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The relationship between tire lateral force and slip angle is of interest to vehicle simulation developers and vehicle design engineers. Lateral force data on a variety of surfaces can not be obtained with the traditional laboratory test technique of an instrumented tire on a moving belt surface. This paper describes how the Cold Regions Research and Engineering Laboratory's (CRREL) Instrumented Vehicle (CIV) was used in a unique configuration to measure tire lateral force versus tire slip angle values on ice, snow and soil surfaces. The data collected show that peak lateral force and the shape of the lateral force versus slip angle curve are related to snow properties, depth and soil type. This paper continues from our previous work of lateral force versus slip angle for winter surfaces. This paper adds wet gravel and pea stone soil surfaces.

Synthetic Automotive Virtual Environment (SAVE) is a research program to develop useful descriptions of high-speed, loose-surface ground vehicle interface dynamics and to apply those findings to synthetic training environments, autonomous vehicle development, active safety systems development, and to the construction of safer roads. Live training for accident avoidance through vehicle control is problematic due to the dangers of having unskilled drivers in critical situations. Furthermore, for a driver to perform the critical skills well in an unexpected driving situation requires that their response become automatic through muscle memory development. A simulator environment removes the student from the potentially dangerous consequences of these situations and allows for repetitive training to develop muscle memory.

Tire cornering forces are often measured in the laboratory on a high-friction surface and little information exists on the nature of cornering on other surfaces. Thus, the impact of winter roads on vehicle behavior is difficult to fully capture in vehicle dynamics simulations. The CRREL (Cold Regions Research and Engineering Laboratory) Instrumented Vehicle was used to measure cornering forces on winter surfaces. The vehicle was instrumented for forces, speeds, and a variety of other measures. Tests were performed at the Keweenaw Research Center in Northern Michigan, during February 2005, and included measurements on ice, packed snow, and undisturbed snow. Packed snow density was 0.5 g/cm3 and loose snow densities ranged from 0.07 to 0.23 g/cm3 with depths from 5 to 23 cm. The test technique involved towing the vehicle in a straight line while sweeping the steering angle from zero to approximately 17 degrees both left and right.

Researchers at the U.S. Army Engineer Research and Development Center (ERDC), Cold Regions Research and Engineering Laboratory (ERDC-CRREL) and the U.S. Army Tank Automotive Research Development and Engineering Center (TARDEC) have developed methods to model the physical interactions of vehicles with deformable terrain surfaces such as snow, mud, and soft soil during vehicle dynamic simulations. This paper describes the methodology that will be used to validate these modeling methods, and presents the results of driving simulations that verify the simulation vehicle dynamics model. Future work will concentrate on validating the physical interactions on deformable terrain using this verified dynamics model. Validation parameters include tri-axial forces at the four tire–terrain interfaces, wheel speeds, vehicle speed, and tri-axial linear accelerations and angular velocities at the vehicle center of gravity.

A virtual, all-season test site for use in real-time vehicle simulators and mobility models was constructed of an Army firing range in Northern Vermont. The virtual terrain will mimic the terrain of our Virtual Data Acquisition and Test Site (VDATS) at Ethan Allen Firing Range (EAFR). The objective is to realistically simulate on- and off-road vehicle performance in all weather conditions for training and vehicle design for the US Army. To this end, several spatial datasets were needed to accurately map the terrain and estimate the state-of-the-ground and terrain strength at different times of the year. The terrain strength is characterized by terramechanics properties used in algorithms to calculate the forces at the vehicle-terrain interface. The performance of the real vehicles will be compared to the simulated vehicle performance of operator-in-the-loop and unmanned vehicles for validation of the simulations.