A Comprehensive Vehicle and Tire
Dynamics Simulation ModelVDANL (Vehicle Dynamics Analysis, Non Linear) is a comprehensive vehicle dynamics simulation program that runs under Windows® 95/98/NT/2000 and is intended for the analysis of passenger cars, light trucks, articulated vehicles and multi-purpose vehicles. The simulation model is designed to permit analysis of virtually all driver induced maneuvering up through limit performance conditions defined by tire saturation characteristics, and includes driver feedback control features.
The Vehicle ModelModel equations cover the full range of lateral/directional and longitudinal motions up through large angles experienced in spin out and rollover. The vehicle model includes components for sprung and unsprung masses, suspension, steering, braking, power train, drive train, and tires. The model includes a comprehensive tire model and properly accounts for the effects of maneuver induced load transfer. The vehicle and tire models are based on past research and have been extensively validated.
Tires - Tire characteristics play a dramatic role in vehicle dynamics since they respond to vehicle maneuvering. The tire model generates lateral and longitudinal tire forces and aligning moments as functions of normal load, slip and camber angle and includes appropriate interactions between these input variables including force saturation.
Suspension - Composite suspension characteristics are designed to represent wheel steer and camber motions relative to the sprung mass and squat/lift forces resulting from tire ground plane forces acting on the suspension geometry. Wheel steer also arises from compliance in response to tire side force and aligning torque.
Steering - Steering Model includes Ackerman steer effects and compliance, and a composite second order characteristic to simulate steering dynamics in response to steering and aligning torque inputs.
Power and Drive Train - Power and drive train model includes engine, transmission, differentials and torque splitting between the front and rear axles. Front, rear and four-wheel-drive can be accommodated.  
STI Tire Model Compared with Field Test Data
Brakes - Brake model includes simulation of vacuum boost run-out and a nonlinear proportioning valve between the front and rear axles. Also includes a generic ABS system. Truck brakes include trailer pneumatic lag and fade due to over heating.
Capabilities and Features
VDANL can be used in a variety of ways to analyze vehicle maneuvering motions, handling and stability. Input control commands (e.g. steering, braking, throttle, aerodynamic) can be applied directly to the open loop vehicle. Under driver model closed loop control the simulation can be excited with r
oad curvature, lane position and speed commands. A large number of vehicle input and response variables can be saved to a file for subsequent analysis and/or plotted using time history and XY formats. An external Windows based plotting utility (WinEP by Mechanical Simulation Corporation, Ann Arbor, MI) is provided for data display and analysis.
Program control is achieved through a Windows® point and click interface. The program can also be controlled with command files containing sequences of program commands. Built in help features provide on-line display of the user's guide and technical reference.
Sample VDANL Menu Screen
Strip Chart Plot of Sample VDANL Results
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XY Plot of Sample VDANL results
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Applications Include:- Dynamic response and stability
- Low-g and limit performance handling
- Traction control and braking
- Suspension design and load transfer
- Closed loop driver/vehicle response problems
- Accident reconstruction
- Trailer Towing
Additional VDANL Features:- Common vehicle dynamics with the STISIM DriveTM driving simulator. Vehicle models can be developed using VDANL, then run in the real-time, driver-in-the-loop simulator.
- A 3D terrain model allows a multi-lane roadway to be defined using simple commands. Horizontal and vertical curves can be defined along with roadway cross-slopes. Surface attributes can be assigned to portions of the roadway, which are recognized by the vehicle tire model, allowing changing tire/roadway characteristics based on position on the roadway. This 3D terrain is common with STISIMDriveTM.
- Open Module option allows users to write code to be integrated into the VDANL simulation, enabling custom simulations to be created. Hardware-in-the-loop simulation is possible using the Open Module and STISIM DriveTM.
- MATLAB® binary file output allowing post-processing and plotting within MATLAB.
Hardware RequirementsVDANL is designed to run on a PC with an Intel® Pentium class processor or compatible with Windows 95/98® or Windows NT/2000®. Systems Technology, Inc.STI has been involved in research and consulting in vehicle dynamics, manual and automatic controls and human factors of aerospace and ground vehicles for over 35 years. Specific experience with the analysis and testing of ground vehicles has resulted in the development of the vehicle model that is the basis for VDANL. Over the last two de
cades our ground vehicle research has focused on the development and validation of comprehensive vehicle dynamic simulations, and the development of enhancements to maximize the efficiency of VDANL applications. Further Information
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