DRIVE: Data-driven Robot Input Vector Exploration

An accurate motion model is a fundamental component of most autonomous navigation systems. While much work has been done on improving model formulation, no standard protocol exists for gathering empirical data required to train models. In this work, we address this issue by proposing Data-driven Robot Input Vector Exploration (DRIVE), a protocol that enables characterizing uncrewed ground vehicles (UGVs) input limits and gathering empirical model training data. We also propose a novel learned slip approach outperforming similar acceleration learning approaches. Our contributions are validated through an extensive experimental evaluation, cumulating over 7 km and 1.8 h of driving data over three distinct UGVs and four terrain types. We show that our protocol offers increased predictive performance over common human-driven data-gathering protocols. Furthermore, our protocol converges with 46 s of training data, almost four times less than the shortest human dataset gathering protocol. We show that the operational limit for our model is reached in extreme slip conditions encountered on surfaced ice. DRIVE is an efficient way of characterizing UGV motion in its operational conditions. Our code and dataset are both available online at this link: https://github.com/norlab-ulaval/DRIVE.Comment: 6 pages, 7 figures, submitted to 2024 IEEE International Conference on Robotics and Automation (ICRA 2024

Invariant Kalman Filtering with Noise-Free Pseudo-Measurements

peer reviewe

51Cr-EDTA plasma clearance in children. One, two, or multiple samples?

Plasma disappearance curves using multiple blood samples are a recognized reference method for measuring glomerular filtration rate (GFR). However, there is no consensus on the protocol for this type of measurement. A two-compartment model is generally considered acceptable for the mathematical description of the concentration–time decay curve. The impact of the fitting procedure on the reported GFR has not been questioned. We defined 8 different fitting procedures to calculate the area under the curve, and from this area under the curve, the GFR. We applied the 8 fitting methods (all considering a full concentration–time curve) on the multiple sample data (8 samples) of 20 children diagnosed with Duchenne muscular dystrophy. We evaluated the effect (variability) on the reported GFR from the different fitting methods and compared these results with GFR-values calculated from late samples only (samples after 120 minutes) and from one-sample methods. In 6 out of 20 cases, the fitting methods on the full concentration–time curve resulted in very different reported GFR-values, mainly because some methods were not able to fit the data, or methods resulted in GFR-values ranging from 0 to 120 mL/min. The reported GFR-result therefore strongly depends on the fitting method, making the full concentration–time method less robust than expected. Compared with a consensus reference GFR, the late sample models did not show fitting issues and may therefore be considered as more robust. Also the one-sample methods showed acceptable accuracy. The late sample methods (using 3 time-points) provide robust and reliable methods to determine GFR

Domain Decomposition for real time Simulation of needle insertion

International audienceOur goal is to develop robotized needle insertion for drug delivery in small animals. We control the robot with a real-time Finite Element simulation that provides accurate models of the deformable environment. To predict the deformations we need to solve a contact problem which is known to be time consuming. To reduce the computational time we use the domain decomposition method: the FE mesh is split in several domains in order to extract paral-lelism for GPU computing and to concentrate the computation time around the needle

Domain Decomposition for real time Simulation of needle insertion

International audienceOur goal is to develop robotized needle insertion for drug delivery in small animals. We control the robot with a real-time Finite Element simulation that provides accurate models of the deformable environment. To predict the deformations we need to solve a contact problem which is known to be time consuming. To reduce the computational time we use the domain decomposition method: the FE mesh is split in several domains in order to extract paral-lelism for GPU computing and to concentrate the computation time around the needle

ÉVALUATION DE LA QUALITÉ DES GÉODONNÉES ET OPERATIONALISATION DE LA DIRECTIVE INSPIRE : RETOUR D'EXPERIENCE

peer reviewedIn the same way as the French Référentiel à Grande Echelle (RGE), the Walloon Public Service aims to set up its own Georepository. This repository is intended to respond to the establishment of an Infrastructure for Spatial Information in the European Community under the INSPIRE directive. It consists among other things in ensuring the availability of the first reference geoadata whose quality is guaranteed and in coherence with the business needs of the users for the Walloon territory. With this in mind, the Geomatics Unit of the University of Liège, in collaboration with the Technical Committee of the Public Service of Wallonia for the Georepository and the Geometrology Departement, proposes a quality control methodology for three prospective geodata of the Georepository: buildings, road axes and addresses. One of the outcomes of this project was the definition of a theorical basis for the validation of geodata quality. This article presents its main findings and conclusions

Characterization of Aroma Active Compound Production during Kombucha Fermentation: Towards the Control of Sensory Profiles

peer reviewedSince the sensorial profile is the cornerstone for the development of kombucha as a beverage with mass market appeal, advanced analytical tools are needed to gain a better understanding of the kinetics of aromatic compounds during the fermentation process to control the sensory profiles of the drink. The kinetics of volatile organic compounds (VOCs) was determined using stir bar sorptive extraction—gas chromatography—mass spectrometry, and odor-active compounds were considered to estimate consumer perception. A total of 87 VOCs were detected in kombucha during the fermentation stages. The synthesis of mainly phenethyl alcohol and isoamyl alcohol probably by Saccharomyces genus led to ester formation. Moreover, the terpene synthesis occurring at the beginning of fermentation (∆-3-carene, α-phellandrene, γ-terpinene, m- and p-cymene) could be related to yeast activity as well. Principal component analysis identified classes that allowed the major variability explanation, which are carboxylic acids, alcohols, and terpenes. The aromatic analysis accounted for 17 aroma-active compounds. These changes in the evolution of VOCs led to flavor variations: from citrus-floral-sweet notes (geraniol and linalool domination), and fermentation brought intense citrusherbal-lavender-bergamot notes (α-farnesene). Finally, sweet-floral-bready-honey notes dominated the kombucha flavor (2-phenylethanol). As this study allowed to estimate kombucha sensory profiles, an insight for the development of new drinks by controlling the fermentation process was suggested. Such a methodology should allow a better control and optimization of their sensory profile, which could in turn lead to greater consumer acceptance

New Fluorinated 1,2,4-Benzothiadiazine 1,1-Dioxides: Discovery of an Orally Active Cognitive Enhancer Acting through Potentiation of the 2-Amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic Acid Receptors

In the search of a potent cognitive enhancer, a series of 3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxides have been synthesized and evaluated as positive allosteric modulators of the AMPA receptors. In the present work, we focused our efforts on the insertion of mono- or polyfluoro- substituted alkyl chains at the 4-position of the thiadiazine ring in an attempt to enhance the pharmacokinetic behavior of previously described compounds. Among all the described compounds, 7-chloro-4-(2-fluoroethyl)-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide, 12b, was shown to exert a strong activity on AMPA receptors in vitro and a marked cognitive-enhancing effect in vivo after oral administration to Wistar rats. Considering its in vivo activity, the metabolic degradation of 12b was studied and compared to that of its nonfluorinated analogue 9b. Taken together, results of this study clearly validated the positive impact of the fluorine atom on the alkyl chain at the 4-position of benzothiadiazine dioxides on activity and metabolic stability

Autonomous space exploration using the Turtlebot mobile platform

Cilj diplomske naloge je implementacija avtonomnega raziskovanja prostora na mobilni platformi Turtlebot, ki uporablja razvojno okolje ROS. Implementirali smo raziskovalni algoritem, ki temelji na zaznavi obrobij in njihovi uporabi kot potencialnih raziskovalnih ciljev. Ker pa lahko algoritem pri izbiri raziskovalnih ciljev upošteva različne kombinacije ocen raziskovanja, smo nato preizkušali in primerjali, katera kombinacija ocen omogoča najbolj učinkovito raziskovanje prostora. Različne strategije izbire raziskovalnih ciljev smo ocenjevali in primerjali na podlagi štirih kriterijev ter referenčne strategije, ki naključno izbira raziskovalne cilje. Podatke za primerjavo smo dobili tako, da smo za vsako strategijo opravili deset uspešnih raziskovanj. Te smo nato kot skupine povprečnih vrednosti in odstopanj primerjali med seboj na podlagi referenčne strategije in kriterijev. Implementirali smo modul, ki poleg raziskanosti prostora in časa raziskovanja omogoča tudi beleženje zgodovine premikov in s tem pot raziskovanja, ki jo opravi Turtlebot.The purpose of this undergraduate thesis is to implement the autonomous exploration of space on the Turtlebot mobile platform that uses the ROS development environment. We implemented an exploration algorithm based on the detection and use of frontier regions as potential exploration goals. Since the algorithm is able to choose an exploration goal based on the combination of different assessments, we tested and compared which combination of goal assessments enables the most efficient exploration of a given space. We assessed and compared different strategies of goal setting on the basis of four criteria and a referential strategy which selects its exploration goals randomly. In order to get the data necessary for comparison, we conducted ten successful explorations per strategy and compared them on the basis of the referential strategy and criteria. We implemented our own module, which tracks the amount of space explored and the time spent for exploration, while also documenting the path traveled by the Turtlebot during exploration