Authors:
Tor Arne Johansen,
Volume: 1, Page 4436 Paper number 1409
Abstract:
For nonlinear systems that satisfy certain regularity conditions it
is shown that upper and lower bounds on the performance (cost function)
can be computed using linear or quadratic programming. The performance
conditions derived from Hamilton-Jacobi inequalities are formulated
as linear inequalities defined pointwise by discretizing the state-space
when assuming a linearly parameterized class of functions representing
the candidate performance bounds. Uncertainty with respect to some
system parameters can be incorporated by also gridding the parameter
set. In addition to performance analysis, the method can also be used
to compute Lyapunov functions that guarantees uniform exponential stability.
Authors:
Peter M. Dower,
Volume: 1, Page 4442 Paper number 1798
Abstract:
In this paper, we consider the problem of computing a state feedback
controller for a class of nonlinear plants without requiring asymptotic
stability of the resulting closed loop system. A simple generalization
of the L2-gain inequality which permits persistent outputs is used
as the objective in the control design. By considering notions of dissipation
and available storage, the controller can be computed by solving a
Hamilton-Jacobi-Bellman-Isaac PDE. Although this PDE rarely admits
analytical solutions, finite differences may be applied to compute
an approximation to both the available storage and the desired state
feedback controller. Due to problems with convergence of conventional
Jacobi value space iterations, a mixed policy space / value space algorithm
is applied.
Authors:
Ram Venkataraman,
Perinkulam S. Krishnaprasad,
Volume: 1, Page 4448 Paper number 2089
Abstract:
In previous work, we had proposed a low (6) dimensional model for a
thin magnetostrictive actuator that was suitable for real-time control.
One of the main results of this modeling effort was the separation
of the rate-independent hysteretic effects from the rate-dependent
linear effects. The hysteresis phenomenon may also be captured by a
(modified) Preisach operator with the average magnetic field as the
input. If one can find an inverse for the Preisach operator, then
the composite system can be approximately linearized. In this paper,
we propose a new algorithm for computation of the inverse for the classical
Preisach model. Prior approaches depended on the linearization of the
operator at the operating point. As numerical differentiation is involved,
this approach can cause divergence. Our algorithm does not linearize
the Preisach operator, but makes use of its strictly incrementally
increasing property. Convergence of the algorithm is proved using the
contraction mapping principle.
Authors:
Jure Medanic,
Albert Pfleger,
Volume: 1, Page 4455 Paper number 62
Abstract:
The paper presents a methodological procedure for systematically exploiting
the information on the dynamics of the response as observed through
simulations to expand the region of attraction of a nominal design.
A particular novelty is that an integral state is added to state feedback
in each region of the partition to provide a mechanism so that the
state is driven towards the desired equilibrium point at the origin.
Authors:
W.P.M.H. Heemels,
M.K. Çamlibel,
J.M. Schumacher,
Volume: 1, Page 4461 Paper number 1653
Abstract:
In this paper we will analyze a time-stepping method for the numerical
simulation of dynamical systems containing Coulomb friction or relay
characteristics. Time-stepping techniques replace the original dynamical
system by a sequence of algebraic problems, that have to be solved
for each time-step. For relay systems the one-step problem can be reformulated
as a linear complementarity problem for which a wide range of solution
algorithms already exists. As the event times at which the relay switches
are ``overstepped,'' the consistency of the method in the sense of
the convergence of a sequence of approximations to an actual solution
of the relay system can be put into question. However, in this paper
we show that the proposed method is consistent even in the case that
the event times accumulate (Zeno behavior). By an example we will illustrate
how the method deals with Zeno trajectories.
Authors:
Tor Arne Johansen,
Kenneth J Hunt,
Volume: 1, Page 4467 Paper number 1405
Abstract:
We propose a novel computational approach to the approximate input/state
feedback linearization problem by interpolating a finite number of
local linear coordinate transforms and static state feedback designs.
For a class of single-input nonlinear systems, the approximate approach
allows the main assumptions underlying exact input/state feedback linearization
(involutivity, smoothness and controllability everywhere) to be relaxed.
Moreover, the present approach relies only on simple numeric linear
algebraic computations, in strong constrast to the exact input/state
feedback linearization approach that relies on the solution of a partial
differential equation and other symbolic computations. In contrast
to related approaches to approximation feedback linearization, the
feedback design need not be restricted to a neighborhood of the equilibrium
manifold. It is shown that the approximation error goes to zero uniformly
as the resolution of the state space partitioning increases. Explicit
expressions for the approximation error allows the accuracy and robustness
of the design to be assessed.
Authors:
Max D. Gunzburger,
Hong-Chul Kim,
Sandro Manservisi,
Volume: 1, Page 4473 Paper number 9
Abstract:
A shape design problem for stationary, viscous, incompressible, two-dimensional
channel flows is considered. The shape of part of the boundary is determined
so that the viscous drag is minimized. The adjoint equation method
is used to derive an optimality system and the shape gradient of the
design functional.
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