Invasive alien species of European Union concern: the use of a faunistic database for the knowledge and future management at a local scale

A research group of the Department of Life Sciences, University of Modena and Reggio Emilia, with the contribution of the Province of Modena and the Emilia-Romagna Region, implemented a faunistic database named Darwin. The database gathers information chiefly on the vertebrate fauna of the province of Modena (Northern Italy). To date, over 20,000 historical and recent records have been collected, regarding 535 vertebrate species and 7 invertebrates (Bivalvia and Crustacea) of high managing interest. Darwin allows to register the modification of the local fauna, with regards to the most problematic taxa and especially to the allochthonous species, which are mainly organisms living in the lowlands that became invasive at different levels. Some of these assumed the role of key species in a variety of ecosystems (e.g., Pseudorasbora parva), some threaten certain autochthonous species already at risk (e.g., Trachemys scripta and Procambarus clarkii), others give rise to economic issues (e.g., Myocastor coypus), whilst the remaining ones have progressively lost their invasivity, becoming rare or sporadic (e.g., Ameiurus melas and Lepomis gibbosus). The database represents a strongly effective tool for the basic knowledge functional to the actions deriving from the European Regulation 2014/1143, regarding the recent “List of invasive alien species of Union concern” (EU 2016/1141). Overall, Darwin collects information on the local distribution of 32 invasive allochthonous species, 7 of which of Union concern, namely: Lithobates catesbeianus, Myocastor coypus, Procambarus clarkii, Pseudorasbora parva, Trachemys scripta, Threskiornis aethiopicus, and Oxyura jamaicensis. The first four species are established within the province, while T. scripta is diffused but not definitively confirmed as breeding, T. aethiopicus is present but not breeding, and O. jamaicensis is observed only occasionally. Thanks to the database the autochthonous species of EU interest comprised in the national IUCN Red list and their competitors could be brought into focus. For instance, we revealed the presence of merely 8 local populations of Emys orbicularis, threatened by the wide distribution of T. scripta, which is reported from over 20 sites within Modena’s territory. Furthermore, we found Austropotamobius pallipes at 122 mid-elevation sites (100-1100 m a.s.l.), whilst its direct competitor P. clarkii, currently expanding to the foothills, was recorded from 101 locations from 10 to 100 m a.s.l. These preliminary results highlight the necessity of control plans towards the two alien species, which could be developed on the basis of the already available distribution patterns. Our research group aims at the constant implementation of the database by adding information from ongoing and forthcoming studies on species of major interest. The existing data, presently used in various control plans, will pave the way to more specific investigations on the invasive alien fauna and increase the effectiveness of future managing actions

Nonlinear and Hybrid Feedbacks with Continuous-Time Linear Systems

In this thesis we study linear time-invariant systems feedback interconnected with three specific nonlinear blocks; a play/stop operator, a switching-reset mechanism, and an adaptive dead-zone. This setup resembles the Lure problem studied in the absolute stability framework, but the types of nonlinearities considered here do not satisfy (in general) a sector condition. These nonlinear blocks give rise to a whole range of interesting phenomena, such as compact sets of equilibria, hybrid omega-limit sets, and state constraints. Throughout the thesis, we use the hybrid systems formalism to describe these phenomena and to analyze these loops. We obtain sharp stability conditions that can be formulated as linear matrix inequalities, thus verifiable with numerically efficient solvers. Finally, we apply the theoretical findings to two automotive applications

Rétroactions non linéaires et hybrides avec systèmes linéaires à temps continu

In this thesis we study linear time-invariant systems feedback interconnected with three specific nonlinear blocks; a play/stop operator, a switching-reset mechanism, and an adaptive dead-zone. This setup resembles the Lure problem studied in the absolute stability framework, but the types of nonlinearities considered here do not satisfy (in general) a sector condition. These nonlinear blocks give rise to a whole range of interesting phenomena, such as compact sets of equilibria, hybrid omega-limit sets, and state constraints. Throughout the thesis, we use the hybrid systems formalism to describe these phenomena and to analyze these loops. We obtain sharp stability conditions that can be formulated as linear matrix inequalities, thus verifiable with numerically efficient solvers. Finally, we apply the theoretical findings to two automotive applications.Dans cette thèse, nous étudions la rétroaction de systèmes linéaires invariants dans le temps reliés entre eux par trois blocs non linéaires spécifiques : un opérateur de lecture/arrêt, un mécanisme de réinitialisation de commutation et une zone morte adaptative. Cette configuration ressemble au problème de Lure étudié dans le cadre de stabilité absolue, mais les types de non-linéarités considérés ici ne satisfont pas (en général) une condition sectorielle. Ces blocs non linéaires donnent lieu à toute une série de phénomènes intéressants, tels que des ensembles compacts d’équilibres, des ensembles hybrides oméga-limites et des contraintes d’état. Tout au long de la thèse, nous utilisons le formalisme des systèmes hybrides pour décrire ces phénomènes et analyser ces boucles. Nous obtenons des conditions de stabilité très précises qui peuvent être formulées sous forme d’inégalités matricielles linéaires, donc vérifiables avec des solveurs numériques efficaces. Enfin, nous appliquons les résultats théoriques à deux applications automobiles

A Hybrid Adaptive Inverse for Uncertain SISO Linear Plants with Full Relative Degree *

International audienceWe propose a hybrid adaptive feed-forward regulator for single-input single-output linear plants with full relative degree. The scheme includes an adaptive law that estimates the inverse of the plant and provides a feed-forward control calculated on the basis of the desired output and its derivatives. The adaptation is performed during discrete time events, called jumps, while the feed-forward action is continuous. This combination leads to a full hybrid system. The advantage of this framework is a conceptual separation between the adaptation dynamics, which is discrete, and the plant dynamics, which is continuous. Under an assumption of a persistence of excitation, we show through examples that the output asymptotically tracks the desired reference and that the estimate of the parameters of the inverse converges

Linear output regulation with dynamic optimization for uncertain linear over-actuated systems

International audienceThis paper considers the linear output regulation problem for uncertain over-actuated plants. The general form of input redundancy considered in this work implies the existence of multiple control inputs and state trajectories compatible with a prescribed reference for the output. On-line selection, according to certain performance criteria, of the most suitable of these inputs-state trajectories leads to a linear output regulation problem with dynamic redundancy allocation. We present a solution that augments the well known internal model control scheme with two additional dynamical systems. The first one, named annihilator, parametrizes the inputs and the corresponding state trajectories that are invisible from the output. The second one, named redundancy allocator, dynamically selects the best solution according to a predefined performance criterion. We derive explicit solutions for the performance criterion equal to relaxed 1, 2, and ∞-norms of the plant input. This setup is a particular case of the dynamic redundancy allocation problem named dynamic input allocation. The proposed solutions can be implemented in an error feedback form and are especially suitable for optimizing sparsity, power and amplitude of the control input. Finally, structural stability, robustness and existence of a unique steady-state are proven

Dynamic input allocation for uncertain linear over-actuated systems

International audienceIn this paper, linear over-actuated systems are considered, i.e., systems with more control inputs than regulated outputs. For these systems, an entire family of input functions and/or state trajectories is compatible with a prescribed reference for the output. The possibility of dynamically selecting on-line the most suitable of these trajectories according to certain performance criteria, leads to the so-called dynamic input allocation problem. In this paper we present, within the general framework of the robust output regulation problem, the design of dynamic input allocators for linear uncertain system, on the basis of two selected performance criteria of practical interest. Specifically, we aim at on-line minimization of the weighted energy and the amplitude of the control input, criteria that are especially suitable for input energy optimization and to deal with saturation limits. Stability and robustness of the ensuing closed-loop system are proved. An example is provided in support of the methodological findings

Implementation of arbitrary periodic dynamic behaviors in networked systems

Decentralized control of networked systems has been widely investigated in the literature, with the aim of regulating the overall state of the system to some desired configuration, thus obtaining coordinated emerging behaviors (e.g. synchronization, swarming, coverage, formation control) by means of local interaction. In this paper we introduce a methodology to solve a tracking problem, that is defining a decentralized control strategy for making a networked system follow an arbitrarily defined periodic setpoint function. The most suitable interconnection topology is defined together with the control law as the solution of a constrained optimization problem, in order to ensure asymptotic tracking. Simulations are provided for validating the proposed control strateg

Coordinated dynamic behaviors in multi-robot systems with time-varying topologies

A control strategy for the execution of coordinated complex dynamic behaviors in multi-robot systems is introduced in this paper. In particular, considering a dependent-independent robot partitioning of a multi-robot system, we introduce a methodology for controlling the independent robots in such a way that, exploiting local interaction, the dependent robots are driven to track desired periodic setpoint trajectories. The control strategy is designed taking explicitly into account variations in the interconnection topology, due to relative movements among the robots

Decentralized Control Strategy for the Implementation of Cooperative Dynamic Behaviors in Networked Systems

Abstract-Decentralized control of networked systems has been widely investigated in the literature, with the aim of obtaining coordinated emerging behaviors (e.g. synchronization, swarming, coverage, formation control) by means of local interaction. In this paper we consider the possibility of injecting external inputs into the networked system, in order to obtain more complex cooperative behaviors. Specifically, we introduce a strategy that makes it possible to control the overall state of the networked system by directly controlling only a subset of the networked agents, namely the leaders. Exploiting local interaction rules, it is possible to define the inputs for the leaders in such a way that each follower is forced to track a desired periodic setpoint. I. INTRODUCTION This paper introduces a methodology to implement dynamic complex behaviors in a networked system. The main objective is to have a subset of agents, called leaders, that are in charge of controlling the overall state of the networked system, in a completely decentralized manner. Generally speaking, the aim of decentralized control strategies is implementing local interaction rules to obtain a coordinated emerging behavior. Mainly investigated coordinated behaviors include aggregation, swarming, formation control, coverage and synchronization [1]- The idea of implementing more complex cooperative behaviors have recently appeared in the literature. For instance, [5], [6] present decentralized strategies for the coordination of groups of mobile robots moving along non-trivial paths. A decentralized strategy is presented in Recently a few works appeared that investigate the possibility of interacting with a networked system, in order to obtain a desired behavior As shown i

A kinematic observer with adaptive dead-zone for vehicles lateral velocity estimation

International audienceIn this paper we tailor the dead-zone based mechanism presented in [3] to the well-known kinematic observer for the estimation of vehicle lateral velocity. We extend the previous results on the dead-zone observer to linear parameter varying systems. The proposed mechanism maintains the structure of the kinematic observer but inserts an adaptive dead-zone at the output injection term. This dead-zone mechanism partially "cuts" the noise and increases the noise rejection performance allowing for the selection of a larger observer gain. We use this freedom to increase the observer gain to attenuate constant bias errors in the acceleration measurements. The proposed solution is easy to implement and requires only measurements acquired from standard on-board sensors. The adaptation parameters are selected solving a suitable Linear Matrix Inequality (LMI), and no manual tuning is required. We show the effectiveness of the proposed solution through numerical simulations