No description available.

The research on autonomous vehicles, and more specifically cooperation between autonomous vehicles, has become a prominent research field during the last cou- ple of decades. One example is the combination of an unmanned aerial vehicle (UAV) together with an unmanned ground vehicle (UGV). The benefits of this are that the two vehicles complement each other, where the UAV provides an aerial view and can reach areas where a ground vehicle can not. Furthermore, since the UAV has a limited range, the UGV can then serve as transport and recharge sta- tion for the UAV. This master thesis studies how model predictive control (MPC) can be used to land a UAV on a moving UGV.  A linear MPC is chosen, since previous work using this has shown promising results. The UAV is chosen to be controlled using commands in pitch, roll and climbing rate. The MPC is designed as a decoupled controller, with a separate horizontal and vertical controller. This allows for a spatial constraint to be im- plemented, which constrains the UAV from entering ground level before arriving above the UGV. It also constrains the UAV from potentially hitting protruding ob- jects on the UGV. The horizontal controller uses a simple planner, which guides the UAV to land on the UGV from behind.  The MPC is evaluated using a additive white Gaussian noise (AWGN) sen- sor error model with zero mean. The scenario used is that the UAV starts 50 m from the UGV, and the UGV starts driving in a given direction turning randomly. The MPC lands successfully in 100 % of the simulations for a wide range of tun- ings. The MPC maintains the same landing statistics with a delay in the sensor information of up to 500 ms. The AWGN could be increased while maintaining successful landings, however with significantly more retakes and longer landing times. Lower AWGN variance only slightly improves performance, suggesting that the MPC is quite robust towards high variance in the state estimation.  The MPC is also compared to a PID controller. The MPC has significantly shorter landing times. The PID has a more oscillatory control signal, however, the PID has a lower variance in landing positions, but a slightly less centered mean on the UGV. The overall results show that an MPC can be used to achieve a flexible controller that can be tuned and reformulated to fit the situation, and performs as good or better compared to a PID controller.  The hardware tests show promising results for the implementation of the MPC. The controller is not tuned and no system identification is done specifi- cally for the physical UAV, suggesting that the controller is robust for varying settings. Even though the UAV never lands on the UGV, the visual behavior and control signal plots suggest that it would be able to land. However, these tests are performed using global navigation satellite system state estimation on a sta- tionary UGV, therefore further tests need to be performed in more challenging scenarios.

A system of an unmanned aerial vehicle (UAV) collaborating with an unmanned ground vehicle (UGV) for use in for example surveillance, reconnaissance, transport and target acquisition is studied. The project investigates the problem of estimating the relative position, velocity and orientation between the UAV and the UGV required to autonomously land the UAV on the UGV during movement. The use of global navigation satellite system (GNSS) receivers are not considered since they are sensitive to interference and spoofing attacks.  The developed estimation system consists of an extended Kalman filter (EKF) using measurements from several sensors, including: a camera, barometers, inertial measurement units (IMUs) and impulse-radio ultra-wide bandwidth (IRUWB) transceivers. Primarily the use of near infrared (NIR) light emitting diodes (LEDs) attached to the UGV and a camera on the UAV is investigated. Several configurations of LED placements, and what errors to expect when measuring them with the camera, are evaluated. The performance is evaluated in both simulations and hardware sensor tests, but no live experiments that include any autonomous landing manoeuvre are conducted.  The results indicate that high estimation precision can be achieved, at close range the errors in position average below 2 cm and in orientation under 0.5 degrees. However, some problems arise from the detection and identification of the LEDs. Further, if measurements of the LEDs are completely missing, the estimation precision suffers due to error accumulation in the inertial navigation. These results indicate that autonomous landing is possible, since the amount of LED measurements and consequently also the estimation precision increases as the relative position decreases.

Transportation is the main source of environmental noise in Europe, with an estimated 125 million people affected by excessive noise levels from road traffic, causing a burden of noise related diseases and having a substantial economic impact on society. In order to reduce exposure to high levels of traffic noise, two approaches are the topic of extensive research: preventing sound from propagating from roads and railways using for example noise barriers, and reducing the sources of noise themselves. The second solution, which addresses directly the cause of the problem, requires improved design methods, with a more systematic resort to multi-functional design. Addressing cross-functions simultaneously reduces the number of design iterations and the high cost of prototyping. The work presented in this thesis aims at developing methods that can be used to design quieter vehicle concepts within a multi-functional approach, and is articulated around two main axis of research, aerodynamic sound generation and sound propagation. The first axis aims at performing an aeroacoustic analysis to predict aerodynamic sound sources. A hybrid method is used on the example of a type of submerged air inlet called a NACA duct, where the near-field flow is solved through detached eddy simulation (DES) and where the far-field acoustics is computed using the Ffowcs Williams and Hawkings integral. Results for the flow for various operating conditions are presented and validated against experimental data from the literature, with very good agreement. Far-field acoustic results are shown, exhibiting levels and components that are strongly dependent on the operating conditions. This analysis gives a framework for future aeroacoustic analysis in the project, and sets the path for the development of air inlets with improved aerodynamic and aeroacoustic characteristics. The second axis focuses on the propagation of sound from a given source, moving in an urban environment. An approximate boundary method is presented, which relies on the Kirchhoff approximation applied to the Kirchhoff-Helmholtz integral equation. Using this approximation speeds up the computational time compared to using a regular boundary element method. The resulting expression is extended to account for multiple scattering through consecutive updates of the surface pressures, and for moving sources through the introduction of a retarded time and of a Doppler shift. Validation tests for this method are presented, from simple scatterers to a more realistic configuration, showing good agreement with analytical, experimental and simulated work. / Fordon är den främsta källan till bullerexponering i Europa med uppskattningsvis 125 miljoner människor som är utsatta för höga ljudnivåer från vägtrafik, vilket kan orsaka bullerrelaterade häsloproblem samt har en betydande ekonomisk effekt på samhället. För att minska exponeringen för höga ljudnivåer från fordon, finns det två angreppssätt som båda idag är ämne för omfattande forskning: att förhindra ljudutbredning från vägar och järnvägar (till exempel med hjälp av bullerskydd), samt att minska ljudnivån från olika bullerkällor. Den sistnämnda, som direkt riktar sig till problemets orsak, kräver förbättrade designmetoder med mer systematisk användning av multifunktionell design. Att hantera flera funktioner hos fordonet samtidigt minskar antalet designiterationer och den höga kostnaden för prototyper. Arbetet som presenteras i denna avhandling syftar till att utveckla metoder som kan användas för att utforma tystare fordonskoncept inom ramen för en multifunktionell strategi och fokuserar på två spår i forskningen: aerodynamisk ljudalstring och ljudutbredning från rörliga källor. Det första spåret i forskningen syftar till att utföra en aeroakustisk undersökning för att modellera aerodynamiska ljudkällor. En hybridmetod tillämpas på ett typ av nedsänkt luftintag, kallat NACA-intag, där källområdet i strömningen löses genom detached eddy simulation (DES) och akustiken i fjärrfältet beräknas enligt Ffowcs Williams och Hawkings integral. Resultat för strömningen för olika driftförhållanden presenteras och valideras mot experimentella data från litteraturen, med mycket god överensstämmelse. Resultat för det akustika fjärrfältet visas, vilket uppvisar nivåer och komponenter som är starkt beroende av driftförhållandena. Denna analys ger en ram för kommande analyser av aeroakustik inom projektet och visar vägen för utvecklingen av luftintag med förbättrade aerodynamiska och aeroakustika egenskaper. Det andra spåret i forskningsprojektet är inriktat på ljudets utbredning från en given källa som rör sig i en urban miljö. En approximativ randvärdesmetod presenteras som bygger på Kirchhoff approximation tillämpad på Kirchhoff-Helmholtz integralekvation. Med hjälp av denna approximation minskas beräkningstiden jämfort med vanlig boundary element method (BEM). Modellen utvecklas sedan för att kunna hantera flera reflektioner genom att det akustiska trycket på ytorna uppdateras för varje reflektion samt för att kunna hantera rörliga källor genom att introducera tidsfördröjningar och Dopplerförskjutning. Validering för denna modell presenteras, från enkla spridare till en mer realistisk urban konfiguration, som visar god överensstämmelse med analytiskt, experimentellt och simulerat data. / <p>QC 20151002</p>

Real-Time Rollover prevention of Unmanned Ground Vehicle (UGV) is very paramount to its reliability and survivability mostly when operating on unknown and rough terrains like mines or other planets.Therefore this research presents the method of real-time rollover prevention of UGVs making use of Adaptive control techniques based on Recursive least Squares (RLS) estimation of unknown parameters, in order to enable the UGVs to adapt to unknown hush terrains thereby increasing their reliability and survivability. The adaptation is achieved by using indirect adaptive control technique where the controller parameters are computed in real time based on the online estimation of the plant’s (UGV) parameters (Rollover index and Roll Angle) and desired UGV’s performance in order to appropriately adjust the UGV speed and suspension actuators to counter-act the vehicle rollover. A great challenge of indirect adaptive control system is online parameter identification, where in this case the RLS based estimator is used to estimate the vehicles rollover index and Roll Angle from lateral acceleration measurements and height of the centre of gravity of the UGV. RLS is suitable for online parameter identification due to its nature of updating parameter estimate at each sample time. The performance of the adaptive control algorithms and techniques is evaluated using Matlab Simulink® system model with the UGV Model built using SimMechanics physical modelling platform and the whole system runs within Simulink environment to emulate real world application. The simulation results of the proposed adaptive control algorithm based on RLS estimation, show that the adaptive control algorithm does prevent or minimize the likely hood of vehicle rollover in real time. / Electrical and Mining Engineering / M. Tech. (Electrical Engineering)

No description available.

This thesis presents a human interface which helps users efficiently allocate multiple unmanned ground vehicles (UGVs) cooperating to accomplish timing-sensitive missions in an urban environment. The urban environment consists of obstacles and a hazardous region. The obstacles represent a "no-go zone" while the hazardous region represents a high-risk area. The main object of this problem is to minimize the team operational cost while satisfying timing constraints. Operational costs for individual vehicles are based on risk and power consumption, and are calculated using path length and vehicle velocity. In this thesis, three types of timing constraints are considered: simultaneous arrival, tight sequential arrival, and loose sequential arrival. Coordination variables and functions are the strategy by which both temporal and spatial information is used to achieve cooperative timing at a minimum cost. Specifically, coordination variables and functions are used to plan trajectories for a team of UGVs that satisfy timing constraints. The importance of properly representing information to users, allowing them to make efficient decisions, is also discussed. Four different control interfaces (temporal, spatial, cost, and coordination variable/function control) were tested. A full factorial design of experiments was performed with response time, workload, and quality of decision as metrics used to evaluate the quality and effectiveness of each interface. Based on the results of this experiment, a final graphical user interface (GUI) was designed and is described. It incorporates a combination of coordination variable/function control and cost control. This GUI is capable of planning paths for vehicles based on cooperative timing constraints and enables users to make high quality decisions in deploying a group of vehicles.

Unmanned vehicle systems, specifically unmanned air vehicles (UAVs) and unmanned ground vehicles (UGVs), have become a popular research topic. This thesis discusses the potential of a UAV-UGV system used to track a human moving through complex urban terrain. This research focuses on path planning problems for both a UAV and a UGV, and presents effective solutions for both problems. In the UAV path planning problem, we desire to plan a path for a miniature fixed-wing UAV to fly through known urban terrain without colliding with any buildings. We present the Waypoint RRT (WRRT) algorithm, which accounts for UAV dynamics while planning a flyable, collision-free waypoint path for a UAV in urban terrain. Results show that this method is fast and robust, and is able to plan paths in difficult urban environments and other terrain maps as well. Simulation and hardware tests demonstrate that these paths are indeed flyable by a UAV. The UGV path planning problem focuses on planning a path to capture a moving target in an urban grid. We discuss using a target motion model based on Markov chains to predict future target locations. We then introduce the Capture and Propagate algorithm, which uses this target motion model to determine the probabilities of capturing the target in various numbers of steps and with various initial UGV moves. By applying some different cost functions, the result of this algorithm is used to choose an optimal first step for the UGV. Results demonstrate that this algorithm is at least as effective as planning a path directly to the current location of the target, and that in many cases, this algorithm performs better. We discuss these cases and verify them with simulation results.

Den snabba utvecklingen av autonomi och fjärrstyrning för obemannade enheter har lett till ett behov inom militären att utforska samspelet mellan användare och olika obemannade enheter, för att kartlägga behov för framtida gränssnitt. Det finns ett tydligt behov av alternativa gränssnitt till de handhållna styrdon som används i dagsläget, då dessa har visat sig ha begränsningar gällande situationsmedvetenhet och kognitiv förmåga hos operatören - något som är särskilt viktigt i högrisksituationer. Det finns vidare belägg för att ett armburet styrdon har potential att möta dessa behov hos framtida gränssnitt. Denna studie undersöker därför möjliga utformningar för ett armburet gränssnitt, och utreder hur väl konceptuella utformningar passar det specifika användningsområdet avsutten spaning i högrisksituation för markförband. Genomgående är fokus att genom en iterativt och användarcentrerad studie kartlägga och precisera behov samt generera konceptuella prototyper utifrån detta. Inledningsvis görs en litteraturstudie, vars resultat sammanställs i ett antal designprinciper för utformning av gränssnitt för obemannade fordon inom militära sammanhang. Principerna används vidare i idé- och konceptgenereringen samt vid framtagandet av lofi-prototyper. Lofi-prototyperna som visualiserar olika koncept för armburna gränssnitt utvärderas därefter i ett användartest med fokusdiskussioner. Detta är den första av två iterationer i användarstudien. Vidare utvecklas ett slutgiltigt helhetskoncept, vilket utvärderas i det andra användartestet. Fokus i studien har vid det här laget riktat in sig specifikt mot användningsområdet avsutten spaning i högrisksituationer för markförband, och utvärderar genom storytelling hur väl ett armburet gränssnitt passar användningsområdet. Resultaten från det första användartestet visar att ett armburet gränssnitt bör utformas som ett komplement till ett huvudstyrdon, samt att det är viktigt att det utformas utifrån soldatnas utrustning och miljö genom att vara litet, lätt och tåligt. Vidare visar resultatet att gränssnittet bör fokusera på mottagandet av information framför att skicka information, och att det bör utformas i syfte att ge användaren snabba, kortfattade notiser om viktig information som enkelt läses av på armen utan att soldaten behöver avbryta sina arbetsuppgifter eller lägga ned sitt vapen. Fysiska knappar, ljusdisciplin samt vibrationer som återkoppling är andra aspekter som resultatet visar är intressanta att undersöka vidare. Resultatet från första iterationen används för att utveckla ett slutgiltigt slutkoncept till det andra användartestet, vilken gestaltas i en prototyp i lera som visualiserar storleken på gränssnittet, likt en smartklocka, och ett antal fysiska knappar. Genom storytelling där deltagarna får ha på sig prototypen på armen och leva sig in i ett realistiskt scenario utvärderas hur väl denna typ av gränssnitt passar användaren och användningsområdet. Resultatet från det andra användartestet visar att ett litet, smidigt gränssnitt på armen som ger snabb, kortfattad information är fördelaktigt i högrisksituationer och spaningssituationer där man behöver gömma sig eller agera dolt. Gränssnittet behöver därmed inte kunna ge detaljerad information och ha avancerad interaktion, utan bör istället fungera i syfte att på ett tyst och snabbt sätt ge en varning genom exempelvis en vibration eller en symbol på skärmen. Således kan användaren få snabba, direkta alert-notiser som signalerar nivån av fara – vilket är efterfrågat i just högrisksituationer – innan man genom exempelvis radiokommunikation kan få mer detaljerad information om faran. Ett annat viktigt resultat från användarstudien är att gränssnittet inte enbart bör fokusera på information från och interaktion med obemannade enheter, utan även interaktion med människor. Det kan exempelvis vara genom att få information från en plutonchef, och kunna bekräfta mottagandet av informationen och eventuellt även kunna svara med korta, förutbestämda textmeddelanden. Detta tillsammans med resultatet om att gränssnittet bör fokusera på mottagande av information gör att studiens fokus ändras från det initiala: interaktion med obemannade enheter, till att istället fokusera på mottagande av information från andra soldater, chefer samt obemannade system. Slutsatser som dras är att gränssnittet bör vara utformat som ett litet, smidigt kompletterande gränssnitt på armen, som ger användaren snabba, direkta notiser med kortfattad information som exempelvis signalerar fara, för att det ska passa användningsområdet. Vidare dras slutsatsen att mängden funktioner som är autonoma i systemet påverkar både utformningen och situationsmedvetenhet, och att detta är ett komplext och till viss del motsägande område att undersöka vidare. Framtida studier anses således kunna beröra områden såsom hur mycket autonomi som är eftersträvansvärt samt hur haptisk återkoppling kan användas i högrisksituationer. / The rapid development of autonomy and remote control within unmanned vehicles has led to a need within the military to explore the interaction between users and various unmanned units, in order to map needs for future interfaces. There is a need for alternative interfaces to the hand-held control devices that are used today, as these have been shown to have limitations regarding situation awareness and cognitive workload of the operator – something that is particularly important in high-risk situations. There is further evidence that an arm mounted controller has the potential to meet these needs of future interfaces. This study therefore examines possible designs for an arm mounted interface and investigates how well conceptual designs fit the specific area of use; high-risk dismounted reconnaissance for ground units. Throughout, the focus is to map and specify needs through an iterative and user centered study and generate conceptual prototypes based on this. Initially, a literature study is carried out, the results of which are compiled into several design principles for the design of interfaces for unmanned vehicles in military contexts. The design principles are further used in idea and concept generation as well as in the development of lofi prototypes. The lofi prototypes that visualize different concepts for an arm mounted interface are then evaluated in a user test with focus discussions. This is the first of two iterations of the user study. Furthermore, a final overall concept is developed, which is evaluated in the second user test. At this point, the focus of the study has been directed specifically at the area of use for scouting in high risk situations for ground units and evaluates through storytelling how well an arm mounted interface fits the area of use. The results from the first user test show above all that an arm mounted interface should be designed as a complement to a main control unit, and that it is important that it is designed based on the soldiers' equipment and environment by being small, light and durable. Furthermore, the results show that the interface should focus on receiving rather than sending information, and that it should be designed to provide the user with quick, concise notices of important information that are easily read on the arm without the soldier having to interrupt his duties or put down his weapon. Physical buttons, light discipline and vibrations as feedback are other aspects that the results show is interesting to investigate further. The result from this first iteration is used to develop a final concept for the second user test, which is embodied in a prototype in clay that visualizes the size of the interface, like a smart watch, and several physical buttons. Through storytelling where the participants get to wear the prototype on their arm and experience a realistic scenario, it is evaluated how well this type of interface suits the user and the area of use. The results from the second user test show that a small, flexible interface on the arm that provides quick, concise information is beneficial in high-risk situations and reconnaissance situations where you need to hide or act covertly. The interface therefore does not need to be able to provide detailed information and have advanced interaction but should instead function with the aim of quietly and quickly giving a warning through, for example, a vibration or a symbol on the screen. Thus, the user can receive quick, direct alert notices that signal the level of danger – which is in demand in high-risk situations in particular – before, for example, radio communication can provide more detailed information about the danger. Another important result of the user study is that the interface should not only focus on information from and interaction with unmanned devices, but also interaction with people. This can be, for example, by receiving information from the command group or a platoon leader and being able to confirm receipt of the information and possibly also be able to respond with short, predetermined text messages. This together with the result that the interface should focus on receiving information causes the focus of the study to change from the initial: interaction with unmanned units, to instead focus on receiving information from other soldiers, managers, and unmanned systems. Conclusions drawn are that the interface should be designed as a small, flexible supplementary interface on the arm, which provides the user with quick, direct notifications with concise information such as signaling danger, in order for it to fit the area of use. Furthermore, it is concluded that the number of functions that are autonomous in the system affects both the design and situational awareness, and that this is a complex and somewhat contradictory area to investigate further. Future studies are thus considered to be able to touch on areas such as how much autonomy is desirable and how haptic feedback can be used in high-risk situations.

The rapid growth of E-commerce around the world has prompted related stakeholders to place a greater emphasis on automation. Catastrophes like pandemics are boosting the public demand for quick and efficient transportation, among others. Automated vehicle technologies are associated with the last-mile delivery operations that lead to improving sustainability and Smart Cities. In this context, Autonomous Vehicles are being explored as a viable urban logistics solution.This empirical thesis conducts a feasibility study to investigate the feasibility of incorporating an Autonomous Vehicle into E-commerce operations in Stockholm, Sweden. A case study is analyzed by foodora AB, a German company that operates as a distributor of food and goods in the Swedish market. The study provides a framework that depicts the issues faced by Q- commerce, Operational Planning, and Stakeholders, respectively when introducing Autonomous Vehicles. The results of the study’s qualitative and quantitative approach show that Stockholm's infrastructure is in line with the sustainability plans and is considered ready for droid operations. According to the findings, the utilization rate that is defined as the number of orders delivered per hour can be as high as 2.4 resulting in a high degree of customer satisfaction. However, regulations, classifications, weather conditions, and internet connectivity continue to be major challenges. Autonomous Vehicles must be included in legislative consideration as a mode of transportation in the future to facilitate operations and safety measures. / Den snabba tillväxten av e-handel runtom i världen har fått närstående intressenter att lägga större vikt vid automatisering. Katastrofer som pandemier ökar allmänhetens krav på bland annat snabba och effektiva transporter. Autonoma fordon är förknippade med ”last-mile” transporter av gods som leder till förbättrad hållbarhet och smarta städer. I detta sammanhang utforskas autonoma fordon som en livskraftig citylogistik-lösning.Denna empiriska avhandling genomför en genomförbarhetsstudie för att undersöka möjligheten att integrera ett autonomt fordon i e-handelsverksamheten i Stockholm, Sverige. I synnerhet analyseras en fallstudie av foodora AB, ett tyskt företag som är verksamma som distributör av matvaror på den svenska marknaden. Studien ger ett ramverk som visar de frågor som Q-handel, operativ planering respektive intressenter står inför vid ett införande av autonoma fordon. Resultaten av studiens kvalitativa och kvantitativa tillvägagångssätt visar att Stockholms infrastruktur är i linje med hållbarhetsplanerna och till synes redo för droid leveranser. Enligt resultaten kan utnyttjandegraden, definierad som antal utförda orderleveranser inom en timme, vara så hög som 2,4, vilket resulterar i en hög grad av kundtillfredsställelse. Regler, klassificeringar, väderförhållanden och internetanslutning är dock fortfarande stora utmaningar. Autonoma fordon måste tas med i lagstiftningen som ett transportmedel i framtiden för att underlätta drift och säkerhetsåtgärder.