Control Architectures for Robotic Assistance in Beating Heart Surgery

Tese de doutoramento em Engenharia Electrotécnica e de Computadores, no ramo de especialização em Automação e Robótica, apresentada ao Departamento de Engenharia Electrotécnica e de Computadores da Faculdade de Ciências e Tecnologia da Universidade de CoimbraDoenças cardiovasculares são a primeira causa de morte no mundo. Todos os anos mais de 17 milhões de pessoas morrem, representando 29% do número total de mortes. As doenças coronárias são as mais críticas, atingindo mais de 7.2 milhões de mortes. Para reduzir o risco de morte, o "bypass" coronário é a intervenção cirúrgica mais comum. Atualmente este procedimento envolve uma esternotomia mediana e um "bypass" cardiopulmonar, permitindo que uma máquina externa implemente as funções de oxigenação e bombeamento de sangue. Contudo, esta máquina externa é fonte de muitas complicações pós-operatórias, incluindo a morte de pacientes. Estes problemas motivam o estudo e desenvolvimento de técnicas cirúrgicas sem parar o funcionamento do coração. Nestes casos, os batimentos cardíacos e a respiração representam as principais fontes de perturbação. Foram desenvolvidos estabilizadores mecânicos para diminuir localmente o movimento cardíaco. Colocado numa região de específica (por exemplo, na artéria coronária), estes estabilizadores limitam o movimento por pressão e sucção. Apesar dos melhoramentos feitos ao longo dos anos, ainda existe um movimento residual considerável, e o cirurgião tem que os compensar manualmente. Torna-se então natural incluir dispositivos robóticos para ajudar na prática médica, melhorando a precisão, segurançae conforto de tarefas cirúrgicas. O sistema cirúrgico da Vinci é atualmente o sistema robótico mais avançado para a prática médica, com elevado desempenho em tarefas de destreza, precisão e segurança, apesar de não fornecer soluções de realimentação táctil, nem de compensação automática de movimentos fisiológicos. O trabalho desta tese é na área da robótica para cirurgias cardíacas com o coração a bater. Baseada na realimentação da força, esta tese explora novas arquiteturas de controlo com compensação automática dos movimentos cardíacos. São feitos testes experimentais em cenários muito realistas, sem utilizar seres vivos. Um robô denominado "Heartbox" equipado com um coração real reproduz movimentos cardíacos, enquanto que outro robô manipulador aplica forças cirúrgicas nesse coração com batimento artificial. As forças de interação fornecem realimentação de contacto ao cirurgião. O principal desafio científico deste trabalho é a ligação de técnicas de compensação autónoma de movimentos fisiológicos com controlo de força e realimentação haptica.Cardiovascular diseases are the first cause of mortality in the world. More than 17 million people die every year, representing 29% of all global deaths. Among these, coronary heart diseases are the most critical ones, reaching up to 7.2 million deaths. To reduce the risk of death the coronary artery bypass grafting (CABG) is the most common surgical intervention. Currently, the procedure involves a median sternotomy, an incision in the thorax allowing a direct access to the heart, and a cardiopulmonary bypass (CPB), where heart and lung functionalities are performed by an extracorporal machine. Unfortunately the heart-lung machine is the greatest source of complications and post-operatory mortality for patients. Problems involved have motivated beating heart surgery that circumvent CPB procedure. Heartbeats and respiration represent the two main sources of disturbances during off-pump surgery. Mechanical stabilizers have been conceived for locally decreasing heart motion. Placed around a region of interest (e.g., coronary artery), these stabilizers constraint the motion by suction or pressure. Despite many improvements done over the years, considerable residual motion still remains and the surgeon have to manually compensate them. Robotic assistance has the potential to offer significant improvements to the medical practice in terms of precision, safety and comfort. Theda Vinci surgical system is the most popular and sophisticated. Although it has considerably improved dexterity, precision and safety, no solution for restoring tactile feedback to the surgeon exists and physiological motion compensation still needs to be manually canceled by the surgeon. The work presented in this thesis focus on robotic assistance for beating heart surgery. Based on force feedback, we designed new control architectures providing autonomous physiological motion compensation. Experimental assessments have been performed through a realistic scenario. A Heartbox robot equipped with an \textit{ex vivo} heart reproduces heart motion and a robot arm generates desired surgical forces on the moving heart. Interaction forces provide the haptic feedback for the surgeon. Merging autonomous motion compensation techniques with force control and haptic feedback is a major scientific challenge that we tackle in this work.FCT - SFRH/BD/74278/201

Compensation for 3D physiological motion in robotic-assisted surgery using a predictive force controller

International audienceThis paper presents a predictive force control approach to compensate for the physiological motion induced by both respiratory and heart beating motions during cardiac surgery. It focuses on the design and implementation of the control algorithm in the context of robotized minimally invasive surgery. The controller is based on a linear predictive control loop using the force information applied on the heart by the instrument. Experimental evaluation highlights the performance of the algorithm for compensating 3D physiological motion

Piezoelectric tantalum pentoxide studied for optical tunable applications

International audiencePiezoelectric transparent thin films are of great interest for use in tunable filters. We present experimental results on Ta2O5 single layers coated on fused-silica substrates with an electron-beam deposition process. Above 450 °C, coatings change from an amorphous to a polycrystallized structure. When this structure shows a preferred orientation matching the piezoelectric tensor of the Ta2O5 crystal and the external electric field, variation in the piezoelectric layer thickness is expected. We detail experimental results in terms of optical (spectrophotometric and scattering measurements) and nonoptical characterizations (x-ray diffraction and scanning electron microscopy). Then the resultant thickness variation under oscillating applied voltage is measured with an extrinsic Fabry-Perot interferometer setup

Juvenile fish assemblages in temperate rocky reefs are shaped by the presence of macro-algae canopy and its three-dimensional structure

International audienceArborescent macro-algae forests covering temperate rocky reefs are a known habitat for juvenile fishes. However, in the Mediterranean, these forests are undergoing severe transformations due to pressures from global change. In our study, juvenile fish assemblages differed between pristine arborescent forests (Cystoseira brachycarpa var. balearica) versus an alternate state: bushland (Dictyotales – Sphacelariales). Forests hosted richer and three-fold more abundant juvenile assemblages. This was consistent through space, whatever the local environmental conditions, along 40 km of NW Mediterranean subtidal rocky shores (Corsica, France). Among Cystoseira forests, juvenile assemblages varied through space (i.e. between localities, zones or sites) in terms of total abundance, composition, richness and taxa-specific patterns. More than half of this variability was explained by forest descriptors, namely small variations in canopy structure and/or depth. Our results provide essential cues for understanding and managing coastal habitats and fish populations. Further studies are needed to explain the residual part of the spatial variability of juvenile fish assemblages and to help focus conservation efforts

FRIPON: a worldwide network to track incoming meteoroids

Context: Until recently, camera networks designed for monitoring fireballs worldwide were not fully automated, implying that in case of a meteorite fall, the recovery campaign was rarely immediate. This was an important limiting factor as the most fragile – hence precious – meteorites must be recovered rapidly to avoid their alteration. Aims: The Fireball Recovery and InterPlanetary Observation Network (FRIPON) scientific project was designed to overcome this limitation. This network comprises a fully automated camera and radio network deployed over a significant fraction of western Europe and a small fraction of Canada. As of today, it consists of 150 cameras and 25 European radio receivers and covers an area of about 1.5 × 106 km2. Methods: The FRIPON network, fully operational since 2018, has been monitoring meteoroid entries since 2016, thereby allowing the characterization of their dynamical and physical properties. In addition, the level of automation of the network makes it possible to trigger a meteorite recovery campaign only a few hours after it reaches the surface of the Earth. Recovery campaigns are only organized for meteorites with final masses estimated of at least 500 g, which is about one event per year in France. No recovery campaign is organized in the case of smaller final masses on the order of 50 to 100 g, which happens about three times a year; instead, the information is delivered to the local media so that it can reach the inhabitants living in the vicinity of the fall. Results: Nearly 4000 meteoroids have been detected so far and characterized by FRIPON. The distribution of their orbits appears to be bimodal, with a cometary population and a main belt population. Sporadic meteors amount to about 55% of all meteors. A first estimate of the absolute meteoroid flux (mag < –5; meteoroid size ≥~1 cm) amounts to 1250/yr/106 km2. This value is compatible with previous estimates. Finally, the first meteorite was recovered in Italy (Cavezzo, January 2020) thanks to the PRISMA network, a component of the FRIPON science project