The usage of a robotic simulator hasprovidedthe advantages of the efficientdevelopment and testing of robotics applications, saving time and resources and making easier publics demonstrations. This thesis project consists on the simulation of a wheel loader at an industrial environment inthe cycle of material handling. For the development of the Project have been used the Robot Operating System (ROS) and Gazebo frameworks which allows to reproduce the 3D map of the work site as well as the robotic wheel loaderand simulate it in a realistic way. The developed softwarealsoprovidesthemechanism to drive the wheel loader throughthereproduced terrain, to controlthe movement of the different articulated joints of the robot, to recompile information of the environmentthroughdifferent sensors (Laser, Odometry, GPS, IMU, etc) and to provide of a waypoint routes to the robot. Furthermore the simulator will be able to reproduce and integrate an asphalt plant modelto the scenario. Allowing an interaction with the wheel loader, this will transport gravel from the piles of the terrain to the pocket of the asphalt plant.

The theme of this diploma thesis is design of skid steer loader with capacity up to 1 tonne. The result of this thesis is a conceptual solution of loader. It describes structural, technological, ergonomic and visual aspects with respect to current trends.

Presently, there is a four-year window to prepare engines for upcoming TIER V regulations through solutions for peak power shaving and downsizing of diesel engines. In particular, Non-road mobile machinery(NRMM) offer a promising and challenging field of application due to their duty cycles, which includes high and short power peaks and extreme working conditions. In this paper, a series hybrid electric powertrain for a mining loader is presented with the goal of reducing the fuel consumption. A full-scale mining loader powertrain prototype was built to exploit the benefits of a series hybrid electric powertrain at low traction requirements with a combination of decentralized e.g. zonal hydraulics. Corespondingly, this paper introduces the structure of the mining loader and initial mathematical model of the system of a Direct Driven hydraulics (DDH). In this research, an experimental test was conducted, and the initial results are presented in this paper.

Volvo Construction Equipment is investigating the potential of hybrid wheel loaders. To determine if this new hybrid wheel loader concept is preferable from an environmental point of view to the latest G- series Volvo wheel loader, a comparative life cycle assessment (LCA) has been performed  on the Volvo L150G wheel loader and a hybrid wheel loader concept. The complete machines have been studied throughout their life cycle: raw material extraction, material processing, manufacturing processes, transportation, use phase, and end of life. In order to quantitatively assess the environmental impact of all lifecycle stages, five different environmental indicators have been used: global warming potential, abiotic resource depletion potential, acidification potential, eutrophication potential and ozone depletion potential. In addition, a sensitivity analysis and two weighting methods are used to interpret the results. The results show that a hybrid wheel loader concept reduces environmental impacts significantly compared to a conventional L150G, except the impact category ADP (element). Moreover, the use phase has by far the greatest impact within the life cycle, for most impact categories (90% of the total life cycle impact). A sensitivity analysis on use phase with impacts also showed the limitations for use in China. / Volvo Construction Equipment undersöker potentialen av hybrid hjullastare. För att avgöra om ett hybrid hjullastare koncept har fördelar ur miljösynpunkt jämfört med en G-serien Volvo hjullastare har en jämförande livscykelanalys (LCA) utförts på Volvo L150G hjullastare och ett hybrid hjullastarkoncept. De kompletta maskinerna har studerats under hela deras livscykel: utvinning av råmaterial, materialbearbetning, tillverkningsprocesser, transport, användningsfas och slutet av skrotningsfasen. För att kvantitativt kunna bedöma miljökonsekvenserna av alla livscykelnskeden har fem olika miljöindikatorer använts: global uppvärmningspotential, abiotiska resursutarmningspotential, försurningspotential, övergödningspotential och ozonnedbrytingspotential. En känslighetsanalys och två viktningsmetoder har tillämpats för att tolka resultaten. Resultaten visar att ett hybrid hjullastarkoncept minskar miljöpåverkan avsevärt jämfört med en konventionell L150G, förutom påverkan från kategorin resursutarmningspotential. Dessutom har användningsprocessen i särklass störst påverkan inom livscykeln för de flesta effekt kategorier (90% av den totala livscykelpåverkan). En känslighetsanalys på användningsprocessen och dess effekter visade också på begränsningar för användning i Kina.

Welded structures susceptible to weld deformations require sequent processing to allow for mounting of precision components. This thesis includes a case study of the rear axle mount on a Volvo L220 wheel loader. A product development process was deployed in order to explore and evaluate alternative mounting methods such that manufacturing cost due to sequent processing could be decreased. Analysis of the frame variations showed any new concepts has to accommodate variations of up to $\delta z=-1.24\pm3.5$ mm. The product development process found two potential concept philosophies; transferring concepts which improves upon the current concept by transferring the processing away from the frame onto smaller components that are cheaper to process, and absorbing concepts that avoids sequent processing by absorbing the frame variations altogether. The transferring concept "Custom Plate" was selected for further development. The concept is based on the principals of reverse engineering by manufacturing a custom plate from a 3D surface map of the deformed mounting surface, placed between the frame and rear axle bridge, matching the surface geometry of both entities. The concept showed no apparent critical strength issues when simulated in CATIA V5. However, the economical gain of the concept is slim and depends heavily what spaces can be allocated for additional processing machinery. Suggestions for further development of the concept are given along with a discussion of improvements outside of the system boundary of the project, such as simulation of welds and welding sequence, and collection, storing, analysis, and visualisation of data.

This thesis was commissioned by Volvo Construction Equipment (Volvo CE) to redesign the front axle casing of their L90 wheel loader to be more in line with their larger wheel loaders. The current L90 front axle casing consists of two parts bolted together in the middle. However, the current assembly process is cumbersome, and as such, Volvo CE wants to determine if a one-piece front axle casing can be implemented into their L90 wheel loaders. Volvo CE’s larger wheel loaders such as the L120 currently have a one-piece design for the front axle casing and can serve as template. This thesis aimed to determine if it was possible to create a one-piece axle casing for the L90 and provide an example of how it would look like. Additionally, the suggested design would need to meet all of Volvo CE’s performance requirements and be on par with the current L90 front axle casing.  The methodology used to develop the redesigned axle casing consisted of performing different finite element analyses (FEA) in Ansys Mechanical to evaluate the casing’s performance. The analysis was preformed using Volvo CE’s guideline and performance criteria in order to determine what areas in the redesigned axle required further adjustment. Additionally, the redesigned casing would be compared against the current L90 casing. This would determine if the redesigned axle could be realistically implemented into a L90 wheel loader.  Applying this methodology led to three different iterations of the axle casing design. Each design iteration following the first one led to improvements in the casing’s mechanical performance. The third and final iteration was able to meet all of Volvo CE’s static and fatigue requirements. The stresses for the redesigned axle casing are, on average, 13% lower than that of the current axle casing at key points around the casing’s ribs. However, the tolerances required to manufacture the redesigned axle casing where slightly higher than the current L90 casing. Nevertheless, the tolerances required to manufacture redesigned axle can be realistically met by a foundry. This thesis was able to provide a plausible redesign that can be implemented in Volvo CE’s current line of L90 wheel loaders.

No description available.

In this study we investigate the propagation of uncertainties in the input forces through a mechanical system. The system of interest was a wheel loader, but the methodology developed can be applied to any multibody systems. The modeling technique implemented focused on efficiently modeling stochastic systems for which the equations of motion are not available. The analysis targeted the reaction forces in joints of interest. The modeling approach developed in this thesis builds a foundation for determining the uncertainties in a Caterpillar 980G II wheel loader. The study begins with constructing a simple multibody deterministic system. This simple mechanism is modeled using differential algebraic equations in Matlab. Next, the model is compared with the CAD model constructed in ProMechanica. The stochastic model of the simple mechanism is then developed using a Monte Carlo approach and a Linear/Quadratic transformation method. The Collocation Method was developed for the simple case study for both Matlab and ProMechanica models. Thus, after the Collocation Method was validated on the simple case study, the method was applied to the full 980G II wheel loader in the CAD model in ProMechanica. This study developed and implemented an efficient computational method to propagate computational method to propagate uncertainties through "black-box" models of mechanical systems. The method was also proved to be reliable and easier to implement than traditional methods. / Master of Science

This paper presents an active component damage reducing control approach for driving manoeuvres of a wheel loader. For this purpose, the front and rear axle loads will be manipulated by force pulses induced into the machine chassis via the lifting cylinders of the function drive. The associated control approach is based on the principles of Reinforcement Learning. The essential advantage of such methods against linear control approaches is that no descriptive system properties are required, but the algorithm automatically determines the system behaviour. Due to the high number of necessary training runs, the algorithm is designed and taught using a validated wheel loader simulation model. After over 850 training runs, an optimal strategy for damping the axle loads could not yet be determined. In spite of the unprecedented convergence, initial improvements of the damage values have already been achieved on tracks that deviate from the training track. Some of these results show a 4.9 % lower component damage compared to a machine setting with no damping system. The results and limits of this strategy are discussed due to a comparison with other scientific active vibration damping approaches. Currently, a linear control method (P-PI-controller) has a higher damage reduction potential, but it is expected that further training runs and another learning algorithm could make the reinforcement learning approach even more effective. Coupling the linear control method with the selflearning approach shows the highest potential for the axle damage reduction.

Wheel loaders are fundamental construction equipment to assist handling of bulk material e.g. gravel and stones. During digging operations, it withstands forces that are both large and very complicated to predict. Moreover, it is very expensive to develop prototypes of wheel loader for verification. Consequently, the Discrete Element Method (DEM) was introduced for gravel modeling a couple of years ago to enable prediction of these forces. The gravel model is connected with a Multibody System (MBS) model of the wheel loader, in this thesis a Volvo L180G. The co-simulation of these two systems is a very computer intensive operation and hence, it is important to investigate which parameters that have the largest influence on the simulation results. The aim of this thesis is to investigate the simulation sensitivity with respect to co-simulation communication interval, collision detection interval and gravel normal stiffness.The simulation results are verified by comparison with measurement data from previous tests performed by Volvo CE. The simulations are compared to investigate the relevant parameters. The conclusion of this thesis is that DEM is a method that in a very good way can predict the draft forces during digging operations.