Path following and lateral stability are crucial issues for autonomous vehicles. Moreover, these problems increase in complexity when handling heavy-duty vehicles due to their poor manoeuvrability, large sizes and mass variation. In addition, uncertainties on mass may have the potential to significantly decrease the performance of the system, even to the point of destabilising it. These parametric variations must be taken into account during the design of the controller. However, robust control techniques usually require offline adjustment of auxiliary tuning parameters, which is not practical and leads to sub-optimal operation. Hence, this work presents an approach to path-following and lateral control for autonomous heavy-duty vehicles subject to parametric uncertainties by using a robust recursive regulator. The main advantage of the proposed controller is that it does not depend on the offline adjustment of tuning parameters. Parametric uncertainties were assumed to be on the payload, and an H∞ controller was used for performance comparison in simulations. The performance of both controllers is evaluated in a double lane-change manoeuvre. Simulation results showed that the proposed method had better performance in terms of robustness, lateral stability, driving smoothness and safety, which demonstrates that it is a very promising control technique for practical applications. Ultimately, experiment tests in a rigid heavy-duty truck validate what was found in simulation results. / O seguimento de caminho e a estabilidade lateral são questões cruciais para veículos autônomos. Além disso, devido à baixa capacidade de manobra, tamanho e grande variação de massa, estes problemas se tornam mais complexos quando se trata de veículos pesados. Adicionalmente, as incertezas na massa têm o potencial de diminuir significativamente o desempenho do sistema, chegando ao ponto de desestabilizá-lo, assim, essas variações paramétricas devem ser consideradas durante o projeto do controlador. No entanto, as técnicas de controle robusto geralmente exigem o ajuste off-line de parâmetros auxiliares do controlador, o que não é prático e lava a uma operação sub-ótima. Assim, este trabalho apresenta uma abordagem de controle de seguimento de caminho e controle lateral para veículos pesados autônomos sujeitos a incertezas paramétricas usando um regulador robusto recursivo. A principal vantagem deste controlador é que ele não depende do ajuste off-line de parâmetros. Assumiu-se que as incertezas paramétricas estavam na carga do veículo, e um controlador H∞ foi usado para comparar o desempenho em simulação. O desempenho de ambos os controladores é avaliado em uma manobra de mudança de faixa. Os resultados de simulação mostraram que o método proposto apresentou melhor desempenho em termos de robustez, estabilidade lateral, suavidade na condução e segurança, o que o demonstra como uma técnica de controle bastante promissora para aplicações práticas. Por fim, testes experimentais em um caminhão rígido reforçam os resultados obtidos em simulação.

Research shows that climate changes we face today is a consequence of the increasing amounts of greenhouse gases that circulate in our atmosphere due to increased human industrial activity. Many firms and industries are therefore increasingly implementing environmental management strategies to reduce greenhouse gas emissions towards a more sustainable environment. These environmental management efforts can be broadly classified under two umbrellas which are sustainable production and sustainable consumption and these two parts need to work together in order to contribute effectively towards a more sustainable environment. The environmental management literature however reveals a gap between sustainable production and sustainable use of vehicles in the automotive industry showing that while the major global environmental impact - greenhouse gas emissions - occurs when vehicles are put to use, the environmental management efforts in the industry are skewed to the production of vehicles.An emerging trend to breach this gap is that vehicle manufacturers are providing extending services to help vehicle users minimize their greenhouse gas emissions. This study analyses the extended service packages of the global truck manufacturer, Scania, against the environmental objectives and initiatives of five road transport companies in Sweden. An exploratory case study approach was used from the perspective of the road freight transport companies to find out if extended services present suitable opportunities to extend environmental management from manufacturers to users in the road freight transport industry. The study found that the extended services provide solutions that help road freighttransport companies to achieve lower fuel consumption and lower emissions from theirvehicles. Road freight transport companies traditionally invest in environmental initiatives to gain marketing advantages but the extended services present a rare opportunity to the companies to compete on profit margins by investing in the extended services. / Market Making of a High-value Business Model in Low Cost Markets: Value Co-Creation in Swedish Industry, CeLS, Project manager: Leif-Magnus Jensen, leif-magnus.jensen@jibs.hj.se, +46 36 10 1881.

Development of a fuel economy model for light-duty and heavy-duty vehicles is part of the Texas Department of Transportation’s “Estimating Texas Motor Vehicle Operating Costs” project. A literature review for models that could be used to predict the fuel economy of light-duty and heavy-duty vehicles resulted in selection of coastdown coefficients to simulate the combined effects of aerodynamic drag and tire rolling resistance. For light-duty vehicles, advantage can be taken of the modeling data provided by the United States Environmental Protection Agency (EPA) for adjusting chassis dynamometers to allow accurate determination of emissions and fuel economy so that compliance with emissions standards and Corporate Average Fuel Economy (CAFE) regulations can be assessed. Initially, EPA provided vehicle-specific data that were relevant to a physics-based model of the forces at the tire-road interface. Due to some limitations of these model parameters, EPA now provides three vehicle-specific coefficients obtained from vehicle coastdown data. These coefficients can be related back to the original physics-based model of the forces at the tire-road interface, but not in a manner that allows the original modeling parameters to be extracted from the coastdown coefficients. Nevertheless, as long as the operation of a light-duty vehicle does not involve extreme acceleration or deceleration transients, the coefficients available from the EPA can be used to accurately predict fuel economy. Manufacturers of heavy-duty vehicles are not required to meet any sort of CAFE standards, and the engines used in heavy-duty vehicles, rather than the vehicles themselves, are tested (using an engine dynamometer) to determine compliance with emissions standards. Therefore, EPA provides no data that could be useful for predicting the fuel economy of heavy-duty vehicles. Therefore, it is necessary to perform heavyduty coastdown tests in order to predict fuel economy, and use these tests to develop vehicle-specific coefficients for the force at the tire-road interface. Given these coefficients, the fuel economy of a heavy-duty vehicle can be calculated for any driving schedule. The heavy-duty vehicle model developed for this project is limited to pre-2007 calendar year heavy-duty vehicles due to the adverse effects of emissions components that were necessary to comply with emissions standards that went into effect January 2007. / text

Fuel consumption is a major economical component of vehicles, particularly for heavy-duty vehicles. It is dependent on many factors, such as driver and environment, and control over some factors is present, e.g. route, and we can try to optimize others, e.g. driver. The driver is responsible for around 30% of the operational cost for the fleet operator and is therefore important to have efficient drivers as they also inuence fuel consumption which is another major cost, amounting to around 40% of vehicle operation. The difference between good and bad drivers can be substantial, depending on the environment, experience and other factors. In this thesis, two methods are proposed that aim at quantifying and qualifying driver performance of heavy duty vehicles with respect to fuel consumption. The first method, Fuel under Predefined Conditions (FPC), makes use of domain knowledge in order to incorporate effect of factors which are not measured. Due to the complexity of the vehicles, many factors cannot be quantified precisely or even measured, e.g. wind speed and direction, tire pressure. For FPC to be feasible, several assumptions need to be made regarding unmeasured variables. The effect of said unmeasured variables has to be quantified, which is done by defining specific conditions that enable their estimation. Having calculated the effect of unmeasured variables, the contribution of measured variables can be estimated. All the steps are required to be able to calculate the influence of the driver. The second method, Accelerator Pedal Position - Engine Speed (APPES) seeks to qualify driver performance irrespective of the external factors by analyzing driver intention. APPES is a 2D histogram build from the two mentioned signals. Driver performance is expressed, in this case, using features calculated from APPES. The focus of first method is to quantify fuel consumption, giving us the possibility to estimate driver performance. The second method is more skewed towards qualitative analysis allowing a better understanding of driver decisions and how they affect fuel consumption. Both methods have the ability to give transferable knowledge that can be used to improve driver's performance or automatic driving systems. Throughout the thesis and attached articles we show that both methods are able to operate within the specified conditions and achieve the set goal.

As the greenhouse effect is an imminent concern, motivation for the development of energy efficient systems has grown fast. Today heavy-duty vehicles (HDVs) account for a growing part of the emissions from the vehicular transport sector. One way to reduce those emissions is by driving at short intervehicular distances in so called platoons, mainly on highways. In such formations, the aerodynamic drag is decreased which allows for more fuel efficient driving, meanwhile the roads are used more efficiently. This thesis deals with the question of how those platoons can be controlled without using communications between the involved HDVs. In this thesis, artificial neural networks are designed and trained to predict the velocity profile for an HDV driving over a section of road where data on the topography are available. This information is used in a model predictive controller to control the HDV driving behind the truck for which the aforementioned prediction is made. By having accurate information about the upcoming behaviour of the preceding HDV, the controller can plan the velocity profile for the controlled HDV in a way which minimizes fuel consumption. To ensure fuel optimal performance, a state describing the mass of consumed fuel is derived and minimized in the controller. A system modelling gear shift dynamics is proposed to capture essential dynamics such as torque loss during shifting. The designed controller is able to predict and change between the three highest gears making it able to handle almost all highway platooning scenarios. The prediction system shows great potential and is able to predict the velocity profile for different HDVs with an average error as low as 0.04 km/h. The controller is implemented in a simulation environment and results show that compared to a platoon without these predictions of the preceding HDV, the fuel consumption for the controlled HDV can be reduced by up to 6 %.

The aim of this thesis is an analysis of bending vibrations of the heavy duty truck transmission and a design of construction modifications. The next target is to evaluate the contribution of the construction modification. In the thesis is also performed analysis of shaft support stiffness.

The thesis deals with computational modelling of heavy duty off-road vehicle driveline components. The thesis is divided to two main parts. The first part deals about modal analysis of selected driveline components. MBS computational study was performed based on modal analysis results. The second part of thesis deals with experimental verification of computational model. Pass-by noise and vibration measurement was performed. Measured signals were processed in frequency domain to find noise and vibration sources.

<div>Traction control (TC) systems have become quite common in on-road passenger vehicles in recent years. However, for vehicles in other applications, they are not as widely available.</div><div>This work presents a methodology for the proper design and implementation of a traction control system for heavy duty off-road machines, using a wheel loader as a reference vehicle.</div><div><br></div><div><div>A simulation model was developed, using standard vehicle dynamics constructs, including equations of motion and a description of the distribution of weight between the axles for different operating conditions. This model contains considerations for resistive forces acting on the machine implement, such as that generated by a work pile. The simulation also incorporates a detailed representation of the slip-friction characteristics between the vehicle tires and the road surface. One objective of this research was to model this interaction accurately, because the system traction behavior is dependent on it. Therefore, a series of tests was run using a state estimator to generate data on the slip-friction relationship at various ground conditions, and the results were incorporated into the simulation model. The dynamics of the machine braking system pressure were also modeled to give a more accurate description of the system response. The result is a mathematical model capable of accurately reproducing the behavior of the real-world system.</div></div><div><br></div><div><div>One of the primary goals of this work was the description of the traction control strategy itself, which should work as effectively and efficiently as possible. Several different aspects of the system were taken into consideration in generating this control structure. First, a relatively simple controller based on a PID control law was created. This controller was updated to account for peculiarities of the traction control system, as well as aspects like time delay. From there, more advanced controllers were created to address certain aspects of the system in greater detail. First, a self-tuning controller based on real-time optimization strategies was developed, to allow the controller to quickly adapt to changes in ground condition. Then, different nonlinear controllers were synthesized which were designed to address the theoretical behavior of the system. All of these controllers were simulated using the system model and then some were run in experiments to show their potential for improving system performance. To improve system efficiency, the machine drivetrain itself was also examined to develop a more efficient control algorithm. By designing a more efficient methodology, traction control congurations which had previously seen increases in fuel consumption of 16% were now able to actually reduce fuel usage by 2.6%.</div></div><div><br></div><div><div>Another main goal of this work was the development of a prototype system capable of implementing the formulated control strategies. The reference machine was modied so that the brakes could be controlled electronically and independently for implementation of the TC system. The vehicle was instrumented using a wide array of sensors, and estimation methodologies for accurately determining vehicle speed and implement forces were designed. The velocity estimator designed in this work is more accurate and more reliable than an industry standard sensor, which is important for traction control implementation. The implement force estimate was also quite accurate, achieving payload estimate errors of less than 2.5%, comparable to commercially-available measurement systems. This setup allowed for tests to be accurately compared, to assess the traction control performance.</div></div><div><br></div><div><div>With the objective of performing experiments on the traction control system, many tests were run to assess its capabilities in various situations. These tests included experiments for characterizing the vehicle behavior so that the simulation model could be updated to accurately reflect the physical machine performance. Another task for the experimental work was the generation of useful metrics for quantifying traction control performance. Laboratory experiments which were very controlled and repeatable were also run for generating data to improve the system model and for comparing traction control performance results side-byside. The test metrics proposed for these experiments provided for accurate, repeatable comparisons of pushing force, tire wear, and brake consumption. For each of these tests, the traction control system saw an increase in pushing force of at least 10% when compared with the stock machine, with certain operating conditions showing increases as high as 60%. Furthermore, every test case showed a decrease in wheel slip of at least 45% (up to 73% for some cases), which translates into increased tire longevity.</div></div><div><br></div><div><div>Other tests were conducted in the eld, designed to mimic the real-world operating conditions of the wheel loader. Various performance comparisons were made for different congurations in which traction control could provide potential benets. These included parameters for comparing overall vehicle performance in a typical truck loading cycle, such as tire wear, fuel consumption, and material moved per load. Initial results for this testing showed a positive result in terms of wheel slip reduction, but other performance parameters such as fuel consumption were negatively impacted. Therefore, the control structure was reexamined extensively and new methods were added to improve those results. The final control implementation saw a 12% reduction in tire slip, while also reducing fuel consumption by 2.6% compared to the stock system. These results show signicant potential for traction control as a technology for maximizing the performance output of construction machines.</div></div>

Heavy duty vehicle (HDV) platooning is currently a big topic both in the academic world and in industry. Platooning is a smart way to solve problems such as safety, traffic congestion, fuel consumption and hazardous exhaust emissions since its concept enables several vehicles to drive close to each other while maintaining all the security requisites. This way, each vehicle will use the so called slipstream effect, an atmospheric drag reduction that occurs behind a traveling vehicle, consuming less fuel and consequently reducing the exhausted gases. Furthermore, it increases the traffic flow since the distance between vehicles is significantly reduced. The concept and idea of platooning is not particularly new, but only in the last few decades new technology made it possible. HDV platooning scenarios for scale model trucks were developed in the completely renovated Smart Mobility Lab, in KTH, Stockholm. A LabVIEW application was developed giving a robust and stable control of the trucks while following and driving on a newly designed and built road network. The trucks are able to follow a predefined trajectory, change lane and road, platoon with each other with different platooning distances, overtake when the platoon master is changed in order to take the lead of the platoon and change speed to catch up, among other features. The last part of this thesis covers the analysis of the scenarios developed in the testbed. These scenarios represent several situations of HDV platooning, particularly the platoon catch-up case. The main object of this study was the saved fuel due to platooning, and the break-even point, i.e. the distance ratio when neither driving alone nor catching up a platoon ahead would be more feasible. Using real HDV models and their fuel consumption models, simulations were performed in order to check the benefits of platooning and the data got from the scenarios was analyzed. Finally, conclusions were drawn from the experiments where the parameters such as HDV weight, speed increment when catching up and intermediate distance when platooning were different in each trial. It was concluded that a single HDV has to travel 8 to 15 times more than the initial distance that separates it from the HDV(s) ahead and it can save 5 to 13% of fuel depending if catching up a single HDV or a platoon an already existing platoon. Furthermore, it is less beneficial for a platoon already formed to decide to catch up another HDV.

Regarding the ground electrical connection in trucks and buses, the requirements of earthing in heavy-duty vehicles were gathered and evaluated. The most important problems in the state-of-the-art grounding devices are corrosion, electrical resistance and uncertainty in the mounting process, altogether with depreciation over time. The goal is to come up with new concepts that can give a more reliable and better ground connection into the frame with faster, easier and safer manufacturing operations. Several methods for attaching different ground connectors to the steel frame are going to be investigated, including bolted connections, press devices, soldering, brazing and local plating spots. It will be shown that the welding operation gives the best electrical results, while lowering mounting costs, time and variability. Two welded connectors are then going to be proposed as the best alternatives and a parallel investigation with both of them is going to be carried out. These new concepts, filed for patent protection, are going to be labelled as “SRM Welded ground stud” and “SRM Welded grounding nut”. The first of them consists of a plated steel threaded stud (M8 or M10) with a ring shaped contact surface built in one of the ends, where the Ø12 mm weld is to be performed onto the uncoated frame. The second concept comprises a stainless steel M10 round nut welded over a punched hole. The optimization will also cover different alternatives for plating metals, contact aid compounds and masking caps for both devices. The risk of mechanical weakening of the frame because of the new welded concepts is going to be tested for the case of the SRM Welded ground stud. The results will show an increase in fatigue resistance of at least 20% compared to the current ground screw. Furthermore, the strength of the welded interface will show higher proof load than the stud itself. The welded nuts, tested with torque loading, will show a sufficient performance as well. The electrical tests present an expected decrease in ground resistance of 40% for the welded stud and an increase of 28% for the welded nuts, compared with the current ground screw. The conclusion of this Master Thesis states the recommendation of the implementation of a new grounding method through the SRM Welded ground stud. Although, some modifications in the transportation process of the frames might be needed because of the new protruding parts, pointing an estimated distance of 20mm from the frame surface. / När det gäller jordad elanslutning i lastbilar och bussar, har kraven på jordning i tunga fordon samlats och utvärderats. De största problemen i de mest avancerade jordade enheterna är korrosion, elektriskt motstånd och osäkerhet i monteringsprocessen, sammantaget med avskrivning över tiden. Målet är att utveckla nya koncept som kan ge en bättre och mer tillförlitlig jordanslutning i ramen med snabbare, enklare och säkrare tillverkning. Flera metoder för att fästa olika mark kontakter till stålramen kommer att undersökas, bland annat skruvförband, pressanordning, lödning, hårdlödning och lokala pläteringsfläckar. Det kommer att visa att svetsning ger den bästa elektriska resultatet, samtidigt som monteringskostnader, tid och variabilitet minskar. Två svetsade kontakter kommer sedan att föreslås som de bästa alternativen och en parallell undersökning med dem båda kommer att genomföras. Dessa nya koncept, för vilka patentskydd har ansökts, kommer att märkas som “SRM Svetsade marktapp” och “SRM Svetsade jordmutter”. Den första av dem består av en pläterad stålgängad tapp med en ringformad kontaktyta byggt i en av ändarna, där svetsen skall utföras på den obelagda ramen. Det andra konceptet består av en rostfri rund mutter svetsad över ett stansat hål. Optimeringen kommer även att omfatta olika alternativ för pläterade metaller, kontaktstöds föreningar och maskeringslock för de båda enheterna. Risken för mekanisk försvagning av ramen på grund av det nya svetsade konceptet kommer att testas med avseende på fallet med SRM Svetsad bottenreglar. Resultaten visar en ökad utmattningshållfasthet på minst 20% jämfört med den nuvarande jordskruven. Dessutom kommer styrkan av den svetsade gränsytan uppvisa en högre provbelastning än tappen själv. De svetsade muttrarna, testade med momentbelastning, kommer också uppvisa en tillräcklig prestanda. De elektriska testerna presenterade en förväntad minskning av markmotståndet på 40% för svetsade tappar och en ökning med 28% för svetsade muttrar, jämfört med den nuvarande jordskruven. Slutsatsen av detta examensarbete anger en rekommendation av genomförandet av en ny jordningsmetod genom en SRM Svetsad marktapp. Trots detta kan vissa ändringar behövas i transportprocessen av ramarna på grund av de nya utskjutande delarna, vilka pekar från ramens yta med ett uppskattat avstånd av 20 mm.