Procedimientos optimizados utilizando métodos simbólicos para la simulación de sistemas dinámicos mediante Bond-Graph

Los esfuerzos en la automatización del método de Bond-Graph en los últimos años se centran en solventar el problema de las coordenadas dependientes que aparecen frecuentemente en los sistemas mecánicos, eléctricos y térmicos. El desarrollo de esta Tesis se centra en aportar un algoritmo de asignación causal especialmente ideado para permitir máxima libertad al modelador, sin que éste se tenga que preocupar de la resolubilidad o no del sistema, y sin tener que tomar ningún tipo de decisión que pueda afectar al cálculo final, de tal forma que se resuelvan los problemas planteados a la hora de simular modelos con causalidad diferencial sin necesidad de tener que modificar el diagrama de grafos. Además, se reduce al máximo el conjunto de ecuaciones diferenciales necesario para poder realizar la simulación mediante la eliminación de las ecuaciones algebraicas del sistema DAEs, en aquellos casos donde sea posible. de esta forma se disminuye el tiempo de computación utilizado en la simulación. Por otra parte, se propone un método para la generación automática y optimizada de las ecuaciones de estado necesarias para el análisis de sistemas lineales y no lineales, formulados mediante la técnica de Bond-Graph. La construcción de dichas ecuaciones se realiza utilizando técnicas de cálculo simbólico. De esta forma, se dispone de las ecuaciones del sistema en un formato que facilita su utilización posterior para resolver problemas de sensibilidad o de optimización. Dicho método tiene en cuenta tanto las no linealidades geométricas que presentan los sistemas mecánicos (tratadas mediante elementos transformer y gyrator de razón variable), como el comportamiento no lineal de elementos básicos elementales (inercias, resortes y resistencias). Por último, con el fin de mostrar la efectividad de los algoritmos propuestos, se ha desarrollado un código para la simulación de sistemas dinámicos mediante la técnica del Bond-Graph en entorno Windows, que implementa las propuestas presentadas a lo largo de la Tesis y que permite tanto la modelización combinada empleando grafos, funciones variables y sentencias condicionales, como la presentación de las ecuaciones diferenciales y algebraicas finales de forma simbólica, todo ello en un entorno amigable y permitiendo postprocesar fácilmente los resultados de las simulaciones efectuadas sin necesidad de tener que realizar una compilación previa

Simulation of a mechanical thrombectomy device based in the use of self-expandable stents for the blood clots extraction

Recently, we have presented some studies concerning the analysis, design and optimization of one experimental device developed in the UK - GPTAD - which has been designed to remove blood clots without the need to make contact with the clot itself, thereby potentially reducing the risk of problems such as downstream embolisation. Based on the idea of a modification of the previous device, in this work, we present a model based in the use of stents like the SolitaireTM FR, which is in contact with the clot itself. In the case of such devices, the stent is self-expandable and the extraction of the blood clot is faciliatated by the stent, which must be inside the clot. Such stents are generally inserted in position by using the guidewire inserted into the catheter. This type of modeling could potentially be useful in showing how the blood clot is moved by the various different forces involved. The modelling has been undertaken by analyzing the resistances, compliances and inertances effects. We model an artery and blood clot for range of forces for the guidewire. In each case we determine the interaction between blood clot, stent and artery

An alternative for human gait modelling using the Bond Graph Technique

The systematic analysis of the human gait with a skeletal or neuromuscular disorder is a valuable clinical instrument to determine the nature and severity of the disease. At present, there are many institutions that have developed a series of numerical models that simulate and analyze biomechanics systems such as the human gait. Many of these models require diverse and segmented programming to incorporate various effects of the dynamics of the body such as the performance of the muscles and tendons, the passive and active resistance to movement, and other physiological effects. One of the alternatives to simulate biomechanical systems is the use of the Bond Graph modeling technique. The modular modeling with multi-domains, a feature of the Bond Graph technique, is one of its potential advantages compare to other methods. The equations generated with the use of this technique are equivalent to those techniques developed with more traditional methods, but the modules can be easier and more comfortable to use in conjunction with models of neuromuscular control functions, models that incorporate the elasticity properties in the bones and tendons, etc. The proposed model, comprised of seven segments, is developed to estimate the torque and the power in the joints. This model is simulated and validated using the processed experimental data of a normal gait in GCD (Gait Cycle Data) format file

Analysis and Simulation of the Leg of an Hexapod Robot for Remote Exploration

The locomotion system is determined by the terrain conditions. The aim of this paper is to introduce the characteristics and simulation of a hexapod legged robot that can be easily used for exploration of abrupt and harsh terrains, Jike the Rio Tinto environment. A walking robot seems like the best option for this kind of terrain. Some of the advantages are that they do not need continuous terrain, they have less problems with sliding and they also have greater capacity to overcome obstacles as they produce Jess harm to the environment that the scientist wants to explore on the contrary when faced with mechanical design they present a design challenge, also in the static and dynamic analysis problem of a legged robot, there is a high complexity that has to be taken into account. This paper shows how to easily cope with the analysis of hexapod robot movement based on a design developed by the Center of Astrobiology INTA-CSIC for operation in RioTinto (Huelva - Spain)

Simulation of the GPTAD applied to the removal of blood clots that arise during Peripheral Vascular Disease

A number of thrombectomy devices using a variety of methods have now been developed to facilitate clot removal. We present research involving one such experimental device recently developed in the UK, called a 'GP' thrombus-aspiration-device (GPTAD). This device has the potential to bring about the extraction of a thrombus. Although the device is at a relatively early stage of development, the results look encouraging. We present an analysis of modelling this device using modelling techniques. Such modelling appears to be highly effective in simulating the device under a variety of conditions with a view to assisting in the optimisation of the GPTAD. The aim of this simulation model is to obtain the minimum pressure necessary to extract the clot and to verify that, both the pressure and the time required to complete the clot extraction are reasonable for use in clinical situations, and are consistent with any experimentally obtained data

Analysis and simulation of the adhesion forces between clot and the artery wall for a novel thrombectomy device applied to the Middle Cerebral Artery

A number of Thrombectomy devices using a variety of methods have now been developed to facilitate clot removal. We present research involving one such experimental device recently developed in the UK, called a 'GP' Thrombus Aspiration Device (TAD). This device has the potential to improve the process of extracting thrombosis clots in the cerebral arteries. The development of a simulation model for this device is shown using Bond-Graph formalism applied to modeling and simulating the adhesion forces between the clot and the artery wall. Bond-Graph technique is a visual methodology that adds more transparency to the processes and it has turned out to be remarkably useful as it is a simple, effective method that can be applied to any physical system where there is a power exchange. Such modelling appears to be able to simulate the device under a variety of conditions which may assist in the optimisation of the `GP' TAD device if the novel design features of the device can be effectively incorporated into the model

Modelling and simulation of a hydraulic power assisted steering system through Bond Graphs

The hydraulic power assisted steering (HPAS) system is one of the most sensitive vehicle interfaces to the driver perception. Comfort and performance parameters such as ride, handling, tactile transfer functions and overall noise levels are directly affected by its performance. The modeling of a HPAS system using the bond graph technique makes possible the combination of hydraulic and mechanical components. This allows physical and design variables such as fluid compressibility and hoses diameters to be evaluated simultaneously. HPAS should be used as a design and tuning tool to develop different system configurations before prototype test build, representing an improvement in terms of product development time and cost for both component and vehicle level

Analysis and 2D Simulation of a Hexapod Robot Leg for Remote Exploration

A walking machine is a wheeled rover alternative, well suited for work in an unstructured environment and specially in abrupt terrain. They have some drawback like speed and power consumption, but they can achieve complex movements and protrude very little the environment they are working on. The locomotion system is determined by the terrain conditions and, in our case, this legged design has been chosen based in a working area like Rio Tinto in the South of Spain, which is a river area with abrupt terrain. A walking robot with so many degrees of freedom can be a challenge when dealing with the analysis and simulations of the legs. This paper shows how to deal with the kinematical analysis of the equations of a hexapod robot based on a design developed by the Center of Astrobiology INTA-CSIC following the classical formulation of equation

Simulation of the `GP´ MTD Device intended for the extraction of blood clots by using the Bond Graph technique

This article covers the analysis and research into a device recently developed by the University of Wolverhampton (UK), called a 'GP' MTD Mechanical Thrombectomy Device, under the direction of Dr G. Pearce. This device will improve the process of extracting thrombosis clots in the cerebral arteries. On the one hand, the development of the simulation model of this device is shown by using Bond-Graph formalism and, on the other hand, the optimization of its performance in the very near future, from the interpretation of the results

Fast Correction of Tiled Display Systems on Planar Surfaces

A method for fast colour and geometric correction of a tiled display system is presented in this paper. Such kind of displays are a common choice for virtual reality applications and simulators, where a high resolution image is required. They are the cheapest and more flexible alternative for large image generation but they require a precise geometric and colour correction. The purpose of the proposed method is to correct the projection system as fast as possible so in case the system needs to be recalibrated it doesn’t interfere with the normal operation of the simulator or virtual reality application. This technique makes use of a single conventional webcam for both geometric and photometric correction. Some previous assumptions are made, like planar projection surface and negligibleintra-projector colour variation and black-offset levels. If these assumptions hold true, geometric and photometric seamlessness can be achievedfor this kind of display systems. The method described in this paper is scalable for an undefined number of projectors and completely automatic