature.
scientific article; zbMATH DE number 1965014
scientific article