The Accuracy and Sensitivity of 2005 to 2008 Toyota Corolla Event Data Recorders in Low-Speed Collisions

Collision related data stored in the airbag control modules (ACM's) of Toyota vehicles can provide useful information to collision investigators, including both front and rear collision severity. Previous studies of ACM's from other manufacturers found that the devices underestimated the actual speed change in low speed frontal collisions. To quantify the accuracy and sensitivity of select 2005 to 2008 Toyota ACM's, in-vehicle crash tests and linear sled tests were performed in both front and rear impact orientations. A 2005 Toyota Corolla with five extra ACM's mounted in the right front seat position underwent a series of vehicle-to-barrier collisions with speed changes of up to 10 km/h. Next, the same six Toyota ACMs underwent a range of crash pulses using a linear sled. In all in-vehicle tests, the speed change reported by the ACM underestimated the actual speed change for frontal collisions, and overestimated the actual speed change for rear-end collisions. The speed change underestimates ranged from 1.3 to 2.6 km/h and the speed change overestimates ranged from 0.6 to 2.2 km/h. The magnitude of the error varied with collision duration and peak acceleration. Threshold accelerations required to initiate the recording of an event were found to be between 2.0 and 2.1g for all of the ACM's tested. A model using the threshold accelerations and a bias was generated to explain the speed change error. This study provides an understanding into the accuracy of the Toyota ACM reported speed change at low speeds and the collision parameters which can affect it.