Modeling And Analysis Of Fault Conditions In Avehicle With Four In-Wheel Motors

University essay from KTH/Fordonsdynamik

Abstract: A vast expansion is found in the field of automotive electronic systems. The expansion iscoupled with a related increase in the demands of power and design. Now, this is goodarena of engineering opportunities and challenges. One of the challenges faced, isdeveloping fault tolerant systems, which increases the overall automotive and passengersafety. The development in the field of automotive electronics has led to the innovationof some very sophisticated technology. However, with increasing sophistication intechnology also rises the requirement to develop fault tolerant solutions.As one of many steps towards developing a fault tolerant system, this thesis presents anexhaustive fault analysis. The modeling and fault analysis is carried out for a vehicle withfour in-wheel motors. The primary goal is to collect as many of the possible failuremodes that could occur in a vehicle. A database of possible failure modes is retrievedfrom the Vehicle Dynamics research group at KTH. Now with further inputs to thisdatabase the individual faults are factored with respect to change in parameters of vehicleperformance. The factored faults are grouped with respect to similar outputcharacterization.The fault groups are modeled and integrated into a vehicle model developed earlier inMatlab/Simulink. All the fault groups are simulated under specific conditions and theresults are obtained. The dynamic behavior of the vehicle under such fault conditions isanalyzed. Further, in particular the behavior of the vehicle with electronic stabilitycontrol (ESC) under the fault conditions is tested. The deviation in the vital vehicleperformance parameters from nominal is computed.Finally based on the results obtained, a ranking system termed Severity Ranking System(SeRS) is presented. The severity ranking is presented based on three essential vehicleperformance parameters, such as longitudinal acceleration ( ), lateral acceleration ( )and yaw rate ( ̇ ). The ranking of the faults are classified as low severity S1, mediumseverity S2, high severity S3 and very high severity S4. A fault tolerant system must beable to successfully detect the fault condition, isolate the fault and provide correctiveaction. Hence, this database would serve as an effective input in developing fault tolerantsystems.

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