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Abstract For a significant length of time, computer simulation programs have been the preferred tools of sociologists to analyse " thus confirm or refute " sociological theories, scenarios, presumptions and assumptions. Many different simulation platforms for various domains exist. The EmIL project aims to create a new simulation platform specifically to analyse norm emergence. This platform is divided into sections, thereby allowing the analysis of individual norm emergence: this is not currently possible, thus EmIL-S may represent a significant improvement over current simulation platforms. This diploma thesis describes the concepts behind the project and provides a prototype for the simulation program EmIL-S. The creation of the prototype and the underlying development process are described in detail. The experience gained during this process is analysed and described. In the course of this analysis, the malfunctions and errors within EmIL-S are explained; the solutions to these malfunctions and errors are noted, along with other proposed improvements. This diploma thesis can also be used as a helpful manual to build simulations within the simulation platform.
Entwicklung eines Regelungsverfahrens zur Pfadverfolgung für ein Modellfahrzeug mit Sattelanhänger
(2009)
Besides the progressive automation of internal goods traffic, there is an important area that should also be considered. This area is the carriage of goods in selected external areas. The use of driverless trucks in logistic centers can report economic efficiency. In particular, these precise control procedures require that trucks drive on predetermined paths. The general aim of this work is the adaption and evaluation of a path following control method for articulated vehicles. The differences in the kinematic behavior between trucks with one-axle trailer and semi-trailer vehicles will be emphasized. Additionally, the characteristic kinematic properties of semi-trailers for the adaptation of a control procedure will be considered. This control procedure was initially designed for trucks with one-axle trailer. It must work in forwards and backwards movements. This control process will be integrated as a closed component on the control software of the model vehicle. Thus, the geometry of the model vehicle will be specified, and the possible special cases of the control process will be discovered. The work also documents the most relevant software components of the implemented control process.
In this work has been examined, how the existing model of the simulation of cables and hoses can be advanced. Therefore an investigation has been made on the main influences to the shape simulation and the factors of constraints and side conditions were analyzed. For the validation of the accuracy, the simulation has to be compared to real specimen behavior. To obtain a very precise digitalization of the shape, the choice was made to use a laser scanner that converts the pointcloud into a .vrml file which can be imported into the simulation environment. The assumption was that the simulation method itself has the highest impact to the simulated shape. This is why the capabilities of the most sophisticated methods have been analyzed. The main criterion for the success of a simulation approach proved not to be accuracy, as expected. Process integration and usability showed to be of higher interest for the efficient exertion. Other factors like the pricing, the functionality and the real-time capability were assayed as well. The analyzed methods are based on the solution of the equations of elasticity with different ways of discetization, finite-elements and a spring-impulse-system. Since the finite-element-system takes several minutes for the computation of the shape and the spring-impulse-system reacts retarded on user manipulation, the competitiveness of these approaches is low. The other methods distinguish more in real-time performance, data interfaces and functionality than in accuracy. For the accuracy of a system, the consideration of other factors proved to be very important. As one of these main factors, the accurate assignment of the material properties was indicated. Until the start of this work, only the finite-element-approach dealt with this factor, but no documentation or validation is provided. In the publications of the other methods, the material properties are estimated to obtain a plausible simulation shape. Therefore the specific material values of real specimen have been measured and assigned to the simulation. With the comparison to the real shape it has been proven that the accuracy is very high with the measured properties. Since these measurements are very costly and time consuming, an investigation on a faster and cheaper way to obtain these values has been made. It has been assumed that with the knowledge of the cross-section it should be possible to compute the specimen behavior. Since the braid distribution changes individually from specimen to specimen, a more general way to obtain the values needed to be found. The program composer has been developed, where only the number of the different braids and the taping is entered. It computes with very high precision the stiffness, the density and the final diameter of the bundle. With the measured values and the fitting to the real shape it has been proven that the simulation approach reflects the precise behavior of cables and hoses. Since the stiffness of the single braids is wasteful to measure, a measurement setup was created where the stiffness has a large impact to the shape. With known density, the stiffness of the specimen can be reconstructed precisely. Thus a fast and beneficial way of obtaining the stiffness of a cable has been invented. The poissons ratio of cables and bundles cannot be measured with a tensile test, since the inner structure is very complex. For hoses, the variation of the inner diameter has been measured during the tensile test as well. The resulting values were reasonable, but their accuracy could not be proven. For cables and hoses, it has been tried to obtain the poissons ratio via the computation of the cross section, but the influence of individual changes and the crosstalk of the braids is very high. Therefore a setup was constructed where the torsion stiffness can be measured. For cables and hoses, the individual cross-sections and taping lead to varying results. For hoses, expected and repeatable good values for the poissons ratio were obtained. The low influence of the poisons ratio in the range between 0 and 0.5 has been proven. Therefore we decided to follow the advice of [Old06] and our own experiences to set the poisons ratio for cables and bundles to 0.25. With the knowledge of the measurability and the capabilities of the developed program composer, a procedure to obtain material properties for bundles has been designed. 1. Measurement of the braid density with via pyknometer or mass, length and diameter. 2. Empirical reconstruction of the stiffness with the designed setup. 3. Composing the bundle with the program composer. 4. Adding a factor for the taping and transfer the values to the simulation. The model of the cable simulation has been improved as follows: The main influences in the simulation of cables and hoses are the simulation method, the material properties and the geometric constraints. To obtain higher accuracy, an investigation on the correct material properties is indispensable. The scientific determination of material properties for the simulation of cables, bundles and hoses has been performed for the first time. The influence of geometrical constraints has been analyzed and documented. The next steps are the analysis of pre-deformation and further investigations to the determination of the poisons ratio with a more precise torsion test. All analysis were made with the simulation approach fleXengine. A comparison to other simulation methods would be of high interest.