Leader-Follower Control with Odometry Error Analysis

In this paper we present a leader-follower control law that enables a mobile robot to track a desired trajectory, and allows us to specify the position in the plane of the follower robot with respect to the leader robot. We first describe the dynamic model of the plant, including input torques, and friction forces. Then the control law is developed using backstepping, and it is proved to asymptotically stabilize the tracking error to the origin. Simulation and experimental results of the closed loop system are presented, highlighting its potential application to formation control. The special case of pure tracking (without bi-dimensional position information use) is analyzed, showing that it can be applied to particular classes of non-feasible trajectories. Finally, motivated by some observations on the experiments, the effects of odometry errors are analyzed, revealing that boundedness of the tracking errors can be guaranteed if absolute position information becomes available periodically

Interconnected Hybrid Systems: A Framework for Multi-agent Systems with Hybrid Interacting Dynamics

We present a new framework for describing multi-agent systems with hybrid interacting dynamics where the interaction between agents occurs at both the continuous and discrete levels. We formally define these multi-agent systems as Interconnected Hybrid Systems and then recast fundamental hybrid concepts such as a hybrid metric, hybrid execution, and reachability in this new interconnected hybrid systems framework. We then prove a necessary and sufficient condition for the existence and uniqueness of the interconnected hybrid executions extending previous work on hybrid systems

Modeling multi-agent systems with hybrid interacting dynamics

We present a new framework for describing multi-agent systems with hybrid interacting dynamics, where the interaction between agents occurs at both the continuous and discrete levels. We define multi-agent systems as Interconnected Hybrid Systems, recast fundamental hybrid concepts such as hybrid execution and reachability in this new interconnected hybrid systems framework, and prove a necessary and sufficient condition for the existence and uniqueness of the interconnected hybrid executions, extending previous work on hybrid systems. We provide conditions on each agent\u27s hybrid model that guarantee the multi-agent system\u27s existence and uniqueness property. Finally, we provide an example that shows how to apply the existence and uniqueness conditions in the design of the agents\u27 dynamics

Preliminary Results on Interconnected Hybrid Systems

We present a new framework for describing multi-agent systems with hybrid individual dynamics where the interaction between agents occurs at both the continuous and discrete levels. We formally define these multi-agent systems as interconnected hybrid systems and then recast fundamental hybrid concepts such as a hybrid metric, hybrid execution, and reachability in this new interconnected hybrid systems framework. We then prove a necessary condition for the existence of the interconnected hybrid executions

Statistical Learning for Optimal Control of Hybrid Systems

In this paper we explore a randomized alternative for the optimization of hybrid systems\u27 performance. The basic approach is to generate samples from the family of possible solutions, and to test them on the plant\u27s model to evaluate their performance. This result is obtained by first presenting the general hybrid optimal control problem, and then converting it into an optimization problem within a statistical learning framework. The results are applied to examples already existing in the literature, in order to highlight certain operational aspects of the proposed methods

Estruturação da vigilância epidemiológica e manejo populacional de suídeos asselvajados (Sus scrofa) para área livre de peste suína clássica do Brasil.

Suplemento 2, ref. 30. Edição dos Resumos do 3 Encontro Nacional de Defesa Sanitária Animal, Foz de Iguaçu, dez. 2013

Plasticity in dendroclimatic response across the distribution range of Aleppo pine (Pinus halepensis)

We investigated the variability of the climate-growth relationship of Aleppo pine across its distribution range in the Mediterranean Basin. We constructed a network of tree-ring index chronologies from 63 sites across the region. Correlation function analysis identified the relationships of tree-ring index to climate factors for each site. We also estimated the dominant climatic gradients of the region using principal component analysis of monthly, seasonal, and annual mean temperature and total precipitation from 1,068 climatic gridpoints. Variation in ring width index was primarily related to precipitation and secondarily to temperature. However, we found that the dendroclimatic relationship depended on the position of the site along the climatic gradient. In the southern part of the distribution range, where temperature was generally higher and precipitation lower than the regional average, reduced growth was also associated with warm and dry conditions. In the northern part, where the average temperature was lower and the precipitation more abundant than the regional average, reduced growth was associated with cool conditions. Thus, our study highlights the substantial plasticity of Aleppo pine in response to different climatic conditions. These results do not resolve the source of response variability as being due to either genetic variation in provenance, to phenotypic plasticity, or a combination of factors. However, as current growth responses to inter-annual climate variability vary spatially across existing climate gradients, future climate-growth relationships will also likely be determined by differential adaptation and/or acclimation responses to spatial climatic variation. The contribution of local adaptation and/or phenotypic plasticity across populations to the persistence of species under global warming could be decisive for prediction of climate change impacts across populations. In this sense, a more complex forest dynamics modeling approach that includes the contribution of genetic variation and phenotypic plasticity can improve the reliability of the ecological inferences derived from the climate-growth relationships.This work was partially supported by Spanish Ministry of Education and Science co-funded by FEDER program (CGL2012-31668), the European Union and the National Ministry of Education and Religion of Greece (EPEAEK- Environment – Archimedes), the Slovenian Research Agency (program P4-0015), and the USDA Forest Service. The cooperation among international partners was supported by the COST Action FP1106, STREeSS