Knowing how much fuel there is in a car is important for a predictable driving experience. Such knowledge will dictate how a person drives, when to refuel and how long they can drive. However unprocessed fuel level signals are highly noisy and therefore misleading.To ensure a good and predictable driving experience it is important to estimate the fuel level. The way this thesis has tackled this problem is by comparing and evaluating different filtering methods.The estimation algorithms were designed based on a saddle type tank developed by Volvo Car Corporation. The fuel level sensor consists of a floater arm and can only detect fuel levels within its maximal and minimal positions. The tank size can deviate from the standard volume and it will affect the measurement. Acceleration, angular orientation and fuel consumption are all factors that disturb fuel level estimation and therefore their relationship to the estimation problem is investigated. An experiment was devised to investigate the relationship between angular orientation, fuel volume and fuel level readings. ARX based models were made including angular orientation or acceleration. The relationship was concluded to be non-linear. The Kalman, $H_{\infty}$, Particle and Recursive Least Squares filters were compared. The Kalman and RLS filters had the most desirable traits and were therefore further developed. Both Kalman and RLS resulted in smooth estimates on the driving cycles tested.The Kalman filter provided a steadier estimate and could be easily tuned for faster convergence to zero. The Kalman filter can easily be changed to accommodate parametric uncertainties which improve its robust qualities.However the relationship between angular orientation and fuel level readings are non-linear. Therefore the RLS method was considered more robust for a reduced biased fuel reading under angular orientations. In conclusion the most desirable filter is a filter that provides the best traits from both filters.

Nowadays, road vehicles, including trucks, are characterized by an increasedcomplexity due to a greater variety of software, and a greater number of sensorsand actuators. As a consequence, there is an increased risk in termsof software or hardware failures that could lead to unacceptable hazards.Thus safety, more precisely functional safety, is a crucial property that mustbe ensured to avoid or mitigate these potential unacceptable hazards. Inthe automotive domain, recently (November 2011), the ISO-26262 safetystandard has been introduced to provide appropriate requirements and processes.More specically, the standard denes the system development processthat must be carried out to achieve a system that can be consideredacceptably safe. To be released on the market, systems must be certied,proofs that the systems are acceptably safe must be provided in terms of astructured argument, known as safety case, which inter-relates evidence andclaims. Certication authorities are in charge of evaluating the validity ofsuch safety cases. In the automotive domain, certication and compliancewith the standard ISO-26262 is becoming mandatory. By now, trucks donot have to be compliant with the standard. However, it is likely that by2016 they will have to. Scania is one of the leading companies in trucksdevelopment. To be ready by 2016, Scania is interested in investigatingISO-26262 as well as safety case provision. Thus this thesis focuses on theprovision of a safety case in the context of ISO-26262 for Fuel Level Estimationand Display System (FLEDS), which is one of the safety-criticalsystems in Scania.1

Safety-critical systems require high quality and dependability levels, where system correctness and safety are major features to avoid any severe outcome. Time and cost are also important challenges that are imposed during the development process. Describing the behavior of a system in a high level provides a realistic vision and anticipation of the system. This presents a valuable opportunity for verifying the system before wasting the intended resources to develop the system. Architecture Description Languages (ADLs) provide the ability to comprise and represent the system level details of components, interactions and configuration. Architecture Analysis and Design Language (AADL) as a family member of ADLs proved its effectiveness in designing software intensive systems. In this report, we present a case study to validate “An Architecture-Based Verification Technique for AADL Specifications”. The technique involves a combination of model checking and model-based testing approaches adapted to an architectural perspective. The objectives of the verification process are 1) to ensure completeness and consistency of an AADL specification, and 2) to ensure conformance of an implementation with respect to its AADL specification. The technique has only been applied to small examples, and the goal of this thesis work is to validate it against a safety-critical system developed by a major vehicle manufacturer. Validation of the technique begins by investigating the system and specifying it in AADL. The defined verification criteria are subsequently applied to the AADL specification which drives the verification process. The case study presents interesting results while performing the model checking (the completeness and consistency checking). Conformance testing, on the other hand, could not be performed on the implemented system but is an interesting topic for future work.

Model-based development is one of the most significant areas in recent research and development activities in the field of automotive industry. As the field of software engineering is evolving, model based development is gaining more and more importance in academia and industry. Therefore, it is desirable to have techniques that are able to identify anomalies in system models during the analysis and design phase instead of identifying them in development phase where it is difficult to detect them and a lot of time, effort and resources are required to fix them. Model checking is a formal verification technique that facilitates the identification of defects in system models during early stages of system development. There are a lot of tools in academia and industry that provide the automated support for model checking.  In this master thesis a vehicle control system of Scania the Fuel Level Display System is modeled in two different model checking tools; Simulink Design Verifier and UPPAAL. The requirements that are to be satisfied by the system model are verified by both tools. After verifying the requirements against the system model and checking the model against general design errors, it is established that the model checking can be effectively used for detecting the design errors in early development phases and can help developing better systems. Both the tools are analyzed depending upon the features supported. Moreover, relevance of model checking is studied with respect to ISO 26262 standard.

This report deals with a thesis in product development and design. This degree project was a final course on the program "Mechanical Engineering - Product Development and Design" at Jönköping University - School of engineering, and was conducted together with Husqvarna Group AB. The project has been carried out by Daniel Flyckt and Oscar Lernstål. The project has been to design and develop a prototype that will help the customer see the fuel level in Husqvarna's chainsaws in an easier way. Today’s solution is a viewing window on one of the sides of the tank. This viewing window partly fulfils its function, but there is definitely room for improvement. The viewing window has had productionrelated problems and it costs Husqvarna money because it becomes an extra step in the process to get a complete for the chainsaws that are ready to use. In order to get a better idea of how to solve the problem with the fuel indication interviews and a competitor analysis were made. This gave a better overview of the project and also gave insight of how competitors had solved the same problem. After that a requirement specification was written to get a solid base in the project. This requirement specification was to great help during the project and used when the concepts that we developed were to be evaluated. Last but not least it was time to make the model that past the screening of the concepts. Catia (a CAD program) was used and the prototype was printed in a SLS and SLA machine. The end result of the project was a prototype that could be tested under simpler conditions, with clearly improved properties in terms of being able to give an indication of fuel. / Denna rapport behandlar ett examensarbete i produktutveckling och design. Detta examensarbete var en avslutande kurs på programmet ”Maskinteknik – Produktutveckling och design” på Jönköpings Tekniska Högskola och genomfördes tillsammans med Husqvarna Group AB. Projektet har genomförts av Daniel Flyckt och Oscar Lernstål. Projektet har gått ut på att utveckla och ta fram en prototyp för att på ett nytt sätt se bränslenivån i Husqvarnas motorsågar. På äldre motorsågar som Husqvarna har sålt finns i dagsläget inget sätt att se mängden bränsle i tanken och dagens lösning innebär att man sätter ett siktfönster på en av tankväggarna. Detta siktfönster uppfyller delvis sin funktion, men det finns definitivt möjlighet till förbättringar. Siktfönstret har haft produktionsrelaterade problem och det kostar givetvis Husqvarna pengar eftersom det blir ett extra steg i arbetet att få en färdig tank till motorsågarna. För att få en bild av hur problematiken såg ut runt bränsleindikationen på morsågen gjordes intervjuer och en konkurrentanalys. Detta för att få en bättre överblick men även för att se hur konkurrenter hade löst samma problem. Senare skrevs en kravspecifikation för att få något att falla tillbaka på under arbetets gång. Denna kravspecifikation användes framgångsrikt när koncepten som togs fram i projektet skulle utvärderas. Sist men inte minst var det dags för att CAD:a upp den modell som gick vidare i gallringen av koncepten. Programvaran Catia användes och prototypen printades ut i en SLS-maskin respektive SLA-maskin. Slutresultatet av projektet blev en prototyp som kunde testas i enklare förhållanden. Med klart förbättrade egenskaper vad gäller att kunna ge en indikation på bränsle jämfört med enbart ett siktfönster.

This work inkluse measurement principles for measuring liquid level in tanks with a focus on fuel. Are described most frequently used types of liquid level sensors, focusing on fuel. The work inkluse design chosen technical solutions fuel level sensor and its technical implementation, including the technical implementation and verification of its functionality and calibration.