Method for Benefit Prediction of Passenger Car Post Impact Stability Control
Examensarbete för masterexamen
Vehicle traffic safety has been attracting considerable attention with an increasing amount of accidents registered in road traffic statistics. Multiple-impact events accident, which accounts for 1/4 to 1/3 of all passenger car accidents, normally causes more severe injury than single-collision accidents. It is common that the car loses directional stability after the first external impulse. Current Electronic Stability Control (ESC) systems are well designed for vehicle yaw motion control due to aggressive driving maneuvers, but not for that under external disturbances on the car body. A post impact stability control (PISC) system is thus envisioned to avoid or mitigate the subsequent events after the first PISC-triggering collision in multiple-impact events accident. In the work presented in this master thesis, a method for benefit prediction of passenger car post impact stability control system is formulated, based on accident statistics and vehicle dynamics simulations. The Germany In-depth Accident Study database is accessed so as to investigate the problematic areas for PISC solution and to select representative accident scenarios as input to a case-by-case simulation study. To gain further understanding of the critical vehicle dynamics situations after being exposed to external disturbances, vehicle motions are reconstructed between the 1st and 2nd events using a passenger car simulation model in MATLAB/Simulink. Using the results from both accident analysis and vehicle dynamics simulations, benefit measures are determined for each representative scenario which can well reflect the 2nd event problems taking the accident environmental factors into account. In the end, PISC benefit is predicted by quantifications on each selected benefit measure, using a PISC function that selects between two controllers, i.e. Differential Braking and Lock Front Axle. It is found out that reduction of kinetic energy is quite necessary and feasible by aggressive braking interventions. It is also found out that robust yaw rate, body side slip angle and path control are specially required under post impact circumstances. Thereafter, requirements on the improvement of each critical measure can be generated and utilized throughout the function development process, especially for the algorithm optimizations.
Farkostteknik , Vehicle Engineering