Motion control optimization of robotic fish tail

"In the daily life people, animals, fishes, birds and insects constantly interact with continuous media such as air or water. It means that synthesis of new robotic systems inside this continuous media and imitation of motion of real objects must be investigated together with media surrounding them. In this report motion of robotic fish tail vibration and simplified interaction with water flow is investigated. The study comprises: (a) preliminary analysis of main goal that is given to scientist to solve the problem; (b) optimization of a main fundamental system; (c) analysis of ideal control actions; (d) synthesis a new structural schemes; (e) calculation of optimal parameters. The preliminary analysis includes 5 steps: analysis of technological processes, choice of base system, choice of control actions, clarification of criteria for optimization and selection of limits. In this report criterion of optimization (for robotic fish tail model inside water) is maximal positive impulse of water forces in the fish tail and hull contact pivot. The main idea is to find out optimal control law for variation of additional area of vibrating tail within limits. The limits are maximal and minimal area of tail interaction with water. For task solution the maximum principle of Pontryagin is used [5 – 14]. It is demonstrated that optimal control action is on bounds of area limits. Examples of synthesis of real mechatronic systems are provided. One example of synthesis is a system with time harmonic moment excitation of tail in the pivot. The other example is a system with adaptive force moment as function of phase coordinates. In both systems area exchange (from maximal to minimal values) has control action as a function of phase coordinates. It is demonstrated that real tail vibration motion is highly stable and provides satisfactory real criterion in the hull contact point

Fin type propulsive devices with varying working area of vibrating tail

The object of the study is a fin type propulsive device of robotic fish moving inside water. The aim of the study is to establish optimal control law for variation of additional area of vibrating tail, which ensures maximal positive impulse of motive forces acting on tail. The problem has been solved using the maximum principle of Pontryagin. It is demonstrated that optimal control action corresponds to the case of bound values of area limits. The proposed method makes it possible to increase effective surface area of the fin within motion cycles, when useful tractive force is formed. But within cycles, when fin motion is hindered by water resistance forces, effective surface area is decreased. Thanks to this energy losses are minimized, and operation of fin propulsive device becomes more effective. Examples on synthesis of real mechatronic systems are provided as wel

How well do physical activity questions perform? A European cognitive testing study

&lt;p&gt;&lt;b&gt;BACKGROUND: &lt;/b&gt;Only few studies have focused on the cognitive processes of the respondents that are involved when answering physical activity questionnaires (PAQs). This study aimed at examining whether two PAQs work as intended with different segments of the survey population in different cultural settings in Europe.&lt;/p&gt;&lt;p&gt;&lt;b&gt;METHODS: &lt;/b&gt;The International Physical Activity Questionnaire - Short Form (IPAQ-SF) and the US National Health Interview Survey - Adult Core Physical Activity Questionnaire (NHIS-PAQ) were tested in Belgium, Estonia, Germany and the UK using a standardized cognitive interviewing procedure. IPAQ-SF measures total vigorous physical activity (PA), moderate PA, walking and sitting. NHIS-PAQ measures leisure-time vigorous PA, light and moderate PA and muscle-strengthening PA. In total 62 persons completed cognitive interviews, at least 15 interviews were conducted in each country.&lt;/p&gt;&lt;p&gt;&lt;b&gt;RESULTS: &lt;/b&gt;Both PAQs performed as intended with young and high-skilled persons and those having a regular exercise schedule. For the others, however, the testing revealed that problems occurred with both PAQs relating to understanding the concepts of &#039;(light and) moderate&#039; and &#039;vigorous&#039; PA, classifying activities into the provided answer options of different PA intensities, recalling instances of &#039;normal&#039; activities such as walking and sitting, and calculating the total duration of more than one activity or instance of an activity. The revealed problems with the questionnaires were quite similar in different countries; profound cultural differences were not observed.&lt;/p&gt;&lt;p&gt;&lt;b&gt;CONCLUSIONS: &lt;/b&gt;Both questionnaires were difficult to answer for many respondents and rather user-unfriendly. They are designed to measure an exactness of PA quantity (frequency and duration) and intensity which would be desirable to obtain from a scientific point of view; however, respondents can hardly provide this information for cognitive reasons. Studies investigating the respondents&#039; perspective are useful for improving physical activity information based on self-reports.&lt;/p&gt;</p

Comparative profiling identifies C13orf3 as a component of the Ska complex required for mammalian cell division

Proliferation of mammalian cells requires the coordinated function of many proteins to accurately divide a cell into two daughter cells. Several RNAi screens have identified previously uncharacterised genes that are implicated in mammalian cell division. The molecular function for these genes needs to be investigated to place them into pathways. Phenotypic profiling is a useful method to assign putative functions to uncharacterised genes. Here, we show that the analysis of protein localisation is useful to refine a phenotypic profile. We show the utility of this approach by defining a function of the previously uncharacterised gene C13orf3 during cell division. C13orf3 localises to centrosomes, the mitotic spindle, kinetochores, spindle midzone, and the cleavage furrow during cell division and is specifically phosphorylated during mitosis. Furthermore, C13orf3 is required for centrosome integrity and anaphase onset. Depletion by RNAi leads to mitotic arrest in metaphase with an activation of the spindle assembly checkpoint and loss of sister chromatid cohesion. Proteomic analyses identify C13orf3 (Ska3) as a new component of the Ska complex and show a direct interaction with a regulatory subunit of the protein phosphatase PP2A. All together, these data identify C13orf3 as an important factor for metaphase to anaphase progression and highlight the potential of combined RNAi screening and protein localisation analyses

The ARROWS project: Adapting and developing robotics technologies for underwater archaeology

ARchaeological RObot systems for the World's Seas (ARROWS) EU Project proposes to adapt and develop low-cost Autonomous Underwater Vehicle (AUV) technologies to significantly reduce the cost of archaeological operations, covering the full extent of archaeological campaign. ARROWS methodology is to identify the archaeologists requirements in all phases of the campaign and to propose related technological solutions. Starting from the necessities identified by archaeological project partners in collaboration with the Archaeology Advisory Group, a board composed of European archaeologists from outside ARROWS, the aim is the development of a heterogeneous team of cooperating AUVs capable of comply with a complete archaeological autonomous mission. Three new different AUVs have been designed in the framework of the project according to the archaeologists' indications: MARTA, characterized by a strong hardware modularity for ease of payload and propulsion systems configuration change; U-C AT, a turtle inspired bio-mimetic robot devoted to shipwreck penetration and A-Size AUV, a vehicle of small dimensions and weight easily deployable even by a single person. These three vehicles will cooperate within the project with AUVs already owned by ARROWS partners exploiting a distributed high-level control software based on the World Model Service (WMS), a storage system for the environment knowledge, updated in real-time through online payload data process, in the form of an ontology. The project includes also the development of a cleaning tool for well-known artifacts maintenance operations. The paper presents the current stage of the project that will lead to overall system final demonstrations, during Summer 2015, in two different scenarios, Sicily (Italy) and Baltic Sea (Estonia

Marine robotics workshop at ICAR 2011, 15TH INTERNATIONAL CONFERENCE ON ADVANCED ROBOTICS TALLINN JUNE 20 - 23 / 2011

Marine robotics is a rapidly growing field within applied and fundamental research. The workshop aims at presenting recent results from academy and industry with a particular emphasis on research projects. The scope of the workshop is broad as it aims at bringing together scientist working on diverse issues ranging from bio-inspired robot design, to sensors, navigation, guidance and control of single and multiple vehicle systems, marine manipulation, and applications as surveillance or archeological studies. The Workshop is scheduled to be a full day event: each speaker will have a maximum of 30 minutes for her/his presentation. A time slot for questions and discussion will be allocated after each presentation in order to foster exchange of ideas and interaction among the participants. A final round-table discussion will also be organized in order to focus on the main issues that will have been raised during the workshop. The presentations and eventual additional material of behalf of the speakers will be collected and distributed to the participants

3D modelling of non-uniform and turbulent flow in vertical slot fishways

Global stocks of freshwater fish have been on the decline for decades, driven in part by the obstruction of their migration routes by anthropogenic barriers. To mitigate such impacts, fishways have been developed to facilitate bidirectional fish migration. These structures are affected by the hydrological variability of rivers, which can cause changes in the up and downstream boundary conditions of fishways, leading to non-uniform hydraulic performance. Current methodologies in fishway design and analysis often assume uniform performance, most commonly relying on 1D approximations of the water level distribution. In this study we highlight the necessity of considering non-uniform performance. We provide an in-depth analysis methodology for non-uniform conditions, demonstrating the necessity of 3D models to correctly characterize non-uniformity and leveraging the synergy between 1D and 3D models. For this VOF method together with two turbulence modelling technics, RANS Standard k-ε and LES Smagorinsky models, are analyzed using OpenFOAM CFD platform.acceptedVersio