Marta Pla-Castells

Interactive terrain simulation and force distribution models in sand piles

This paper presents an application of Cellular Automata in the field of dry Granular Systems modelling While the study of granular systems is not a recent field, no efficient models exist, from a computational point of view, in classical methodologies Some previous works showed that the use of Cellular Automata is suitable for the development of models that can be used in real time applications This paper extends the existing Cellular Automata models in order to make them interactive A model for the reaction to external forces and a pressure distribution model are presented and analyzed, with numerical examples and simulations.

Physically-Based Interactive Sand Simulation

The interactive simulation of 3D terrains has been approached from sever al perspectives. Due to the complexity of the system involved, most of the models proposed focus on a visually realis tic animation of the scene, rather than on a physically-based accurate simulation of a granular system. Those m lack generality when interacting with the environment; in most cases, no reaction forces are computed, co nsidering only soil deformation. This limitation reduces their usability in applications such as driving simulators. We pr opose the use of a theoretical discrete model that considers normal forces for 3D real-time simulation of granular systems. We also extend this model to consider horizontal forces, allowing a wider range of interaction s. Several numerical tests have been implemented and detailed results have been analyzed which show a good mo del performance.

Elevation cable modeling for interactive simulation of cranes

In this paper, the way to simulate hoisting cables in real time is addressed. We overcome instability in such simulation by considering a two-layered model: a model for the dynamics of a cable passing through a set of pulleys and an oscillation model based on the classical one-dimensional wave equation. The first layer considers the interaction between the cable and pulleys with the elevation equipment, while the second layer simulates cable oscillation. Numerical instability is avoided by suspending the oscillation layer when required. Due to the system properties, this can be carried out in such a way that does not cause significant loss in the system quality. It considers the oscillation of the cable between every pair of pulleys, collision detection and the variation of the cable length very efficiently. Rendering issues are discussed, with remarks on how to prevent aliasing artifacts in the cable. Efficiency is analyzed, including performance tests which show that the model can be run very efficiently. The paper also covers how to integrate the model in a complex multibody simulation with a high degree of interactivity.

Crane collision modelling using a neural network approach

Abstract The objective of the present work is to find a Collision Detection algorithm to be used in the Virtual Reality crane simulator (UVSim®), developed by the Robotics Institute of the University of Valencia for the Port of Valencia. The method is applicable to box-shaped objects and is based on the relationship between the colliding object positions and their impact points. The tool chosen to solve the problem is a neural network, the multilayer perceptron, which adapts to the characteristics of the problem, namely, non-linearity, a large amount of data, and no a priori knowledge. The results achieved by the neural network are very satisfactory for the case of box-shaped objects. Furthermore, the computational burden is independent from the object positions and how the surfaces are modelled; hence, it is suitable for the real-time requirements of the application and outperforms the computational burden of other classical methods. The model proposed is currently being used and validated in the UVSim Gantry Crane simulator.

Approximation of Continuous Media Models for Granular Systems Using Cellular Automata

In this paper a new cellular automata model suitable for granular systems simulation is presented. The proposed model is shown to be equivalent to a particularization of the well known BCRE model of granular systems and a correspondence between the parameters of the presented model and the BCRE model is also set, allowing to fit these parameters for a given system. The model has the advantage over other cellular automata models of being more realistic in the behavior of the surface of heaps and slopes. The dynamics of the CA is analyzed in order to confirm that it also has one of the most important features of these systems, 1/f noise.

Forecasting Adverse Weather Situations in the Road Network

Weather is an important factor that affects traffic flow and road safety. Adverse weather situations affect the driving conditions directly; hence, drivers must be informed about the weather conditions downstream to adapt their driving. In the framework of intelligent transport systems, several systems have been developed to know the weather situations and inform drivers. However, these systems do not forecast weather in advance, and they need the support of road operators to inform drivers. This paper presents a new autonomous system to forecast weather conditions in a short time and to give users the information obtained. The system uses a set of algorithms and rules to determine the weather and to forecast dangerous situations on the road network. It has been implemented using a multiagent approach and tested with real data. Results are very promising. The system is able to forecast adverse situations with a high degree of quality. This quality makes it possible to trust in the system and to avoid the supervision of operators.

Deploying harmonized ITS services in the framework of EasyWay project: traffic management plan for corridors and networks

In the last decade, the use of new technologies in the transportation domain has made possible the development of the Intelligent Transport System (ITS). However, the ITS services were deployed isolated. The purpose of the EasyWay Project is to involve all the European countries to deploy harmonized ITS services taking into account the European citizen as final In this paper, an introduction of EasyWay project is done, including the ITS concept services and the Deployment Guidelines. A deployment guideline for traffic management and corridors is presented. Using this guideline, a real Spanish Traffic management Plan is analyzed.

A Mixed Model for Real‐Time, Interactive Simulation of a Cable Passing Through Several Pulleys

A model of a cable and pulleys is presented that can be used in Real Time Computer Graphics applications. The model is formulated by the coupling of a damped spring and a variable coefficient wave equation, and can be integrated in more complex mechanical models of lift systems, such as cranes, elevators, etc. with a high degree of interactivity.

Texture advection on discontinuous flows

Texture advection techniques, which transport textures using a velocity field, are used to visualize the dynamics of a flow on a triangle mesh. Some flow phenomena lead to velocity fields with discontinuities that cause the deformation of the texture which is not properly controlled by these techniques. We propose a method to detect and visualize discontinuities on a flow, keeping consistent texture advection at both sides of the discontinuity. The method handles the possibility that the discontinuity travels across the domain of the flow with arbitrary velocity, estimating its speed with least-squares approximation. The technique is tested with different sample scenarios and with two avalanche scenes, showing that it can run at interactive rates.

Simulador de realidad virtual para la formación de operadores de grúa Torre

La utilizacion de simuladores basados en realidad virtual proporciona una solucion a los diferentes inconvenientes del entrenamiento de operadores de maquinaria pesada. Entre las ventajas aportadas al ambito de formacion, se encuentran la reduccion de riesgos laborales y costes economicos, el incremento en la productividad, y la utilizacion como herramienta objetiva de evaluacion. Este articulo presenta un sistema instruccional basado en simulacion para el entrenamiento de operadores de grua Torre. Este simulador destaca por su enfoque formativo mediante la inclusion de material docente interactivo, el aprendizaje en la maniobrabilidad de una grua Torre a traves de un conjunto de ejercicios y circuitos de entrenamiento, y la utilizacion de tecnicas de realidad virtual del estado del arte (como shaders de iluminacion, tecnicas de sombreado y avatares cooperativos) que incrementan la experiencia de realismo obtenida. Se describe la arquitectura que compone el simulador, el diseno del entorno virtual basado en OpenSceneGraph, el sistema de autoevaluacion, y las caracteristicas de realismo del modelo dinamico de la grua, como son la influencia del viento y las colisiones de los cables con otros objetos del entorno virtual. El sistema se complementa con un puesto de instructor que facilita el control, la evaluacion, y la monitorizacion de los puestos de entrenamiento de un aula multipuesto.