This thesis describes the mechanical design of a prototype vehicle developed for a company located in California. The project was based on an earlier vehicle located at KTH, Transport Labs, and investigated if the existing concept for the vehicle would work as a concept for an autonomous prototype, with focus on component layout and increased forces. The design of the vehicle is based on a concept with a carbon fiber bottom plate, two separate suspension modules with electric hub motors and steer by wire. In addition a steering interface, seats and a roll cage is added to the base. Quadrant symmetric design and four wheel steering/drive makes the vehicle move equally good forward and reverse. The steering is controlled by individual rotating actuators mounted at each wheel, meaning that the vehicle, apart from acquiring a low turning radius also can angle the wheel in the same direction and drive with so called crab steer where the car is moving sideways without rotating itself. The brake system contains a regular manual hydraulic brake system in parallel with an autonomous brake system. The project was started by generating a list of requirements. This was then considered when doing the design in CAD (Solid Edge). The design was validated with ADAMS (MBS) and ANSYS Workbench (FEA). The majority of the project was carried out in Sweden at KTH where the driveline of the vehicle was designed and assembled. The driveline was then transported to California where the vehicle was finalized and tested. The test carried out indicated that the concept was working as a prototype but that some of the components needed to be upgraded. All tests needed was not carried out which led to that the maximum speed of the vehicle was limited to 40 km/h Further durability-, and high load tests will be carried out in order to, with suitable safety, raise the maximum speed. The maximum steering angle of each wheel acquired was 23 degrees that, with four wheel steering, means an effective steering angle of 46 degrees. The cars minimum turning radius was around 5 meters. / Detta examensarbete beskriver den mekaniska konstruktionen av ett prototypfordon för ett företag beläget i Kalifornien. Projektet utgick från ett befintligt fordon på KTH, Transport Labs och undersökte hur vida det befintliga konceptet för det fordonet fungerade för en autonom prototyp, med särskilt hänseende till komponentplacering och ökade krafter. Fordonet är konstruerad runt en bottenplatta av kolfiber, två separata hjulupphängningar med elektriska navmotorer och så kallad ”steer by wire” samt kompletteras med ett förargränssnitt, säten och rullbur. Kvadrant symmetriska design och fyrhjuls styrning/drivning gör att fordonet för sig lika bra framåt som bakåt. Styrningen sköts av en individuell roterande motor fäst vid varje hjul vilket innebär att fordonet, utöver att få en låg svängradie, även kan vinkla alla hjul åt samma håll och uppnå så kallad krabbstyrning där bilen rör sig i sidled utan att själv rotera. Bromssystemet består av ett vanligt manuellt hydrauliskt bromssystem parallell kopplat med ett autonomt aktiverat bromssystem. Projektet inleddes med generering av en kravspecifikation. Denna låg sedan som grund för konstruktionen som genomfördes i Solid Edge (CAD). Konstruktionen validerades med hjälp av ADAMS (MBS) och ANSYS Workbench (FEM). Största delen av projektet genomfördes i Sverige på KTH där drivlinan av fordonets konstruerades och monterads. Denna flögs sedan till Kalifornien där fordonet färdigställdes och testades på plats. De genomförda testerna tydde på att konceptet fungerade bra som prototyp men att vissa komponenter behövde uppgraderas. Full testning han inte genomföras vilket ledde till att den maximala hastigheten begränsades till 40 km/h. Vidare uthållighets- och höglasttester kommer genomföras för att, på ett säkert sätt, kunna öka den maximala tillåtna hastigheten. Den maximala styrvinkeln för varje hjul uppgick till 23 grader vilket, med fyrhjulningsstyrning, innebär en effektiv styrvinkel på 46 grader. Bilens minimi svängradie uppgick till cirka 5 meter.

Previous studies have shown that many drivers are unable to provide the right amount of steering torque when facing an imminent collision with an upcoming obstacle. In some cases, drivers under-react i.e., they provide too low steering inputs and thus collide with the obstacle in front; in other cases, drivers might apply a higher steering input than necessary, potentially resulting in the vehicle leaving the road or losing stability. The EMA function is an active safety feature which has the sole objective of providing steering torque interference when performing such a manoeuvre. The motivation for the thesis work is to overcome some limitations of the existing MA function which does not incorporate the ability to differentiate driver reactions. In this thesis, an Evasive Manoeuvre Assist (EMA) function is designed to adapt to both types of the drivers, by an optimised steering torque overlay. The existing current EMA function is always amplifying the driver steering inputs using a feed-forward controller. The focus of this thesis work is to identify and dene a proper steering sequence reference model for closed-loop feedback control design. A simple single-point preview model is designed first to calculate the reference steering angle. A few test scenarios are set-up using the IPG CarMakerTMsimulation tool. The reference model is then tuned with respect to the amplitude and frequency by batch simulations to obtain the optimal steering prole. A feedback controller is then designed using this reference model. The controller is implemented in a real-time environment, using a Volvo rapid-prototype test vehicle. Preliminary variation tests have shown that the developed controller can enhance both an over-reacting and under-reacting driver's performance during an evasive manoeuvre, by applying assistance/resistance EPAS torque timely. The designed EMA function is shown to accommodate different driver reactions and provide intuitive torque interference. As opposed to the earlier notion that the EMA function only assists the driver with an additional steering wheel torque, it was shown that the optimal steering torque overlay might be in the form of assistance or resistance.

The introduction of autonomous vehicles in traffic is driven by expected gains in multiple areas, such as improvement of health and safety, better resource utilization, pollution reduction and greater convenience. The development of more competent algorithms will determine the rate and level of success for the ambitions around autonomous vehicles. In this thesis work an intersection management system for a mix of autonomous and manually driven vehicles is created. The purpose is to investigate the strategy to combine turn intention prediction for manually driven vehicles with scheduling of autonomous vehicle. The prediction method used is support vector machine (SVM) and scheduling of vehicles have been made by dividing the intersection into an occupancy grid and apply different safety levels. Real-life data comprising recordings of large volumes of traffic through an intersection has been combined with simulated vehicles to assess the relevance of the new algorithms. Measurements of collision rate and traffic flow showed that the algorithms behaved as expected. A miniature vehicle based on a prototype for an autonomous RC-car has been designed with the purpose of testing of the algorithms in a laboratory setting. / Införandet av autonoma fordon i trafiken drivs av förväntade vinster i flera områden, såsom förbättring av hälsa och säkerhet, bättre resursutnyttjande, minskning av föroreningar och ökad bekvämlighet. Utvecklingen av mer kompetenta algoritmer kommer att bestämma hastigheten och nivån på framgång för ambitionerna kring autonoma fordon. I detta examensarbete skapas ett korsningshanteringssystem för en blandning av autonoma och självkörande bilar. Syftet är att undersöka strategin att kombinera prediktion av hur manuellt styrda bilar kommer att svänga med att schemalägga autonoma bilar utifrån detta. Prediktionsmetoden som använts är support vector machine (SVM) och schemaläggning av bilar har gjorts genom att dela upp korsningen i ett occupancy grid och tillämpa olika säkerhetsmarginaler. Verklig data från inspelningar av stora volymer trafik genom en korsning har kombinerats med simulerade fordon för att bedöma relevansen av de nya algoritmerna. Mätningar av kollisioner och trafikflöde visade att algoritmerna uppträdde som förväntat. Ett miniatyrfordon baserat på en prototyp av en självkörande radiostyrd bil har tagits fram i syfte att testa algoritmerna i laboratoriemiljö.