Since the advent of machine learning and machine vision methods, progress has been made in tackling the long-standing research question of autonomous grasping of arbitrary objects using robotic end-effectors. Building on these efforts, we focus on a subset of the general grasping problem concerning the automation of a forwarder. This forestry vehicle collects and transports felled and cut tree logs in a forest environment to a nearby roadside landing. The forwarder must safely and energy-efficiently grip logs to minimize fuel consumption and reduce loading times. In this thesis project, we develop a data-driven model for predicting the expected outcome of grasping attempts made by the forwarder's crane. For a given pile of logs, such a model can estimate the optimal horizontal location and angle for applying the claw grapple, enabling effective grasp planning. We utilize physics-based simulations to create a ground truth dataset of 12 500 000 simulated grasps distributed across 5000 randomly generated log piles. Our semi-generative, supervised model is a fully convolutional network that inputs the orthographic depth image of a pile and returns images predicting the corresponding grasps' initial grapple angle and outcome metrics as a function of position. Over five folds of cross-validation, our model predicted the number of grasped logs and the initial grapple angle with a normalized root mean squared error of 15.77(2)% and 2.64(4)%, respectively. The grasps' energy efficiency and energy waste were similarly predicted with a relative error of 14.43(2)% and 21.06(3)%. / Sedan tillkomsten av maskininlärnings- och maskinseendebaserade metoder har betydande framsteg gjorts inom forskningsområdet för autonom greppning av godtyckliga objekt med en robotisk sluteffektor. Vi bygger vidare på dessa resultat och fokuserar på en del av det generella greppningsproblemet gällande automatisering av en skotare. Denna skogsmaskin samlar in och transporterar fällda och kapade trädstammar från avverkningsplats till upplag intill närliggande skogsbilväg. Skotaren måste greppa och lyfta stockarna på ett säkert och energieffektivt sätt för att minimera bränsleförbrukningen samt minska lastningstiderna. I detta examensarbete utvecklar vi en datadriven modell för att förutsäga det förväntade resultatet av gripförsök utförda av skotarens kran. För en given timmerstockshög kan en sådan modell uppskatta den optimala positionen och vinkeln för att applicera skotarens gripklo, vilket möjliggör effektiv planering av lastningen. Vi använder fysikbaserade simuleringar för att skapa ett dataset med 12 500 000 simulerade gripförsök fördelade över 5000 slumpmässigt genererade timmerhögar. Vår semi-generativa, övervakade modell är ett djupt faltningsnätverk utan helt sammankopplade neuronlager som tar in en ortografisk djupbild av en timmerhög och returnerar bilder som predikterar de motsvarande gripförsökens initiala gripvinkel och resultatmått som en funktion av position. Vid en femfaldig korsvalidering förutsåg vår modell antalet greppade stockar och den initiala gripvinkeln med ett normaliserat rotmedelkvadratfel på 15.77(2)% respektive 2.64(4)%. Gripförsökens energieffektivitet och energiförlust predikterades på liknande sätt med ett relativt fel på 14.43(2)% och 21.06(3)%.

Mit Hilfe der Matlab/ADAMS-Co-Simulation wird ein ebenes Koppelgetriebe (5- Gelenk) untersucht und anschließend die Wirkpaarung mit einem Stückgut betrachtet. Dabei werden verschiedene Modellierungsstufen angewendet und die Simulationsergebnisse Messergebnissen vom Versuchsstand gegenübergestellt. Daneben wird die grundlegende Herangehensweise beim Einsatz dieser Simulationswerkzeuge erläutert.

Nowadays, increasing pressure from legislation and customer demands in the automotive industry are forcing manufacturers to produce greener vehicles with lower emissions and fuel consumption.As a result, electrified and hybrid vehicles are a growing popular alternative to traditional internal combustion engines (ICE). The noise from an electric vehicle comes mainly from contact between tyres and road, wind resistance and driveline. The noise emitted from the driveline is for the mostpart related to the gearbox. When developing a driveline, it is a factor of importance to estimate the noise radiating from the gearbox to achieve an acceptable design.Gears are used extensively in the driveline of electric vehicles. As the gears are in mesh, a main intrusive concern is known as gear whine noise. Gear whine noise is an undesired vibroacoustic phenomenon and is likely to originate through the gear contacts and be transferred through themechanical components to the housing where the vibrations are converted into airborne and structure-borne noise. The gear whine noise originates primarily from the excitation coming from transmission error (TE). Transmission error is defined as the difference between the ideal smoothtransfer of motion of a gear and what is in practice due to lack of smoothness.The main objective of this study is to simulate the vibrations generated by the gear whine noise in an electric powertrain line developed by AVL Vicura. The electric transmission used in this study provides only a fixed overall gear ratio, i.e. 9.59, under all operation conditions. It is assumed thatthe system is excited only by the transmission error and the mesh stiffness of the gear contacts. In order to perform NVH analysis under different operating conditions, a multibody dynamics model according to the AVL Excite program has been developed. The dynamic simulations are thencompared with previous experimental measurements provided by AVL Vicura.Two validation criteria have been used to analyse the dynamic behaviour of the AVL Excite model: signal processing using the FFT method and comparison with the experimental measurements.The results from the AVL Excite model show that the FFT criterion is quite successful and all excitation frequencies are properly observed in FFT plots. Nevertheless, when it comes to the second criterion, as long as not all dynamic parameters of the system such as damping or stiffnesscoefficients are provided with certainty in the model, it is too difficult to investigate the accuracy of the AVL Excite model. Another investigation is a numerical design study to analyses how the damping coefficients influence the response. After reducing the damping parameters, the results show that the housing and bearings have the highest influence on the response. If more acceptable results are desired,future studies must be concentrated on these to obtain more acceptable damping values. / För närvarande tvingar ökat tryck från lagstiftning och kundkrav inom bilindustrin tillverkarna attproducera grönare fordon med lägre utsläpp och bränsleförbrukning. Som ett resultat ärelektrifierade och hybridfordon ett växande populärt alternativ till traditionellaförbränningsmotorer (ICE). Bullret från ett elfordon kommer främst från kontakten mellan däckoch väg, vindmotstånd och drivlinan. Bullret från drivlinan är i huvudsak relaterat till växellådan.Vid utveckling av en drivlina är det av betydelse att uppskatta bullret från växellådan för att uppnåen acceptabel design.Utväxlingar används i stor utsträckning i elfordons drivlina. Eftersom kugghjulen är i kontaktuppstår ett huvudproblem som är känt som ett vinande ljud från kugghjulskontakten.Kugghjulsljud är ett oönskat vibro-akustiskt fenomen och uppstår sannolikt på grund avkugghjulkontakterna och överförs via de mekaniska komponenterna till växellådshuset därvibrationerna omvandlas till luftburet och strukturburet ljud. Kugghjulsljudet härstammarhuvudsakligen från exciteringen som kommer från transmissionsfel (TE) i kugghjulskontakten.Överföringsfelet definieras som skillnaden mellan den ideala smidiga rörelseöverföringen hoskugghjulen och rörelsen som sker i verkligheten på grund av ojämnheter.Huvudsyftet med denna studie är att simulera vibrationerna som genereras avkugghjulskontakterna i en elektrisk drivlina utvecklad av AVL Vicura. Den elektriska drivlinan somanvänds i denna studie har endast ett fast utväxlingsförhållande, dvs 9,59, för alladriftsförhållanden. Det antas att systemet är exciterat endast av överföringsfelet och kugghjulensstyvhet i kuggkontakterna. För att kunna utföra NVH-analys under olika driftsförhållanden har enstelkroppsdynamikmodell utvecklats med hjälp av programmet AVL Excite. De dynamiskasimuleringarna jämförs sedan med tidigare experimentella mätningar som tillhandahålls av AVLVicura.Två valideringskriterier har använts för att analysera det dynamiska beteendet hos AVL Excitemodellen:signalbehandling med FFT-metoden och jämförelse med experimentella mätningar.Resultaten från AVL Excite-modellen visar att FFT-kriteriet är ganska framgångsrikt och allaexcitationsfrekvenser observeras korrekt i FFT-diagrammen. Men när det gäller det andra kriteriet,så länge som inte alla dynamiska parametrar i systemet, såsom dämpnings- ellerstyvhetskoefficienter, är tillförlitliga i modellen, är det för svårt att undersöka exaktheten hos AVLExcite-modellen.En annan undersökning som utförts är en numerisk designstudie för att analysera hurdämpningskoefficienterna påverkar responsen. Efter minskning av dämpningsparametrarna visarresultaten att växellådshus och lager har störst inflytande på resultatet. Om mer acceptabla resultatär önskvärda måste framtida studier koncentreras på dessa parametrar för att uppnå mer acceptabladämpningsvärden.

Simulation of maneuvers with multibody models of rotorcraft vehicles is an important research area due to its complexity. During the maneuvering flight, some important design limitations are encountered such as maximum loads and maximum turning rates near the proximity of the flight envelope. This increases the demand on high fidelity models in order to define appropriate controls to steer the model close to the desired trajectory while staying inside the boundaries. A framework based on the hierarchical decomposition of the problem is used for this study. The system should be capable of generating the track by itself based on the given criteria and also capable of piloting the model of the vehicle along this track. The generated track must be compatible with the dynamic characteristics of the vehicle. Defining the constraints for the maneuver is of crucial importance when the vehicle is operating close to its performance boundaries. In order to make the problem computationally feasible, two models of the same vehicle are used where the reduced model captures the coarse level flight dynamics, while the fine scale comprehensive model represents the plant. The problem is defined by introducing planning layer and control layer strategies. The planning layer stands for solving the optimal control problem for a specific maneuver of a reduced vehicle model. The control layer takes the resulting optimal trajectory as an optimal reference path, then tracks it by using a non-linear model predictive formulation and accordingly steers the multibody model. Reduced models for the planning and tracking layers are adapted by using neural network approach online to optimize the predictive capabilities of planner and tracker. Optimal neural network architecture is obtained to augment the reduced model in the best way. The methodology of adaptive learning rate is experimented with different strategies. Some useful training modes and algorithms are proposed for these type of applications. It is observed that the neural network increased the predictive capabilities of the reduced model in a robust way. The proposed framework is demonstrated on a maneuvering problem by studying an obstacle avoidance example with violent pull-up and pull-down.

The focus of interest in this study is the RHex robot, which is a hexapod robot that is capable of locomotion over rugged, fractured terrain through statically and dynamically stable gaits while stability of locomotion is preserved. RHex is primarily a research platform that is based on over five years of previous research. The purpose of the study is to build a virtual prototype of RHex robot in order to simulate different behavior without manufacturing expensive prototypes. The virtual prototype is modeled in MSC ADAMS software which is a very useful program to simulate flexible multibody dynamical systems. The flexible half circular legs are modeled in a finite element program (MSC NASTRAN) and are embedded in the main model. Finally a closed loop control mechanism is built in MATLAB to be able to simulate real autonomous RHex robot. The interaction of MATLAB and MSC ADAMS softwares is studied.

Modeling and simulation of granular matter has important applications in both natural science and industry. One widely used method is the discrete element method (DEM). It can be used for simulating granular matter in the gaseous, liquid as well as solid regime whereas alternative methods are in general applicable to only one. Discrete element analysis of large systems is, however, limited by long computational time. A number of solutions to radically improve the computational efficiency of DEM simulations are developed and analysed. These include treating the material as a nonsmooth dynamical system and methods for reducing the computational effort for solving the complementarity problem that arise from implicit treatment of the contact laws. This allow for large time-step integration and ultimately more and faster simulation studies or analysis of more complex systems. Acceleration methods that can reduce the computational complexity and degrees of freedom have been invented. These solutions are investigated in numerical experiments, validated using experimental data and applied for design exploration of iron ore pelletising systems. / <p>This work has been generously supported by Algoryx Simulation, LKAB (dnr 223-</p><p>2442-09), Umeå University and VINNOVA (2014-01901).</p>

Mit Hilfe der Matlab/ADAMS-Co-Simulation wird ein ebenes Koppelgetriebe (5- Gelenk) untersucht und anschließend die Wirkpaarung mit einem Stückgut betrachtet. Dabei werden verschiedene Modellierungsstufen angewendet und die Simulationsergebnisse Messergebnissen vom Versuchsstand gegenübergestellt. Daneben wird die grundlegende Herangehensweise beim Einsatz dieser Simulationswerkzeuge erläutert.

L’éolien offshore est l’énergie marine la plus avancée et utilisée dans le monde. Afin d’accroître l’énergie extraite du vent, les dimensions des éoliennes deviennent plus importantes et les parcs éoliens sont installées de plus en plus loin des côtes, où les mers sont plus agitées et les vents plus forts. De fait, les opérations marines sont plus complexes et plus chères et les fenêtres météo sont écourtées et se raréfient. Dans le cadre de cette thèse, un logiciel de simulation numérique des opérations marines est développé, en particulier pour des applications de descentes et de remontées de colis lourds. L’Algorithme aux Corps Rigides Composites, implémenté dans le logiciel InWave, est utilisé pour modéliser le système multicorps. Un modèle de câble et de treuil est développé, suivant la théorie multicorps utilisée, et comparé à la théorie câble classique dite « lumped mass ». Les efforts hydrodynamiques ainsi que les interactions hydrodynamiques sont modélisés par une théorie potentiel instationnaire satisfaisant l’hypothèse de faible perturbation, dite « weak-scatterer ». L’approche « weak-scatterer » du logiciel WS_CN est étendue aux simulations multi-flotteurs et validée par comparaison avec des données expérimentales. InWave et WS_CN sont couplés afin de résoudre l’interaction houle-structure pour des systèmes multicorps articulés en mer. Un couplage fort est adopté pour sa robustesse. L’équation de couplage est établie et validée via des comparaisons avec WS_CN. Le logiciel ainsi crée se nomme InWaveS_CN et utilise un code d’intégration en Python. Une nouvelle stratégie de maillage, basée sur un algorithme de découpe de maillages et une méthode par avance de front, est développée dans WS_CN. Enfin, des essais en bassin d’une opération de redressement ont été menés à l’ECN. La comparaison entre les simulations numériques et les données expérimentales offre une première et prometteuse validation d’InWaveS_CN. / Offshore wind represents the most advanced and used marine energy in the world. To increase the wind power extraction, turbines grow in size and wind farms are installed further offshore in presence of rough seas and strong winds. Marine operations become more challenging and expensive, weather windows are shorter and less frequent. This PhD work focuses on the development of a numerical tool to simulate marine operations with consistency, in particular lowering and lifting operations. The Composite-Rigid-Body Algorithm, implemented in the numerical tool InWave, is used to model multibody systems. A cable model and a winch model are developed following this multibody approach and compared to the classical low-order lumped mass theory. Hydrodynamic loads and hydrodynamic interactions are simulated using an unsteady potential flow theory based on the weakscatterer hypothesis, implemented in the numerical tool WS_CN. This approach is extended to multibody simulations and validated with comparisons to experimental data. InWave and WS_CN are coupled to solve wavestructure interaction for articulated multibody systems with large relative motions in waves. A tight coupling is selected for its robustness. The coupling equation is derived and validated from comparisons with WS_CN. This leads to the creation of a new numerical tool, InWaveS_CN, using Python as glue code language. A new mesh strategy, based on the coupling between a panel cutting method and an advance front method, is developed in WS_CN. Experiments of an upending operation were conducted at Ecole Centrale de Nantes. The comparison between the numerical simulations and the experimental data leads to a first and promising validation of InWaveS_CN.

Indiana University-Purdue University Indianapolis (IUPUI) / This thesis presents a comprehensive study of the effects of material, geometric and operational parameters on flat belt-drives steady-state belt stresses, belt slip, and belt-drive efficiency. The belt stresses include: belt rubber shear, normal, axial and lateral stresses; reinforcements tension force; and tangential and normal belt-pulley contact stresses. Belt slip is measured using the driven over driver pulleys’ angular velocity ratio. Each parameter was varied over a range to understand its impact on the steady-state belt-drive response. The material parameters studied are belt axial stiffness and damping, belt bending stiffness and damping, and belt-pulley friction coefficient. The geometric parameters studied are pulley center distance, pulleys diameter ratio, and belt thickness. The operational parameters studied are the driver pulley angular velocity and the driven pulley opposing torque (load). A high-fidelity flexible multibody dynamics parametric model of a two-pulley belt-drive system was created using a commercial multibody dynamics code. In the model the belt’s rubber matrix is represented using three-dimensional brick elements and the belt’s reinforcements are represented using one dimensional beam elements at the top surface of the belt. An asperity-based Coulomb friction model is used for the friction forces between the pulley and belt. The pulleys are modeled as rigid bodies with a cylindrical contact surface. The equations of motion are integrated using an explicit solution procedure. Unlike prior models which use one-dimensional truss or beam elements for the belt, the present model uses a three-dimensional belt model which introduces the effect of the thickness of the belt rubber matrix (modeled using brick elements). This enables a more accurate prediction of the belt stresses and slip than prior models. This thesis resolves in more details the complex stick-slip friction behavior of an axially flexible belt coupled with the shear effects of a flexible rubber cushion and at the same time shows the effect of the main system parameters on this stick-slip behavior. Some of the important conclusions of the thesis include: (1) the driver pulley has two distinct contact zones - a negative traction zone and a positive traction zone - while only one traction zone is present over the driven pulley; (2) the width of the negative traction zone on the driver pulley increases with the belt-pulley coefficient of friction and decreases with the belt axial stiffness; (3) the maximum belt tension and normal contact stress occur on the driver pulley and increase with the belt thickness, belt axial stiffness, and coefficient of friction; (4) belt-drive energy efficiency increases with the belt axial stiffness, and decreases with belt thickness, belt bending damping, belt operating speed, and operating torque load. The belt-drive modeling methodology presented in this thesis which enables accurate prediction of the belt stresses and slip can in turn be used to more accurately predict the fatigue life, wear life, and energy efficiency of belt-drives.

The goal of this project is to develop virtual surgical simulation software in order to simulate the suturing and knot tying processes associated with surgical thread. State equations are formulated using Lagrangian mechanics, which is useful for the conservation of energy. Solver methods are developed with theory based in Differential Algebraic Equations (DAEs) which concern governing Ordinary Differential Equations (ODEs) that are constraint with Algebraic Equations (AE). An implicit integration scheme and Newton's method is used to solve the system in each step. Furthermore, a collision response process based on the Linear Complementarity Problem (LCP) is implemented to handle collisions and measure their forces. Models have been developed to represent the different types of objects. A spline model is used to represent the suture and mass-spring model for the tissue. They were both selected for their efficiency and base on real physical properties. The spline model was also chosen as it is continuous and can be evaluated at any point along the length. Other objects are also defined such as rigid bodies. The Lagrangian multiplier method is used to define the constraints in the model. This allows for the construction of complex models. An important constraint is the suturing constraint, which is created when a sufficient force is applied by the suture tip on to the tissue. This constraint allows only a sliding point along the suture to pass through a specific point on the tissue. This results in a virtual suturing model which can be built on for use in surgical simulations. Further investigations would be interesting to increase performance, accuracy and scope of the simulator. / Det här projektet syftar till att utveckla mjukvara för virtuell simulering av kirurgi som involverar knytande av suturtråd. Lagranges ekvationer används för att härleda energibevarande tillståndsekvationer. Lösningsmetoderna grundar sig i teori från området Differential-Algebraiska Ekvationer (DAEer), som avser att kontrollera Ordinära Differentialekvationer (ODEer) med algebraiska bivillkor. Ett implicit integrationsschema och Newtons metod används för att lösa systemet i varje steg. Utöver det så implementeras en kollisionsrespons-process baserad på det linjära komplementaritetsproblemet (LCP) för att hantera kollisioner och mäta deras krafter. Modeller har utvecklats för att representera olika typer av objekt. En spline-modell används för att representera suturtråden och ett mass-fjäder system för vävnaden. Valet baserades på deras höga prestanda samt starka anknytning till objektens fysiska egenskaper. Spline-modellen valdes också då dess kontinuitet innebär att den går att evaluera för en godtycklig punkt inom dess domän. Andra objekt, såsom stela kroppar, finns också definierade. Lagrangemultiplikator används för att definiera bivillkor i modellen. Detta tillåter konstruktionen av komplexa modeller. Ett viktigt bivillkor är sutur-bivillkoret som uppstår när tillräcklig kraft från spetsen på den kirurgiska nålen appliceras på vävnaden. Detta bivillkor tillåter att endast en glidande punkt längsmed suturen passerar genom en specifik punkt på vävnaden. Detta resulterar i en virtuell modell för stygn som kan byggas vidare på för användning i kirurgiska simulationer. Det vore intressant med ytterligare undersökningar för att förbättra prestandan, precisionen och simulatorns omfattning.