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Technical Paper

Driver Model of Steering Based on Target Position and Orientation

A driver model of steering is developed using quartic prediction curve and dual sight distances. The target orientation and position information is incorporated into the quartic prediction curve. The model assumes that the driver gazes on a fixed point if it is a point of concern. Upon reaching a minimum distance, the driver's gaze shifts to normal. Driving simulation were conducted on a workstation with stereo vision of road consisting of straight line segments joined with angles of 5, 10 or 15 degrees. Five subjects performed driving simulation with 3 DOF model of a passenger car at the constant speed of 15 m/s. Model parameters are obtained through the curve fitting of the driver model to the experimental data. The results shows that the distances and time delay change predictably according to the road curvature.
Technical Paper

Virtual Prototyping for Military Vehicle Acquisition

The emergence of high-speed parallel computers, new mechanical system dynamic simulation formulations, and a range of driver-in-the-loop vehicle simulators is shown to provide a qualitatively new virtual prototyping tool to support military vehicle acquisition. The state-of-the-art of driver-in-the-loop simulation and projections regarding its refinement for use in military vehicle development are outlined, with emphasis on providing a virtual prototyping capability that accounts for operator-vehicle interaction, prior to fabrication and test of prototypes. It is shown that the potential now exists to investigate trade-offs involving vehicle design and operator effectiveness that heretofore required a physical prototype. This will permit the engineering community to optimize the design of military vehicles for the soldier, beginning early in the design and development process and continuing through product improvement.
Technical Paper

Multiple User Defined End-Effectors with Shared Memory Communication for Posture Prediction

Inverse Kinematics on a human model combined with optimization provides a powerful tool to predict realistic human postures. A human posture prediction tool brings up the need for greater flexibility for the user, as well as efficient computation performance. This paper demonstrates new methods that were developed for the application of digital human simulation as a software package by allowing for any number of user specified end-effectors and increasing communication efficiency for posture prediction. The posture prediction package for the digital human, Santos™, uses optimization constrained by end-effectors on the body with targets in the environment, along with variable cost functions that are minimized, to solve for all joint angles in a human body. This results in realistic human postures which can be used to create optimal designs for things that humans can physically interact with.
Technical Paper

Benefits from Heads-Up Lane Departure Warnings Predicts Safety in the Real-World

We examined relative effectiveness of heads-up visual displays for lane departure warning (LDW) 39 younger to middle aged drivers (25-50, mean = 35 years) and 37 older drivers (66-87, mean = 77 years). The LDW included yellow “advisory” visuals in the center screen when the driver started drifting toward the adjacent lane. The visuals turned into red “imminent” when the tires overlapped with the lane markers. The LDW was turned off if the driver activated the turn signal. The visuals could be easily segregated from the background scene, making them salient but not disruptive to the driver’s forward field of view. The visuals were placed adjacent to the left and right lane markers in the lower half of the center screen.
Technical Paper

Parameter Determination and Vehicle Dynamics Modeling for The National Advanced Driving Simulator of the 2006 BMW 330i

The paper discusses the development of a model for the 2006 BMW 330i for the National Advanced Driving Simulator's (NADS) vehicle dynamics simulation, NADSdyna. The front and rear suspensions are independent strut and link type suspensions modeled using recursive rigid-body dynamics formulations. The suspension springs and shock absorbers are modeled as force elements. The paper includes parameters for front and rear semi-empirical tire models used with NADSdyna. Longitudinal and lateral tire force plots are also included. The NADSdyna model provides state-of-the-art high-fidelity handling dynamics for real-time hardware-in-the-loop simulation. The realism of a particular model depends heavily on how the parameters are obtained from the actual physical system. Complex models do not guarantee high fidelity if the parameters used were not properly measured. Methodologies for determining the parameters are detailed in this paper.
Technical Paper

A Musculoskeletal Model of the Upper Limb for Real Time Interaction

With the ever-increasing power of real time graphics and computational ability of desktop computers, the desire for a real-time simulation of the musculoskeletal system has become more pronounced. It is important that this simulation is realistic, interactive, runs in real time, and looks realistic, especially in our climate of Hollywood special-effects and stunning video games. An effective simulation of the musculoskeletal system hinges on three key features: accurate modeling of kinematic movement, realistic modeling of the muscle attachment points, and determining the direction of the forces applied at the points. By taking known information about the musculoskeletal system and applying it in a real time environment, we have created such a model of the human arm. This model includes realistic constraints on the joints and real-time wrapping algorithms for muscle action lines.
Technical Paper

Analysis of the STI Tire Model

The STI (System Technology Inc.) tire model is one of the most important semi-empirical (steady-state) tire models currently applied in the vehicle dynamics simulation software package of the National Advanced Driving Simulator (NADS). The STI tire model is presented originally based on tire contact length directly and the contact length is required to provide. Based on the concepts of nominal slip in both longitudinal and lateral directions, the STI tire model is analyzed and rewritten. It shows that the STI tire model does not actually depend on the contact length. Meanwhile, the model parameters are partially assigned new physical definitions, for example, static/dynamic stiffness and shape factors. Some simplified expressions are given based on further assumption conditions. The simplified expressions are also obtained regarding longitudinal slip at arbitrary speeds (including low speed, zero speed and stand still), which is originally presented by Bernard.
Technical Paper

Muscle Forces and Fatigue in a Digital Human Environment

Since muscles act to translate an electrical impulse from the central nervous system into motion, it is essential to have a suitable mathematical model for muscles and groups of muscles for a virtual soldier environment. This paper presents a methodology in which the muscle contraction is broken down into three distinct physiological processes: calcium release and re-absorption by the sarcoplasmic reticulum, the rate at which calcium binds and unbinds to troponin, and the generation of force due to cross-bridge cycling and the elasticity of the muscle fibers. These processes have been successfully modeled by Ding and Wexler as a system of coupled differential and algebraic equations. These equations give the calcium-time history and the force time history of the muscle. By varying the electrical stimulation rates, the muscles can produce forces of varying magnitude and duration over which the force can be maintained.
Journal Article

Forward Collision Warning: Clues to Optimal Timing of Advisory Warnings

We examined the effectiveness of a heads-up Forward Collision Warning (FCW) system in 39 younger to middle aged drivers (25-50, mean = 35 years) and 37 older drivers (66-87, mean = 77 years). The warnings were implemented in a fixed based, immersive, 180 degree forward field of view simulator. The FCW included a visual advisory component consisting of a red horizontal bar which flashed in the center screen of the simulator that was triggered at time-to-collision (TTC) 4 seconds. The bar roughly overlapped the rear bumper of the lead vehicle, just below the driver’s line-of-sight. A sustained auditory tone (∼80 dB) was activated at TTC=2 to alert the driver to an imminent collision. Hence, the warning system differed from the industry standard in significant ways. 95% Confidence intervals for the safety gains ranged from -.03 to .19 seconds in terms of average correction time across several activations. Older and younger adults did not differ in terms of safety gains.
Technical Paper

Adaptive Cruise Control: First Impressions Matter

Advanced driver assistance systems (ADAS) show tremendous promise for increasing safety on our roadways. However, while these technologies are rapidly infiltrating the American passenger vehicle market, many consumers have little to no experience or knowledge of them prior to getting behind the wheel. The Technology Demonstration Study was conducted to evaluate how the ways in which drivers learn about ADAS affect their perceptions of the technologies. This paper investigates drivers’ knowledge of the purpose, function, and limitations of the advanced driver assistance technology of adaptive cruise control (ACC), along with ratings of perceived usefulness, apprehension, and effort required to learn to use ACC.