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This paper describes a human-in-the-loop motion-based simulator which was designed, built and used to measure the duty cycle of a combat vehicle in a virtual simulation environment. The simulation environment integrates two advanced crewstations which implement both a driver's station and a gunner's station of a simulated future tank. The simulated systems of the tank include a series hybrid-electric propulsion system and its main weapon systems. The simulated vehicle was placed in a virtual combat scenario which was then executed by the participating Soldiers. The duty cycle as measured includes the commands of the driver and gunner as well as external factors such as terrain and enemy contact. After introducing the project, the paper describes the simulation environment which was assembled to run the experiment. It emphasizes the design of the experiment as well as the approach, challenges and issues involved.

This paper describes a human-in-the-loop motion-based simulator which was built to perform controlled fuel economy measurements for both a conventional and hybrid electric HMMWV. The simulator was constructed with a driver's console, visualization system, and audio system all of which were mounted on the motion base simulator. These interface devices were then integrated with a real-time dynamics model of the HMMWV. The HMMWV dynamics model was built using the real-time vehicle modeling tool SimCreator®, which, in turn was integrated with two powertrain models implemented with Gamma Technologies GT-Drive product. These two powertrains consisted of a conventional configuration and a series hybrid-electric configuration. They were then run on four different standard Army fuel consumption courses to replicate tests which had previously been conducted at the proving ground. Experiments were performed for varying speeds with two experienced proving ground drivers.

Simulations of ground vehicles are extensively used by military and commercial vehicle developers to aid in the design process. In the past, ground vehicle simulations have focused on non-real-time models. However with the advancement of computers and modeling methodologies, real-time multi-body models have become one of the standard tools used by vehicle developers. Multi-body models are composed of joint, body, and force elements which map well into a modular modeling approach. Based on recursive techniques a set of reusable components were developed for use in a graphical simulation and modeling environment. The components were then connected to form a real-time multi-body model of a Ford Taurus. Finally, the Taurus model was integrated with simulator cueing subsystems to build a complete driving simulator. The performance of the Taurus model was compared with test data. It was found that the vehicle model was both accurate and ran much faster than real-time.

Standard visual database modeling practices in driving simulation reduce geometric complexity of terrain surfaces by using texture maps to simulate high frequency detail. Typically the vehicle dynamics model queries a correlated database that contains the polygons from the high level of detail of the visual database. However the vehicle dynamics database does not contain any of the high frequency information included in the texture maps. To overcome this issue and enhance both the visual and vehicle dynamics databases, a mathematical model of the high frequency content of the ground surface is developed using a set of Non-Uniform Rational B-Splines (NURBS) patches. The patches are combined in the terrain query by superimposing them over the low-frequency polygonal terrain, reintroducing the missing content. The patches are also used to generate Bump Map textures for the image generator so that the visual representation matches the terrain query.

The use of driving simulation in vehicle design and development is growing. For maximal benefit, vehicle models used in the driving simulator must be rapidly reconfigurable and easy to develop. To evaluate potential modeling concepts, vehicle dynamics and vehicle subsystems are developed using modular model components. These are integrated with simulator cueing subsystems, using the same modeling concepts, to build a complete driving simulator. It was found that the vehicle dynamics and the simulator could be reconfigured easily to meet user needs.