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This paper highlights the results of a program to study the effects of truck aerodynamics, splash, and spray. The approach has involved state of the art review and assessment, analysis, laboratory tests, model scale wind tunnel experiments, full scale tests, cost effectiveness analysis, and field evaluations. This paper summarizes the latter activities. The emphasis has been on devices fixed to trucks which can modify the air flow properties around the truck and reduce the formation and propagation of splash and spray as experienced by adjacent motorists. Such devices have been conceptualized, developed as prototypes, and tested under full scale and over the road conditions.

Analytical results describing moped lateral-directional response properties are presented. Design characteristics of four example mopeds related to directional handling are presented and compared with sample motorcycle properties. Resultant moped dynamics are quantified and compared. Using a nominal moped example, the sensitivity of the vehicle dynamics to operational and design variables, such as speed, loading and tire properties, is shown. Implications for rider/moped handling are reviewed.

Models have been developed to describe the dynamic response and performance of drivers, vehicles, and driver-vehicle systems; and recent experiments have provided some quantification and refinement. This paper summarizes the theory and the data, and attempts to provide part of the transition between properties of the human and the assessment of safety performance in driving. The model and data shown emphasize steering or directional control situations. Simulation experiments with random crosswind gust disturbances were used to measure driver-vehicle describing functions for a number of driver subjects and experimental replications. The results are consistent with previous data and show good repeatability within subjects on successive runs. Interpretation of the data in terms of the driver-vehicle model indicates that the driver's outputs can be explained in simplest terms as functions of lateral position and heading.

Motorcycle braking test procedures and results are presented. Both straight line and combined cornering and braking maneuvers were used. Test conditions included various initial speeds, turn radii, surface skid numbers, and levels of braking effort for two instrumented motorcycles. The effect of braking on transient yaw response in turns is demonstrated, also. Overall, the results show that repeatable safety related response and performance measures can be obtained using the prescribed procedures with expert test riders.

A theoretical and experimental investigation of the effects of antilock braking (ALB) on motorcycle braking in a turn (BIT) is described. The analyses involved computer simulation of the dynamic interaction among rider, motorcycle, ALB, and roadway during BIT maneuvers; and instrumented full scale BIT tests with expert and novice riders. The analyses and full scale tests used an example all mechanical, independent front and rear ALB system. The results showed that ALB can help maintain motorcycle stability in straightline and gradual turns at high and excessive brake force levels. In more severe turns, the motorcycle can capsize at low brake force levels, below those which are typically needed to trigger ALB operation. As a consequence, from a fundamental standpoint, contemporary conventional ALB systems cannot be considered to influence or improve motorcycle stability during limit braking in moderate or near limit turns.

A review, analysis and enumeration are presented of factors relevant to motorcycle airbag feasibility research. This includes: an update of the status of related research in the motorcycle airbag feasibility field; relevant experience and factors from the car airbag field; additional unique factors and considerations for motorcycles; and the potential need to address motorcyclist out-of-position riding; other sizes of riders; motorcycle seating layout variation; resistance to and consequences of unintended deployment on a motorcyclist; neck injury criteria and dummy neck biofidelity; injury risk-benefit considerations; environmental exposure on motorcycles; and discussion of feasibility definition and factors.

An updated evaluation of the effects on predicted injuries of an example crush protective device (CPD) proposed for application to All-Terrain Vehicles (ATVs) is described. As in previous evaluations, this involved extending and applying the test and analysis methods defined in ISO 13232 (2005) for motorcycle impacts, to evaluate the effects of the example CPD in a sample of simulated ATV overturn events. Updated modeling refinements included lowering the energy levels of the simulated overturn events; accounting for potential mechanical/ traumatic (compressive) asphyxia mechanisms; refining and calibrating the force-deflection characteristics of helmet, head, legs and soil so as to reduce potential over-prediction of head and leg injuries; and calibrating the simulation against aggregated injury distributions from actual accidents.

A prototype safety analysis system has been developed to assess and forecast vehicle safety that can assist vehicle developers integrate various safety technologies into future production vehicles. The prototype system can be used to assess the actual safety in existing vehicles based on fatal accident and vehicle registration data (e.g., US FARS and Polk data); and to estimate the safety in future vehicles based on the estimated effectiveness of candidate passive and active safety technologies (e.g., Curtain Airbags, CMBS) using a systems model with a representative sample of in-depth accident data (e.g., NASS/CDS). Therefore, the prototype system is a useful tool which can be used to estimate the net overall effectiveness of various candidate safety technologies combined, providing a metric which can be used to help optimize the effectiveness of integrated vehicle safety systems.

The results of a wind tunnel study and a computer simulation are used to determine the effects of aerodynamics on the lateral-directional stability and crosswind response of passenger car/utility trailer combinations. Single and tandem axle utility trailer configurations, with and without drag reducing add-on aerodynamic fairings, were considered with both sedan and station wagon tow cars. Results showed that including aerodynamic terms in the six degree of freedom model reduces the trailer tow angle stability and damping by a few percent. More importantly, the random crosswind response, expressed in terms of tow car yaw velocity, was amplified about 20 to 30 percent when a drag reducing device was added to the trailer.

Results of a study to analyze and correlate handling-related driver/vehicle system response and performance data are reported. Steering control tasks involving maneuvers and disturbance regulation are emphasized. Correlations between vehicle handling parameters, objective measures, and subjective rating data have been made. These have lead to the tentative definition of values of steering gain and effective yaw time constant which are preferred for satisfactory handling qualities and performance for passenger automobiles.

A simulator intended for driver/vehicle applied research and driver behavior studies is described. Designed and developed by Dynamic Research, Inc. in Torrance, CA, it features a 180 deg forward field of view, an animated graphics roadway scene, modular vehicle dynamics models, instrumented cabs with steering control loaders and aural cueing, an electrohydraulic hexapod motion base with ±2 ft of stroke in each leg, and system operation and data acquisition functions. Automobile and motorcycle cabs are available. Studies to date have considered steering and pedal controls layout, high speed brake in turn, and driver workload related to the use of an in-dash navigation and route guidance system.

An analytical method applicable to design and development of antilock brake systems is described. Dynamic components of antilock systems --- including vehicle, sensor, and modulator--are examined using nonlinear feedback control techniques. An overall design approach is illustrated via an example involving a motorcycle front brake and typical pneumatic modulator. A computer simulation is used to generate time and frequency responses of system components. These data are used to identify the preferred feedback structure. Results show that a stable antilock limit cycle can exist for wheel angular acceleration feedback, among other possibilities. Overall the method and results can provide additional insight into detailed requirements for antilock components and systems, and may hold potential for reducing development time and costs.

The characteristics, functionality, limitations, and applications of mid-level driving simulators are reviewed and discussed. For this paper a mid-level simulator is defined as one which has a large roadway scene display typically comprising animated computer graphics, it may have a motion system or be fixed base, it should have a dedicated cab with a steering feel system and interactive controls and displays, it has a parametrically configurable vehicle dynamics model, data acquisition is provided for, and the simulator is intended to be used for driver behavior research and vehicle or highway research and development studies. Possible simulator sickness issues are discussed, and categories of mid-level driving simulator applications are noted. Approximately 20 different contemporary driving simulators are included in the survey.