Search Results

Rider control techniques and the handling qualities of all terrain vehicles (ATVs) are discussed. A manual control view is taken of the rider/vehicle/terrain system, including control inputs to the ATV and perceptual feedbacks to the rider. Steering control, overturning stability, and acceleration limits are considered. The important role of rider body movement is discussed. Comparisons are drawn with motorcycles and off road buggies. Vehicle system requirements that can be important from a design standpoint are reviewed.

The design and development of a top fuel drag motorcycle are reviewed from the standpoints of performance, stability and handling, and rider safety. The paper begins with a summary of design requirements related to longitudinal performance, lateral/directional stability and control, structural properties, rider factors, organizational rules, and the fact that drag racing is a spectator sport. A contemporary top fuel dragster design is used as an example case study. Analytical results illustrate the effects of aerodynamics, and varying other design parameters, on performance and stability. A principal result is that adequate down load must be maintained on the front tire. The results suggest that safety and good handling need not compromise ultimate performance, and that the required tradeoffs can be guided by analysis at the design stage.

In recent years, sophisticated audio systems have been installed on touring motorcycles. One feature of these systems is the provision for headphones on or inside the safety helmets. With such an installation, the rider must still be able to perceive safety-related sounds, such as the siren of an emergency vehicle. This paper considers the spectral characteristics of sirens and ambient motorcycle noise, and the sound attenuation of helmets in general. This leads to the specification of characteristics for an audio filter which attenuates the program amplitude in the spectral region of a siren. The result permits the rider to hear a siren with adequate warning, yet maintains the desired high level of sound quality.

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.

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.

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.

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.

Analytical and experimental studies of the transient and oscillatory behavior of motorcycles are reported. Three example vehicles were used. The effects of adding load, changing operating conditions, and modifying the vehicle configuration are shown. The phenomenon known as cornering weave is illustrated and interpreted.

Preliminary results of a study to develop lateral-directional handling test procedures for motorcycles are presented. One is a steady-state turn, accomplished with a range of forward speeds and turn radii. The other is a single lane change maneuver, using various degrees of severity and forward speeds. Several example motorcycles were studied analytically and via full scale tests. Data from onboard instrumentation show the effects of vehicle and operational differences on selected response and performance measures. This paper comprises a progress report, and the work is continuing.

A theoretical and empirical view is taken of motorcycle lateral-directional dynamics, handling, and rider control behavior. The analytical development includes equations of motion for the vehicle and a multiple loop feedback model for the control response of the rider/cycle system. Connections with manual control and vehicle response data are shown. The effects of changing fork geometry, operating conditions, and tire lag properties are discussed. Implications are drawn for handling requirements, vehicle design, and rider control techniques.