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Vehicle Dynamics Library – Release 3.0

Vehicle Dynamics Library 3.0 is part of Modelon’s 2017.2 release.

New Features

General Availability of VDL.Motorsports

VDL has been gaining additional functionality to support our Motorsports customers for nearly ten years. Some functionality and components were not generally available due to competitive and contractual constraints. We are now able to make these additional components generally available to all VDL users. One of the highlights of this functionality is an extensive list of pushrod/pullrod suspension linkages. As with all suspension linkages in VDL, these linkages are optimized for performance and ready-to-use in real-time applications. These components have been successfully used in driver-in-loop simulators for several years.

Additional VDL.Motorsports Functionality

Additional Motorsports functionality includes:

  • Pushrod/pullrod suspension linkages: Twenty additional suspension pushod/pullrod linkages have been added that include kinematic or compliant variants of steerable and non-steerable suspensions allowing any combination of linear or rotational springs and dampers.
  • Truck Arm Rear Suspension: A truck arm rear suspension has been added that is typically used by our NASCAR customers. This suspension is also ready-to-use for real-time applications.
  • Torsion-Bar Antirollbars: Two torsion-bar antirollbars have been added: Torsion-bar and Torsion-bar/MonoStrut. These type of antirollbars are quite typical in open wheel chassis due to packaging contraints.
  • Ground Impact Models: These models provide accurate reactive forces when chassis components/bodyworks impact the ground/road surface. Typical applications are modeling of impact forces when the valence, splitter or skidplate contacts the ground.

Existing VDL.Motorsports Functionality

Some of the existing VDL.Motorsports functionality includes:

  • Tuners and tunables: These components can be used to adjust many different properties of the vehicle, such as camber, toe, and ride heights. For example, the length of the tierods in a suspension are often adjusted until a desired static toe is achieved.
  • Ground Proximity Sensors: Ground proximity information is commonly required in vehicle dynamics simulations. Most commonly, this information is used in the contact calculations for wheels. Other applications include ride heights for aerodynamics calculations and ground impacts.
  • Ride Height Dependent Aerodynamics Models: Four aerodynamics models that are dependent on front/rear ride heights. The different models demonstrate how to represent lift/drag/side aerodynamic forces using either a polynomial or tabular data.
  • Cornering Ground Model: This ground model allows modification of the ground surface curvature based on input signals. The chassis velocity and curvature result in lateral, longitudinal and vertical accelerations being applied to the vehicle. This model is typically used to evaluate chassis states at different points on the race track.

Support for the FTire Tire Model

VDL has been extended to include support of the cosin FTire® tire force model. The FTire wheel model fully supports VDL built-in ground models, cosin road property files, and OpenCRG road descriptions.

FTire (Flexible Structure Tire Model)

FTire is a full 3D nonlinear in-plane and out-of-plane tire simulation model. It is used by engineers in the vehicle and tire industry worldwide. Sophisticated 2D and 3D rigid and flexible road surface description models and evaluation methods, and powerful toolboxes for tire and road data processing make FTire the most comprehensive software package for tire dynamics simulation on the market. FTire is designed for vehicle comfort simulations and prediction of road loads on road irregularities even with extremely short wave-lengths. It can also be used as a structural dynamics based, highly nonlinear and dynamic tire model for handling studies without limitations or modification to input parameters. FTire explains most of the complex tire phenomena on a mechanical, thermodynamical, and tribological basis, with very good correlation to measurements.

Please see the FTire Forces block in VDL for more information, requirements, and limitations.

Realtime Simulation using Parallelization

Parallelized code can be generated from Modelica models according to the (OpenMP, 2015) standard. In VehicleDynamics.RealTime and throughout VDL, components have been added that take advantage of this functionality. These components allow the model to be decoupled so separate parts of the vehicle model can be simulated in parallel to distribute the workload of solving the systems of equations across multiple cores.

For more information about these components, please see RealTime.Information.

Examples.Realtime.Parallelization provides an example of how to use these new components. Please see the information layer of the Examples.Realtime.Parallelization.Chassis.CompactLEKPacejka02 to see how the configure parallelization of different chassis subsystems.

Added Reduced-Fidelity Chassis and Suspension Models

Reduced-fidelity chassis models have simpler suspension linkages that have fewer moving parts and lower overall complexity. These chassis models fill in the gap between a very simple planar chassis and full multibody chassis model. Reduced-fidelity chassis models are more desirable in drivability simulations where the straightline behavior and longitudinal dynamics of the chassis are the main interest. A key benefit of using reduced-fidelity chassis models is that parameters required to represent them is significantly lower than a full multibody chassis model. In order to use these models to represent a chassis for drivability work, it is only necessary to provide the chassis mass, track width, wheelbase and approximate spring rates.

Lumped mass model: The suspension is modeled to allow each wheel to translate vertically with respect to the chassis body. Ride and roll stiffness is modeled using vertical springs and dampers. This model allows the chassis to heave, pitch and roll.

Swing Arm model: The suspension is modeled to allow each wheel to swing on a control arm about a single axis. Ride and roll stiffness is modeled using vertical springs and dampers. This model allows the chassis to heave, pitch and roll.

Polynomial model: The suspension is modeled using polynomials that define the kinematic and compliant model of the wheel with respect to the chassis body. The model allows the chassis to heave, pitch and roll.

Examples of these models can be found in Examples.ReducedFidelity.

Improvements/Changes

Added Additional Transmission Examples

Additional automatic and manual transmissions have been added to include examples of configurations now commonly used in passenger cars.

Automatic transmission

  • FiveSpeed
  • SixSpeed
  • SevenSpeed
  • EightSpeed

Manual transmission

  • FiveSpeed
  • SixSpeed

All references to the AutomaticI and ManualH transmissions have been changed to Automatic.FiveSpeed and Manual.FiveSpeed, respectively.

A tutorial package was also added to describe the steps necessary if the number of gears should be altered for automatic and manual transmissions: UsersGuide.Tutorials.Transmission.

Added Independent Suspension Templates for Trucks

Independent suspension templates have been added that are based on the Suspensions.Interfaces.Axle2 and Suspensions.Interfaces.Axle2S interfaces used in truck templates. This is to make it easier to build a trunk model with either independent of dependent suspensions. Examples of independent truck suspensions and an example chassis using these suspensions have also been added: Chassis.Examples.Truck2is_2i.

Minor Changes

  • All images have been moved from VehicleDynamics/images to VehicleDynamics/Resources/Images. Please update all references to refer to the new location.
  • All external files (.dxf) used for visualizers have been moved from VehicleDynamics/images to VehicleDynamics/Resources/Shapes. Please update all references to refer to the new location.

Conversion of User Libraries

User libraries will automatically be converted from version 2.5. These conversions are made using the included conversion script: VehicleDynamics/Resources/Scripts/Convert_to_3.0.mos.

Requirements

Vehicle Dynamics Library 3.0 is based on Modelon Base Library 3.0 and Modelica Standard Library 3.2.2.

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