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)

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

Sensitivity analysis to assess the influence of the inertial properties of railway vehicle bodies on the vehicle’s dynamic behaviour

A sensitivity analysis has been performed to assess the influence of the inertial properties of railway vehicles on their dynamic behaviour. To do this, 216 dynamic simulations were performed modifying, one at a time, the masses, moments of inertia and heights of the centre of gravity of the carbody, the bogie and the wheelset. Three values were assigned to each parameter, corresponding to the percentiles 10, 50 and 90 of a data set stored in a database of railway vehicles. After processing the results of these simulations, the analyzed parameters were sorted by increasing influence. It was also found which of these parameters could be estimated with a lesser degree of accuracy for future simulations without appreciably affecting the simulation results. In general terms, it was concluded that the most sensitive inertial properties are the mass and the vertical moment of inertia, and the least sensitive ones the longitudinal and lateral moments of inertia

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

Simulation of an Asynchronous Machine by using a Pseudo Bond Graph

For engineers, computer simulation is a basic tool since it enables them to understand how systems work without actually needing to see them. They can learn how they work in different circumstances and optimize their design with considerably less cost in terms of time and money than if they had to carry out tests on a physical system. However, if computer simulation is to be reliable it is essential for the simulation model to be validated. There is a wide range of commercial brands on the market offering products for electrical domain simulation (SPICE, Lab VIEW PSCAD, Dymola, Simulink,, Simplorer,...). These are powerful tools, but require the engineer to have a perfect knowledge of the electrical field. This paper shows an alternative methodology to can simulate an asynchronous machine using the multi domain Bond Graph technique and apply it in any program that permit the simulation of models based in this technique; no extraordinary knowledge of this technique and electric field are required to understand the process

Simulation Model of the Scanner Servocontrols for the Orientation of a Fighter Aircraft by Using the Bond Graph Technique

Nowadays the use of complex models has increased the requirements of the simulation tools and techniques for working and analyzing with different domains at the same time. This work focuses on the study of the Scanner servocontrols of a fighter aircraft. The model has the feature of integrating various physical domains into the same system (electrical, mechanical and system control environments) with different dimensions in each domain. The technique used is the Bond Graph (BG), which is typically used in fields where different physical domains coexist, just as in the case we are dealing with, where such domains are fundamental. At the beginning of the study, the different coordinate references are introduced and the physical subsystems are also described. After this the different subsystems are presented in the form of BG submodels one by one and the global Multibond Graph (MBG) model is displayed. Lastly, an example of simulation is shown and some important conclusions are reached

Modelling the Interoperability and the Use of Control Equipment in Electrical Substations

Simulators can be defined as information systems which reliably reproduce specific phenomena and they are mainly used in training, although their field of application has grown to include manufacturing and medicine among others. In electrical engineering, simulation is an indispensable tool when working with complex systems due to the fact that it enables engineers to understand how systems work without actually needing to see them. They can learn how they work in different circumstances and optimize their design with considerably less cost in terms of time and money than if they had to carry out tests on a physical system. By using computer simulation, not only can an electrical system be designed, but it can also be optimized and its behavior examined in-depth more quickly and cheaply than by using prototypes, tests or analytical studies. Therefore, by being able to see the responses produced as the different parameters are varied, a much deeper understanding of the system under study is reached. In order to properly simulate a virtual world, technologies such as realistic graphics and dynamic simulation with real-time calculations must be used. Peripherals must be used for the system to interact with the user and the immersion comes as a result of stimuli to sight, hearing and touch. A critical factor is the possibility to solve the equations in real-time; that is, there should be no delay compared to the normal environment’s response. There is an important amount of effort being directed towards these objectives. This paragraphs deals with the development of an operation simulator for training and the fundamental objective is to develop a simulator for electrical substations. It will present the methodology to model, simulate and optimize the interoperability and the use of control equipment in electrical an substation to train operators by means of a virtual reality environment

Caracterización de vehículos ferroviarios para analizar la sensibilidad de sus parámetros dinámicos

Este trabajo forma parte de un proyecto más amplio, cuya finalidad es realizar un estudio de sensibilidad que permita determinar qué grado de exactitud se requiere en la definición de los principales parámetros que influyen en la dinámica de los vehículos ferroviarios. Como paso previo a este análisis de sensibilidad, es preciso seleccionar un vehículo de referencia en el que basar dicho estudio. Dicho vehículo se empleará como punto de partida, para después variar el valor de los parámetros que lo caracterizan, a fin de determinar su influencia sobre la dinámica de marcha. Para alcanzar este objetivo se ha construido una base de datos de vehículos ferroviarios, que almacena las características de los parámetros que afectan al comportamiento dinámico de los vehículos. El valor de referencia correspondiente a cada parámetro puede asociarse al promedio de los valores almacenados en la base de datos, y sus rangos de variación pueden obtenerse a partir de las medidas de dispersión de estos datos. Se ha realizado un test de normalidad sobre los datos almacenados en la base de datos, encontrándose que la hipótesis de normalidad resulta, en general, inapropiada, lo que requiere el uso de estimadores más robustos de los habituales. Aunque el estudio de sensibilidad podría basarse en el vehículo ficticio definido por los valores promedio de cada parámetro, cabe la posibilidad de que este vehículo promedio presente un comportamiento dinámico distinto al que tendría un vehículo real. Para evitar este posible contratiempo, se han utilizado técnicas de escalado multidimensional para seleccionar los registros de la base de datos más próximos al vehículo promedio. Para determinar cuál de estos vehículos resulta más apropiado, se ha comparado su comportamiento dinámico empleando técnicas de simulación de sistemas multicuerpo. A partir de los resultados obtenidos en estas simulaciones, se ha valorado el comportamiento de cada modelo desde el punto de vista de la seguridad, de la agresión a la vía y del confort, siguiendo las indicaciones de la norma EN-14363. Finalmente, se ha seleccionado como vehículo de referencia aquél que, presentando un comportamiento adecuado, requiere el menor esfuerzo computacional para llevar a cabo las simulaciones

Managing Industrial Simulator Visual Databases Using Geographic Information Systems

Geographic Information Systems are developed to handle enormous volumes of data and are equipped with numerous functionalities intended to capture, store, edit, organise, process and analyse or represent the geographically referenced information. On the other hand, industrial simulators for driver training are real-time applications that require a virtual environment, either geospecific, geogeneric or a combination of the two, over which the simulation programs will be run. In the final instance, this environment constitutes a geographic location with its specific characteristics of geometry, appearance, functionality, topography, etc. The set of elements that enables the virtual simulation environment to be created and in which the simulator user can move, is usually called the Visual Database (VDB). The main idea behind the work being developed approaches a topic that is of major interest in the field of industrial training simulators, which is the problem of analysing, structuring and describing the virtual environments to be used in large driving simulators. This paper sets out a methodology that uses the capabilities and benefits of Geographic Information Systems for organising, optimising and managing the visual Database of the simulator and for generally enhancing the quality and performance of the simulator

Reduced simulation´s model of a wheel loader by using the Bond Graph technique to use in training simulators

This paper presents a model developed for simulating earth moving machines like wheel loaders. The developed model is used for real time simulation and is included in a full machinery simulator designated for the training. The model includes a mechanical model of the chassis, axles, suspension systems, hydraulic actuators and mechanical models of the arms. All the models have been simulated using Bond Graph elements (Karnopp et al. 1990). The complete model has been developed as a modular system, using sub-models of each of the above-mentioned components. This approach helps to minimize both the number and complexity of the system equations obtained from the overall model. Some simulation examples and results are also included