Adaptive optimal operation of a parallel robotic liquid handling station

Results are presented from the optimal operation of a fully automated robotic liquid handling station where parallel experiments are performed for calibrating a kinetic fermentation model. To increase the robustness against uncertainties and/or wrong assumptions about the parameter values, an iterative calibration and experiment design approach is adopted. Its implementation yields a stepwise reduction of parameter uncertainties together with an adaptive redesign of reactor feeding strategies whenever new measurement information is available. The case study considers the adaptive optimal design of 4 parallel fed-batch strategies implemented in 8 mini-bioreactors. Details are given on the size and complexity of the problem and the challenges related to calibration of over-parameterized models and scarce and non-informative measurement data. It is shown how methods for parameter identifiability analysis and numerical regularization can be used for monitoring the progress of the experimental campaigns in terms of generated information regarding parameters and selection of the best fitting parameter subset.BMBF, 02PJ1150, Verbundprojekt: Plattformtechnologien für automatisierte Bioprozessentwicklung (AutoBio); Teilprojekt: Automatisierte Bioprozessentwicklung am Beispiel von neuen Nukleosidphosphorylase

Multi-contact tactile exploration and interaction with unknown objects

Humans rely on the sense of touch in almost every aspect of daily life, whether to tie shoelaces, place fingertips on a computer keyboard or find keys inside a bag. With robots moving into human-centered environment, tactile exploration becomes more and more important as vision may be occluded easily by obstacles or fail because of different illumination conditions. Traditional approaches mostly rely on position control for manipulating objects and are adapted to single grippers and known objects. New sensors make it possible to extend the control to tackle problems unsolved before: handling unknown objects and discovering local features on their surface. This thesis tackles the problem of controlling a robot which makes multiple contacts with an unknown environment. Generating and keeping multiple contacts points on different parts of the robot fingers during exploration is an essential feature that distinguishes our work from other haptic exploration work in the literature, where contacts are usually limited to one or more fingertips. In the first part of this thesis, we address the problem of exploring partially known surfaces and objects for modeling and identification. In multiple scenarios, control and exploration strategies are developed to compliantly follow the surface or contour of a surface with robotic fingers. Whereas the methods developed in the first part of this thesis perform well on objects with limited size and variation in shape, the second part of the thesis is devoted to the development of a controller that maximizes contact with unknown surfaces of any shape and size. Maximizing contact allows to gather information more rapidly and also to create stable grasps. To this end, we develop an algorithm based on the task-space formulation to quickly handle the control in torque of an actively compliant robot while keeping constraints, particularly on contact forces. We also develop a strategy to maximize the surface in contact, given only the current state of contact, i.e. without prior information on the object or surface. In the third part of the thesis, an additional application of the developed hand controller is explored. The problem of autonomous grasping using only tactile data is tackled. The arm motion is generated according to search and grasping strategies implemented with Dynamical Systems (DS). We extend existing approaches to locally modulate dynamical systems (DS) to enable sensing-based modulation, so as to change the dynamics of motion depending on task progress. This allows to generate fast and autonomous object localization and grasping in one flexible framework. We also apply this algorithm to teach a robot how to react to collisions in order to navigate between obstacles while reaching

Transition du matin des vents de pente dans une vallée alpine étroite

Les caractéristiques précises de la transition du matin dans la couche limite atmosphérique au-dessus d’un terrain alpin restent encore peu connues. La grande hétérogénéité spatiale influençant le budget énergétique ainsi que la formation de vents de pente et de vallée sont quelques unes des conséquences de ce type de terrain complexe. Pour étudier les transitions du cycle diurne des vents de pente, une campagne de mesures a été réalisée dans le Val Ferret (Valais, Suisse) durant l’été 2010. Un réseau de stations météorologiques a été déployé le long d’une pente abrupte (25° à 45°) en parallèle avec des mesures de profils atmosphériques par ballon sonde. Les résultats suggèrent que la couche d’inversion nocturne est détruite 2-3 h après le lever du soleil local. Contrairement à un terrain plat, la destruction n’est pas uniquement due au réchauffement par la surface mais également par la subsidence causée par un écoulement anabatique sur le haut de la pente. Deux régimes de vent sont observés grâce aux profils atmosphériques : des vents catabatiques durant la nuit et des vents ascendants de vallée durant la journée. Les vents catabatiques mesurés sont des écoulements superficiels caractérisés par un jet à quelques mètres au-dessus de la surface. Le changement de direction de vent du régime nocturne à diurne s’effectue premièrement à quelques mètres au-dessus du sol puis près de la surface à cause de la stabilité atmosphérique. L’équation de quantité de mouvement révèle que la formation des vents catabatiques est principalement due au déficit de température nocturne. Les mesures de températures près de la surface indiquent la présence d’un flux de chaleur contraire au gradient qui pourrait supposer le transport de chaleur par des bulles d’air chaudes générées par la surface en direction de la couche d’air stable située au-dessus

Multi-contact haptic exploration and grasping with tactile sensors

Haptic exploration has received a great deal of attention of late thanks to the variety of commercially available tactile sensors. While the majority of previous works consider control of a single contact point at a time, we tackle simultaneous control of multiple contact points on several links. In addition, we use information from the existing tactile signals to increase the number of points in contact. We demonstrate the usefulness of this form of control to speed up exploration, scanning and to compliantly grasp unknown objects. Our controller requires to know only the parts of the robot on which it is desirable to make contact and does not need a model of the environment besides the robot itself. We validate the algorithm in a set of experiments using a robotic hand covered with tactile sensors and arm. In a grasping application, the active adaptation of the fingers to the shape of the object ensures that the hand encloses the object with multiple contact points. We show that this improves the robustness of the grasp compared to simple enclosing strategies. When combined with an exploration strategy, our multi-contact approach offers an efficient use of tactile sensors on the whole surface of robotic fingers, and enables the robot to perform a rapid exploration of complex, non convex shapes while maintaining low contact forces. It is robust to variation in the approach angle and to changes in the geometry and orientation of the object

Signatures of Non-Markovianity in Cavity-QED with Color Centers in 2D Materials

Light-matter interactions of defects in two dimensional materials are expected to be profoundly impacted by strong coupling to phonons. In this work, we combine ab initio calculations of a defect in hBN, with a fully quantum mechanical and numerically exact description of a cavity-defect system to elucidate this impact. We show that even at weak light-matter coupling, the dynamical evolution of the cavity-defect system has clear signatures of non-markovian phonon effects, and that linear absorption spectra show the emergence of hybridised light-matter-phonon states in regimes of strong light-matter coupling. We emphasise that our methodology is general, and can be applied to a wide variety of material/defect systems.Comment: 7 pages, 3 figures + 8 pages supplemen