<p>Ever-increasing need for freight transportation and mounting environmental concerns call for a cleaner and more efficient energy source. Hybrid electric vehicles have shown potential to reduce both petroleum usage as well as harmful emissions. In this thesis, a newly developed series hybrid electric powertrain by a small start-up company is studied on a route between Florence, Kentucky and Cambridge, Ohio hubs to evaluate potential fuel savings due to hybridization.</p> <p> </p> <p>An experimental testing protocol to calculate fuel economy has been developed and the real-world fuel economy of this hybrid electric powertrain is calculated. A vehicle simulation model representing the experimental powertrain is created in Autonomie and this vehicle model is simulated on three distinct drive cycles obtained from experimental testing phase. These results are compared with a conventional class 8 truck to evaluate fuel savings. The simulation analysis indicates that fuel economy of hybrid is better on only one of the three drive cycles under consideration. Further, it is determined that the existing powertrain does not meet the gradeability criterion. To remedy this, a series electric hybrid powertrain with different compo-</p> <p>nent sizes is then modeled and simulated on the same drive cycles. The modified powertrain is found to result in fuel economy improvement on all three drive cycles considered while also meeting the gradeability requirement. The effect of drive cycle on fuel economy of a hybrid powertrain is also studied in this thesis.</p><br>

<div>Class 8 trucks on average drive the most miles and consume the most fuel of any major vehicle category annually. Indiana specifically is the fifth busiest state for commercial freight traffic and moves $750 billion dollars of freight annually, and this number is expected to grow by 60% by 2040. Reducing fuel consumption for class 8 trucks would have a significant benefit on business and the proportional decrease in CO₂ would be exceptionally beneficial for the environment.</div><div><br></div><div>Platooning is one of the most important strategies for increasing class 8 truck fuel savings. Platooning alone can help trucks save upwards of 7% platoon average fuel savings on flat ground. However, it can be difficult for a platooning controller to maintain a desired truck separation during uncoordinated shifting events. Using a high-fidelity simulation model, it is shown that simultaneous shifting–having the follow truck shift whenever the lead truck shifts (unless shifting would cause its engine to overspeed or underspeed)–decreases maximum truck separation by 24% on a moderately challenging grade route and 40% on a heavy grade route.</div><div><br></div><div>Model Predictive Control (MPC) of the follow truck is considered as a means to reduce the distance the follow truck falls behind during uncoordinated shifting events. The result in simulation is a reduction in maximum truck separation of 1% on a moderately challenging grade route and 19% on a heavy grade route. However, simultaneous shifting largely alleviates the need for MPC for the sake of tracking for the follow truck.</div><div><br></div><div>A different MPC formulation is considered to dynamically change the desired set point for truck separation for routes through a strategy called Route Optimized Gap Growth (ROGG). The result in simulation is 1% greater fuel savings on a moderately challenging grade route and 7% greater fuel savings on a route with heavy grade for the follow truck.</div>

This thesis deals with CFD simulation of platooning vehicles and their aerodynamic characteristics, created in Star CCM+ software. The main focus is on their aerodynamic drag dependency on different spacing between vehicles which allowed to evaluate the most energy efficient distance for platoon of vehicles. Furthermore, the procedure how to calculate the fuel consumption is described for set of variables.

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Today’s way of driving works very well, but there can be substantial improvements made in the road systems and in the vehicles themselves. Many of the disadvantages of current road systems and vehicles can be removed in the future by using appropriate information and communication technology. A disadvantage that has been considered to be a major problem for many years is the fossil fuel-consumption of vehicles. Hybrid-cars and all-electric cars are being developed to reduce the use of fossil-based fuels. Since it could take a long time for these new types of vehicles to replace vehicles currently using internal combustion engines, development must also seek to improve current vehicles. Fuel-savings and safety are two major aspects that researchers and vehicle manufacturers are trying to address. One approach that provides fuel-savings is driving in a convoy. Both Scania and Volvo are currently developing this approach. They aim to achieve the same goal, but in two different ways - since they do not build upon the exact same concepts. Scania is a major manufacturer of trucks and buses, while Volvo is a major manufacturer of trucks, buses, and cars. Both are seeking to improve the fuel-savings for trucks and busses, but Volvo is also seeking to improve fuel-savings for cars. Unfortunately, with every solution are new problems. Convoy driving brings advantages, but appropriate communication between the vehicles of the convoy and those seeking to join a convoy is necessary for this approach to work well. This is particularly challenging as these vehicles are in moving while communicating. For this reason, the communication needs to utilize wireless links. This thesis shows in more detail how the inter-vehicle communication works using Wi-Fi and why this is a good media to use when driving a convoy. The testing of Wi-Fi between two driving vehicles and in implementation of two model vehicles shows another perspective of Wi-Fi than today’s use of it. / Dagens sätt att köra i samhället fungerar väldigt bra men det finns naturligtvis massor av nackdelar med olika vägsystem och fordonen själva. Dessa nackdelar kan i framtiden försvinna med utvecklingen av IT-systemen. En stor nackdel som setts som ett problem sen flera år tillbaka är bränsleförbrukningen hos fordonen. Det finns hybridbilar och t.o.m. elbilar vilka utvecklas i syfte att spara på jordens bränsle resurser. Men eftersom det antagligen kommer ta flera tiotals år innan dessa fordon kommer ersätta dagens fordon med bränslemotorer så måste utvecklingen också gå i två vägar, nämligen att förbättra dagens bränsledrivna fordon. Bränsleförbrukning och säkerhet är de två främsta aspekterna vid denna typ av utveckling. Ett system som faktiskt förbättrar bränslebesparing är att köra på led som en konvoj. Detta körsystem utvecklas just nu av två större företag, Scania och Volvo. De siktar mot samma mål men har två olika tillvägagångssätt då de inte är i grunden exakt likadana företag. Scania bygger lastbilar och bussar medan Volvo förutom dessa fordon även bygger bilar. Detta ger Volvo en chans att även förbättra bilkörandet. Men med varje lösning kommer det nya problem. Detta sätt att köra ger givetvis fördelar men man oroar sig ändå för kommunikationen som behövs för detta system. Detta är inte enheter som står stilla på exempelvis ett kontor eller flygplats, utan det är enheter som rör sig ständigt, vilket betyder att kommunikationen måste vara trådlös. Denna rapport går in mer i detalj hur den externa kommunikationen mellan fordon fungerar med Wi-Fi och varför det är ett bra protokoll att använda i konvojer. Testerna med Wi-Fi körandes i två bilar och även i två små modellbilar ger Wi-Fi ett annat perspektiv än dagens användning.

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