The Accuracy and Sensitivity of 2003 and 2004 General Motors Event Data Recorders in Low-Speed Barrier and Vehicle Collisions

Abstract

This study evaluates the accuracy of crash data stored in the airbag sensing and diagnostic modules (SDMs) of General Motors vehicles in low speed crashes. A secondary objective was to determine the sensitivity of the SDMs to specific collision pulse parameters such as speed change, peak acceleration and duration. First, three 2004 vehicles underwent 136 vehicle-to-barrier and vehicle-to-vehicle collisions with speed changes up to 8 km/h. Then, 2003 and 2004 model year SDMs underwent a range of crash pulses using a linear sled. In all of the tests, the speed change reported by the SDM underestimated the actual speed change. The speed change underestimates ranged from 0.2 to 2.9 km/h, except for several anomalous tests in which the underestimate was as high as 12.3 km/h. The magnitude of this error varied with crash pulse shape. Increasing crash pulse duration and decreasing peak acceleration increased the difference between the actual and SDM reported speed change. The threshold accelerations for the SDMs tested ranged from 1.1 to 2.7 g. Threshold acceleration models explain the variations in accuracy. The accuracy curves generated are suitable for use in collisions which fall within the scope of the collision severities and types tested. If the SDM's threshold acceleration is known, the accuracy of a different model year SDM can be calculated.