A General Approach to Study the Reliability of Complex Systems

摘要

In recent years new complex systems have been developed in the automotive field to increase safety and comfort. These systems integrate hardware and software to guarantee the best results in vehicle handling and make products competitive on the market. However, the increase in technical details and the utilization and integration of these complicated systems require a high level of dynamic control system reliability. In order to improve this fundamental characteristic methods can be extracted from methods used in the aeronautical field to deal with reliability and these can be integrated into one simplified method for application in the automotive field. Firstly, as a case study, we decided to analyse VDC (the Vehicle Dynamics Control system) by defining a possible approach to reliability techniques. A VDC Fault Tree Analysis represents the first step in this activity: FTA enables us to recognize the critical components in all possible working conditions of a car, including cranking, during 'key-on'-'key-off phases, which is particularly critical for the electrical on-board system (because of voltage reduction). By associating FA (Functional Analysis) and FTA results with a good FFA (Functional Failure Analysis), it is possible to define the best architecture for the general system to achieve the aim of a high reliability structure. The paper will show some preliminary results from the application of this methodology, taken from various typical handling conditions from well established test procedures for vehicles.