Flotteur pour la surveillance pluridisciplinaire de l’environnement marin. De l’expertise métier aux codes embarqués

As part of an ERC (European Research Council) project conducted at Geoazur from 2009 to 2015 by Guust Nolet, an autonomous profiler float equipped with a hydrophone and able to carry up to 8 sensors has been developed. It aims to acquire data in oceanic areas, poorly covered by current instrumentation. However, these data are necessary to carry out studies in various scientific fields, for example, to study the internal structure of the earth in geosciences (via the recording of seismic waves propagating inside the earth), the thermal balance of oceans in climatology, or the distribution of marine mammals in the oceans in biology. Most data must be processed before being transmitted by satellite because of the very limited transmission bandwidth. Data processing applications are usually developed by embedded systems specialists who have a good knowledge of the characteristics specific to the instrument. However, the need to involve these specialists greatly limits the flexibility, or even the ability of scientists to adapt the applications to their needs.In order to enable scientists to write applications for the instrument, we have created the MeLa (Mermaid Language) programming language, specifically designed for the Mermaid float. The language makes it possible to hide embedded systems specific aspects. It is based on computer models that allow computing the resources usage of the instrument (i.e., processor, power, satellite transmission) in order to ensure that the instrument limits are not exceeded. Models are also used to compose (i.e., combine) several applications to be installed on the same instrument and to ensure that they are compatible. Finally, models are used to generate reliable and efficient code (i.e., without bugs and efficient), on the one hand, to simulate applications on a personal computer and verify their behavior, and, on the other hand, to generate the embedded code used to program the instruments.This thesis is organized into four chapters. In the first chapter, we start by presenting the scientific and social issues involved in the acquisition of data in the oceans, then we introduce the Mermaid float and how it can respond to these issues and end by presenting different programming approaches for this type of instrument. The second chapter corresponds to an article published in the OCEANS 2019 conference proceedings. It shows the technical aspects of the MeLa language and in particular how we use models and how the approach is validated on an Arduino development board. The third chapter corresponds to an article published in the Sensors journal and is more focused on the use of language, a development method is proposed, and two applications are developed for the detection of earthquakes and the detection of blue whales. In the final chapter, we summarize the conclusions and offer a perspective of future developments.Dans le cadre d’un projet ERC (European Research Council) mené à Geoazur de 2009 à 2015 par Guust Nolet, un flotteur profileur autonome équipé d’un hydrophone et pouvant accueillir jusqu’à 8 capteurs a été développé. Il vise à acquérir des données en zones océaniques, faiblement couvertes par l’instrumentation actuelle. Ces données sont pourtant nécessaires pour réaliser des études dans différents domaines scientifiques, par exemple, pour étudier la structure interne de la terre en géosciences (via l’enregistrement d’ondes sismiques ayant traversées l’intérieur de la terre), le bilan thermique des océans en climatologie, ou encore la répartition des cétacés dans les océans en biologie. Toutes ces données doivent être traitées avant leur transmission à cause des capacités de transmission par satellite qui sont très limités. Les applications de traitement des données sont usuellement développées par des spécialistes en systèmes embarqués ayant une bonne connaissance des caractéristiques spécifiques à l’instrument. Cependant, passer par ces spécialistes limite grandement les capacités d’adaptation des applications en fonction des besoins des scientifiques.Afin de permettre aux scientifiques d’écrire des applications pour l’instrument, nous avons créé le langage de programmation MeLa (Mermaid Language), spécifiquement conçu pour le flotteur Mermaid. Le langage permet de cacher les aspects propres aux systèmes embarqués. Il est basé sur des modèles informatiques à partir desquels nous calculons l’utilisation des ressources de l’instrument (i.e., processeur, énergie, transmission satellite) afin de s’assurer que les limites de l’instrument ne soient pas dépassées. Les modèles sont aussi utilisés pour composer (i.e., combiner) plusieurs applications devant être installées sur un même instrument et s’assurer qu’elles sont compatibles. Finalement, les modèles sont utilisés pour générer du code fiable et efficace (i.e., sans bugs et performant), d’une part pour simuler les applications sur un ordinateur personnel et vérifier leurs comportements, et d’autre part pour générer le code embarqué servant à la programmation des instruments.Ce manuscrit de thèse est organisé en quatre chapitres. Dans le premier chapitre, nous commençons par la présentation des différentes problématiques scientifiques et sociales concernées par l’acquisition de données dans les océans, nous introduisons ensuite le flotteur Mermaid et la manière dont il peut répondre à ces problématiques et terminons par présenter les différentes approches de programmation de ce type d’instruments. Le deuxième chapitre correspond à un article publié à l’occasion de la conférence OCEANS 2019. Il décrit les aspects techniques du langage MeLa et en particulier la manière dont nous utilisons les modèles et validons cette approche sur une carte de développement Arduino. Le troisième chapitre correspond à un article publié dans la revue Sensors et est plus axé sur l’utilisation du langage, une méthode de développement est proposée et deux applications sont présentées pour la détection de séismes et la détection de baleines bleues. Dans le chapitre final, nous récapitulons les conclusions et offrons une perspective des développements futurs

Multidisciplinary, autonomous, Lagrangian floats for seismology, ocean acoustics and marine environmental science

International audienceWe have developed autonomous, Lagrangian floats that make seismo-acoustic measurements in the oceans, with mission durations of 4+ years and running (http://earthscopeoceans.org). Earthquakes generate seismic waves that traverse the solid earth, convert to acoustic waves when they hit the seafloor from below, and are recorded by the hydrophone on our “Mermaid” floats drifting at ~1500m depth.In the long-term, we aim for dense and even global coverage of the oceans for seismology, following the model of oceanography’s Argo initiative, or of internationally federated seismometer networks on land. In order to grow the network, we are exploring synergies with oceanography and the marine environmental sciences.We present technical developments towards the first multidisciplinary mission in 2024 in the Mediterranean, whose floats will run embedded applications in two frequency ranges: the seismic (~0.1-5 Hz) as well as the “conventional” ocean acoustics range (10 Hz to 30 kHz). It will feature detection and classification algorithms for earthquakes, rainfall, marine mammal vocalizations, and ship noise. While energy-limited, these seismological floats carry significantly larger batteries than Argo floats and allow for up to eight physical/chemical/other sensors and their analysis algorithms, whose concurrent needs are managed by a domain-specific language written for the purpose (Bonnieux 2020)

Easy development of monitoring applications for an autonomous float

International audienceAutonomous floats have been used for decades to monitor physical properties of the oceans. More recently, these instruments have been used to record seismic signals in the oceans in order to improve tomographic images resolution at the global scale. A hydrophone is used to monitor the acoustic landscape but all the data cannot be sent through satellite communication since it is costly and power consuming. Therefore an algorithm is used to detect seismic signals. Monitoring the acoustic landscape of the oceans can also be used to study marine wildlife (whales, fishes, etc.) and the impact of human activities, or to study meteorology. For each of these monitoring activities specific algorithms must be developed and implemented on the instrument. But developing and implementing such algorithms on the float by traditional means requires much effort and expertise in embedded software.To overcome this, we have followed a Model Driven Engineering approach. This approach consists of a Domain Specific Language (DSL) - called MeLa - that targets the development of applications for the float. The language allows to write applications at a higher level of abstraction such that embedded software development skills is not required. The underlying model is used to compute several properties (e.g., battery lifetime, cost of satellite transmission), to merge several applications that have been defined separately, and generate code that can be deployed on the float. An experiment has been conduced to develop an improved version of the seismic detection application, and a whales detection application. The developers of these applications were a geoscientist and a biologist that are not experts in embedded software development. The results show that the developers were able to successfully develop applications by themselves and to take into account the limited capacities of the float. The applications have been tested on the float's electronic board with real data.The proposed approach allows scientists to develop monitoring applications for autonomous floats without the help of embedded software experts. We expect that it will enable the multidisciplinary monitoring of the oceans at the global scale

Model driven programming of autonomous floats for multidisciplinary monitoring of the oceans

International audienceMonitoring of the oceans with autonomous floats is of great interest for many disciplines. Monitoring on a global scale needs a multidisciplinary approach to be affordable. For this purpose, we propose an approach that allows oceanographers from different specialities to develop applications for autonomous floats. However, developing such applications usually requires expertise in embedded systems, and they must be reliable and efficient with regards to the limited resources of the floats (e.g., energy, processing power). We have followed a Model Driven Engineering approach composed of i) a Domain Specific Language to allow oceanographers to develop applications, ii) analysis tools to ensure that applications are efficient and reliable, iii) a composition tool to allow the deployment of different applications on a same float, and iv) a code generator that produce efficient and reliable code for the float. We present our approach with a biological and a seismological application. We validate it with technical metrics and an experiment

Modular seismo-acoustic float technology for coastal and open ocean observation

International audienceLagrangian floats are used since the early 2000s for monitoring temperature and salinity of the oceans, and more recently for recording tele-seismic waves. This technology is originally dedicated to global monitoring because it's drifting with oceanic currents over thousands of kilometers. Recent developments have shown that the floats can also be equipped with an anchoring or semi-anchoring system to prevent the current drift. It opens up even more possible applications for many multidisciplinary ocean science studies. However, it also highlights the needs of modularity to handle different users, and evolving needs, while reducing development time without affecting reliability and cost of the instrument. We introduce some use cases from seismology to biology to identify the main requirements of modularity and discuss about software and hardware limitations. We present our approach of modular software, with a domain-specific language, allowing deployment of several applications, on a float equipped with high and low frequency hydrophones for multidisciplinary acoustic monitoring. A first prototype will be deployed in 2024 and further developments are to come in the next years

Easy development of monitoring applications for an autonomous float

International audienceAutonomous floats have been used for decades to monitor physical properties of the oceans. More recently, these instruments have been used to record seismic signals in the oceans in order to improve tomographic images resolution at the global scale. A hydrophone is used to monitor the acoustic landscape but all the data cannot be sent through satellite communication since it is costly and power consuming. Therefore an algorithm is used to detect seismic signals. Monitoring the acoustic landscape of the oceans can also be used to study marine wildlife (whales, fishes, etc.) and the impact of human activities, or to study meteorology. For each of these monitoring activities specific algorithms must be developed and implemented on the instrument. But developing and implementing such algorithms on the float by traditional means requires much effort and expertise in embedded software.To overcome this, we have followed a Model Driven Engineering approach. This approach consists of a Domain Specific Language (DSL) - called MeLa - that targets the development of applications for the float. The language allows to write applications at a higher level of abstraction such that embedded software development skills is not required. The underlying model is used to compute several properties (e.g., battery lifetime, cost of satellite transmission), to merge several applications that have been defined separately, and generate code that can be deployed on the float. An experiment has been conduced to develop an improved version of the seismic detection application, and a whales detection application. The developers of these applications were a geoscientist and a biologist that are not experts in embedded software development. The results show that the developers were able to successfully develop applications by themselves and to take into account the limited capacities of the float. The applications have been tested on the float's electronic board with real data.The proposed approach allows scientists to develop monitoring applications for autonomous floats without the help of embedded software experts. We expect that it will enable the multidisciplinary monitoring of the oceans at the global scale

MeLa: A Programming Language for a New Multidisciplinary Oceanographic Float

International audienceAt 2000 m depth in the oceans, one can hear biological, seismological, meteorological, and anthropogenic activity. Acoustic monitoring of the oceans at a global scale and over long periods of time could bring important information for various sciences. The Argo project monitors the physical properties of the oceans with autonomous floats, some of which are also equipped with a hydrophone. These have a limited transmission bandwidth requiring acoustic data to be processed on board. However, developing signal processing algorithms for these instruments requires one to be an expert in embedded software. To reduce the need of such expertise, we have developed a programming language, called MeLa. The language hides several aspects of embedded software with specialized programming concepts. It uses models to compute energy consumption, processor usage, and data transmission costs early during the development of applications; this helps to choose a strategy of data processing that has a minimum impact on performances. Simulations on a computer allow for verifying the performance of the algorithms before their deployment on the instrument. We have implemented a seismic P wave detection and a blue whales D call detection algorithm with the MeLa language to show its capabilities. These are the first efforts toward multidisciplinary monitoring of the oceans, which can extend beyond acoustic applications

Global passive acoustic monitoring of the oceans with MERMAID Argo floats

International audienceWe introduce a multidisciplinary acoustic version of MERMAID floats, equipped with a hydrophone for listening to sounds up to 20 kHz, and capable of carrying several other sensors. The MERMAID float is currently used by seismologists for earthquake recordings; the Earthscope-Ocean organization has deployed almost 100 floats in the middle of the Pacific Ocean, Mediterranean Sea and China Sea. The new version with high frequencies will enable global passive acoustic monitoring for several fields of research such as the study of cetaceans, meteorology or anthropological activity.It is capable of embedded processing to reduce the amount of data to transmit, which is limited to a maximum of a few megabytes per month. New algorithms can be developed by scientists with a specific programming language called MeLa, similar to Python or Matlab languages, to allow the development of applications with a limited knowledge of embedded systems. The MeLa language also takes into account the processing and energy limitations of the instrument, to ensure that the applications will behave as expected (e.g. without missing samples), and will not drain the battery too fast for ensuring a lifetime of 5 years per instrument.We have implemented four applications that are 1) a seismic detection algorithm based on signal level triggering and power estimation between different wavelet scales, 2) a fin whale detection algorithm based on a deep neural network, 3) a rain and wave gauge using a power ratio between two frequencies, and 4) an ambient noise measurements with usual spectral density estimation. Over the air programming allows applications to be updated or installed even once the float is deployed at sea. We are searching for collaboration scientific data interpretation and/or other applications developments. First trial in the Mediterranean Sea will occur in 2024

Global passive acoustic monitoring of the oceans with MERMAID Argo floats

International audienceWe introduce a multidisciplinary acoustic version of MERMAID floats, equipped with a hydrophone for listening to sounds up to 20 kHz, and capable of carrying several other sensors. The MERMAID float is currently used by seismologists for earthquake recordings; the Earthscope-Ocean organization has deployed almost 100 floats in the middle of the Pacific Ocean, Mediterranean Sea and China Sea. The new version with high frequencies will enable global passive acoustic monitoring for several fields of research such as the study of cetaceans, meteorology or anthropological activity.It is capable of embedded processing to reduce the amount of data to transmit, which is limited to a maximum of a few megabytes per month. New algorithms can be developed by scientists with a specific programming language called MeLa, similar to Python or Matlab languages, to allow the development of applications with a limited knowledge of embedded systems. The MeLa language also takes into account the processing and energy limitations of the instrument, to ensure that the applications will behave as expected (e.g. without missing samples), and will not drain the battery too fast for ensuring a lifetime of 5 years per instrument.We have implemented four applications that are 1) a seismic detection algorithm based on signal level triggering and power estimation between different wavelet scales, 2) a fin whale detection algorithm based on a deep neural network, 3) a rain and wave gauge using a power ratio between two frequencies, and 4) an ambient noise measurements with usual spectral density estimation. Over the air programming allows applications to be updated or installed even once the float is deployed at sea. We are searching for collaboration scientific data interpretation and/or other applications developments. First trial in the Mediterranean Sea will occur in 2024

Observer des ondes sismiques en milieu marin

Il y a une dizaine d'années, l'un de nous (Gusst Nolet) travaillant avec Frederik Simons à l'Université de Princeton, avait observé une onde sismique P d'un séisme lointain de magnitude 6. Bien qu'il n'est pas rare de voir un séisme de cette ampleur, dont environ 200 se produisent chaque année, leur méthode d'observation était unique : aidé par des collègues de la Scripps Institution of Oceanography, ils avaient utilisé un flotteur SOLO, à 700m sous la surface de la mer près de San Diego, Californie, qu'ils avaient équipé, avec pas mal de bricolage improvisé, d'un hydrophone. L'importance de cette observation historique ne doit pas être sous-estimée, car elle aurait le mérite d'ouvrir les océans à des observations sismiques à grande échelle