Felisolering av hytt- och chassikomponenter på tunga fordon
This master of science thesis is focusing on how the fault handling on hardware connected toa control unit on a Scania vehicle is working. To the hardware counts buttons levers, sensorsand CAN. The work has been concentrated upon how the fault handling is working and if it ispossible to find any new fault modes.The control unit that has been studied is called the Coordinator and is the core in Scanias threenetworks of control units. The Coordinators work is to transmit messages between the threenetworks and to process signals from buttons, levers and sensors. The values is then usedinternally or is sent to other control units on the CAN networks. The work has been dividedinto three parts: a literature study about different methods and notations in fault detection anddiagnosis, an analyze about the fault handling of the hardware and one analyze about theCAN-traffic.The fault handling on the Coordinator is built upon different, often very simple test. Most ofthe tests are plausibility tests or of limit check type. To improve the fault handling asuggestion is to use tests that look more on how faults appear based on time. One such test hasbeen made to find faults whit a common error cause. Time based tests can also detect glitch ina contact or unnatural behaviour.Because one of the Coordinators tasks is to transfer messages between the different CANnetworksthe CPU-load will be affected of the bus-load. A test showed that there is a linearrelation between the bus-load and the CPU-load. Information about the bus-load can improvethe fault isolation on CAN errors. If the bus-load is high the fault is depending on a high busload.If the busload is normal or low the fault is very likely depending on a physical fault as afaulty control unit or a broken network.A future work is to lock at systematic faults that can appear when hardware is not connectedcorrect.