J-MOD2^{2}: Joint Monocular Obstacle Detection and Depth Estimation

In this work, we propose an end-to-end deep architecture that jointly learns to detect obstacles and estimate their depth for MAV flight applications. Most of the existing approaches either rely on Visual SLAM systems or on depth estimation models to build 3D maps and detect obstacles. However, for the task of avoiding obstacles this level of complexity is not required. Recent works have proposed multi task architectures to both perform scene understanding and depth estimation. We follow their track and propose a specific architecture to jointly estimate depth and obstacles, without the need to compute a global map, but maintaining compatibility with a global SLAM system if needed. The network architecture is devised to exploit the joint information of the obstacle detection task, that produces more reliable bounding boxes, with the depth estimation one, increasing the robustness of both to scenario changes. We call this architecture J-MOD$^{2}$. We test the effectiveness of our approach with experiments on sequences with different appearance and focal lengths and compare it to SotA multi task methods that jointly perform semantic segmentation and depth estimation. In addition, we show the integration in a full system using a set of simulated navigation experiments where a MAV explores an unknown scenario and plans safe trajectories by using our detection model

Analysis of chattering phenomenon in industrial S6-high rolling mill

Chatter in rolling mills is the undesirable vibration observed in most of the rolling mills operating at high speed and rolling thin strip. In this work the authors discuss some problems relative to the vibrations occurring in a S6-high cold rolling mill. It can result in not good surface finish for some applications and, rare cases, in gauge variations in the rolled strip and it is considered to be the result of interaction between rolling mill structure and rolling-process. Three basic types of chatter can be classified in rolling mills: torsional, third-octave mode, and fifth-octave-mode chatter. S6-high rolling mill is an innovative mode to work the steel: it allows the use of very small work rolls laterally guided by individually adjustable side support rolls, which are supported by two rows of roller bearings mounted in cassettes. It has six rolls able to roll steel strip coming directly from hot rolling mill train. A proposed solution based on empirical observations, vibration analysis and considerations of a model is described with the aim to improve the quality of the product and increasing production

Local sign stability and its implications for spectra of sparse random graphs and stability of ecosystems

We study the spectral properties of sparse random graphs with different topologies and type of interactions, and their implications on the stability of complex systems, with particular attention to ecosystems. Specifically, we focus on the behaviour of the leading eigenvalue in different type of random matrices (including interaction matrices and Jacobian-like matrices), relevant for the assessment of different types of dynamical stability. By comparing numerical results on Erdős–Rényi and Husimi graphs with sign-antisymmetric interactions or mixed sign patterns, we propose a sufficient criterion, called strong local sign stability, for stability not to be affected by system size, as traditionally implied by the complexity-stability trade-off in conventional models of random matrices. The criterion requires sign-antisymmetric or unidirectional interactions and a local structure of the graph such that the number of cycles of finite length do not increase with the system size. Note that the last requirement is stronger than the classical local tree-like condition, which we associate to the less stringent definition of local sign stability, also defined in the paper. In addition, for strong local sign stable graphs which show stability to linear perturbations irrespectively of system size, we observe that the leading eigenvalue can undergo a transition from being real to acquiring a nonnull imaginary part, which implies a dynamical transition from nonoscillatory to oscillatory linear response to perturbations. Lastly, we ascertain the discontinuous nature of this transition

Groundwater and earthquake: brief remarks about seismic effects on groundwater resources availability in Valnerina

Not available

Local sign stability and its implications for spectra of sparse random graphs and stability of ecosystems

We study the spectral properties of sparse random graphs with different topologies and type of interactions, and their implications on the stability of complex systems, with particular attention to ecosystems. Specifically, we focus on the behaviour of the leading eigenvalue in different type of random matrices (including interaction matrices and Jacobian-like matrices), relevant for the assessment of different types of dynamical stability. By comparing the results on Erdos-Renyi and Husimi graphs with sign-antisymmetric interactions or mixed sign patterns, we introduce a sufficient criterion, called strong local sign stability, for stability not to be affected by system size, as traditionally implied by the complexity-stability trade-off in conventional models of random matrices. The criterion requires sign-antisymmetric or unidirectional interactions and a local structure of the graph such that the number of cycles of finite length do not increase with the system size. Note that the last requirement is stronger than the classical local tree-like condition, which we associate to the less stringent definition of local sign stability, also defined in the paper. In addition, for strong local sign stable graphs which show stability to linear perturbations irrespectively of system size, we observe that the leading eigenvalue can undergo a transition from being real to acquiring a nonnull imaginary part, which implies a dynamical transition from nonoscillatory to oscillatory linear response to perturbations. Lastly, we ascertain the discontinuous nature of this transition.Comment: 55 pages, 17 figure

Modeling and Simulation of Robotic Grasping in Simulink Through Simscape Multibody

Grasping and dexterous manipulation remain fundamental challenges in robotics, above all when performed with multifingered robotic hands. Having simulation tools to design and test grasp and manipulation control strategies is paramount to get functional robotic manipulation systems. In this paper, we present a framework for modeling and simulating grasps in the Simulink environment, by connecting SynGrasp, a well established MATLAB toolbox for grasp simulation and analysis, and Simscape Multibody, a Simulink Library allowing the simulation of physical systems. The proposed approach can be used to simulate the grasp dynamics in Simscape, and then analyse the obtained grasps in SynGrasp. The devised functions and blocks can be easily customized to simulate different hands and objects

Contact mechanics analysis of a soft robotic fingerpad

The precision grasping capabilities of robotic hands is a key feature which is more and more required in the manipulation of objects in several unstructured fields, as for instance industrial, medical, agriculture and food industry. For this purpose, the realization of soft robotic fingers is crucial to reproduce the human finger skills. From this point of view the fingerpad is the part which is mostly involved in the contact. Particular attention must be paid to the knowledge of the mechanical contact behavior of soft artificial fingerpads. In this paper, artificial silicone fingerpads are applied to the last phalanx of robotic fingers actuated by tendons. The mechanical interaction between the fingerpad and a flat surface is analyzed in terms of deformations, contact areas and indentations. A reliable model of fingertip deformation properties provides important information for understanding robotic hand performance, that can be useful both in the design phase and for defining control strategies. The approach is based on theoretical, experimental, and numerical methods. The results will be exploited for the design of more effective robotic fingers for precision grasping of soft or fragile objects avoiding damages

Il triangolo imperfetto. Russia, Turchia e Azerbaigian nello scacchiere caucasico.

Russia, Turchia e Azerbaigian nello scacchiere caucasic