Vehicle Dynamics Library 3.1 is part of Modelon’s 2018.1 release.

New Features

Integrated support for Delft Tyre Models

Support for DelftTyre tyre models is now fully integrated into the VDL. The separate DelftTyre package is no longer required to run experiments with DelftTyre tyre models.

Through Strut

A strut with feedthrough of translational connectors has been added in Suspensions.Linkages.Struts. This is meant to be used for attaching the translational spring component to the damper strut or vice versa. An example would be a 'coilover' or coil spring over shock where the spring is assembled over the damper body.

Kinematic FiveLink Linkage

A fully kinematic FiveLink linkage has been added.

Tabular 1-Dimensional Rear Suspension

A tabular 1D rear suspension (Suspensions.Rear.Tabular1D) has been added in addition to the existing tabular 2D rear suspension. This suspension only requires kinematics data for wheel travel, not opposite side wheel travel. As a result of this addition, the tabular 2D suspension has been renamed from Tabular to Tabular2D.

Vehicle Interfaces

The VehicleInterfaces migration package contains templates and examples of using VDL components with interfaces from VehicleInterfaces library.

Available migration components include:

  • Migration.VehicleInterfaces.Chassis
  • Migration.VehicleInterfaces.Drivers
  • Migration.VehicleInterfaces.Drivelines
  • Migration.VehicleInterfaces.ElectricalMachines
  • Migration.VehicleInterfaces.EnergyStorage
  • Migration.VehicleInterfaces.Engines
  • Migration.VehicleInterfaces.PowertrainMounts
  • Migration.VehicleInterfaces.Roads
  • Migration.VehicleInterfaces.Transmissions

The VehicleDynamics.Examples.VehicleInterfaces package contains experiment examples using the migration components.

Improvements/Changes

Minor Changes

  • A bug in the Linkages.Independent.Internal.Ackermann steering component caused the ackermann factor to be applied equally to both sides. This is now fixed.
  • Chassis.Suspensions.SingleAxles models now have consistent behavior of toe/camber settings.
  • The OpenCRG ground now uses OpenCRG 1.1.1
  • The Suspensions.Linkages.Mounts.Interfaces.Base1 linkage mount interface has been aligned with the other mount interfaces. This means that the replaceable rigid mounts inside suspension linkage templates can be replaced with switches and attached to other frames without duplicating the template. The conversion script handles most cases, but there could be customized models where it is not. If you run into problems, frame_b has been renamed to frame_b1.

Obsolete Models

DATA_DIR and DIR

The DATA_DIR and DIR strings will be removed in coming releases. It is recommended to use the Modelica.Utilities.Files.loadResource function instead which handles file paths in a better way.

Truck components with non-vectorized hub connectors

The truck interfaces have been made more general with the recently introduced vectorized hub connectors. Thus, templates and interfaces based on the old structure are obsolete and will be removed in coming releases. These include

  • Experiment templates under Examples.Trucks.Templates
  • Chassis.Interfaces.Trailer4_4
  • Chassis.Interfaces.Trailer6
  • Chassis.Interfaces.Truck2_2
  • Chassis.Interfaces.Truck2_4

Use the new generic Chassis.Interfaces.Truck, Chassis.Interfaces.SemiTrailer and Chassis.Interfaces.FullTrailer interfaces instead and set the appropriate number of front and rear axles. Refer to existing Vehicles.Chassis.Examples.Truck2s_222 for more information.

Conversion of User Libraries

User libraries will automatically be converted from version 3.0. These conversions are made using the included conversion script: VehicleDynamics/Resources/Scripts/Convert_to_3.1.mos.

Requirements

Vehicle Dynamics Library 3.1 is based on Modelon Base Library 3.1 and Modelica Standard Library 3.2.2.

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.

New Features

Slalom maneuver

A new ISO Slalom maneuver has been introduced. There is a new RoadBuilder function Grounds.RoadBuilder.slalom to create the road file and an example experiment (Examples.Manuevers.Slalom) that uses it.

 

 

New functionality in suspension test rigs

The suspension test rigs can now actuate suspension roll angle while maintaining a predefined total axle load. This is a common load case when evaluating a suspension.

When running with contact patch height as input to the test rig, there is now the option to specify a switch time when the rig switches from controlling wheel center height to controlling contact patch height. This allows the zero height for contact patch height to be defined where wheel center height is zero. This gives more consistent results for varying tire radius and stiffness.

Improvements/Changes

Updated interfaces for heavy vehicles

Chassis interfaces for heavy vehicles have been updated. There is now a single interface with vectorized hubs (Vehicles.Chassis.Interfaces.Truck) that is used for all truck and tractor models. Similarly, new interfaces for trailers have been added (Vehicles.Chassis.Interfaces.SemiTrailer and Vehicles.Chassis.Interfaces.FullTrailer). SemiTrailer has one group of axles while FullTrailer has one front and one rear group. Note that existing truck and trailer templates have been updated to extend from these new interfaces.

Having a single interface for all truck models allows us to create more experiment templates which are valid for all trucks regardless of the axle configuration. Experiment templates for trucks are now available in Vehicles.Chassis.Experiments.Templates.Trucks.

The Change class menu can now be used to redeclare to any truck example in VDL and any custom model that extends the single Truck interface model.

Minor Changes

  • The icon_file parameter has been removed from Atmospheres.Interfaces.Base and all standard atmosphere models.
  • The summary variables of the chassis motion blocks (i.e., Chassis.Motion.FreeMotion) are supposed to return chassis states resolved at the summary resolve point (r0_summary). The position variables: summary_r_x, summary_r_y, summary_r_z were incorrectly returning the position at the vehicleFrame. These variables now appropriately return the position at the summary resolve point.

Obsolete Models

  • Migration.ParsFiles was removed. The models associated with ParsFiles were obsolete due to significant restructuring of the PARS files. These models were removed to avoid confusion. (#553)

Conversion of User Libraries

User libraries will automatically be converted from version 2.4. These conversions are made using the included conversion script: VehicleDynamics/Resources/Scripts/Convert_to_2.5.mos.

Requirements

Vehicle Dynamics Library 2.5 is based on Modelon Base Library 2.6 and Modelica Standard Library 3.2.2.

New Features

Additional Strut Components

New bushing mounted strut components were introduced in VDL version 2.2. These struts are mounted to the chassis and suspension with bushings. Based on requests from numerous customers, we have added two additional struts that provide mechanical frames connectors on the interface. This allows the connection of the antirollbar, for example, to the strut body.

The new struts are found in Vehicles.Chassis.Suspensions.Linkages.Struts.Mounted. The bushing components are replaceable, and Struts.Mounted.Strut4 has two sets of translational flanges where one can be parameterized to attach either inside or outside the mount bushings. This is useful when springs and dampers are co-located in the suspension but attach on different sides of the mount bushings. Two examples are shown here:

Path Visualizer

A path visualizer has been added to provide a visual cue of the path to which the closed-loop lateral driver model is driving towards. The path visualizer is available in both the Grounds.TabularRoad and Grounds.OpenCRG ground models. The visualization is turned on by setting visualize_path=true. The ISO double lane change maneuver with path visualization:

Improvements/Changes

Additional Chassis Initialization Parameters

Additional parameters have been added to the Vehicles.Chassis.Interfaces.Base interface class to make it possible to specify more initial states of the chassis with respect to ground. The parameters: p_x_start, p_y_start, p_z_start, w_z_start have been added to the base interface. These parameters are available on the Initialization tab for all chassis models as show below

Closed-Loop Driver Summary Variables

Three summary variables have been added to provide information about the desired path and velocity that the closed-loop driver is driving towards. These include:

  • summary_rP_x - x-coordinate of driver's desired path
  • summary_rP_y - y-coordinate of driver's desired path
  • summary_vP - desired vehicle velocity

Wheel Carrier Components

There were some minor changes and improvements to the wheel carrier components in Chassis.Suspensions.Linkages.WheelCarrier.

  • Axle: The axle has been modified to be based on a new axle template. Every component in the template is defined as replaceable. The axle can now be either compliant or rigid with the same implementation that has been available in the upright.
  • Hub: An optional offset has been added to offset the hub frame along the spin axis.
  • Upright: The existing compliant component has been made replaceable.

Obsolete Models

Conversion of User Libraries

User libraries will automatically be converted from version 2.3. These conversions are made using the included conversion script: VehicleDynamics/Resources/Scripts/Convert_to_2.4.mos.

Requirements

Vehicle Dynamics Library 2.4 is based on Modelon Base Library 2.5 and Modelica Standard Library 3.2.2.

New Features

New Independent Suspension Linkages

Two new independent suspension linkages: fourlink and trapezoidal have been introduced. Both suspension linkages have either steerable or non-steerable configurations, as well as kinematic and multiple compliant versions.

A fourlink suspension is effectively a double wishbone suspension with either the lower or upper wishbone split into two separate fore/aft links and a steer link. Each link has a separate attachment point to the upright.

A trapezoidal suspension has a lower wishbone with a link connected to the upright, a single upper link and a steer link.

Kinematics and Compliance (K&C) Experiments Using Wheel Test Rig

In version 2.1, a live tire suspension test rig was added that allows the application of external forces and torques at either the contact patch or wheel center/hub. Experiment templates and examples have been added to allow you to perform virtual K&C experiments using this live wheel rig. K&C experiments are now broken into two groups: HubRig and WheelRig depending on which suspension test rig is used.

Example K&C experiments using the live tire rig can be found in: KCAnalysis.Examples.WheelRig.

Functional Mockup Interface Examples

Examples have been added to demonstrate how models can be both imported and exported as a Functional Mockup Unit (FMU) from VDL using the Functional Mockup Interface (FMI). The FMI allows for cross-platform deployment of models. The exported FMUs can be used with prepared example models in Simulink®, located in the VDL installation directory: VehicleDynamics/Resources/Simulink/FMI.

Using these Simulink® example models require the FMI Toolbox for MATLAB/Simulink®. The new examples can be found in Examples.FMI.

MATLAB® and Simulink® are registered trademarks of The MathWorks, Inc.

Improvements/Changes

Added Static Loadcases Suspension Experiment

The live tire suspension test rig has been modified to allow the wheel pads to be driven with a force input. Previously, it was only possible to drive the wheel pads with a displacement input. A new StaticLoads controller and an example WheelRig.StaticLoads experiment have been added that demonstrate this new functionality.

Dashboard Connector Changes

The dashboardInformation connector has been eliminated from the Vehicle and Driver standard interfaces to facilitate custom interfacing between drivers and vehicles. The signalBus now carries all generic signal information between the driver and the vehicle. The dashboardInformation connector is still available inside the signalBus as signalBus.dashboard. In order to make an external connection to the dashboardInformation connector, an instance of DashboardInformation has to be added and connected to signalBus.dashboard. Ignition and Start commands for the engine are now only sent over the signalBus and not in the dashboard interface.

We suggest to now use the signalBus for sending custom signals between the driver and vehicle. The signalBus is available in the standard driver interface.

Minor Changes

  • All road files that are required in example experiments are now included in the VehicleDynamics/Resources/Data/Roads folder. Users are no longer required to run the 'Build Road' script prior to running an example experiment.

Obsolete Models

Conversion of User Libraries

User libraries will automatically be converted from version 2.2. These conversions are made using the included conversion script: VehicleDynamics/Resources/Scripts/Convert_to_2.3.mos.

Requirements

Vehicle Dynamics Library 2.3 is based on Modelon Base Library 2.4 and Modelica Standard Library 3.2.2.

     

New Features

Cornering Ground Model

A new Cornering ground model has been added. This ground model allows modification of the ground surface position, orientation and curvature based on input signals. This ground model can be used in quasi-steady state simulations to evaluate chassis states at a particular straight-line or cornering condition. The chassis velocity and curvature result in lateral, longitudinal and vertical accelerations being applied to the vehicle. This ground model is particularly useful in motorsports applications to evaluate chassis states at different points on the race track. Examples using the Cornering ground can be found in under Examples.QuasiSteadyState and Examples.QuasiSteadyState.BankedCornering.

Bushing Visualization

The bushing visualizer has been changed to make it easier to see the relative displacement between frame_b (red cylinder) and frame_a (dark grey cylinder). The updated bushing visualizer can be seen in the image below. The visualizer also makes it easier to understand the axes related to the force {fx, fy, fz} and torque {tx,ty,tz} components. This can be seen in the annotated image below.

New Strut Components

New bushing mounted strut components have been introduced. These struts are mounted to the chassis and suspension with bushings. They are found in Suspensions.Linkages.Struts.Mounted. The bushing components are replaceable, and Strut2 has two sets of translational flanges where one can be parameterized to attach either inside or outside the mount bushings. This is useful when springs and dampers are co-located in the suspension but attach on different sides of the mount bushings. Two examples are shown here:

New Pitman-Idler Steering Model

A new pitman-idler steering model has been introduced. This model has been used previously in NASCAR and military applications and is now included as another steering model option.

Improvements/Changes

Changes to Steering Templates

The steering templates have been modified to have additional construction options including a replaceable steering shaft. If you were using either of these templates, you must add a connection between the steeringShaft axle flanges (axle_a and axle_b) as shown in the image below. The following templates were changed:

  • GearSteeringWheel
  • RackSteeringWheel

Ground Function Update

There was a discrepancy in how ground coordinates (sG) were defined in Grounds.Flat depending on whether the enable_sG flag was true or false. For enable_sG=false, the sG[1,2] coordinates would be defined in the x,y plane in world coordinates even when the road was inclined while when enable_sG=true they would be defined in the inclined road plane. See illustration below.

The flat_rG_0 function has now been updated so the surface coordinate (sG) are always defined in the inclined ground plane (green arrow) regardless of if sG functions are used.

User's Guide Moved

All content from the external User's guide has been migrated into online documentation in the library. Basic information is found in the User's guide section while more specific information on subcomponents is found in Information classes in each subpackage, see for example Grounds and Vehicles.Chassis.

New Hub Component

A new Hub component has been added. This component was added to properly handle alignment parameters for wheel carriers. Wheel carriers can either be aligned by toe and camber or a spin axis (n0H). The sign of these parameter is different depending on whether applied to a left or right wheel carrier. Previously, the sign change was often done in the suspension linkage. With the new hub component, the same toe/camber can be entered for both the left and right linkage and the left_linkage parameter in the Hub component will handle the sign changes.

Minor Changes

  • The wheel templates allowing external inputs have been modified to use a new Inputs contact calculation block. If you were using either of the templates listed below, you must redeclare the contact calculation block in your wheel to use the new Inputs contact calculation block. The following templates were changed:

    • ConventionalInputs
    • ConventionalInputs2

  • The sign on the output torque in Engines.Torques.TabularIgnitionControl has been corrected. The torque output is now positive for forward driving torque. If you are using the torque output from Engines.Tabular or Engines.TabularExternalControl or the VDL_eng_trq signal on the signalbus, you will need to take this sign change into account. (#580)
  • Grounds.Flat_new has been merged into Grounds.Flat, if you were using Flat_new, the conversion script will update your models to use Flat instead, all parameters can be used as before. (#697)
  • RigidSwitch2 and RigidSwitch3 have been renamed to Mounts.Switches.Switch2 and Mounts.Switches.Switch3, respectively. The conversion script will automatically update your models to reflect these changes. (#700)
  • The pedal_to_clamp_gain parameter in Brakes.Lumped has been renamed to pedal_to_pressure_gain to better reflect it's purpose. The pressure is converted to clamp force in the brake disc components.
  • The AArm component has been modified such that user-entered mass and inertia properties are resolved in frame_a, as stated in the documentation. Previously, the user-entered mass and inertia properties were incorrect in that they were resolved in frame_b. (#679)
  • The WindSpeedSensor has been modified to allow an external resolve frame. (#707)

Obsolete Models

  • Grounds.Flat_new

Requirements

Vehicle Dynamics Library 2.2 is based on Modelon Base Library 2.3 and Modelica Standard Library 3.2.1.

     

New Features

OpenCRG® Ground Model

The OpenCRG® project provides open file formats and open source tools for the detailed description and evaluation of 3D road surfaces. OpenCRG® data sets are designed to describe very detailed patches of road surfaces making them suitable for a broad range of applications including e.g. tire and driving simulations.

The OpenCRG ground model supports both binary and textual OpenCRG® data files.

More information about OpenCRG® and the OpenCRG® project can be found on its website: opencrg.org.

OpenCRG® is a registered trademark of Daimler AG, Germany.

Planar Filtering for Wheel/Contact Calculation

A planar contact calculation filtering method has been added to the Generic contact calculation block. The planar filtering method calculates a center frame and contact frame based on a plane on the ground surface. The plane is defined by four contact points/frames. The contact frames are located on the ground surface in the hub plane, but offset from the hub as defined by the offsetGrid parameter. This method is best suited for grounds with significant variation in height and road normal, as with the Belgian Block road pictured above.

There are now three choices for the filtering parameter of the Generic contact calculation block: None, Geometry weighted, and Planar. This new filtering method is selected by choosing "Planar".

Tabular Steering Systems

Two new steering systems were added: GearTabular and RackTabular. These two steering systems allow you to define gear/rack displacements relative to steering wheel angle using tabular data. Two components, TabularLever and TabularRack were added to allow creation of these models using existing steering templates.

Improvements/Changes

  • A wheel_number parameter was added to all wheel components. The wheel_number is often required in external tire force models. This parameter was previously used in the contact calculation and sensor components. For consistency, this parameter was added to the tire forces, hub and visualization interfaces. The wheel_number is now propagated to all these components in the base wheel template. (#672)
  • Some suspension linkage templates were missing switchable mounts to allow you to attach the ride spring and damper to either the lower control arm, upper control arm, or upright. The follow templates were changed: (#649)

    • DoubleWishboneSTT2
    • DoubleWishboneSTT3
    • DoubleWishboneTT2
    • DoubleWishboneTT3

Obsolete Models

  • Removed old steering templates (ConventionalRackSteeringWheel and RackPinion) that were no longer used. (#650)

Requirements

Vehicle Dynamics Library 2.1 is based on Modelon Base Library 2.2 and Modelica Standard Library 3.2.1.

     

Version 2.0 contains additional suspension and chassis test rigs, new ground sensors and new aerodynamics models. These additions, as well as some changes, are described below.

New Features

Pacejka '94 Tire Contact Force Model

Support for the Pacejka '94 'Magic Formula' contact force model has been added. The Pacejka '94 contact force model provides the benefit that it requires fewer coefficients than newer models; is more commonly used than the Pacejka '02 model; and is used in many other vehicle dynamics software products. By supporting this contact force model natively in VDL, the Pacejka '94 tire coefficients can be shared between VDL and other simulation tools. The equations for this contact force model are described in the paper: 

Pacejka, H.B., and Bakker, E. (1993): The Magic Formula tyre model
Proceedings of 1st Colloquium on Tyre Models for Vehicle Analysis, Delft 1991, ed. H.B. Pacejka, Suppl. Vehicle System Dynamics, 21, 1993.

Suspension Wheel Test Rig

A new live tire suspension test rig has been added that allows the application of external forces and torques at either the contact patch or wheel center/hub. In physical kinematics and compliance tests, it is quite common to have a wheel and tire mounted on the suspension. It is the intent of this new rig to be able to better mimic the actual physical tests. Example suspension experiments using this new rig can be found in: Examples.WheelRig.

Chassis Kinematics & Compliance Experiments

Two new chassis-level kinematics and compliance experiments have been added: FourPostNoWheels & KinematicsCompliance. These rigs not only allow vertical excitation of the chassis, they also allow the application of external forces and torques at either the contact patch or wheel center/hub. 

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. Three new sensors have been added to report the proximity of a frame to ground:

  • ClosestPoint - outputs the closest point located on the ground surface to the sensor
  • ClosestPointInPlane - outputs a point located on the ground surface at the point of intersection of a plane and ground
  • IntersectionAlongLine - outputs a point located on the ground surface at the point of intersection of a line and ground

Existing ground sensors that were previously located in Chassis.Sensors have been moved to Ground.Sensors. This includes the following sensors:

  • FrameInPlaneThreePoints
  • FrameOnGround
  • GroundCurvature
  • GroundHeight
  • VelocityOfGround

Ride Height Dependent Aerodynamics Models

Four new aerodynamics models have been added that are dependent on front/rear ride heights. The different models demonstrate how to represent lift/drag/side aerodynamic forces using either a polymonial or tabular data: 

  • PitchPolynomialLD
  • PitchPolynomialLDS
  • PitchTabularLD
  • PitchTabularLDS

Improvements

An overview of some of the changes that have been made and issues that have been fixed in this version are included in the following lists. 

Uncritical issues (i.e., issues that do not affect simulation results): 

  • RevoluteSB has been recreated to be consistent with RevoluteBB. The old RevoluteSB has been renamed to RevoluteSB_. This old version is deprecated and will be removed in the next release. A new RevoluteBS option was also added. (#640)
  • Renamed Suspensions.Linkages.Mechanisms.RASURLU.steeringLink to steerLink to be more consistent with other suspension linkages. (#641)
  • In Wheels.Interfaces.Base, the wheel_number parameter was changed so that it is no longer conditionally enabled based on the enable_signal_bus parameter. This parameter is now always enabled for modification. (#643)

Conversion of user libraries

A conversion script is required to convert some models from version 1.9 to version 2.0.

Version 1.9 is a major maintenance release with many changes to the Wheels interface and templates. A conversion script is required to accommodate the changes described below. This will convert models from version 1.8 to the current version.

Support for TYDEX Standard Tyre Interface Tire Models

The Standard Tyre Interface (STI) was defined by the TYDEX working group, see VehicleDynamics.Vehicles.Chassis.Wheels.Information.Literature for more details.

The existing, built-in tire models in VDL have separate blocks for calculating forces and contact calculations (tire/ground interaction). For STI-compatible tire models, the forces and contact calculations are combined. Further, the VDL tire models calculate the tire forces at the contact patch, and the hub model is responsible for transforming those forces for application at the hub. STI-compatible tire models calculate the tire forces at the hub.

New Wheel Interfaces and Templates

The fundamental differences between the VDL tire models and STI-compatible tire models mean that the existing templates for wheels, forces, hubs, and contact calculations in the VDL could not be used. VDL has now been extended to support STI-compatible tire models that calculate the forces at the hub by adding new wheel, forces, and hub interfaces and templates. A partial list includes:

  • Wheels.Templates.BaseHF
  • Wheels.Templates.ConventionalHF
  • Wheels.Hubs.MultiBodyHF
  • Wheels.ContactCalculation.Templates.BaseHF
  • Wheels.TireForces.Interfaces.BaseHF

Wheel.ContactForces Renamed To Wheel.TireForces

As described above, STI-compatible tire models could be considered hub force tire models. As hub force tire models are now supported, Wheels.ContactForces was renamed to Wheels.TireForces.

Support for the Delft-Tyre family of tire models

VDL was been extended to include support of the TNO Delft-Tyre product line which includes MF-Tyre® and MF-Swift® tire force models. The Delft-Tyre wheel model fully supports VDL built-in ground models, TNO road property files, and OpenCRG road descriptions.

MF-Tyre

MF-Tyre is the Delft-Tyre standard implementation of the renowned Pacejka Magic Formula that includes the latest developments. With MF-Tyre the engineer can simulate validated steady-state and transient behavior up to 8Hz, making it the ideal tire model for handling and control prototyping analyses. Pure cornering and braking as well as combined conditions are accurately described. The robust extrapolation properties of MF-Tyre make the model suitable for the simulation of conditions that go beyond the measurement conditions.

MF-Swift

MF-Swift is the high frequency (100Hz) extension to MF-Tyre. MF-Swift adds generic 3D obstacle enveloping and tire belt dynamics to MF-Tyre's tire-road contact force and moment simulation. Typical application areas for MF-Swift are vehicle comfort analysis, suspension vibration analysis, development of vehicle control systems, such as ABS or ESC, and handling and stability analysis like braking and power-off in a turn on an uneven road.

Please see the Delft-Tyre Forces block for more information, requirements, and limitations.

Changes from Version 1.8

An overview of some of the changes that have been made and issues that have been fixed in this version are included in the following lists.

Uncritical issues (i.e., issues that do not affect simulation results):

  • The Modelon-specific StateSelection type in the Modelon Library has been removed. All VDL components that referenced that type now use the Modelica predefined StateSelect enumeration.
  • There were changes in the Modelon Library Visualizers where references to the Modelon-specific type Finish have been changed to Modelica standard type Color. This effects some VDL components.

Modelica Standard Library Version: 3.2.1

Version 1.8 is a major maintenance release with many changes and assured compatibility with the updated Modelica Language Specification (Version 3.2.1). A conversion script is required to accommodate the changes described below. This will convert models from version 1.6, 1.7 and 1.7.1 to the current version.

Additional Tuners, Tunables and Setup Experiment

Tuners and tunables 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.

Chassis tuning or setup is applicable in both OEMs and Motorsports. Tuning tasks can range from simply automating ride height adjustments to fully replicating a physical setup procedure used in Motorsports, such as adjustments for toe/camber, ride heights, trackbar height, driver in/out, fuel, and ballast position. Please see the new Setup experiment for more information and a detailed example.

Examples using the Modelon.DataAccess package

The Modelon.DataAccess is an architecture for data management allowing users to populate models with data from sources outside the Modelica environment. In this release, an example has been added to demonstrate how a vehicle model can be completely parameterized to data from external files using the DataAccess functionality. Please see the new DataAccess example in the top-level Examples package.

Elimination of Booleans in Wheel Visualization

In the continued efforts to improve real-time performance, the boolean visualization modes in wheels have been modified to be Reals:

Sliding visualization warning: The tire is considered to be sliding if the slidingState > slidingThreshold. If the tire is sliding, it will be displayed in red ({255,0,0}).

Contact visualization warning: The tire is considered to be in contact with the road if the contactState >= contactThreshold. If the tire is not in contact, i.e. has lifted off the road, it will be displayed in yellow ({255,255,0}).

Valid visualization warning: The tire is considered to be valid if the validState >= validThreshold. If the tire is invalid, it will be displayed in blue ({0,0,255}).

Changes to Powertrain.Engine Models

The Tabular engine and it's torque block (TabularIgnitionControl) were restructured to make is easier to add custom engine torque models. The TabularIgnitionControl was changed to focus purely on a rotational 1D representation of the engine's torque characteristics. As such, the multi-body frame mount has been removed and the inertia and visualizers have been moved out of this component and into the engine component. Also, the torque block has been modified in the engine so that it is replaceable.

Changes to ShakerN and PivotingPlanes Ground Models

The parameters and input connectors to the ShakerN and PivotingPlanes ground models have been changed. Previously, the location of the posts and size of the input connectors was based on two parameters, grid_x and grid_y. The size of the input connector was then [size(grid_x,1),[size(grid_y,1)]]. For a typical 4 post configuration, this size was [2,2]. It was determined that this approach was confusing and inconsistent between the two models. It was confusing because it was difficult to determine how the grid actually corresponded to an individual wheel.

As such, there is now a single parameter grid_x_y. The size of each input connector is then defined as [size(grid_x_y,1)]. For a typical 4 post configuration, this size is [4]. The post locations and input connector index now corresponds directly to the wheel_number. Therefore, the inputs for the left front wheel are index #1, right front wheel are index #2, etc. Please see the information layer for each ground model for more information: ShakerN and PivotingPlanes.

Changes from Version 1.7.1

An overview of some of the changes that have been made and issues that have been fixed in this version are included in the following lists.

Uncritical issues (i.e., issues that do not affect simulation results):

  • Removed obsolete visualization parameters in Wheels.
  • Removed obsolete parameters {housing_position,clutch_position} in Powertrain.Visualizers.
  • Removed obsolete parameters {gear_position,clutch_position} in Powertrain.Transmissions.
  • Removed obsolete parameters {r0MT,r0DT,n0MT,q0MT,n0DT,q0DT} in Vehicles.Templates.FrontEngineCar.

Modelica Standard Library Version: 3.2.1

Version 1.7.1 is a minor maintenance release. 

Added Flatpad Chassis Experiment

The flatpad is a simulation of the chassis sitting stationary on a flat pad/ground. The chassis is constrained from moving laterally, longitudinally and in yaw by the fixedRig robot. The steering is also locked by inputting a constant zero steer input into the steerRobot. This type of simulation is useful to look at the static balance of the car. This allows you to adjust spring preloads as necessary to trim the chassis as necessary based on either changing payloads or changes in spring rates. This is also a good simulation to use to evaluate the static toe and camber of the vehicle. By changing the steering input to a different source, the steering effect on the chassis can also be characterized.

Improvements to Online Help

  • Added Frequently Asked Questions found in the VDL User's Guide to the online help.
  • Updated Examples Information to include links to many of the examples found throughout VDL.
  • Improved documentation of tabular suspensions to better describe contents of tables.

Changes from Version 1.7

Some of the changes that have been made and issues that have been fixed in this version are included in the following lists.

Minor library additions:

  • Added an example for a steerable suspension in a rig.
  • Added two examples for steering systems in a rig.

Critical issues:

  • Modifications to tabular suspensions to ensure proper behavior in different vehicle coordinate systems.
  • The longitudinal acceleration in the quasi-static cornering events were incorrect in version 1.7. This error has been resolved and the acceleration is now correct and consistent with version 1.6.

Modelica Standard Library Version: 3.2

Version 1.7 is a major maintenance release with many changes in the underlying Modelica code to ensure better compliance to the Modelica Language Specification (Version 3.2).

Examples using the Modelon.DataAccess package

The Modelon.DataAccess is a new architecture for data management allowing users to conveniently populate models with data from sources outside the Modelica environments. Examples of using the DataAccess functionality will continually be added to VDL. In this release, some example experiments have been modified to take advantage of DataAccess. For example in SingleTrack, the parameters associated with the single track model are determined in the ParameterIdentification experiment and referenced in the DoubleLaneChangeVerification experiment.
Please see the release notes for 1.6 for more information on the capabilities of the DataAccess package.

Animation view commands added

Commands have been added to many experiments to modify the animation view in the active animation window. The commands allow the user to quickly view a vehicle, chassis, or suspension from the front, side, rear, top or isometric perspective. Most of the example experiments within VDL have these commands available. This is accomplished by extending a new experiment template called AnimationViews.

Changes from Version 1.6

An overview of some of the changes that have been made and issues that have been fixed in this version are included in the following lists.

Uncritical issues (i.e., issues that do not affect simulation results):

  • Animation of body disappears when copying examples
  • specular_coefficient parameter not propagated to visualizers in Chassis.Bodies.Visualizers
  • Correct info layer link in Examples.RunningOverCrest.RunningOverCrest
  • Added command to plot desired/actual path in plotClosedLoopDriver function
  • Added Linkages/Experiments/Examples/LinkageInRig
  • Corrected spelling error in parameter name sx_tabel_width

Modelica Standard Library Version: 3.2

Version 1.6 of VDL contains the following main enhancements:

Powertrain

The Powertrain sub-package has been extended with components that allow for powertrain oriented analysis.

  • Template-based engine models with cycle resolved characteristics. The new models allow to study the mechanics of the engine, and engine-induced vibrations.
  • Engine, transmission and driveline mounts integrated in templates, including different options for mount characteristics.
  • Updated transmission models that can handle arbitrary number of gears, with optional gear dependent compliance and backlash for vibration analysis. Automatic transmission with torque converter and compliant lock-up-clutch. Slip-based continuously variable gear.
  • KERS, flywheel that can capture and release kinematic energy, based on rotating inertia.

The new powertrain components are designed to work well together with the rest of the vehicle and typical applications are drivability and take-off. The package has also been extended with dedicated powertrain test scenarios that makes use of test rigs to evaluate engine vibrations, acceleration performance etc.

Tuning

VDL supports tuning of vehicle and chassis. This allow for automatic tuning of e.g. camber, toe, cross weight, and ride height. In the library, there are sub-packages Tunables that contains components such as mounts, seats, and links that can be adjusted during simulation. The tunables fit in the standard suspension architectures to facilitate configuration.

Grounds and Roads

Support for explicit contact point calculation so that the contact point can be performed in the ground model instead of the wheel or impact component. This allows for more convenient plug in of external ground and road models.

DataAccess

A new architecture for data management is introduced available in the DataAccess.

  • It allows users to conveniently populate models with data from sources outside the Modelica environments.
  • Users can also define own data hierarchies that do not have to match the model hierarchies.
  • Data can both be read from and written to the source. This gives a convenient way to link several simulations together.
  • The architecture further allows for convenient switching between different sources and source types with single changes.
  • DataAccess is especially suited for model export as it allows users to conveniently change model parameters in a consistent way regardless on how the model is exported (C-code, .dll, .exe, FMU, Simulink, etc.).
  • DataAccess can be made compatible with any format, by default it comes with support for XML.

Modelica Standard Library Version: 3.2

Version 1.5 has been improved especially with new functionalities to support steady-state, and quasi steady-state analysis.

Library additions  

  • New generic models and experiment that handles quasi steady-state driving events such as cornering, corner entry, corner exit, braking.
  • New sensors for height over ground and ground curvature. New set of linkage templates (requires the suspension option).
  • Introducing mounts that allow for more convenient customization of suspension linkage (requires the suspension option).
  • Electric vehicle example (requires the driveline option). Improved tabular suspensions.

Modelica Standard Library Version: 3.2

Version 1.4 has been improved especially with new functionalities to improve signal routing. User models from earlier versions must be converted using the included conversion script. Please refer to the Dymola User Manual for details on how to do this.

Library additions

  • A new option Active Safety that contains especially
    • models of safety systems such as ABS, ESP and more.
    • single track models with parameter identification experiment, also used as reference models for e.g. ESP models.
    • Support for traffic interaction and sensors to detect external objects. Can be used for e.g. brake assist function development and traffic interaction studies.
  • A new signal bus concept has been implemented to better support signal routing. Especially this means that no signal bus connections are required. Access to the signals can be made from anywhere within the model. Also vectorized signals are possible.
  • Improved driveline models
    • System layout also of different clutches and gears allow for easy design of different types of differentials, both active and passive. To illustrate this, examples of torque on demand clutches and active differentials are included in the library (requires the driveline option).
    • Visualization is added to improve understanding and analysis of the behaviour. It is also possible to visualize the torque flow through the driveline.
    • Improved clutch model with integrated compliance.
    • New components to support hybrid drivelines (requires the driveline option)
  • Improved initialization of shaft models, especially relevant to steering models.
  • Improved RoadBuilder format and tabular ground models.
    • New improved format that supports also closed tracks.
    • More RoadBuilder functions available, both for center-line description (x,y,z) and curvature-based descriptions.
    • Improved performance due to better numerics (numerical Jacobians eliminated).

Version 1.3.1 is a release made with Dymola 7.2 and contains minor bug fixes, primarily relating to automatic drivers and missing Simulink examples.

Version 1.3 is the first version that supports Modelica 3 and Modelica Standard Library (MSL) 3.0 User models from earlier versions must be converted using the included conversion script. Please refer to the Dymola User Manual for details on how to do this.

Conversion to Modelica 3 specification taking advantages of new language features

  • Vehicle Dynamics Library is now using MSL3.0 and is compatible with other Modelica 3 libraries.
  • The balanced-model concept has been implemented.
  • Restructuring of many models, especially the wheel models have a new structure that makes it easier to understand.
  • More flexible interfaces and templates using conditional connectors: This allow for the same templates to handle different subsystem configurations, e.g. Automatic and Manual transmission.
  • Better indication of the signal flow in test rig experiments: The use of specialized signal connectors is minimized which makes it easier to understand and modify the experiment setups.
  • New summary variable declaration that makes it easier for users to add their own variables.

Library additions

  • Support for uneven road through contact point filtering, see VehicleDynamics.Vehicles.Chassis.Experiments.Examples.WheelLoader (This example requires VDLTrucks option).
  • Support for both time- and distance-based preview in driver models: This facilitates the use of drive-cycle following drivers, see VehicleDynamics.Drivers.Experiments.Examples.DriveCycle.
  • New gear-set models suitable for handling: Manual, Automatic, CVT
  • Included length offset in links makes it easer to make adjustment studies on suspensions with design-freeze components
  • Improved structure of steering models: Predefined components for rack-and-pinion and pinion-gear makes it easer to modify and build user-defined steering models.
  • Improved structure of engine and transmission models makes it easier to add user-defined models and models from other libraries.
  • New drive shaft model with ideal characteristics: The shaft preserves the rotational velocity independently of shaft bend angles (Requires the VDLDrivelines option).
  • Default StateSelect.Always change to StateSelect.Prefer in Linkage components.
  • Humidity removed from atmosphere models

Minor maintenance release with:

  • Improved contact point calculation.
  • Improved wheel vizualization.
  • GST tire model imroved with support for similarity-based road friction variations and tabular pure-slip models.

VDL has been optimized to be used with Dymola 7.0.

  • New VDL option annotations require this version of Dymola. Currently, the available options are VDLCars, VDLTrucks, VDLSuspensions, VDLDrivelines and VDLParsfiles.
  • VDL 1.2 uses Modelica Standard Library 2.2.2.

Units can be automatically converted in this Dymola release so this VDL release will be the last release including the same variables with different units for summary tables (such as yaw rate w_z and w_z_deg). The variables with no unit suffix will remain as they exist.

Examples have been restructured to include experiments and components

  • Most main packages contain Examples packages for components (these should be duplicated to be customized).
  • Most Experiments packages contain Examples of complete models to simulate.
  • New examples for Realtime simulation (available with Dymola Realtime option).
  • New examples for simulation from Simulink (available with Dymola Simulink option).

Library additions

  • Suspension Links and Joints have cut-force summary variables and visualization vectors to easily find and see the forces transmitted by suspension joints.
  • The vehicleFrame can be rotated to a user-defined coordinate system (Forward-Leftward-Upward system, or FLU), allowing hardpoints from other coordinate systems to be directly used.
  • A linear tyre model is new.
  • New MultiBody instant rotation axis sensors can easily be attached to the hubs to visualize the roll center or kingpin axis.
  • Aggregated joint mechanisms are easier to understand and include the cut-force summary at joints.
  • A visualized dashboard example can directly animate the driver actions during the experiment.
  • Atmosphere with input signal for wind.
  • Upright with a lumped elasticity.
  • Suspension hub/axle motion sensor replacing suspension experiment variables.
  • Added tabular steering models for Cars and Trucks.
  • Chassis.Bodies package is structured more logically.
  • Interpolation methods for tabular gears (Translational and Rotational).
  • Added MultiBody sensors and visualizers.

The Trucks and Heavy Vehicles modeling extension to VDL is new (Beta status, available with VDLTrucks option)

  • Detailed truck and trailer chassis models including full and semi-trailer versions.
  • Single or twin tyres can be used with all suspension models.
  • Detailed tabular and geometric axle-based suspension models.
  • Chassis structure components (rigid or elastic frames, truck cabin with suspension, fifth-wheel and other hitches).
  • Configurable payloads, possibly dynamic (simulate a liquid tank trailer).

Driveline modeling has been extended (Beta status, available with VDLDrivelines option)

  • New shaft model includes 3-d constant-velocity (CV) or universal joints.
  • Driveline shafts have a debugging mode with visualization.
  • Rotational3D components can visualize the connector orientation.

Tabular gears have been extended to use numerical interpolation, enhancing the real-time capability.

  • Tabular gear are extended to use numerical interpolation that does not use the external LAPACK routine, enhancing real-time capability
  • SedanTEKBakker chassis parameters have been improved (rear damping)
  • Bakker tyre model load default parameter fixed
  • Improved transition between gears in gearSet

VehicleDynamics Library is a commercial and licensed Modelica™ library for the Dymola™ modeling and simulation environment. The scope of the library is simulation of complete road vehicles with focus on chassis dynamics. The chassis models are based on multibody mechanics with detailed models of wheel suspensions and tyres. The library covers all components required to build complete experiments for vehicle-dynamics analysis, including powerful road descriptions and driver models.

Main features

Highlight features of the library are:

  • Easy to build custom models and experiments from a large collection of components, templates, and test rigs
  • Intuitive and easy-to-learn user interaction for model construction and experiment analysis
  • Flexible to modify and customize subsystems, roads/maneuvers, chassis geometry, etc.
  • Most Modelica source-code is available for the user
  • Kinematic and elasto-kinematic suspensions, described with geometric linkages or tables
  • State-of-the-art tyre models
  • Detailed animation of simulation results
  • Summary records for easy plotting of variables of general interest
  • The RoadBuilder package allows complete flexibility in 3D road construction with driver reference trajectories
  • Driver models for open-loop and closed-loop driving. Custom test cases are conveniently specified using driver instructions
  • Powerful 3D driveline models, basic transmission and engine models
  • Flexible bus concept for convenient signal passing between sub-models, and also to Simulink

Changes from Version 1.0

This release of the VehicleDynamics Library provides considerable enhancements compared to earlier versions:

  • Improved library structure with enhanced set of experiment templates and components.
  • The UsersGuide is improved and distributed printed and as pdf.
  • The examples are extended with steer-by-wire application, control of active chassis systems and more.
  • The driver models are improved and contain perception, planning and tracking tasks as well as physical driver-vehicle interfaces.
  • A PowerTrain level is introduced for easier inclusion of non-conventional drives such as hybrids.
  • A new tyre model with physical extrapolation of pure slip data is included.
  • Dashboard model allow for driver-vehicle information exchange.

This is the first official release of the VehicleDynamics Library.