Paul A. Grygier
National Highway Traffic Safety Administration
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Paul A. Grygier.
SAE transactions | 2004
Mohamed Kamel Salaani; Gary J. Heydinger; Paul A. Grygier
This paper discusses techniques for estimating steering feel performance measures for on-center and off-center driving. Weave tests at different speeds are used to get on-center performances for a 1994 Ford Taurus, a 1998 Chevrolet Malibu, and a 1997 Jeep Cherokee. New concepts analyzing weave tests are added, specifically, the difference of the upper and lower curves of the hysteresis and their relevance to driver load feel. For the 1997 Jeep Cherokee, additional tests were done to determine steering on-center transition properties, steering flick tests, and the transfer function of handwheel torque feel to handwheel steering input. This\ transfer function provides steering system stiffness in the frequency domain. The frequency domain analysis is found to be a unique approach for characterizing handwheel feel, in that it provides a steering feel up to maximum steering rate possible by the drivers.
SAE transactions | 2003
Mohamed Kamel Salaani; Gary J. Heydinger; Paul A. Grygier
This paper presents the development of a real-time vehicle dynamics model of the heavy tractor-trailer combination used in the National Advanced Driving Simulator. The model includes multi-body dynamics of the tractor andtrailer chassis, suspension, and steering mechanisms. The rigid body model is formulated using recursive multi-body dynamics code. This model is augmented with subsystem models that include tires, leaf springs, brakes, steering system, and aerodynamic drag. This paper also presents parameter measurement and estimations used to set up the model. Also included are models for brake fade, steering torque resistance, and defective tires.
SAE transactions | 2003
Mohamed Kamel Salaani; Paul A. Grygier; Gary J. Heydinger
This paper evaluates the heavy tractor-trailer handling dynamics model used in the National Advanced Driving Simulator. The comparison between simulation and experiments were done using lane change, slowly increasing steer, pulse steer, step steer, and straight-line braking maneuvers. The paper discusses tractor-trailer instrumentation and the results offield experiments.
SAE transactions | 1997
Jeffrey P. Chrstos; Paul A. Grygier
As part of the National Advanced Driving Simulator (NADS) program, the Vehicle Research and Test Center (VRTC) in East Liberty, Ohio is evaluating the NADS vehicle dynamics software. As part of VRTC’s effort, an extensive vehicle testing program to provide data for the simulation evaluation was performed. This paper describes VRTC’s testing of a 1994 Ford Taurus GL passenger car. Each of the test maneuvers run by the Taurus are described, along with instrumentation setup, control actuation, test conditions, and driver procedures. The test data reduction and processing are detailed. Sample results of the testing and an analysis of test repeatablility and measurement noise are also presented.
SAE transactions | 2004
Mohamed Kamel Salaani; Gary J. Heydinger; Paul A. Grygier
This paper presents the details of the model for the physical steering system used on the National Advanced Driving Simulator. The system is basically a hardware-in-the-loop (steering feedback motor and controls) steering system coupled with the core vehicle dynamics of the simulator. The systems torque control uses cascaded position and velocity feedback and is controlled to provide steering feedback with variable stiffness and dynamic properties. The reference model, which calculates the desired value of the torque, is made of power steering torque, damping function torque, torque from tires, locking limit torque, and driver input torque. The model also provides a unique steering dead-band function that is important for on-center feel. A Simulink model of the hardware/software is presented and analysis of the simulator steering system is provided.
SAE 2006 World Congress & Exhibition | 2006
Mohamed Kamel Salaani; Gary J. Heydinger; Paul A. Grygier
There exists a fairly extensive set of tire force measurements performed on dry pavement. But in order to develop a lowcoefficient of friction tire model, a set of tire force measurements made on wet pavement is required. Using formulations and parameters obtained on dry roads, and then reducing friction level to that of a wet road is not sufficient to model tire forces in a high fidelity simulation. This paper describes the process of more accurately modeling low coefficient tire forces on the National Advanced Driving Simulator (NADS). It is believed that the tire model improvements will be useful in many types of NADS simulations, including ESC and other advanced vehicle technology studies.
ASME 2003 International Mechanical Engineering Congress and Exposition | 2003
M. Kamel Salaani; Gary J. Heydinger; Paul A. Grygier; W. Riley Garrott
Despite the advances in computer graphics speed and quality, Image Generator (IG) delys are unavoidable due to the demanding details and complex scenarios run at the National Advanced Driving Simulator (NADS), in particular for urban traffic scenes. This paper introduces a new dynamic compensation algorithm for automotive driving simulator visual displays. The compensation method is based on an original approach used by NASA Ames Research Center for flight simulator applications. The compensator designed has nearly zero phase with well-maintained magnitued within the bandwidth. The algorithm has magnitude attenuation outside the bandwidth without altering the desired frequency response of the compensator. This paper discusses the compensation method, and presents results from the NADS showing drivers’ ability to steer the vehicle through corners without excessive overshoot resulting from human reactions to visual delays. The results demonstrate that compensating for visual delays for high-end driving simulators is vital for real-time fidelity.Copyright
SAE transactions | 2005
Brian Christopher Zaugg; Gary J. Heydinger; Dennis A. Guenther; Ashley L. Dunn; Scott B. Zagorski; Paul A. Grygier
This paper discusses the improvement of a heavy truck anti-lock brake system (ABS) model currently used by the National Highway Traffic Safety Administration (NHTSA) in conjunction with multibody vehicle dynamics software. Accurate modeling of this complex system is paramount in predicting real-world dynamics, and significant improvements in model accuracy are now possible due to recent access to ABS system data during on-track experimental testing. This paper focuses on improving an existing ABS model to accurately simulate braking under limit braking maneuvers on high and low-coefficient surfaces. To accomplish this, an ABS controller model with slip ratio and wheel acceleration thresholds was developed to handle these scenarios. The model was verified through testing of a Class VIII 6x4 straight truck. The Simulink brake system and ABS model both run simultaneously with TruckSim, with the initialization and results being acquired through Matlab. This paper provides a description of the ABS controller and TruckSim vehicle models, an analysis of the field test data, and a comparison of the simulation and field test results.
SAE transactions | 2005
Mohamed Kamel Salaani; Gary J. Heydinger; Paul A. Grygier
Steering activity in response to. deviations from the intended straight-ahead vehicle path is an important factor of vehicle-driver on-center performance. Traditionally, setting the parameters of vehicle models for stability analysis does not involve vehicle properties that make the vehicle deviate from its intended path with no steering input. However, for closed loop simulations where driver steering activity is considered a fundamental human performance measure, the ability of the vehicle model to faithfully generate path deviations in response to external forces is required for steering performance measures fidelity. Path deviations cause the driver to make small steering angle corrections to keep the vehicle on its intended straight path. It is in fact a natural driving load that should be included in every closed loop simulation before considering any study involving driving loads and driver distractions. This paper explains the physics of these small deviations and proposes a model that mimics path deviations seen on the road. A comparison is made between vehicle road data measurements and simulation results.
SAE transactions | 1997
W. Riley Garrott; Paul A. Grygier; Jeffrey P. Chrstos; Gary J. Heydinger; Kamel Salaani; J. Gavin Howe; Dennis A. Guenther