Dennis A. Guenther

Measured Vehicle Inertial Parameters- NHTSA's Data Through November 1998

This chapter, from a comprehensive text on occupant and vehicle responses in rollovers, consists primarily of a printed listing of the National Highway Traffic Safety Administrations (NHTSA) Light Vehicle Inertial Parameter Database which cover 496 vehicles. Part one of the listing contains vehicle description and configuration data, plus wheelbase, track width, roof height, weight, and test comments. Part two contains vehicle description and configuration data, C.G. position, moments of inertia, roll/yaw products of inertia, tilt table ratio, and static stability factor data. The authors also offer a brief discussion of the accuracy of inertial measurements, including selected graphs of quantities listed in the database for some of the 1998 model year vehicles tested. Electronic copies of the Light Vehicle Inertial Parameter Database, which also contain Vehicle Identification Numbers (VIN) for the vehicles tested, may be obtained by contact Dr. W.R. Garrott (riley.garrott@nhtsa.dot.gov).

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 NHTSAs 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.

Active roll control for rollover prevention of heavy articulated vehicles with multiple-rollover-index minimisation

This paper presents the application of a nominal control design algorithm for rollover prevention of heavy articulated vehicles with active anti-roll-bar control. This proposed methodology is based on an extension of linear quadratic regulator control for ‘state derivative-induced (control coupled) output regulation’ problems. For heavy articulated vehicles with multiple axles, a performance index with multiple rollover indices is proposed. The proposed methodology allows us to compare the usefulness of various control configurations (i.e. actuators at different axles of the vehicle) based on the interaction of this control configuration with vehicle dynamics. Application of this methodology to a specific heavy articulated vehicle with a tractor semi-trailer shows that a single active anti-roll-bar system at the trailer unit gives better performance than multiple-axle actuators at tractor and trailer together with the single lane change manoeuvre as the external disturbance. Thus, the proposed methodology of this paper not only highlights the importance of the interactions between control and vehicle dynamics in rollover prevention problems but, in fact, proposes a novel technique to exploit the benefits of these interactions judiciously.

New Model for Simulating the Dynamics of Pneumatic Heavy Truck Brakes with Integrated Anti-Lock Control

This paper introduces a new nonlinear model for simulating the dynamics of pneumatic-over-mechanical commercial vehicle braking systems. The model employs an effective systems approach to accurately reproduce forcing functions experienced at the hubs of heavy commercial vehicles under braking. The model, which includes an on-off type ABS controller, was developed to accurately simulate the steer, drive, and trailer axle drum (or disc) brakes on modern heavy commercial vehicles. This model includes parameters for the pneumatic brake control and operating systems, a 4s/4m (four sensor, four modulator) ABS controller for the tractor, and a 2s/2m ABS controller for the trailer. The dynamics of the pneumatic control (treadle system) are also modeled. Finally, simulation results are compared to experimental data for a variety of conditions.

In-Depth Analysis of the Influence of High Torque Brakes on the Jackknife Stability of Heavy Trucks

Published NHTSA rulemaking plans propose significant reduction in the maximum stopping distance for loaded Class-VIII commercial vehicles. To attain that goal, higher torque brakes, such as air disc brakes, will appear onprime movers long before the trailer market sees significant penetration. Electronic control of the brakes on prime movers should also be expected due to their ability to significantly shorten stopping distances. The influence upon jackknife stability of having higher performance brakes on the prime mover, while keeping traditional pneumatically controlled s-cam drum brakes on the trailer, is discussed in this paper. A hybrid vehicle dynamics model was applied to investigate the jackknife stability of tractor-semitrailer rigs under several combinations of load, speed, surface coefficient, and ABS functionality. These simulations were run to simulate brake-in-turn (B.I.T.) scenarios for a tractor-semitrailer articulated vehicle which is near the maximum drive-through speed limit for various vehicle weight / surface coefficient conditions. ECBS-disc brake equipped tractors were directly compared to those having s-cam drum brakes. This study shows that the simulated presence of ECBS-disc brakes on the tractor results in no degradation of the performance of the rig, in terms of jackknife stability, while braking in a turn. Furthermore, the elaborate vehicle simulations showed significant reduction in the tractor maximum yaw rate and hitch articulation angle seen during the simulation, for those simulated vehicles equipped with disc brakes and electronically controlled braking systems (ECBS).

Derivation and Validation of New Analytical Planar Models for Simulating Multi-Axle Articulated Vehicles

This paper discusses the derivation and validation of planar models of articulated vehicles that were developed to analyze jackknife stability on low-μ surfaces. The equations of motion are rigorously derived using Lagranges method, then linearized for use in state-space models. The models are verified using TruckSim, a popular nonlinear solid body vehicle dynamics modeling package. The TruckSim models were previously verified using extensive on-vehicle experimental data [1, 2]. A three-axle articulated model is expanded to contain five axles to avoid lumping the parameters for the drive and semitrailer tandems. Compromises inherent in using the linearized models are discussed and evaluated.

HEAD IMPACT RECONSTRUCTION - HIC VALIDATION AND PEDESTRIAN INJURY RISK

Experimental reconstructions of pedestrian accidents involving head injury sustained primarily from hood impact were conducted to determine the relationship between HIC and injury severity. The purpose was to establish the capability of predicting pedestrian head injury severity in simple laboratory tests. The reconstruction test results were analyzed by a median ranking technique to provide a family of curves showing probability of injury of AIS 3, 4, and 5 severities as a function of HIC. Results of the two analyses were compared to determine the degree of agreement between the HIC/injury-risk relationship derived from controlled experiments with cadavers and that derived from uncontrolled accidents involving live people. Specific accident cases are cited to illustrate the use of this relationship by the accident reconstructionist in estimating probable vehicle speed from injury outcome.

Comparison of models simulating occupant response with air bags

Two computer models, ABAG 19 and HSRI-3D, were validated against experimental data to determine and compare their capability for simulating the responses of air bag restrained automobile occupants in severe frontal collisions. Standard sets of model input parameters were developed for both driver and passenger. The primary objective was to determine which model was best suited for determining potential crashworthiness in a large number of production vehicles. Advantages and disadvantages of the models were determined, using criteria such as accuracy, ease of use, quality of documentation and user orientation. For the covering abstract see IRRD 810752. (Author/TRRL)

An investigative study of a wave-energy device

This paper presents the methodology and design of an offshore float device to capture the power in waves. Results, both experimental and theoretical, reveal that a simple modification of a mechanical cycle can lead to a significant increase in the energy that is developed. A prototype device, to be tested on the Great Lakes, is presented with experimental results obtained from laboratory testing. The responses of the prototype system are correlated to illustrate that wave power can provide significant amounts of energy. The novel method analyzed, when employed on other float devices, increases the energy output of the system. The recovery concept presented increases the deliverable energy that can be captured from a bouyant float following the free passage of a wave: this is accomplished by sequential capture (preloading) and release of the buoyant float at critical stages of wave passage. Displacement-work-energy concepts presented illustrate that preloading a float in the trough of the wave and subsequent release of it under the wave crest, as a mechanical cycle, can lead to a return of more energy than was required to preload the float and provide a net increase of energy that might be extracted from a wave alone.

Control Strategies for a Roll Simulator for Recreational Off-Highway Vehicles

Control strategies for a two degree-of-freedom roll simulator are presented. The simulator consists of a sled-platform assembly that translates along rails. A Recreational Off-Highway Vehicle (ROV) is mounted on the platform, which has the freedom to rotate about a roll axis. The roll axis is nominally perpendicular to the rails and parallel to the ground plane. This can be altered by using the third degree-of-freedom (static) that yaws the platform and changes the angle of the roll axis with respect to the rails. This angle is incorporated to achieve the appropriate acceleration vector. The assembly accelerates to a desired speed via a hydraulic motor and is decelerated with a magnetic particle brake at a specified deceleration level (nominally 0.7 g). Coordination of two mechanical systems proved to be difficult due to inherent lags in both systems. The cable-drum system created many problems as tension needs to be maintained in the cable at all times. Using only knowledge of the physical system, results showed reasonable agreement with desired levels. The roll motions showed excellent correlation with the desired levels.Copyright