Research on the influencing factors of steering system FTTI based on CRITIC weighting method

As an important parameter of the functional safety of the electric power steering (EPS), fault tolerance time interval (FTTI) needs to be determined during the vehicle design stage. The existing methods usually determine FTTI by means of real vehicle testing or simulation. However, in the design stage, there is no real vehicle available for testing, nor is there rea l vehicle test data to build a vehicle model. Therefore, it is not easy to be applied in actual engineering development. In this paper, taking the safety goal “Avoid loss of steering assistance” as the object, the key influencing parameters of FTTI of steering system are analyzed. The CRITIC (Criteria Importance Through Intercriteria Correlation) weighting method is used to determine the influence weights of different parameters on FTTI, and the FTTI comprehensive scores of different vehicle models are calculated. The comprehensive scores are then used to evaluate the FTTI values of specific vehicle models. By using this method, the FTTI value can be determined more accurately in the design stage, reducing costs and improving development efficiency.