RESUMO
PURPOSE: Retinal vein cannulation is an experimental procedure during which a clot-dissolving drug is injected into an obstructed retinal vein. However, due to the fragility and minute size of retinal veins, such procedure is considered too risky to perform manually. With the aid of surgical robots, key limiting factors such as: unwanted eye rotations, hand tremor and instrument immobilization can be tackled. However, local instrument anatomy distance and force estimation remain unresolved issues. A reliable, real-time local interaction estimation between instrument tip and the retina could be a solution. This paper reports on the development of a combined force and distance sensing cannulation needle, and its experimental validation during in vivo animal trials. METHODS: Two prototypes are reported, relying on force and distance measurements based on FBG and OCT A-scan fibres, respectively. Both instruments provide an 80 [Formula: see text] needle tip and have outer shaft diameters of 0.6 and 2.3 mm, respectively. RESULTS: Both prototypes were characterized and experimentally validated ex vivo. Then, paired with a previously developed surgical robot, in vivo experimental validation was performed. The first prototype successfully demonstrated the feasibility of using a combined force and distance sensing instrument in an in vivo setting. CONCLUSION: The results demonstrate the feasibility of deploying a combined sensing instrument in an in vivo setting. The performed study provides a foundation for further work on real-time local modelling of the surgical scene. This paper provides initial insights; however, additional processing remains necessary.
Assuntos
Cateterismo/instrumentação , Micromanipulação/instrumentação , Oclusão da Veia Retiniana/cirurgia , Procedimentos Cirúrgicos Robóticos/instrumentação , Animais , Cateterismo/métodos , Humanos , Modelos Animais , Agulhas , Veia Retiniana , Suínos , Tomografia de Coerência Óptica/métodosRESUMO
The paper investigates the specificity of Linear Parameter Varying (LPV) modeling and robust controller design on a widely used Type 1 Diabetes Mellitus model. LPV systems can be seen as an extension of linear time invariant systems, which allows us to extend some powerful control methodologies to the highly nonlinear and uncertain models of the human metabolism. Different LPV models are proposed with their own advantages and disadvantages. The possible choices are separately analyzed for both controller and observer design perspective.
Assuntos
Diabetes Mellitus Tipo 1/metabolismo , Algoritmos , Metabolismo dos Carboidratos , Simulação por Computador , Glucose/metabolismo , Humanos , Modelos Lineares , Modelos BiológicosRESUMO
The possibilities of the supporting effect of the fibula and of its preclusion are discussed. The indication of the fibulotomia is dealt with. According to the authors' standpoint in the case of the anatomical reposition of the tibial fracture and after its staple synthesis the supporting effect of the fibula is not be be feared. In these cases the reposition and the osteosynthesis of the fibula neutralize fairly well also the motive forces acting on the tibial fracture.