Towards a human-in-the-loop control for a smart orthotic system

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Eletrónica Médica)Stroke is the main cause of paralysis. This pathology has provoked a considerable increase of persons with motor impairments. With a therapy focused on each clinical case, the total or partial recovery can be achieved. Powered orthoses have been developed to promote an effective recover, based on repetitive gait training and user’s active participation. Many control approaches have been developed to control these devices, but none of them promotes an user-oriented strategy focused to the user’s needs. In an attempt of solving this issue, a new approach named Human-in-the-loop is emerging. This strategy allows the adaptation of some assistive parameters based on the user’s energetic cost, promoting a therapy tailored to each end-user needs. However, to estimate the energy expenditure, the use of non-ergonomic sensors, not suitable for clinical context, is required. Thus, it is necessary to find new ways of estimating energy expenditure using wearable and comfortable sensors. In this dissertation, the first steps to introduce the Human-in-the-loop strategy into a powered orthosis are presented. For this purpose, two strategies were developed: a strategy that allows the angular trajectory adaptation in real-time and other that promotes a stiffness adaptation all over the gait cycle. Both strategies were validated with healthy subjects. In the first strategy, the orthosis was able to modify its assistance in a fraction of microseconds, and the end-users were able to follow her with a median error below 10%. Regarding the second strategy, the results show that the orthosis allowed an effective change in the systems’ interaction stiffness, promoting an active participation of each user during its assistance. The energetic impact of using the robotic assistive device is also presented. As it promotes an energy expenditure augmentation in more than 30% in comparison to walk without the device, the necessity of implementing the Human-in-the-loop strategy was highlighted. In an attempt of finding an ergonomic technique to estimate the energetic cost, the use of machine learning algorithms was tested. The results, obtained with a MLP and a LSTM, prove that it is possible to estimate the energy expenditure with a mean error close to 11%. Future work consists in the implementation of the model in real-time and the collection of more data with the aforementioned control approaches, in a way of constructing a more robust model.O AVC é uma das maiores causas de paralisia. Esta patologia, cada vez mais com maior incidência nos jovens, tem provocado um aumento considerável de pessoas com problemas de mobilidade. Com uma terapia focada a cada caso clínico, a recuperação total ou parcial pode ser conseguida. As ortóteses ativas têm vindo a ser desenvolvidas com o propósito de promover uma recuperação eficaz, baseada em treinos repetitivos e numa participação ativa dos utilizadores. Várias abordagens de controlo têm vindo a ser desenvolvidas para controlar estes dispositivos, mas nenhuma delas promove uma estratégia orientada às necessidades do utilizador. Na tentativa de solucionar este problema, uma nova abordagem, designada por Human-in-the-loop está a emergir. Baseada no custo energético, esta estratégia permite adaptar parâmetros da assistência, promovendo uma terapia focada e direcionada a cada utilizador. No entanto, para estimar o custo energético, recorre-se ao uso de sensores que não são adequados para contexto clínico. Assim, torna-se necessário estudar novas formas de estimar o custo energético. Nesta dissertação são apresentados os primeiros passos para introduzir o controlo Human-in-the-loop numa ortótese ativa. Para isso, duas estratégias foram apresentadas: uma estratégia que permite adaptar a trajetória angular da ortótese, em tempo real, e outra que promove a adaptação da complacência do sistema ao longo do ciclo da marcha. Ambas foram validadas com sujeitos saudáveis. Relativamente à primeira abordagem, a ortótese foi capaz de modificar a sua assistência em microssegundos, e os utilizadores foram capazes de a seguir com um erro mediano inferior a 10%. No que diz respeito à segunda abordagem, os resultados mostram que a ortótese promoveu uma alteração eficaz da complacência de interação, promovendo uma participação ativa do utilizador durante a sua assistência. O impacto energético do uso do sistema robótico é, também, apresentado. Promovendo um aumento do custo energético em mais de 30%, a necessidade da estratégia Human-in-the-loop foi realçada. Na tentativa de encontrar uma técnica para estimar o custo energético, recorreu-se ao uso de machine learning. Os resultados, obtidos com uma MLP e uma LSTM, provam que é possível estimar o custo energético com um erro médio próximo dos 11%. Trabalho futuro passa pela implementação do modelo em tempo real e a recolha de mais dados com as abordagens de controlo apresentadas, de forma a construir um modelo mais robusto

A multi-camera and multimodal dataset for posture and gait analysis

Monitoring gait and posture while using assisting robotic devices is relevant to attain effective assistance and assess the user’s progression throughout time. This work presents a multi-camera, multimodal, and detailed dataset involving 14 healthy participants walking with a wheeled robotic walker equipped with a pair of affordable cameras. Depth data were acquired at 30 fps and synchronized with inertial data from Xsens MTw Awinda sensors and kinematic data from the segments of the Xsens biomechanical model, acquired at 60 Hz. Participants walked with the robotic walker at 3 different gait speeds, across 3 different walking scenarios/paths at 3 different locations. In total, this dataset provides approximately 92 minutes of total recording time, which corresponds to nearly 166.000 samples of synchronized data. This dataset may contribute to the scientific research by allowing the development and evaluation of: (i) vision-based pose estimation algorithms, exploring classic or deep learning approaches; (ii) human detection and tracking algorithms; (iii) movement forecasting; and (iv) biomechanical analysis of gait/posture when using a rehabilitation device.This work has been supported by the Fundação para a Ciência e Tecnologia (FCT) with the Reference Scholarship under Grant 2020.05708.BD and under the national support to R&D units grant, through the reference project UIDB/04436/2020 and UIDP/04436/2020

Time goals in ruptured abdominal aortic aneurysm – the experience of a tertiary centre

INTRODUCTION: Guidelines state that ruptured abdominal aortic aneurysms should be treated shortly after the diagnosis and ideally within 90 minutes. The main aim of this study is to assess the referral pattern of our centre regarding the intervals between the diagnosis of ruptured AAA and the surgical repair, considering the geographical referral areas of our hospital. METHODS: We conducted an observational, retrospective cohort study from a single centre. The study population included all patients with the diagnosis of symptomatic or ruptured abdominal aortic aneurysm referred to Centro Hospitalar e Universitário Lisboa Norte (CHULN) between 2012 and 2021. The moment of diagnosis was assumed to be the time of the CT angiography and the moment of treatment was assumed as the time of entering the operating room (OR). RESULTS: During the study period a total of 150 patients (90.7% men, mean age 78.3, SD 8.7) were treated. Of these, 86% presented as ruptured aneurysms while 14% presented as symptomatic aneurysms. The median time between the diagnosis and the initiation of surgical treatment was 150 (+/- 132) minutes. Only 22% of patients were treated within 90 minutes of diagnosis and this remained unchanged throughout the study period. No statistically significant difference was observed between the median time intervals registered for survivors and deceased patients at 24 hours (p = 0.907), 48 hours (p = 0.743) and 30 days (p = 0.605) post-surgery. CONCLUSION: In our study, only 22% of patients with ruptured or symptomatic abdominal aortic aneurysms are treated within the recommended time frame. Although there is no significant impact on mortality, the authors recognize unavailability of information regarding patients that died before arrival to our hospital as a relevant limitation

TREATMENT OF AORTIC DISSECTIONS USING A COMBINATION OF THE STABILISE AND CERAB TECHNIQUES — TECHNICAL NOTE

Introduction: Endovascular treatment of type B aortic dissection has focused on the covering of the proximal entry tear. However, recently, concern has emerged regarding the distal aortic remodeling and new techniques such as the Stent-Assisted Balloon-Induced Intimal Disruption and Relamination (STABILISE) technique have gained more acceptance. We describe a technical note regarding the combination of the STABILISE technique in addition to the Covered Reconstruction of the Aortic Bifurcation (CERAB) technique to achieve complete aortic remodeling. Methods: The authors describe a stepwise approach regarding the endovascular repair of type B aortic dissections. A simple TEVAR is performed first. If the patient still shows signs of true lumen compression, a STABILISE technique is performed in order to achieve true lumen expansion and complete aortic remodeling. However, in some patients, false lumen perfusion and true lumen compression at the very distal aorta is maintained due to distal comunicating tears. In these patients, if there are still signs of infra-renal aortic or iliac compression/occlusion or distal thrombosis of the false lumen, a simultaneous CERAB is performed. Conclusion: By combining these techniques, we aim to cover both the proximal tear and the distal comunicating tears resulting in a complete flap apposition, false lumen obliteration, re-expansion of the true lumen and achieve optimal remodeling

Boas práticas na gestão de repositórios

Apresentação realizada no âmbito do Workshop "Boas práticas na gestão de Repositórios" integrado na "13.ª Conferência Lusófona de Ciência Aberta", Maputo, Moçambique, 10 - 12 outubro de 2022

Markerless gait analysis vision system for real-time gait monitoring

On this paper a vision-based contact and markerless method for gait evaluation is proposed, and validated in different experimental setups against commercial motion capture systems (Vicon) and inertial gait analysis tools (GaitShoes). While the development goal is its integration on the ASBGo Smart Walker platform, only an inexpensive depth camera is required. It is shown to have reasonable results when computing gait metrics in real time, in different experimental setups, from different walker types, vision hardware and walking scenarios. Performance is evaluated through RMSD values for several gait metrics. Results illustrate that the proposed approach can be a valuable non-invasive, contactless and low cost alternative to gait analysis systems used in clinical rehabilitation environments.This work has been supported by the FEDER Funds through COMPETE 2020 — Programa Operacional Competitividade e Internacionalizacão (POCI) and P2020 with the Reference Project EML under Grant POCI-01-0247-FEDER-033067; COMPETE 2020 — Programa Operacional Competitividade e Internacionalizacão (POCI) with the Reference Project under Grant POCI-01-0145-FEDER-006941

On the way for a better methodology in teaching/learning instrumentation for measurements at mechanical engineering Compulsory Syllabus

Instrumentation for Measurements is a course of 3rd year, 2nd semester, in the 5-year Mechanical Engineering degree, run at Faculty of Engineering of University of Porto (FEUP) under the responsibility of the first author, in which around 60% of the time is devoted to 'hands on' laboratory activity, involving a large number of students.The teachers team of this course has a broad rangecurricular training, not only in their different degrees butalso in several post graduate fields of specialisation. Thisbrings a transversal perspective, which is very importantwhen dealing with the teaching/learning of multidisciplinary matters.Continuous (theoretical and experimental) assessment hasbeen used during the last 4 years. It has been carefullyplaned and programmed at the very beginning of thesemester, exploring different student capabilities, eitherindividually or in group.This paper presents the methodologies that were used andcomments their advantages and disadvantages.Index Terms - Teaching/learning methodologies, hands onlaboratory, continuous assessment, experimental training

ENDOLEAK TIPO IIIB: A PROPÓSITO DE UM CASO CLÍNICO

Os endoleaks (EL) do tipo IIIb resultam de um defeito no tecido da endoprótese e são uma complicação tardia rara, mas grave, inerente à correção endovascular de aneurismas da aorta (EVAR). Neste trabalho, os autores descrevem o caso de um homem de 81 anos submetido em 2013 a EVAR, devido a aneurisma da aorta abdominal (AAA) de 87mm. O procedimento decorreu sem intercorrências, assim como os primeiros dois anos de follow-up, após os quais, houve um crescimento gradual do saco aneurismático até aos 100mm, sem haver, no entanto, qualquer evidência de EL na angiotomografia computorizada (angioTC). O doente foi submetido a laparotomia exploradora, com abertura do saco aneurismático e constatação intra-operatória de EL tipo IIIb, tendo sido realizada hemostase e epiploplastia. O diagnóstico deste tipo de EL é difícil e muitas vezes apenas realizado intra-operatoriamente. Contudo, dado o elevado risco associado a esta complicação do EVAR, deve ser mantido um elevado índice de suspeição diagnóstica e a sua correção realizada atempadamente. Neste cenário, e dado não haver atualmente um gold standard de tratamento, a cirurgia aberta assume-se como uma arma terapêutica valiosa que permite não só o diagnóstico, como uma correção definitiva destas complicações