1,346 research outputs found
The Explanatory Potential of Artificial Societies
It is often claimed that artificial society simulations contribute to the explanation of social phenomena. At the hand of a particular example, this paper argues that artificial societies often cannot provide full explanations, because their models are not or cannot be validated. Instead, artificial societies may sometimes provide potential explanations. It is shown that these potential explanations, if they contribute to our understanding, considerably differ from the standard kind of potential causal explanations. Instead of possible causal histories, simulations offer possible functional analyses of the explanandum. The paper discusses how these two kinds of potential explanations differ, and how possible functional analyses can be appraised
Global optimal control of perturbed systems
We propose a new numerical method for the computation of the optimal value
function of perturbed control systems and associated globally stabilizing
optimal feedback controllers. The method is based on a set oriented
discretization of state space in combination with a new algorithm for the
computation of shortest paths in weighted directed hypergraphs. Using the
concept of a multivalued game, we prove convergence of the scheme as the
discretization parameter goes to zero
Performance of Sensitivity based NMPC Updates in Automotive Applications
In this work we consider a half car model which is subject to unknown but
measurable disturbances. To control this system, we impose a combination of
model predictive control without stabilizing terminal constraints or cost to
generate a nominal solution and sensitivity updates to handle the disturbances.
For this approach, stability of the resulting closed loop can be guaranteed
using a relaxed Lyapunov argument on the nominal system and Lipschitz
conditions on the open loop change of the optimal value function and the stage
costs. For the considered example, the proposed approach is realtime applicable
and corresponding results show significant performance improvements of the
updated solution with respect to comfort and handling properties.Comment: 6 pages, 2 figure
Analysis of unconstrained nonlinear MPC schemes with time varying control horizon
For discrete time nonlinear systems satisfying an exponential or finite time
controllability assumption, we present an analytical formula for a
suboptimality estimate for model predictive control schemes without stabilizing
terminal constraints. Based on our formula, we perform a detailed analysis of
the impact of the optimization horizon and the possibly time varying control
horizon on stability and performance of the closed loop
Asymptotic stability equals exponential stability, and ISS equals finite energy gain---if you twist your eyes
In this paper we show that uniformly global asymptotic stability for a family
of ordinary differential equations is equivalent to uniformly global
exponential stability under a suitable nonlinear change of variables. The same
is shown for input-to-state stability and input-to-state exponential stability,
and for input-to-state exponential stability and a nonlinear
estimate.Comment: 14 pages, several references added, remarks section added, clarified
constructio
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