Autonomous heavy vehicles will enable the promise of decreased energy consumption through the ability to platoon in closer formation than is currently safe or legal. It is therefore increasingly important to understand the complex and dynamic wake interactions between vehicles operating in close proximity for aerodynamic gains. In recent years, a growing body of research has documented a bi-stable, shifting wake generated behind the Ahmed reference bluff body. At the same time, studies of platooning Ahmed bodies have focused on changes to the body forces and moments at different following distances or lateral offsets, typically based around time-averaged measurements or steady-state CFD. The present study attempts to understand the implications of bi-stability in the wake of two square-back, platooning Ahmed bodies, given the potential for transient instabilities. Temporally-correlated static pressures were measured on two identical wind tunnel models at various following distances to uncover the time-dependent interactions between platooning vehicles. Bi-stability is highly dependent on symmetry and the uniformity of oncoming flow, and it is shown that a shifting bi-stable wake behind the lead vehicle leads to correlated, bi-stable flow patterns on the following vehicle, even in the absence of a lateral offset. At a following distance of 0.25L, pressure data indicated there may be a point where this bi-stable behavior reaches a critical point between suppression and amplification, significantly affecting the aerodynamic loads on the lead vehicle. This leads to the conclusion that bi-stable wake interactions between vehicles may be useful to consider in the context of real-time organization of vehicle platoons.

Yes / In the automotive industry, modern cyber-physical systems feature cooperation and autonomy. Such systems share information to enable collaborative functions, allowing dynamic component integration and architecture reconfiguration. Given the safety-critical nature of the applications involved, an approach for addressing safety in the context of reconfiguration impacting functional and non-functional properties at runtime is needed. In this paper, we introduce a concept for runtime safety analysis and decision input for open adaptive systems. We combine static safety analysis and evidence collected during operation to analyse, reason and provide online recommendations to minimize deviation from a system’s safe states. We illustrate our concept via an abstract vehicle platooning system use case. / DEIS H2020 Project under Grant 732242.

No / In the automotive industry, modern cyber-physical systems feature cooperation and autonomy. Such systems share information to enable collaborative functions, allowing dynamic component integration and architecture reconfiguration. Given the safety-critical nature of the applications involved, an approach for addressing safety in the context of reconfiguration impacting functional and non-functional properties at runtime is needed. In this paper, we introduce a concept for runtime safety analysis and decision input for open adaptive systems. We combine static safety analysis and evidence collected during operation to analyse, reason and provide online recommendations to minimize deviation from a system’s safe states. We illustrate our concept via an abstract vehicle platooning system use case. / This conference paper is available to view at http://hdl.handle.net/10454/17415.

Coordination for truck platooning refers to the active formation of a group of heavy-duty vehicles traveling at close spacing to reduce the overall truck operations costs. Conventionally, this coordination is achieved by optimizing various truck-related parameters, such as schedules, velocities, and routes, based on an objective function that minimizes a certain cost, for example, fuel usage. However, prevalent algorithms for the coordination problem are typically integer-constrained, which are not only hard to solve but are not readily scalable to increasing fleet sizes and networks. In this paper, to overcome these limitations, we propose a centralized formulation to optimize the truck parameters and solve a multidimensional objective cost function including fuel, operation time costs and preferential penalty. Furthermore, to improve the scalability of our proposed approach, we propose a decentralized algorithm for the platoon coordination problem involving multiple fleets and objectives.We perform both theoretical and numerical studies to evaluate the performance of our decentralized algorithm against the centralized solution. Our analysis indicates that the computation time of the proposed decentralized algorithms is invariant to the increasing fleet size, at the cost of a small relative gap to the optimum cost given by the centralized method.We discuss these results and present future directions for research.

For an environmentally sustainable society thetransportation of goods must be optimized. The next step inmaking truck transportation more sustainable is platooning.Platooning is when vehicles drive close together in a line whichrequires implementation of a control system. The aim of thisproject is to tune and implement a stabilizing controller thatcan handle various scenarios. This paper proposes a PIDcontroller to solve the problem of achieving platooning. Using asimulation environment written in Python, the PID controlleris tuned for three specific scenarios; platooning, merging andsplitting. To obtain a smooth control signal setpoint weightingwas implemented. The results presented in the report show thatPID controller can create a stable platoon for the range oftested scenarios. However, these results are purely theoreticaland while promising, more tests must be done to determine ifthe results hold in practice. / För att kunna uppnå ett hållbart samhällemåste lastbilstransporter effektiviseras. Nästa steg i utvecklingenmot mer h°allbara lastbilstransporter är konvojkörning. Konvojkörning syftar på att fordon kör nära varandra i led. Dettäar dock inte möjligt för mänskliga chaufförer att åstadkommaoch därmed krävs det något typ av kontrollsystem. Syftet medprojektet är att konstruera en kontroller som kan hanteratre stycken scenarion, nämligen konvojkörning, separering ochsammanslagning. Rapporten föreslår en PID-regulator för atthantera dessa scenarion. En simuleringsmiljö byggdes upp iPython och där justerades reglerparametrarna för att klaraav uppgiften. För att göra PID-kontrollen stabil implementeradessetpoint-weighting. Resultaten visar att PID-regulatorn kanerhålla en stabil konvoj för de utförda testerna. Resultaten ärdock helt teoretiska och även om de är lovande måste fler testergöras innan konkreta slutsatser om hur lösningen fungerar ipraktiken kan dras. / Kandidatexjobb i elektroteknik 2021, KTH, Stockholm

The need for sustainable transportation solutions is urgent as the demand for mobility of goods and people is expected to multiply in the upcoming decades. One promising solution is truck platooning, which shows great potential in reducing the fuel consumption and operational costs of trucks.  In order to utilize the benefits of truck platooning to the fullest, trucks with different routes in a transportation network need coordination to efficiently meet and form platoons. This thesis addresses platoon coordination when trucks form  platoons at hubs, where some trucks need to wait for others in order to meet, and there is a reward for platooning and a cost for waiting. Three contributions on the topic platoon coordination are presented in this thesis. In the first contribution, we consider platoon coordination among trucks that have pre-defined routes in a network of hubs, and the travel times are either deterministic or stochastic. The trucks are owned by competing transportation companies, and each truck decides on its waiting times at hubs in order to optimize its own operational cost. We consider a group of trucks to form a platoon if it departs from a hub and enters the road at the same time. The strategic interaction among trucks when they coordinate for platooning is modeled by non-cooperative game theory, and the Nash equilibrium is considered as the solution concept when the trucks make their decisions at the beginning of their journeys. In case of stochastic travel times, we also develop feedback-based solutions wherein trucks repeatedly update their decisions. We show in a simulation study of the Swedish transportation network that the feedback-based solutions achieve platooning rates up to 60 %. In the second contribution, we propose models for sharing the platooning profit among platoon members. The platooning benefit is not equal for all trucks in a platoon; typically, the lead truck benefits less than its followers. The incentive for transportation companies to cooperate in platooning may be low unless the profit is shared. We formulate platoon coordination games based on profit-sharing models, and in a simulation of a single hub, the outcomes of the platoon coordination games are evaluated. The evaluation shows that the total profit achieved when the trucks aim to maximize their own profits, but the platooning benefit is evened out among platoon members, is nearly as high as when each truck aims to maximize the total profit in the platooning system.  In the last contribution, we study a problem where trucks arrive to a hub according to a stochastic arrival process. The trucks do not share a priori information about their arrivals; this may be sensitive information to share with others. A coordinator decides, based on the statistical distribution of arrivals, when to release the trucks at the hub in the form of a platoon. Under the assumption that the arrivals are independent and identically distributed, we show that it is optimal to release the trucks at the hub when the number of trucks exceeds a certain threshold. This contribution shows that simple and dynamic coordination approaches can obtain a high profit from platooning, even under high uncertainty and limited a priori information. / Under de kommande decennierna förväntas efterfrågan på transport av varor och passagerare mångfaldigas, vilket innebär att behovet av hållbara transportlösningar är brådskande. En lovande lösning är konvojkörning, som visar stor potential att minska bränsleförbrukningen och driftskostnaderna för lastbilar. För att utnyttja fördelarna med konvojkörning till fullo behöver lastbilar koordineras för att effektivt mötas och bilda konvojer. Den här avhandlingen behandlar koordinering av lastbilar som kan bilda konvojer på transporthubbar, där vissa lastbilar måste vänta på andra lastbilar för att bilda konvojer, och det finns en belöning för konvojkörning och en kostnad för att vänta. Tre bidrag som behandlar konvojkoordinering presenteras i den här avhandlingen. Det första bidraget behandlar koordinering av lastbilar med förutbestämda rutter i ett transportnätverk med deterministiska eller stokastiska restider. Lastbilarna ägs av konkurrerande transportföretag, och varje lastbil beslutar om sina väntetider på hubbarna längs med sin rutt för att optimera sin driftskostnad. Vi antar att lastbilar bildar en konvoj om de avgår från en hubb och kör in på vägen samtidigt. Den strategiska interaktionen mellan lastbilar när de koordinerar för konvojbildning modelleras med icke-kooperativ spelteori, och vi betraktar Nashjämvikt som lösningskoncept när lastbilarna beslutar om sina väntetider i början av sina resor. I fallet med stokastiska restider utvecklar vi även lösningar där lastbilarna tillåts uppdatera sina väntetider längs med sina resor. I en simuleringsstudie över det svenska transportnätverket visas att när lastbilarna tillåts uppdatera sina väntetider uppnås en konjovkörningsgrad på 60%. I det andra bidraget utreds modeller för att dela på vinsten från konvojkörning. Fördelarna med konvojkörning är inte lika för alla lastbilar i en konvoj; vanligtvis är fördelen större för följarlastbilarna än för ledarlastbilen. Således kan incitamenten för transportföretag att samarbeta i form av konvojkörning vara låga om inte vinsterna från konvojkörning delas. Baserat på vinstdelningsmodeller formulerar vi konvojkoordineringsspel. I en simulering av en transporthubb utvärderar vi utfallet från konvojkoordinationsspelen. Det visar sig att den totala vinsten som uppnås när lastbilarna försöker maximera sina egna vinster, men vinsten från konvojkörning jämnas ut helt bland konvojmedlemmar, är nästan lika hög som när varje lastbil försöker att maximera den totala vinsten i systemet. I det sista bidraget studeras ett koordineringsproblem där lastbilar anländer till en transporthubb enligt en stokastisk ankomstprocess. Lastbilarna delar inte förhandsinformation om sina ankomster; detta kan vara känslig information att dela. En koordinator bestämmer, baserat på den statistiska sannolikhetsfördelningen av ankomster, när lastbilarna på transporthubben ska släppas iväg i form av en konvoj. Under antagandet att ankomsterna är statistiskt oberoende och likafördelade, visar vi att det är optimalt att släppa iväg lastbilarna från transporthubben i form av en konvoj när antalet lastbilar överskrider en viss tröskel. Detta bidrag visar att enkla och dynamiska koordineringsmetoder kan erhålla en hög vinst från konvojkörning, även under hög osäkerhet och begränsad förhandsinformation. / <p>Länk till den offentliga granskningen tillkännages via: https://www.kth.se/profile/alexjoha</p><p>QC 20200609</p>

Vehicle platooning is an advanced vehicle maneuver that allows for the simultaneous control of several vehicles traveling on the roadway cite{al2010experimental}. Automated platoons, when activated in tractor trailer convoys, have a high potential of increasing the fuel efficiency and improving the utilization of roadways by allowing more vehicles to share the road at the same time. The increased fuel efficiency translates to lower cost on goods and motivates a more environmentally friendly and sustainable economy. In order to achieve the promised fuel savings from vehicle platooning, the vehicles need to follow each other at shorter headways than in typical driving scenarios. The reduced separation distance between the lead and follow vehicle reduces visibility and the reaction time available for the follow vehicle; this renders most modern Active Driver Assist Systems (ADAS) ineffective since they are not designed for operation in such short headway conditions. The focus of this work is related to understanding and improving the failures of Lane Keep Assist (LKA) systems in the follow vehicles of a platoon. In this work, the source of lane detection degradation when using a monocular forward facing camera in short headway platooning is identified. Furthermore, a novel lane augmentation algorithm is proposed to improve the lane detection capability of follow vehicles in a platoon. The lane augmentation process utilizes a longitudinal transformation of lane parameters from the lead to the follow vehicles. The transformation utilizes an accurate understanding of the relative spatial position and orientation of the two vehicles. The transformation also requires a reliable communication system between the two vehicles such as a Vehicle-to-Vehicle (V2V) module. The work presented in this thesis develops theory, simulation and verification using real world data of the proposed cooperative lane augmentation. The results of this work indicate that it is possible to improve vehicle platooning performance by distributing the required sensing across multiple agents of the platoon. / Master of Science / Vehicle platooning is an advanced vehicle maneuver that allows for the simultaneous control of several vehicles traveling on the roadway cite{al2010experimental}. Automated platoons, when activated in tractor trailer convoys, have a high potential of increasing the fuel efficiency and improving the utilization of our roadways by allowing more vehicles to share the road at the same time. The increased fuel efficiency translates to lower cost on goods and motivates a more environmentally friendly and sustainable economy. In order to achieve the promised fuel savings from vehicle platooning, the vehicles need to follow each other at closer distances (headway) than in typical driving scenarios. The reduced separation distance between the lead and follow vehicle reduces visibility and the reaction time available for the follow vehicle; this renders most modern Active Driver Assist Systems (ADAS) ineffective since they are not designed for operation in such short headway conditions. The focus of this work is related to understanding and improving the failures of Lane Keep Assist (LKA) systems - the automated system used to keep the vehicle in the center of the lane - in the follow vehicles of a platoon. In the proposed scenario, the LKA uses a single forward facing camera to detect the lane lines ahead of the vehicle. The detected lanes serve as inputs to the lateral position (steering) controller in order to keep the vehicle in the center of the lane. In this work, the source of lane detection degradation in a follow vehicle of a short headway platoon is identified. Furthermore, a novel cooperative lane detection algorithm is proposed to improve the lane detection capability of the follow vehicles. The proposed algorithm utilizes lane information transformed from the lead to follow vehicle frame. The transformation utilizes the relative spatial position and orientation of the two vehicles. Additionally, a reliable communication protocol between the vehicles is required to transport the lane information. The work presented in this thesis develops theory, simulation and verification using real world data of the proposed algorithm. The results of this work indicate that lane keeping performance in a platoon can be improved using cooperative lane detection.

Intelligent Transport Systems (ITS) are aiming to provide innovative services related to different modes of transport and traffic management, and enable various users to be better informed and make safer, more coordinated and smarter use of transport networks. Cooperative-ITS (C-ITS) support connectivity between vehicles, vehicles and roadside infrastructure, traffic signals as well as with other road users. In order to enable vehicular communications European Telecommunication Standards Institute (ETSI) delivered ITS-G5 -- a of set of C-ITS standards. Considering the goals of C-ITS, inter-vehicle communications should be reliable and efficient. In this thesis we study the performance, efficiency, and dependability of ITS-G5 communications for Cooperative adaptive cruise control (C-ACC) and platooning C-ITS applications. We provide an overview of currently available and ongoing standardization targeting communications in C-ACC/platooning. We study the performance of ITS-G5 beaconing in a C-ACC/platooning scenario, where we show that its performance may deteriorate when implemented in cooperative driving applications due to the kinematic-dependent design of the message triggering mechanism. We explain in detail the cause of this phenomenon and test it for a wide range of parameters. Also, we study the influence of different available ITS-G5 legitimate setups on the C-ACC/platooning fuel efficiency and demonstrate that proper communication setup may enhance fuel savings. This thesis also proposes a jamming denial-of-service attack detection algorithm for platooning. The main advantage of our detector is its short learning phase that not exceed a second and low detection delay of a few hundreds of milliseconds. Under some assumptions, the proposed algorithm demonstrates the ability to detect certain types of attacks with average probability above 0.9. / ACDC

<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>

Esta dissertação de mestrado apresenta um estudo do processo de formação de pelotões em rodovias de pista simples brasileiras e a dispersão desses pelotões nas faixas adicionais de subida. Este estudo foi realizado usando-se dados empíricos coletados na SP 255, uma rodovia de pista simples do estado de São Paulo. Um dos trechos estudados possuía faixas adicionais nos aclives e o outro era sem faixas adicionais. Para caracterizar a formação de pelotões, três aspectos foram estudados: a porcentagem de veículos em pelotões, o tamanho médio dos pelotões e a recomposição dos pelotões após o término de uma faixa adicional. Modelos matemáticos foram adaptados para representar o processo de formação de pelotões em rodovias brasileiras. Visando fornecer subsídios para futuros projetos de faixas adicionais, a dispersão dos pelotões nas faixas adicionais de subida foi analisada considerando-se as seguintes medidas de desempenho: taxa de ultrapassagem, velocidade média da corrente, porcentagem de veículos em pelotões e comprimento de faixa para a dispersão dos pelotões. Os resultados do estudo da dispersão dos pelotões mostram que as faixas adicionais melhoram o nível de serviço não apenas na direção onde são implantadas, mas também na direção do tráfego oposto uma vez que cerca de 70 a 75% do fluxo no sentido analisado divergem para as faixas adicionais, proporcionando uma porcentagem maior de gaps adequados para a dispersão dos pelotões do fluxo oposto. / This master thesis presents a study of the platoon formation process in the Brazilian two-lane roads and the dispersion of these platoons in the passing lanes. This study was developed using empirical data collected in the SP 255, a two-lane road of the state of São Paulo. One of the segments studied had passing lanes on upgrades and another was without passing lanes. In order to characterize the platoon formation, three aspects were studied: the percent of vehicle in platoon, the mean platoon size and the platoon recomposition after the end of a passing lane. Mathematical models were adapted to represent the platoon formation in the Brazilian roads. Aiming to aid future auxiliary lanes projects, the platoon dispersion in the climbing lanes was analyzed considering the following service measures: overtaking rate, mean speed, percent of vehicle traveling in platoons and lane length used to disperse the platoons. The results of the platoons dispersion study show that the auxiliary lanes improve the level of service not only in the direction of they are constructed, but also in the opposing flow. It\'s verified that around 70 to 75% of the flow in the analyzed direction diverge to auxiliary lanes, providing a greater percentage of gaps suitable to platoon dispersion in the opposing flow.