22 research outputs found

    Control and Estimation Methods Towards Safe Robot-assisted Eye Surgery

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    Vitreoretinal surgery is among the most delicate surgical tasks in which physiological hand tremor may severely diminish surgeon performance and put the eye at high risk of injury. Unerring targeting accuracy is required to perform precise operations on micro-scale tissues. Tool tip to tissue interaction forces are usually below human tactile perception, which may result in exertion of excessive forces to the retinal tissue leading to irreversible damages. Notable challenges during retinal surgery lend themselves to robotic assistance which has proven beneficial in providing a safe steady-hand manipulation. Efficient assistance from the robots heavily relies on accurate sensing and intelligent control algorithms of important surgery states and situations (e.g. instrument tip position measurements and control of interaction forces). This dissertation provides novel control and state estimation methods to improve safety during robot-assisted eye surgery. The integration of robotics into retinal microsurgery leads to a reduction in surgeon perception of tool-to-tissue forces at sclera. This blunting of human tactile sensory input, which is due to the inflexible inertia of the robot, is a potential iatrogenic risk during robotic eye surgery. To address this issue, a sensorized surgical instrument equipped with Fiber Bragg Grating (FBG) sensors, which is capable of measuring the sclera forces and instrument insertion depth into the eye, is integrated to the Steady-Hand Eye Robot (SHER). An adaptive control scheme is then customized and implemented on the robot that is intended to autonomously mitigate the risk of unsafe scleral forces and excessive insertion of the instrument. Various preliminary and multi-user clinician studies are then conducted to evaluate the effectiveness of the control method during mock retinal surgery procedures. In addition, due to inherent flexibility and the resulting deflection of eye surgical instruments as well as the need for targeting accuracy, we have developed a method to enhance deflected instrument tip position estimation. Using an iterative method and microscope data, we develop a calibration- and registration-independent (RI) framework to provide online estimates of the instrument stiffness (least squares and adaptive). The estimations are then combined with a state-space model for tip position evolution obtained based on the forward kinematics (FWK) of the robot and FBG sensor measurements. This is accomplished using a Kalman Filtering (KF) approach to improve the instrument tip position estimation during robotic surgery. The entire framework is independent of camera-to-robot coordinate frame registration and is evaluated during various phantom experiments to demonstrate its effectiveness

    A 5-DOFs Robot for Posterior Segment Eye Microsurgery

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    In retinal surgery clinicians access the internal volume of the eyeball through small scale trocar ports, typically 0.65 mm in diameter, to treat vitreoretinal disorders like idiopathic epiretinal membrane and age-related macular holes. The treatment of these conditions involves the removal of thin layers of diseased tissue, namely the epiretinal membrane and the internal limiting membrane. These membranes have an average thickness of only 60 μm and 2 μm respectively making extremely challenging even for expert clinicians to peel without damaging the surrounding tissue. In this work we present a novel Ophthalmic microsurgery Robot (OmSR) designed to operate a standard surgical forceps used in these procedures with micrometric precision, overcoming the limitations of current robotic systems associated with the offsetting of the remote centre of motion of the end effector when accessing the sclera. The design of the proposed system is presented, and its performance evaluated. The results show that the end effector can be controlled with an accuracy of less than 30 μm and the surgical forceps opening and closing positional error is less than 4.3 μm. Trajectory-following experiments and membrane peeling experiments are also presented, showing promising results in both scenarios

    Augmented Reality

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    Augmented Reality (AR) is a natural development from virtual reality (VR), which was developed several decades earlier. AR complements VR in many ways. Due to the advantages of the user being able to see both the real and virtual objects simultaneously, AR is far more intuitive, but it's not completely detached from human factors and other restrictions. AR doesn't consume as much time and effort in the applications because it's not required to construct the entire virtual scene and the environment. In this book, several new and emerging application areas of AR are presented and divided into three sections. The first section contains applications in outdoor and mobile AR, such as construction, restoration, security and surveillance. The second section deals with AR in medical, biological, and human bodies. The third and final section contains a number of new and useful applications in daily living and learning

    Programmable Multistable Mechanisms: Design, modeling, characterization and applications

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    Multistable Mechanisms are mechanical devices having more than one stable state. Since these mechanisms can maintain different deformations with zero force, they are advantageous for low power environments such as wristwatches and medical devices. In this thesis, I introduce programmable multistable mechanisms (PMMs), a new family of multistable mechanisms where the number, position, and stiffness of stable states can be controlled by programming inputs modifying the boundary conditions. PMMs can be synthesized by combining bistable mechanisms. This method was used to produce the T-mechanism, a PMM consisting of two double parallelogram mechanisms (DPMs) connected orthogonally where each DPM consists of two parallel beams connected centrally by a rigid block and axially loaded by programming input. An analytical model based on Euler-Bernoulli beam theory was derived to describe qualitatively the stability behaviour of the T-mechanism. The model approximates the mechanism's stiffness by a sixth order polynomial from which the reaction force and strain energy expressions can be estimated. These explicit formulas provide analytical expressions for the number, position, and stiffness of stable and unstable states as functions of the programming inputs. The qualitative stability behavior was represented by the programming diagram, bifurcation diagrams and stiffness maps relating the number, position and stiffness of stable states with the programming inputs. In addition, I showed that PMMs have zero stiffness regions functioning as constant-force multistable mechanisms. Numerical simulations validated these results. Experimental measurements were conducted on the T-mechanism prototype manufactured using electro-discharge machining. An experimental setup was built to measure the reaction force of the mechanism for different programming inputs. I verified the possible configurations of the T-mechanism including monostability bistability, tristability, quadrastability, zero stiffness regions, validating my analytical and numerical models. Compared to classical multistable mechanisms which are displaced between their stable states by imposing a direct displacement, PMMs can be displaced by modifying mechanism strain energy. This property increases the repeatability of the mechanism as the released energy is independent of the driving parameters, which can be advantageous for mechanical watches and medical devices. Accurate timekeepers require oscillators having repeatable period independent of their energy source. However, the balance wheel spiral spring oscillator used in all mechanical watches, suffers from isochronism defect, i.e., its oscillation period depends on its amplitude. I addressed this problem by introducing novel detached constant force escapements for mechanical wristwatches based on PMMs. In the medical domain, I applied PMMs to construct a retinal vein cannulation needle for the treatment of retinal vein occlusion. PMMs based needles produce sufficient repeatable puncturing energy with a predefined stroke independent of the operator input. Numerical simulations were used to model and dimension our proposed tool and satisfy the strict requirements of ophthalmologic operations. The tool was manufactured using 3D femto-laser printing of glass. An experimental setup was built to characterize the tool's mechanical behavior and to verify my computations. The tool was applied successfully to cannulate retinal veins of pig eyes

    Development and preliminary results of bimanual smart micro-surgical system using a ball-lens coupled OCT distance sensor

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    Bimanual surgery enhances surgical effectiveness and is required to successfully accomplish complex microsurgical tasks. The essential advantage is the ability to simultaneously grasp tissue with one hand to provide counter traction or exposure, while dissecting with the other. Towards enhancing the precision and safety of bimanual microsurgery we present a bimanual SMART micro-surgical system for a preliminary ex-vivo study. To the best of our knowledge, this is the first demonstration of a handheld bimanual microsurgical system. The essential components include a ball-lens coupled common-path swept source optical coherence tomography sensor. This system effectively suppresses asynchronous hand tremor using two PZT motors in feedback control loop and efficiently assists ambidextrous tasks. It allows precise bimanual dissection of biological tissues with a reduction in operating time as compared to the same tasks performed with conventional onehanded approaches. © 2016 Optical Society of America.1

    Realidade aumentada num simulador virtual de tomada de decisão clínica

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    A presente investigação teve como objetivo verificar se a Realidade Aumentada (RA) potencia o desenvolvimento de competências de tomada de decisão clínica no diagnóstico e tratamento de feridas crónicas, aumenta a motivação dos estudantes e a usabilidade do simulador virtual e-FER. O e-FER é um simulador online de tomada de decisão clínica utilizado na formação inicial de enfermeiros, permitindo simular o diagnóstico e tratamento de casos clínicos virtuais de feridas crónicas. Para o presente estudo foi acrescentada uma componente de RA com novos casos clínicos, no sentido de investigar os seus efeitos na motivação, usabilidade e desenvolvimento de competências no diagnóstico e tratamento de feridas crónicas. Desenvolveu-se um estudo quase-experimental com uma amostra de 54 estudantes a frequentar o primeiro ano de Enfermagem. Realizou-se uma análise comparativa entre o desempenho dos grupos experimental (que utilizou o e-FER tradicional e depois com RA) e de controlo (que utilizou apenas o e-FER tradicional), com base nos dados extraídos a partir do simulador virtual e-FER. Os dados relativos à motivação dos estudantes e usabilidade do sistema foram recolhidos através de questionário. Os resultados obtidos permitem concluir que a RA potenciou o desempenho dos estudantes, particularmente nos parâmetros de diagnóstico da ferida, com diferenças estatisticamente muito significativas (p<0,001) nos testes de Mann-Whitney U e Wilcoxon, registando-se ainda índices elevados de motivação e usabilidade do simulador, mesmo com a introdução de um dispositivo adicional na atividade.The goal of this investigation was to verify if Augmented Reality (AR) enhances the development of clinical decision-making skills in wound diagnosis and treatment, increases student motivation and the usability of the e-FER virtual simulator. The e-FER is an online clinical decision-making simulator used in the initial training of nurses, allowing to simulate the diagnosis and treatment of virtual clinical cases of chronic wounds. In this study an AR component was added with new clinical cases, in order to investigate its effects on motivation, usability and the development of wound diagnosis and treatment skills. A quasi-experimental study was conducted with a sample of 54 students attending the first year of a Nursing program. A comparative analysis between the progress of the experimental group (who used the traditional e-FER and then with AR) and the control group (who used only the traditional e-FER) was made using the data extracted from the e-FER virtual simulator. Data on student's motivation and system usability were collected through a questionnaire. The results showed that AR enhanced student performance, particularly in wound diagnostic parameters, with highly statistically significant differences (p<0,001) in the Mann-Whitney U and Wilcoxon tests, and registering high levels of motivation and simulator usability, even with the introduction of an additional device in the activity

    WICC 2016 : XVIII Workshop de Investigadores en Ciencias de la Computación

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    Actas del XVIII Workshop de Investigadores en Ciencias de la Computación (WICC 2016), realizado en la Universidad Nacional de Entre Ríos, el 14 y 15 de abril de 2016.Red de Universidades con Carreras en Informática (RedUNCI

    Flexible robotic device for spinal surgery

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    Surgical robots have proliferated in recent years, with well-established benefits including: reduced patient trauma, shortened hospitalisation, and improved diagnostic accuracy and therapeutic outcome. Despite these benefits, many challenges in their development remain, including improved instrument control and ergonomics caused by rigid instrumentation and its associated fulcrum effect. Consequently, it is still extremely challenging to utilise such devices in cases that involve complex anatomical pathways such as the spinal column. The focus of this thesis is the development of a flexible robotic surgical cutting device capable of manoeuvring around the spinal column. The target application of the flexible surgical tool is the removal of cancerous tumours surrounding the spinal column, which cannot be excised completely using the straight surgical tools in use today; anterior and posterior sections of the spine must be accessible for complete tissue removal. A parallel robot platform with six degrees of freedom (6 DoFs) has been designed and fabricated to direct a flexible cutting tool to produce the necessary range of movements to reach anterior and posterior sections of the spinal column. A flexible water jet cutting system and a flexible mechanical drill, which may be assembled interchangeably with the flexible probe, have been developed and successfully tested experimentally. A model predicting the depth of cut by the water jet was developed and experimentally validated. A flexion probe that is able to guide the surgical cutting device around the spinal column has been fabricated and tested with human lumber model. Modelling and simulations show the capacity for the flexible surgical system to enable entering the posterior side of the human lumber model and bend around the vertebral body to reach the anterior side of the spinal column. A computer simulation with a full Graphical User Interface (GUI) was created and used to validate the system of inverse kinematic equations for the robot platform. The constraint controller and the inverse kinematics relations are both incorporated into the overall positional control structure of the robot, and have successfully established a haptic feedback controller for the 6 DoFs surgical probe, and effectively tested in vitro on spinal mock surgery. The flexible surgical system approached the surgery from the posterior side of the human lumber model and bend around the vertebral body to reach the anterior side of the spinal column. The flexible surgical robot removed 82% of mock cancerous tissue compared to 16% of tissue removed by the rigid tool.Open Acces

    An Experimental Feasibility Study on Robotic Endonasal Telesurgery

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    Novel robots have recently been developed specifically for endonasal surgery. They can deliver several thin, tentacle-like surgical instruments through a single nostril. Among the many potential advantages of such a robotic system is the prospect of telesurgery over long distances
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