196,604 research outputs found
Is time-optimal speed planning under jerk constraints a convex problem?
No full textWe consider the speed planning problem for a vehicle moving along an assigned trajectory, under maximum speed, tangential and lateral acceleration, and jerk constraints. The problem is a nonconvex one, where nonconvexity is due to jerk constraints. We propose a convex relaxation, and we present various theoretical properties. In particular, we show that the relaxation is exact under some assumptions. Also, we rewrite the relaxation as a Second Order Cone Programming (SOCP) problem. This has a relevant practical impact, since solvers for SOCP problems are quite efficient and allow solving large instances within tenths of a second. We performed many numerical tests, and in all of them the relaxation turned out to be exact. For this reason, we conjecture that the convex relaxation is always exact, although we could not give a formal proof of this fact. (c) 2024 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
Fractal time statistics of AE-index burst waiting times: evidence of metastability
No full textRecent observations and analyses evidenced that the magnetotail, as well as the magnetospheric dynamics are characterised by a scale-free behaviour and intermittence.
These results, along with numerical simulations on cellular automata, suggest that the observed scale-invariance may
be due to forced and/or self-organised criticality (FSOC), meaning that the magnetotail operates near a marginally stable
state (Chang, 1999). On the other hand, it was underlined that a complex magnetic field topology in the geotail regions may play a relevant role in the impulsive energy relaxation (Consolini and Chang, 2001).Published419-4233.9. Fisica della magnetosfera, ionosfera e meteorologia spazialeJCR Journalope
Fractal time statistics of AE-index burst waiting times: evidence of metastability
No full textRecent observations and analyses evidenced that the magnetotail, as well as the magnetospheric dynamics are characterised by a scale-free behaviour and intermittence. These results, along with numerical simulations on cellular automata, suggest that the observed scale-invariance may be due to forced and/or self-organised criticality (FSOC), meaning that the magnetotail operates near a marginally stable state (Chang, 1999). On the other hand, it was underlined that a complex magnetic field topology in the geotail regions may play a relevant role in the impulsive energy relaxation (Consolini and Chang, 2001
L’educazione all’imprenditorialità
No full textISFOL, Consolini M., L’educazione all’imprenditorialità, Intervento a "Workshop Isfol-Fse", Roma, Isfol, 13 dicembre 2012. Isfol OA: Presentation. Fasi e prodotti della ricerca Isfol, in corso di realizzazione, "Educazione e formazione all'imprenditorialità". 13/12/2012presentation. fasi e prodotti della ricerca isfol, in corso di realizzazione, "educazione e formazione all'imprenditorialità". 13/12/2012 l’educazione all’imprenditorialità marta consolin
Virtual Holonomic Constraints for Euler-Lagrange Systems
No full textThis paper investigates virtual holonomic constraints for Euler-Lagrange systems with n degrees-of-freedom and n - 1 controls. In our framework, a virtual holonomic constraint is a relation specifying n - 1 configuration variables in terms of a single angular configuration variable. The enforcement by feedback of such a constraint induces a desired repetitive behavior in the system. We give conditions under which a virtual holonomic constraint is feasible, i.e, it can be made invariant by feedback, and it is stabilizable. We provide sufficient conditions under which the dynamics on the constraint manifold correspond to an Euler- Lagrange system. These ideas are applied to the problem of swinging up an underactuated pendulum while guaranteeing that the second link does not fall over
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