Computation of Safe and Reachable Sets for Model-Free Dynamical Systems: Aircraft Longitudinal Dynamics

Author(s):  
Pavan Kumar Nuthi ◽  
Kamesh Subbarao
Author(s):  
EYKE HÜLLERMEIER

In this paper, fuzzy initial value problems for modelling aspects of uncertainty in dynamical systems are introduced and interpreted from a probabilistic point of view. Due to the uncertainty incorporated in the model, the behavior of dynamical systems modelled in this way will generally not be unique. Rather, we obtain a large set of trajectories which are more or less compatible with the description of the system. We propose so-called fuzzy reachable sets for characterizing the (fuzzy) set of solutions to a fuzzy initial value problem. Loosely spoken, a fuzzy reachable set is defined as the (fuzzy) set of possible system states at a certain point of time, with given constraints concerning the initial system state and the system evolution. The main-part of the paper is devoted to the development of the numerical methods for the approximation of such sets. Algorithms for precise as well as outer approximations are presented. It is shown that fuzzy reachable sets can be approximated to any degree of accuracy under certain assumptions. Our method is illustrated by means of an example from the field of economics.


10.29007/rs5n ◽  
2020 ◽  
Author(s):  
Edward Kim ◽  
Parasara Sridhar Duggirala

Reachable set computation is one of the many widely-used techniques for the verification of safety properties of dynamical systems. One of the simplest algorithms for computing reachable sets for discrete nonlinear systems uses parallelotope bundles and Bernstein polynomials. In this paper, we describe Kaa, a terse Python implementation of reachable set computation which leverages the widely used symbolic package sympy. Additionally, we simplify the user interface and provide easy-to-use plotting utilities. We believe that our tool has pedagogical value given the simplicity of the implementation and its user- friendliness.


Author(s):  
Ross P. Anderson ◽  
Maurizio Porfiri

Information-theoretical notions of causality provide a model-free approach to identification of the magnitude and direction of influence among sub-components of a stochastic dynamical system. In addition to detecting causal influences, any effective test should also report the level of statistical significance of the finding. Here, we focus on transfer entropy, which has recently been considered for causality detection in a variety of fields based on statistical significance tests that are valid only in the asymptotic regime, that is, with enormous amounts of data. In the interest of applications with limited available data, we develop a non-asymptotic theory for the probability distribution of the difference between the empirically-estimated transfer entropy and the true transfer entropy. Based on this result, we additionally demonstrate an approach for statistical hypothesis testing for directed information flow in dynamical systems with a given number of observed time steps.


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