A model-based residual approach for human-robot collaboration during manual polishing operations

A fully robotized polishing of metallic surfaces may be insufficient in case of parts with complex geometric shapes, where a manual intervention is still preferable. Within the EU SYMPLEXITY project, we are considering tasks where manual polishing operations are performed in strict physical Human-Robot Collaboration (HRC) between a robot holding the part and a human operator equipped with an abrasive tool. During the polishing task, the robot should firmly keep the workpiece in a prescribed sequence of poses, by monitoring and resisting to the external forces applied by the operator. However, the user may also wish to change the orientation of the part mounted on the robot, simply by pushing or pulling the robot body and changing thus its configuration. We propose a control algorithm that is able to distinguish the external torques acting at the robot joints in two components, one due to the polishing forces being applied at the end-effector level, the other due to the intentional physical interaction engaged by the human. The latter component is used to reconfigure the manipulator arm and, accordingly, its end-effector orientation. The workpiece position is kept instead fixed, by exploiting the intrinsic redundancy of this subtask. The controller uses a F/T sensor mounted at the robot wrist, together with our recently developed model-based technique (the residual method) that is able to estimate online the joint torques due to contact forces/torques applied at any place along the robot structure. In order to obtain a reliable residual, which is necessary to implement the control algorithm, an accurate robot dynamic model (including also friction effects at the joints and drive gains) needs to be identified first. The complete dynamic identification and the proposed control method for the human-robot collaborative polishing task are illustrated on a 6R UR10 lightweight manipulator mounting an ATI 6D sensor

Parametric and semiparametric estimation of ordered response models with sample selection and individual-specific thresholds

This paper provides a set of new Stata commands for parametric and semiparametric estimation of an extended version of ordered response models that accounts for both sample selection problems and heterogeneity in the thresholds for the latent variable. The standard estimator of ordered response models is therefore generalized along three directions. First, we account for the presence of endogenous selectivity effects that may lead to inconsistent estimates of the model parameters. Second, we control for both observed and unobserved heterogeneity in response scales by allowing the thresholds to depend on a set of covariates and a random individual effect. Finally, we consider two alternative specifications of the model, one parametric and one semiparametric. In the former, the error terms are assumed to follow a multivariate Gaussian distribution and the model parameters are estimated via maximum likelihood. In the latter, the distribution function of the error terms is instead approximated by following Gallant and Nychka (1997), and the model parameters are estimated via pseudo–maximum likelihood. After discussing identification and estimation issues, we present an empirical application using the second wave of the Survey on Health, Ageing and Retirement in Europe (SHARE). Specifically, we estimate an ordered response model for self-reported health on different domains by accounting for both sample selection bias due to survey nonresponse and reporting bias in the self-assessments of health.

Liver involvement in pediatric celiac disease

Celiac disease (CD) is an intestinal inflammatory disease that manifests in genetically susceptible individuals when exposed to dietary gluten. It is a common chronic disorder, with a prevalence of 1% in Europe and North America. Although the disease primarily affects the gut, the clinical spectrum of CD is remarkably varied, and the disease can affect many extraintestinal organs and systems, including the liver. The hepatic dysfunction presenting in CD ranges from asymptomatic liver enzyme elevations or nonspecific reactive hepatitis (cryptogenic liver disorders), to chronic liver disease. In this article, we review the clinical presentations and possible mechanisms of CD-related liver injury to identify strategies for the diagnosis and treatment of these disorders in childhood

The Naples warped hard chine hulls systematic series

An experimental study was carried out to evaluate still water performance of a Systematic Series of hard chine hulls in planing and semiplaning speed range. Models of the Naples Systematic Series (NSS) were of varying length-to-beam ratios of the parent hull. The parent hull, shaped with warped bottoms, was derived from a pre-existing hull extensively tested in a towing tank. This hull was validated by many work boats built in the last fifteen years. To simplify the construction of vessels with rigid panels (aluminium alloy, plywood or steel) the original hull form was transformed to obtain developable hull surfaces. The models were tested at Re>3.5×106, in speed ranges Fr=0.5−1.6 and Fr∇=1.1−4.3. The series studies the influence of LP/BC and Ⓜ ratios that vary respectively in the ranges of 3.45–6.25 and 4.83–7.49, for two positions of CG. All the models were tested both with and without interceptors. To enable model-ship correlation following the ITTC recommendations, in addition to the resistance coefficients of the models, dynamic wetted lengths and surfaces were provided as tables. To facilitate the implementation of Velocity Predict Programs, all the data (resistances, lengths and surfaces) were also furnished in polynomial form. In addition to the use of series in the design field, this study was done to provide data to improve the numerical simulations of a planing craft. With this aim, in addition to the resistance data, the wave profiles, obtained by wave cuts, were provided to carry out validation procedures

L'effetto 'country of origin' sull'intenzione d'acquisto del consumatore: un'analisi metodologica

This study investigates, from the methodological perspective, how research on the influence of the country of origin effect has been conducted. To this end, the study reviews main published literature of the last five years, categorizing the documents according to various methodological issues. The growing use of the multi cue approach and the prevalent use of quantitative methods, even if based on non-probability sampling, are observed. Further, limits on the analyzed researches are pointed out. Results allow some suggestions to fill the research gaps,from the methodological point of view, and implications for future research

A new logic for Controllable pitch propeller management

In this study we want to propose an active logic that, continuously, optimizes the configuration of the propeller and motor speed taking into account changes in resistance and wake. The working principle of the control system is based on the measurement of the torque absorbed by the pro-peller and the engine speed, to obtain the actual thrust and advance speed coefficients. Based on these data, the controller identifies the configuration of the propeller for the best performance of the entire propulsion chain, from engine to propeller. Moreover, in addition to torque and speed limits of the en-gine, the control system chooses pitch angle taking into consideration the propeller’s cavitation

-In silico functional characterization of a double histone fold domain from the Heliothis zea virus 1

BACKGROUND: Histones are short proteins involved in chromatin packaging; in eukaryotes, two H2a-H2b and H3-H4 histone dimers form the nucleosomal core, which acts as the fundamental DNA-packaging element. The double histone fold is a rare globular protein fold in which two consecutive regions characterized by the typical structure of histones assemble together, thus originating a histone pseudodimer. This fold is included in a few prokaryotic histones and in the regulatory region of guanine nucleotide exchange factors of the Sos family. For the prokaryotic histones, there is no direct structural counterpart in the nucleosomal core particle, while the pseudodimer from Sos proteins is very similar to the dimer formed by histones H2a and H2b RESULTS: The absence of a H3-H4-like histone pseudodimer in the available structural databases prompted us to search for proteins that could assume such fold. The application of several secondary structure prediction and fold recognition methods allowed to show that the viral protein gi|22788712 is compatible with the structure of a H3-H4-like histone pseudodimer. Further in silico analyses revealed that this protein module could retain the ability of mediating protein-DNA interactions, and could consequently act as a DNA-binding domain. CONCLUSION: Our results suggest a possible functional role in viral pathogenicity for this novel double histone fold domain; thus, the computational analyses here reported will be helpful in directing future biochemical studies on gi|22788712 protein

Hub-and-Spoke or else? Free trade agreements in the 'enlarged' European Union

The object of this paper is to estimate if and how the Central European Free Trade Agreement (CEFTA) and the Baltic Free Trade Agreement (BFTA) exerted a significant impact on intra-European trade, effectively reducing the influence of the European Association Agreements (EAs) in shaping the European trade structure as a hub-and-spoke system - with the EU15 being the hub and the CEECs the spoke. This paper analyses bilateral trade flows between eight CEECs and EU-23. We estimate a gravity equation using a system GMM dynamic panel data approach. Results support the assumptions that gravity forces and "persistence effects" matter. With respect to the effect of free trade agreements, evidence is found that Free trade agreements between CEECs matter: There is evidence that the presence of intra-periphery agreements helped expand intra-periphery trade and limited the emergence of a "hub-and-spoke" relationship between CEECs and EU. This results have important policy implications for the trade strategy of "future" EU members of the Southeastern European Countries as well as of the Southern Mediterranean Countries. According to the empirical results, these countries should move towards a regional free-trade area as exemplified by the CEFTA and the BFTA to avoid "hub-and-spoke" effects.Trade flows, regional integration, EU eastward enlargement, gravity model, dynamic panel data

La Convenzione sui diritti dell’infanzia. Un’ipotesi di educazione alla genitorialità come laboratorio di corresponsabilità educativa e didattica

L’autore in questo contributo, partendo dalla Convenzione sui diritti dell’infanzia del 1989, propone un modello di educazione alla genitorialità come un laboratorio di corresponsabilità educativa e didattica per migliorare la qualità della scuola dell’autonomia