Modelling objects and simulating them do not always map to each other, and often requires defining additional information outside the scope of the original model to achieve an accurate simulation. For example: cables in \textit{AGX Dynamics} (a simulation library from Algoryx AB) are entirely defined by its physical parameters (e.g. Young's modulus, stiffness, etc.), radius, and the route through which the cables run. This thesis explores two approaches to closing the gap between the modelling of a cable and the creation of one in AGX Dynamics through evaluating current methods applied to generating a route and radius from a mesh. Two methods are identified as being useful in generating a route for a cable from a mesh: one which is a surface simplification algorithm, creating approximations of models using non-manifold meshes with radii defined at each vertex, and another method which creates a skeleton from a model using the surface's curvature to gradually shrink the model into a zero-volume shape. Both methods are evaluated using two different approaches to measuring the closeness to the original mesh from the results: using the metric introduced in the surface simplification method applied along the route, and measuring the mean distance from each point on the surface to the route. We show a clear advantage in the first method's inherent way of approximating the radius of the model but also its lack of detail. We also demonstrate that the second method produces more detailed skeletons, but in turn has issues with skewed routes which do not follow the original mesh. Both methods have their own advantages and disadvantages and with improvements to both radius calculations or adaptions to the fundamental algorithms, they could provide a great way of creating AGX cables from mesh models.

The purpose of this project is to implement obstacle avoidance algorithms to drive the articulated vehicle autonomously in an unknown environment, which is simulated by AgX Dynamics™ simulation software and controlled by Matlab® programming software. Three driving modes are developed for driving the vehicle (Manual, Semi-autonomous and Autonomous) in this project. Path tracking algorithms and obstacle avoidance algorithms are implemented to navigate the vehicle. A GUI was built and used for the manual driving mode in this project. The semi-autonomous mode checked different cases: change lanes, U-turn, following a line, following a path and figure 8 course. The autonomous mode is implemented to drive the articulated vehicle in an unknown environment with moving to a pose path tracking algorithm and VFH+ obstacle avoidance algorithm. Thus, the simulation model and VFH+ obstacle avoidance algorithm seems to be working fine and still can be improved for the autonomous vehicle. The result of this project showed a good performance of the simulation model. Moreover, this simulation software helps to minimize the cost of the articulated vehicle since all tests are in the simulation rather than in the reality.

This thesis treats how to generate collision information for multibody simulations in AgX Dynamicswhere the geometries are described with the data structure boundary representation, BREP. BREP is adata structure that contains the exact mathematical description of each individual surface. To describecomplex surfaces exact and efficient non uniform rational basis spline, NURBS, is used and for trivialsurfaces like planes or spheres simpler equations is used. Since all surfaces in a BREP is described veryaccurate, the accuracy for the collision information can be set high without affecting the amount of dataneeded to describe the geometries.To make AgX Dynamics able to calculate forces in a multibody simulation, collision informationabout were and how much two geometries are intersecting is required. The collision information containswere the overlap between two geometries is, how much the objects have penetrated each other and thedirection for which the objects have to separate. To find the penetration depth and the overlap theNewton Raphson method were used. The experiments conducted, showed that it is possible to useBREPs as a description of geometries to produce the collision information needed for the physics engineused by AgX Dynamics to handle collisions. A comparison between trimesh and BREP for producingthe collision information, shows that data usage is much lower for the representation of geometries withBREPs than trimesh. The results also shows that the accuracy can be significantly higher than fortrimesh as the data usage for trimesh becomes non practical to handle when the required accuracy ishigh. With the high accuracy and with the smooth surfaces used with the BREP the artificial friction isalmost negligible except for cases were intersection points could not be found all around the intersectioncurves due to limitations in the algorithm. / Detta examensarbete behandlar hur man skapar kollisionsinformation för flerkropps simuleringar i AgXDynamics där geometrier beskrivs med datastrukturen boundary representation, BREP. BREP är endatastruktur som innehåller den exakta matematiska beskrivningen för varje enskild yta. Att beskrivakomplexa ytor exakta och effektivt med non uniform rationell basis spline, NURBS, används och förtriviala ytor som plan eller sfärer kan enklare ekvationer används. Eftersom alla ytor i en BREP beskrivsexakt, kan noggrannheten för kollisions informationen sättas högt utan att påverka den mängd data sombehövs för att beskriva geometrier.För att göra AgX Dynamics kunna beräkna krafter i en flerkroppssimulering, krävs kollisions informationom var och hur mycket två geometrier kolliderar. Kollisions informationen innehåller varöverlappningen mellan två geometrier är, hur mycket objekten har penetrerat varandra och den riktningsom föremålen ska separeras. För att hitta penetrationsdjup och överlapp användes Newton Raphsonsmetod. De experiment som utförts, visade att det är möjligt att använda BREPs som en beskrivning avgeometrier för att producera kollisions information som behövs för att den fysikmotor som används avAGX Dynamics ska kunna hantera kollisioner. En jämförelse mellan trimesh och BREP för att producerakollisionen informationen, visar att dataanvändning är mycket lägre när geometrier representeras medBREPs än trimesh. Resultaten visar också att noggrannheten kan vara väsentligt högre för BREP änför trimesh eftersom dataanvändning för trimesh blir opraktiskt att hantera när noggrannheten är hög.Med hög noggrannhet och med de släta ytor som används med BREP blev den artificiella friction nästanförsumbar, utom i fallen där skärningspunkter inte kunde hittas runt hela skärningskurvor på grund avbegränsningar i algoritmen.

Training simulators are valuable tools in education of forest machine operators. One important part of the education is to learn about damages occurring due to the forest machines and how they can be avoided. Two types of damages are especially severe, soil compaction and formation of wheel ruts. Compaction reduces the amount of water and nutrients in the soil, and impedes root growth. Furthermore, water is gathered in wheel ruts, leading to transport of organic materia and heavy metals into water courses. These damages can be avoided through planning of the harvesting activities with respect to season, weather, and the conditions on the site. The main focus point is to avoid driving on wet soil, since wetness makes it more susceptible to damage.  The aim of this thesis is to investigate how this should be incorporated in a simulator. Implementations are made in Unreal Engine with AGX Dynamics for Unreal, which already has a deformable terrain called AGX Terrain. This terrain was investigated by creating two terrain materials, representing dry and wet Swedish forest soil, and driving a forwarder on them.  AGX Terrain was found to be simple to use and gave fair results, the rut depths were comparable in size with empirical results. However, it was limited in the sense that shearing was not taken into account and there was no possibility of having different material properties across the terrain. A potential solution to these problems is suggested, in which a more extensive way of computing stress propagation and the resulting damages is used. Further investigations has to be made in order to find out if this approach is of good use.