Robert Larson

Vehicle Rollover Testing, Methodologies in Recreating Rollover Collisions

Rollover crashes are complex events with many factors influencing the initiation of the rollover and the subsequent motion of the vehicle. There exists a need for testing methods that can accurately replicate conditions that happen in real-world rollovers. This chapter, from a comprehensive text on occupant and vehicle responses in rollovers, presents two testing methodologies that consider how to create rollover tests that closely mimic a specific accident scenario and thus that are useful in accident reconstruction and evaluation of vehicle performance in specific situations. The authors describe the development of the Roller Coaster Dolly (RCD), a text fixture that can release a vehicle at speed onto flat or sloping terrain with any desired initial roll, pitch, and yaw angle. The authors also describe a test methodology that utilizes a crashworthy steering controller. This method can replicate and study the entire crash sequence of an on-road maneuver-induced rollover. The authors describe and illustrate (photographs) the use of both tests, concluding that these tests expand the realm of rollover collision scenarios that can be recreated by testing.

Electromyographic activity and posturing of the human neck during rollover tests

Lateral head motions, torso motions, lateral neck bending angles, and electromyographic (EMG) activity patterns of five human volunteer passengers are compared to lateral motions of a Hybrid III ATD during right-left and left-right fishhook steering maneuvers leading to vehicular tip-up. While the ATD maintained relatively fixed lateral neck angles, live subjects leaned their heads slightly inward and actively utilized their neck musculature to stiffen their necks against the lateral inertial loads. Except for differences in neck lateral bending, the Hybrid III ATD reasonably reflects occupant kinematics during the pre-trip phase of on-road rollovers.

Development of a computational method to predict occupant motions and neck loads during rollovers

The mechanics of on-road, friction-induced rollovers were studied with the aid of a three-dimensional computer code specifically derived for this purpose. Motions of the wheels, vehicle body, occupant torso, and head were computed. Kanes method was utilized to develop the dynamic equations of motion in closed form. On-road rollover kinematics were compared to a dolly-type rollover at lesser initial speed, but generating a similar roll rotation rate. The simulated on-road rollover created a roof impact on the leading (drivers) side, while the dolly rollover simulation created a trailing-side roof impact. No head-to-roof contacts were predicted in either simulation. The first roof contact during the dolly-type roll generated greater neck loads in lateral bending than the on-road rollover. This work is considered to be the first step in developing a combined vehicle and occupant computational model for studying injury potential during rollovers.

Heavy Truck Rollover Crashworthiness: Testing Methods and Development of Recommended Practices

Testing methods and SAE (Society of Automotive Engineers) Recommended Practices were developed for evaluating both the ability of a truck cab to resist roof loading in a rollover environment and the occupant kinematics and injury potential for occupants in a 90-degree heavy truck rollover. In evaluating a heavy truck roof for its ability to resist rollover loads, real-world accident data was analyzed and full-scale tests were performed to define the rollover environment. It was found that testing methods currently in place for passenger cars were not sufficient to represent the loading mechanisms that typically occur in a heavy truck rollover. An SAE Recommended Practice (RP) for both dynamic and quasi-static roof load testing was developed, and tests were conducted to evaluate their use. To evaluate heavy truck occupant safety in a 90-degree rollover, independent of roof intrusion, a rollover simulator was developed. The simulator allows occupant restraints, seats, and interiors to be evaluated for injury mechanisms. An RP for the full cab rollover simulator was written and evaluated with a series of tests. (A) For the covering abstract see ITRD E106540.

Single-Vehicle Rollovers Involving an Initial Off-Roadway Excursion Followed by a Return to Roadway: A NASS Study and Vehicle Response Measurement

This paper will describe an investigation that seeks to understand how rollovers occur in real-world crashes, both by studying real-world crashes and by analyzing vehicle-handling tests to gain insights into potential mechanisms of pre-crash loss of control. In particular, this study focuses on one type of rollover, namely single-vehicle rollovers that follow a pattern of the vehicle first leaving the roadway and then returning to the roadway typically out-of-control. The aims of this study included the following: (1) to describe the frequency and characteristics of single-vehicle rollovers involving an off-roadway excursion followed by a complete, if only temporary return to the roadway; (2) to the extent possible, given available data, to assess the nature and consequences of driver inputs during the crash sequence; (3) to define characteristics of crash scenarios which include a substantial proportion of this subset of single-vehicle rollovers. In order to accomplish these aims, case files from the National Automotive Sampling System, Crashworthiness Data System (NASS CDS, 1997-2001) were reviewed. The overall purpose of this review was to understand the mechanisms involved with loss of control and provide this information to support further research on preventing loss of control on the roadway subsequent to off-roadway excursion and roadway reentry. To further illustrate the mechanism that leads to loss of control when a vehicle returns to the roadway, the results of testing conducted to compare a vehicles response to steering maneuvers on pavement versus the same steering maneuvers initiated on a road edge is presented. This paper presents the results of these tests, focusing on the effect that the change in surface has in amplifying the yaw rate and sideslip response of the vehicle. Finally, the results of the testing are compared to the insights gained from the NASS CDS real-world crash study, to garner further insight into some of the mechanisms involved with this type of accident.

Testing and Analysis of Autonomous Emergency Braking Systems Using the Euro NCAP Vehicle Target

Passenger cars are increasingly available equipped with Autonomous Emergency Braking (AEB). AEB systems detect likely forward collisions and apply the vehicle’s brakes if the driver fails to do so, reducing vehicle speed in order to mitigate or potentially avoid a collision. The performance of these systems is experimentally evaluated in tests including those specified by the European New Car Assessment Program (Euro NCAP) and by the Insurance Institute for Highway Safety (IIHS). In both of these testing programs the subject vehicle is driven towards a Euro NCAP Vehicle Target, an inflatable device designed to have visual and radar reflective characteristics similar to the rear of a compact car.The results reported by Euro NCAP and the IIHS have revealed significant differences in the AEB test results achieved by various AEB-equipped vehicles. Such differences exist even between vehicles with similar sensing technologies, suggesting that the source of such disparities may be differences in sensor data processing methods or differences in collision mitigation and avoidance strategies. This paper details the performance of AEB as well as Forward Collision Warning (FCW) systems when tested with the Euro NCAP Vehicle Target. These results are analyzed, exploring the differences in the performance of these systems under the test conditions and discussing possible reasons for the observed disparities.Copyright