A note on the reachability of a Fibonacci control system
Motivated by applications in robotics, we investigate a discrete control system related Fibonacci sequence and we characterize its reachable set.
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arXiv subjects
Anna Chiara Lai
Publications and source records attributed to Anna Chiara Lai.
A Fibonacci control system with application to hyper-redundant manipulators
We study a robot snake model based on a discrete linear control system involving Fibonacci sequence and closely related to the theory of expansions in non-integer bases. The present paper includes an investigation of the reachable workspace, a more general analysis of the control system underlying the model, its reachability and local controllability properties and the relation with expansions in non-integer bases and with iterated function systems.
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A control model for zygodactyl bird's foot
In this paper we are interested to the zygodactyly phenomenon in birds, and in particolar in parrots. This arrangement, common in species living on trees, is a distribution of the foot with two toes facing forward and two back. We give a model for the foot, and thanks to the methods of iterated function system we are able to describe the reachability set. Moreover we give a necessary and sufficient condition for the grasping problem. Finally we introduce a hybrid dynamical system modeling owl's foot in various stages of hunting (flying, attack, grasp).
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Robot's hand and expansions in non-integer bases
We study a robot hand model in the framework of the theory of expansions in non-integer bases. We investigate the reachable workspace and we study some configurations enjoying form closure properties.
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Geometrical aspects of expansions in complex bases
We study the set of the representable numbers in base $q=pe^{i\frac{2π}{n}}$ with $ρ>1$ and $n\in \mathbb N$ and with digits in a arbitrary finite real alphabet $A$. We give a geometrical description of the convex hull of the representable numbers in base $q$ and alphabet $A$ and an explicit characterization of its extremal points. A characterizing condition for the convexity of the set of representable numbers is also shown.
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Negative bases and automata
We study expansions in non-integer negative base -β introduced by Ito and Sadahiro. Using countable automata associated with (-β)-expansions, we characterize the case where the (-β)-shift is a system of finite type. We prove that, if β is a Pisot number, then the (-β)-shift is a sofic system. In that case, addition (and more generally normalization on any alphabet) is realizable by a finite transducer. We then give an on-line algorithm for the conversion from positive base β to negative base -β. When β is a Pisot number, the conversion can be realized by a finite on-line transducer.
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Generalized golden ratios of ternary alphabets
Expansions in noninteger bases often appear in number theory and probability theory, and they are closely connected to ergodic theory, measure theory and topology. For two-letter alphabets the golden ratio plays a special role: in smaller bases only trivial expansions are unique, whereas in greater bases there exist nontrivial unique expansions. In this paper we determine the corresponding critical bases for all three-letter alphabets and we establish the fractal nature of these bases in function of the alphabets.
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