David P Stoten

BIFURCATION TAILORING VIA NEWTON FLOW-AIDED ADAPTIVE CONTROL

The aim of bifurcation tailoring is to design an appropriate control law such that the controlled system has a desired bifurcation diagram. After describing two open-loop bifurcation tailoring techniques, this paper proposes a new open-loop plus close-loop bifurcation tailoring method based on a combination of the Newton-flow algorithm and the minimal control synthesis (MCS) adaptive control strategy. This method is applied to the Duffing system as an illustrative example.

Continuation Methods for Aircraft Models Subject to Integrator Wind-Up

Modern full authority flight control systems often use integrators to achieve steadystate tracking of command inputs. Rapid, high performance demands on these systems can lead to control surface saturation. This combination of saturation and integral control can cause the well known problem of integrator wind-up. The basis for most integrator wind-up protection schemes is to limit the integrator when the associated surface saturates and to free the integrator when the control surface desaturates. This paper presents two methods by which Bifurcation Analysis can be applied to an aircraft with integral control which undergoes control surface saturation. Since bifurcation-based techniques require the system to be smooth, applications to flight dynamics models have in the past been limited to operating regions free of saturation. Thus the processes demonstrated in this paper — for both a simple analytical example and a 5 th order nonlinear aircraft model — indicate that they can play a role in controller design and evaluation at extremes of the operating envelope.