National Yang Ming Chiao Tung University
Publishes on Adaptive Control of Nonlinear Systems, Stability and Control of Uncertain Systems, Control Systems and Identification. 114 papers and 1k citations.
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This paper presents a computational solution to an important optimization problem arising in optimal sensitivity theory. The approach is to treat the multivariable problem exactly as the scalar problem in that stability constraints are handled via interpolation. The resulting computations are easily implemented using existing methods.
Loss of control is a major factor in fatal aircraft accidents. Although definitions of loss of control remain vague in analytical terms, it is generally associated with flight outside of the normal flight envelope, with nonlinear influences, and with a significantly diminished capability of the pilot to control the aircraft. Primary sources of nonlinearity are the intrinsic nonlinear dynamics of the aircraft and the state and control constraints within which the aircraft must operate. This paper examines how these nonlinearities affect the ability to control the aircraft and how they may contribute to loss of control. Specifically, the ability to regulate an aircraft around stall points is considered, as is the question of how damage to control effectors impacts the capability to remain within an acceptable envelope and to maneuver within it. It is shown that, even when a sufficient set of steady motions exist, the ability to regulate around them or transition between them can be difficult and nonintuitive, particularly for impaired aircraft. Examples are provided using NASA’s generic transport model.
The majority of fatal aircraft accidents are associated with loss-of-control . Yet the notion of loss-of-control is not well-defined in terms suitable for rigorous control systems analysis. Loss-of-control is generally associated with flight outside of the normal flight envelope, with nonlinear influences, and with an inability of the pilot to control the aircraft. The two primary sources of nonlinearity are the intrinsic nonlinear dynamics of the aircraft and the state and control constraints within which the aircraft must operate. In this paper we examine how these nonlinearities affect the ability to control the aircraft and how they may contribute to loss-of-control. Examples are provided using NASA s Generic Transport Model.
It is shown that D.S. Bernstein and W.M. Hadad's (ibid., vol.34, no.3, p.293, 1989) necessary condition for full-order mixed H/sub 2/ and H/sub infinity / optimal control is also sufficient, and that J.C. Doyle et al.'s (Proc. Amer. Control Conf., p.2065, 1989) sufficient condition for full-order mixed H/sub 2/ and H/sub infinity / optimal control is also necessary. They are duals of one another.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Generating families of linear models from nonlinear parameter-dependent equations requires explicit analytical characterization of the equilibrium surface. Doing so in terms of the original system parameters is generally not possible. Introducing an alternative parameterization, we propose an efficient method for computing local linear parameter-dependent families. Although local, these families can be constructed anywhere, specifically around bifurcation points where other methods fail.