An Automated Procedure for Implementing Steer Input during Ditch Rollover CAE Simulation

Vehicle manufacturers conduct tests to develop crash sensing system calibrations. Ditch fall-over is one of a suite of laboratory tests used to develop rollover sensing calibrations that can trigger deployment of safety devices like roof rail airbags and seat belt pretensioners. The ditch fall-over test simulates a flat road followed by a ditch on one side of the road. The vehicle heads into the ditch and the driver applies swift steer input once the ditch slope is sensed. Typically, the steer input is applied when the two down-slope wheels on the ditch side enter the ditch. Multi-Body Dynamics (MBD) software can be used for virtual simulation of these test events. Conventionally in simulations, the vehicle-model is run without steer input and the marking line crossing time is observed/manually recorded from observation of simulation video. This recorded time is used to apply the steer input and the full event is then re-simulated. This latched time varies with respect to vehicle speed, initial location of vehicle, etc. Time latching is very important to apply steer input consistently in every simulation run. There is very little literature available on time latching in simulations. In this research, an algorithm for mimicking automatic steering input for ditch rollover simulation was developed and implemented. A sensor feature in MBD software solver is used to latch the time of crossing the marking line. The sensor and time latching combination is used to trigger the steer input. Thus, the steer input becomes simple, free from manual errors and automatic. It also accounts for changes in initial speed, initial location of vehicle, etc.