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Technical Paper

Application of Force Balance Method in Accident Reconstruction

In the field of accident reconstruction, there has been a significant amount of effort devoted to the calculation and derivation of vehicle crush energy and vehicle stiffness. ...This ultimately increases the accuracy of the overall accident reconstruction. In this paper, examples will be given to illustrate the use of such a methodology. ...But, oftentimes, crush profiles and/or crush stiffnesses are not available and accident constructionists face the situation of insufficient information. In some such cases, the force balance method can be used to reduce the uncertainty.
Journal Article

Comparison of Heavy Truck Engine Control Unit Hard Stop Data with Higher-Resolution On-Vehicle Data

These data provide useful information to accident reconstruction personnel. In past studies, these data have been analyzed and compared to higher-resolution on-vehicle data for several heavy trucks and several makes of passenger cars. ...The goal of this study was to help accident reconstruction professionals better understand engine ECU “hard stop” data currently available on most commercial vehicles.
Technical Paper

Vehicle Handling and Control Following Front Ball Joint Failure

Following many accidents, one of the involved vehicles is found with partial or total separation of one of its wheels. ...In those cases, it is often asserted that before the accident occurred one of the involved vehicles might have undergone a sudden loss of control as a result of a spontaneous partial or total wheel separation. ...Next some case studies of accidents involving wheel loss are examined. Finally, the results of a series of tests are discussed in which ball joint failures are caused to occur as the vehicle is being driven.
Technical Paper

Scenario Regeneration using a Hardware-in-the-loop Simulation Platform to Study ABS and ESC Performance Benefits

In this study, the HIL simulation environment was used to recreate a simulation of an actual accident scenario involving a single tractor semi-trailer combination. The scenario was then simulated with and without an antilock brake system (ABS) and electronic stability control (ESC) system to investigate the crash avoidance potential afforded by the tractor equipped with the safety systems. ...The crash scenario was interpreted as a path-following problem, and three possible driver intended paths were developed from the accident scene data. The driver-intended paths were set up in the HIL simulation environment and simulated with and without driver model braking, ABS, and ESC to determine the potential crash avoidance advantages afforded by the systems.
Technical Paper

Modeling of a 6×4 Tractor and Trailers for Use in Real Time Hardware in the Loop Simulation for ESC Testing

The 2010 accident statistics NHTSA's report reveals that large trucks have a fatal accident involvement rate of 1.22 vehicles per 100 million vehicle miles traveled compared to 1.53 for light trucks and 1.18 for passenger cars. ...This translates to a fatal accident involvement rate of 32.35 vehicles per 100,000 registered large trucks compared to 17.02 for light trucks and 13.09 for passenger cars.
Technical Paper

Engine and Load Torque Estimation with Application to Electronic Throttle Control

The first method is based on the reconstruction of the in-cylinder pressure based on the measured engine block vibration. The second one exploits a nonlinear estimation technique, in which the difference between the instantaneous measurement of crankshaft angular velocity and an estimate of the same velocity, based on a model of the engine, forms the input to a sliding-mode observer.
Technical Paper

Response of the 6-Month-Old CRABI in Forward Facing and Rear Facing Child Restraints to a Simulated Real World Impact

The data from these instruments is examined and compared to the observed kinematics for each dummy, and to the injuries suffered in the actual accident. It is shown that the forward facing front seat placement of the 6-month-old and infant/car seat exposes that occupant to at least twice the accelerations and forces compared to rear-facing placement in the rear seat.
Technical Paper

Smart Icing Systems for Aircraft Icing Safety

Aircraft incidents and accidents in icing are often the result of degradation in performance and control. However, current ice sensors measure the amount of ice and not the effect on performance and control.
Technical Paper

Drive Scenario Generation Based on Metrics for Evaluating an Autonomous Vehicle Controller

An important part of automotive driving assistance systems and autonomous vehicles is speed optimization and traffic flow adaptation. Vehicle sensors and wireless communication with surrounding vehicles and road infrastructure allow for predictive control strategies taking near-future road and traffic information into consideration to improve fuel economy. For the development of autonomous vehicle speed control algorithms, it is imperative that the controller can be evaluated under different realistic driving and traffic conditions. Evaluation in real-life traffic situations is difficult and experimental methods are necessary where similar driving conditions can be reproduced to compare different control strategies. A traditional approach for evaluating vehicle performance, for example fuel consumption, is to use predefined driving cycles including a speed profile the vehicle should follow.
Journal Article

Vehicle Coast Analysis: Typical SUV Characteristics

Typical factors that contribute to the coast down characteristics of a vehicle include aerodynamic drag, gravitational forces due to slope, pumping losses within the engine, frictional losses throughout the powertrain, and tire rolling resistance. When summed together, these reactions yield predictable deceleration values that can be related to vehicle speeds. This paper focuses on vehicle decelerations while coasting with a typical medium-sized SUV. Drag factors can be classified into two categories: (1) those that are caused by environmental factors (wind and slope) and (2) those that are caused by the vehicle (powertrain losses, rolling resistance, and drag into stationary air). The purpose of this paper is to provide data that will help engineers understand and model vehicle response after loss of engine power.
Technical Paper

Delta-V, Barrier Equivalent Velocity and Acceleration Pulse of a Vehicle During an Impact

Delta-V and Barrier Equivalent Velocity (BEV) are terms that have been used for many years to describe aspects of what happened to a vehicle when an impact occurred. That is, they are used to describe some physical change in the vehicle state before the impact as compared to after the impact. Specifically, the Delta-V describes the change in the vehicle velocity vector from just before the impact until just after the impact. The BEV attempts to quantify the energy required to cause the damage associated with an impact. In order to understand what happens to a vehicle and its occupants during an impact, it is necessary to examine the acceleration pulse undergone by the vehicle during the impact. The acceleration pulse describes, in detail, how the Delta-V occurs as a function of time, and is related with the deformation of the vehicle as well as the object contacted by the vehicle during an impact.
Technical Paper

Characterization of Vehicle Occupant Compartment Material Properties Using MADYMO: Methodology and Validation

During a motor-vehicle collision, an occupant may interact with a variety of interior structures. The material properties and construction of these structures can directly affect the occupant's kinetic response. Simulation tools such as MADYMO (Mathematical Dynamical Models) can be used to estimate the forces imparted to an occupant for injury mechanism and causation evaluation relative to a particular event. Depending on the impact event and the specific injury mechanism being evaluated, the selection of proper material characteristics can be quite important. A comprehensive literature review of MADYMO studies illustrates the prevalent use of generic material characteristics and the need for improved property estimation and implementation methods.
Journal Article

The Design of a Suspension Parameter Identification Device and Evaluation Rig (SPIDER) for Military Vehicles

This paper describes the mechanical design of a Suspension Parameter Identification Device and Evaluation Rig (SPIDER) for wheeled military vehicles. This is a facility used to measure quasi-static suspension and steering system properties as well as tire vertical static stiffness. The machine operates by holding the vehicle body nominally fixed while hydraulic cylinders move an “axle frame” in bounce or roll under each axle being tested. The axle frame holds wheel pads (representing the ground plane) for each wheel. Specific design considerations are presented on the wheel pads and the measurement system used to measure wheel center motion. The constraints on the axle frames are in the form of a simple mechanism that allows roll and bounce motion while constraining all other motions. An overview of the design is presented along with typical results.
Technical Paper

Suspension Parameter Measurement Using Side-Pull Test To Enhance Modeling of Vehicle Roll

This paper describes a new laboratory test facility for measuring suspension parameters that affect rollover. The Side-Pull mechanism rolls the test vehicle through a cable attached rigidly at its center of gravity (CG). Changes in wheel camber and wheel steer angles are measured as a function of body roll angle. The roll test simulates a steady-state cornering. Thus, both compliance and kinematic forces are fed simultaneously to the vehicle as they would be applied in a real cornering situation. The lateral load transfer, and roll angle as a function of simulated lateral acceleration is determined. The Side-Pull Roll Measurement has advantages over the conventional roll tests where the rolling force couple is applied vertically. The Side-Pull mechanism rolls the vehicle in a unrestricted way with horizontal forces applied at the tire / pad contact and the CG location. Thus, the measurements take into account coupling of compliance with roll.
Technical Paper

Fast Algorithm for On-Board Torque Estimation

Electronic Throttle Control systems substitute the driver in commanding throttle position, with the driver acting on a potentiometer connected to the accelerator pedal. Such strategies allow precise control of air-fuel ratio and of other parameters, e.g. engine efficiency or vehicle driveability, but require detailed information about the engine operating conditions, in order to be implemented inside the Electronic Control Unit (ECU). In order to determine throttle position, an interpretation of the driver desire (revealed by the accelerator pedal position) is performed by the ECU. In our approach, such interpretation is carried out in terms of a torque request that can be appropriately addressed knowing the actual engine-vehicle operating conditions, which depend on the acting torques. Estimates of the torque due to in-cylinder pressure (indicated torque), as well as the torque required by the vehicle (load torque), must then be available to the control module.
Technical Paper

Comparison of Collision and Noncollision Marks on Vehicle Restraint Systems

Markings or observable anomalies on vehicle seat belt restraint systems can be classified into two categories: (1) Those caused by collision forces, or “loading marks” and (2) those created by noncollision situations, or “normal usage marks” [1]. A survey was conducted of both crash tested and non-crash tested vehicles in order to collect data on both categories of markings. This paper examines and analyzes the markings caused by both collision and noncollision load scenarios in order to illustrate and evaluate their unique differences as well as provide a general pattern of severity relative to different loading conditions.
Technical Paper

Experimental Evaluation of Fishhook Maneuver Performance of a Kinetic Suspension System

Kinetic Pty Ltd and Tenneco Automotive have developed a passive suspension system called a Kinetic system. The motivation for the design of the system is discussed, and the function of the system is explained. The system improves handling, stability, and ride by passively decoupling roll stiffness from articulation stiffness and roll damping from bounce damping. Improved stability is evaluated by conducting NHTSA's Roll Rate Feedback Fishhook tests on a small SUV equipped with the Kinetic system. Results of the testing are presented, and benefits to rollover are discussed.