Chapter 2 — How To Use HVE¶

Updated Markdown edition of the HVE User's Manual (HVE Version 5, Seventh Edition, January 2006), Chapter 2, pages 2-1 through 2-104. Verified against the current HVE application source (HVEINV-64/HVERSNT.rc and related dialogs). Because of its length, Chapter 2 is split into three parts:

Part	Contents
Part A (this file)	Getting Started, HVE Menu Bar, HVE Modes, Starting a New Case, Creating Humans/Vehicles/Environments, 3-D Editor, Creating Events, Setting Up Events, Executing Events, Choosing Options
Part B — 02b	Creating Report and Playback Windows, Playback Controller, Audit Trail, Creating Case Files, Creating Databases, Printing Results, Setting the View (cameras, overlays)
Part C — 02c	Selecting User Options (Key Results, show toggles, Grid, Units, Render, Simulation Controls, Playback, Calculation Options, DyMESH, Get Surface Info, Preferences), Getting Help, Video Interface

We think you will find HVE easy to use. All the operations are simple and intuitive. You'll find yourself thinking more about the objects in your study (humans, vehicles and environments) and much less about data (weight, wheelbase and other details).

Using HVE involves performing the following steps:

Use the HVE Human Editor to select and create all the humans involved in your study.
Use the HVE Vehicle Editor to select and create all the vehicles involved in your study.
Use the HVE Environment Editor to select and create the environment involved in your study.
Use the HVE Event Editor to set up and execute reconstruction and simulation models which analyze the interactions between the selected humans, vehicles and environment.
Use the HVE Playback Editor to combine multiple events into a single coherent sequence involving multiple humans and vehicles. You can also use the Playback Editor to create printed, plotted and video output showing and documenting the events.

Getting Started¶

To start HVE, use the Start, Programs, HVE cascade menu to select the HVE program icon, just as you would start any other program on your computer. After starting HVE, the current Editor will be displayed, along with the menu bar.

Figure 2-1: HVE, ready to begin. The HVE Menu Bar and current editor (in this case, the Vehicle Editor) are displayed. The Mode pushbuttons on the toolbar allow the user to select the current editor.

The HVE Menu Bar allows the user to select from the following pull-down menus:

File Menu — Provides access to file handling, printing and video output information.
Edit Menu — Provides access to editing functions used in various portions of HVE, such as the 3-D Editor.
View Menu — Provides access to various viewing options.
Mode Menu — Provides access to select the current editor, and to add new or previous objects to the editor.
Set-up Menu — Provides access to event set-up options.
3-D Edit Menu — Provides access to 3-D Editor functionality.
Options Menu — Provides access to various user options and preferences.
Help Menu — Provides access to HVE's extensive on-line help system, HVE version information and also EDC Technical Support information.

Each of these menus provides access to important user information and options which apply to all HVE operations. Refer to the Menu Reference section of this manual for detailed information about each option available in the HVE Menu Bar.

(updated: the current menu resource, IDR_MAINFRAME in HVEINV-64/HVERSNT.rc, confirms this menu bar: File, Edit, View, Mode, Set-up, 3-D Edit, Options, Help. The current File menu includes New, Open, Save, Save As, Export Preview Case, Print, Print All, Video Creator, Export, FBX Export, recent files and Exit. The Help menu now also includes a User Manuals submenu — HVE, EDCRASH, EDGEN, EDHIS, EDSMAC, EDSMAC4, EDVDS, EDSVS, EDVSM, EDVTS, SIMON, Damage Studio, GATB and ReadDataFile — plus Online Licensing options for registering a User ID code and refreshing licenses.)

HVE Modes¶

HVE's functional design is based on the following five modes:

Human Mode — Provides access to the Human Editor
Vehicle Mode — Provides access to the Vehicle Editor
Environment Mode — Provides access to the Environment Editor
Event Mode — Provides access to the Event Editor
Playback Mode — Provides access to the Playback Editor

Each of these modes has an editor used for creating and studying the objects (humans, vehicles and environment) of interest. The desired mode is selected by pressing the desired mode button at the top of the current editor (see Figure 2-1).

(updated: modes may also be selected from the Mode menu, which assigns the keyboard shortcuts Ctrl+1 (Human), Ctrl+2 (Vehicle), Ctrl+3 (Environment), Ctrl+4 (Event) and Ctrl+5 (Playback), and provides Add... New/Previous and Information... (Ctrl+I) options.)

Starting A New Case¶

A case is a file containing the results of an HVE session. If you didn't open a case when you started HVE, you can do so using the Open Case option found in the File menu. The Open Case option displays the File Selection dialog which displays all your previously run case filenames. Simply double-click on the desired filename and the case file will be loaded.

If you choose not to open a case file, you will begin a new case.

Figure 2-2: The Open Case File Selection dialog allows the user to open previously saved cases (*.hve files).

Creating Humans, Vehicles and Environments¶

The first step is to create the humans, vehicles and environment to be studied.

Creating Humans¶

Humans are created and edited using the HVE Human Editor. To create the required humans:

Click on the Human Mode button on the toolbar. This puts HVE in Human Mode.
Click on Add New Object to display the Human Information dialog (see Figure 2-3).
Choose the human location (any of nine occupant positions or pedestrian).
Choose the human according to Sex, Age, Weight percentile and Height percentile.
Choose OK.

The selected human is now displayed in the Human Viewer. At this point you may choose to edit the current human's properties (refer to the Human Editor section of this manual for details; see also the code-verified Human Information dialog reference). The above steps are repeated for each human to be included in the study.

Figure 2-3: The HVE Human Editor and Human Information dialog (Human Name, Location, Sex, Age, Weight Percentile, Height Percentile).

Creating Vehicles¶

Vehicles are created and edited using the HVE Vehicle Editor. To create the required vehicles:

Click on the Vehicle Mode button on the toolbar.
Click on Add New Object to display the Vehicle Information dialog (see Figure 2-4).
Choose the vehicle Type, Make, Model, Year and Body Style.
If desired, edit the Number of Axles, Driver Location, Engine Location and Drive Axle.
Choose OK.

The selected vehicle is now displayed in the Vehicle Viewer. At this point you may choose to edit the current vehicle's properties (refer to the Vehicle Editor section of this manual for details; see also the Vehicle Information dialog reference).

Repeat the above steps for each vehicle to be included in the study.

NOTE: A multi-vehicle train (e.g., a tractor-trailer) is created by creating its individual vehicle units, one at a time, using the Vehicle Editor.

Figure 2-4: The HVE Vehicle Editor and Vehicle Information dialog (Vehicle Name, Vehicle Type, Make, Model, Year, Body Style, Source Database, Number of Axles, Driver Location, Engine Location, Drive Axle(s)).

Creating Environments¶

To create the environment:

Click on the Environment Mode button on the toolbar.
Click on Add New Object to display the Environment Information dialog.
Select the City, State and Country using the Location Database.
Enter the Time and Date of the Event.
Enter the Angle of the X axis (relative to North) of the earth-fixed coordinate system used in your study.
Enter the Wind Speed and Direction.
Enter the Barometric Pressure and Ambient Temperature.
Enter the Gravitational Constant.

NOTE: The latitude, longitude and hours from GMT, along with the time and date of the accident and angle of the X axis, are used to position the sun in your environment.

Choose Sky Attributes to display the Sky Attributes dialog. Enter or modify the atmospheric visibility conditions (Sky Color, Fog Type, Maximum Visibility and Fog Color).
Choose Open to load an existing environment 3-D geometry file and/or a scanned photograph of the environment.

NOTE: The File Selection dialog includes an option list allowing the user to select the file format (h3d, dxf, rgb, etc.) and the desired input file. Where necessary, HVE converts the selected file into the HVE file format.

NOTE: The Options pushbutton allows the user to scale and rotate the environment model as required for HVE's SAE coordinate system.

Choose OK.

The environment is now displayed in the Environment Viewer.

Figure 2-5: The Environment Information dialog (Current Location, Latitude, Longitude, GMT offset, Environment Name, Date and Time of accident, Angle of X Axis, Wind Speed and Direction, Barometric Pressure, Temperature, Gravity, Environment 3-D Geometry File, Environment Scanned Image File, Sky Attributes).

3-D Editor¶

Figure 2-6: HVE 3-D Editor, used for creating and editing 3-D geometry data used to visualize the humans, vehicles and environment for the current case. The 3-D Editor has four viewers (Perspective plus X-Y, Y-Z and X-Z).

The 3-D Editor is a 3-D modeling tool which may be used to create and edit the 3-D geometry data used for visualizing environments.

The 3-D Editor is started in Environment Mode by selecting the 3-D Edit menu option, then selecting Launch 3-D Editor. The current object is loaded for editing. In this case, it has the current environment loaded and ready for editing its visual and surface friction properties.

For more information about the 3-D Editor, refer to the 3-D Editor tab in the Tools section of this manual (see also the code-verified 3-D Editor reference).

(updated: the current 3-D Edit menu contains Launch 3-D Editor (Ctrl+L), Material Color..., Material Texture..., a Manipulators submenu (Direct, Jack, Trackball, Centerball, Handle Box, Transform Box, Tab Box), Object Attributes..., Viewer, and Close 3-D Editor.)

Creating Events¶

An HVE event is a single reconstruction or simulation analysis of one or more humans and vehicles in the current environment. Event Mode is where all the action (or interaction) is. The calculation model is actually executed in Event Mode.

To create an HVE event:

Click on the Event Mode button on the toolbar. The Event Editor is displayed.
Click on Add New Object to display the Event Information dialog (see Figure 2-7).
Select the human and vehicle objects and the calculation model (see below).
Choose Calculation Options to display and edit any program options.
Choose OK.

Figure 2-7: The Event Information dialog — Event Name, Humans List, Vehicles List, Event Humans and Vehicles, Calculation Method.

See also: Event Information and the per-model Calculation Options references.

Choosing A Calculation Model¶

The choice of calculation models is dependent upon the needs of the study. Normally, reconstruction models are executed first, because they provide part or all of the initial conditions required to execute simulations.

Reconstruction Models¶

According to SAE [6.4], a reconstruction is the determination of initial conditions (usually impact speed) based on post-accident evidence. To execute an HVE reconstruction program in the HVE Event Editor, the user normally supplies (for each vehicle) some or all of the following information during Event Mode:

Pre-impact position
Impact position
Path positions between impact and rest
Rest position
Vehicle damage

NOTE: The actual requirements are dependent on the particular reconstruction method.

The reconstruction calculations usually provide some or all of the following results:

Initial Velocity
Velocity at Begin Perception
Velocity at Begin Reaction
Velocity at Begin Braking
Velocity at Impact
Velocity at Separation
Final Velocity
Delta-V during Impact
Energy absorbed during Impact
PDOF during Impact

Simulation Models¶

According to SAE [6.4], a simulation is the prediction of human or vehicle paths and damage based on initial conditions (position and velocity). To execute an HVE simulation program in the HVE Event Editor, you will usually supply (for each human and/or vehicle) some or all of the following information during Event Mode:

Initial position and velocity
Driver Controls (for vehicles)
Collision Pulse (for vehicles)
Mesh (for vehicles)
Payload (for vehicles)
Wheels (for vehicles)
Accelerometers (for vehicles)
Restraints (for occupant simulation)
Contacts (for occupant and pedestrian simulation)

NOTE: The actual requirements are dependent on the particular simulation method.

The simulation calculations usually provide some or all of the following results (reported as a function of time):

Sprung Mass Kinematics (position, velocity and acceleration)
Sprung Mass Kinetics (forces)
Accelerometers (velocity and acceleration)
Damage (vehicle exterior crush geometry and force)
Tire Conditions (contact patch location, forces, slip angles, skidding)
Wheel Conditions (position and orientation, forces and moments at wheels and suspensions)
Connections (articulation angles, forces and moments)
Driver Controls (throttle, braking, steering and gear selection, HVE Driver Path Follower results)
Contact Surface Data (force, deflection)
Belt Data (stretch and tension)
Airbag Data (pressure, radius, force)

User-written Reconstruction and Simulation Models¶

HVE has an open architecture which allows users to write their own reconstruction and simulation models. Users are urged to consider this feature, especially when existing models don't quite consider all the issues. Refer to Appendix VII (HVE Developer's Toolkit Overview) and references 1.2 and 1.3 for specific instructions on how to produce your own reconstruction and simulation models.

Setting Up Events¶

Figure 2-8: The Set-up Menu allows the user to choose from the available Event Set-up options.

Events are set up after the objects (humans and vehicles) and calculation method are selected. Event set-up involves the following steps:

Assign the required positions and velocities for each object
Assign the desired driver controls (throttle, braking, steering and gear selection tables for simulations; wheel data for reconstructions)
Assign any damage profile data
Assign any payload data
Assign any collision pulse
Assign any mesh data (tessellation, inter-vehicle friction)
Assign any wheel data (tire blow-out, wheel displacement, brake adjustment)
Assign any accelerometer positions
Assign restraints (belts and airbag usage information) for occupant simulations
Assign contacts (allowable interactions between human ellipsoids and vehicle contact surfaces) for occupant and pedestrian simulation

Event setup options are available using the Set-up Menu (see Figure 2-8).

(updated: the current Set-up menu contains Position/Velocity... (Ctrl+P), Driver Controls... (Ctrl+D), Damage Profiles... (Ctrl+M), Collision Pulse... (Ctrl+U), Vehicle Mesh..., Payload..., Wheels... (Ctrl+W), Accelerometers..., Contacts... (Ctrl+T), a Restraints... submenu with Airbags... (Ctrl+G) and Belts... (Ctrl+B), plus Signals and Notes items that postdate the 2006 manual.)

Assigning Positions and Velocities¶

Every simulation or reconstruction model requires positioning of humans and/or vehicles within the environment. Simulations and some reconstruction models also require that velocities be entered. Positioning is always the first step during event set-up.

HVE allows the user to position humans and vehicles within the environment using direct manipulation of the object, or by entering position coordinates and orientations in the Position/Velocity dialog (see Figure 2-9).

Using direct manipulation, first select the object within the Event Viewer, then drag and drop it at the desired location. Roll, pitch and yaw manipulators allow rotation of the human or vehicle about its coordinate axis system to provide the proper orientation (see Figures 2-9 and 2-10 for vehicles and humans, respectively).

If the actual coordinates and orientation of the selected human or vehicle are known, it is easiest to simply enter them directly in the Position/Velocity dialog.

Figure 2-9: Vehicles are positioned using the translation and rotation manipulators, or by entering data directly into the Position/Velocity dialog.

Figure 2-10: Humans are positioned, like vehicles, using the translation and rotation manipulators, or by entering data directly into the Position/Velocity dialog.

NOTE: For occupant simulations, the human is positioned relative to the vehicle. Therefore, the vehicle should be positioned first.

HVE allows the user to enter positions and velocities for the following path locations:

Initial Position
Begin Perception
Begin Braking
Impact
Separation
Point On Curve
End Of Rotation
Final/Rest

The positions and velocities provided by the user are dependent upon the requirements of the selected model. Simulations require only initial positions and velocities. Reconstructions normally require impact and rest positions.

Target Positions¶

The user may enter human and vehicle positions even though they are not actually used by the simulation or reconstruction. These are called target positions, and appear as translucent objects. Target positions provide visual feedback to the user regarding the desired path of the human or vehicle. If a simulated object passes through the target, the user can tell very quickly it is on the correct path. By observing that the simulated object misses the target, the user can make the necessary adjustments and rerun the simulation.

Target positions are also used by the HVE Path Follower. In this case, the user-entered target positions are used to define a path. Using the HVE Path Follower, simulation models determine the driver steering, braking and throttle inputs required to follow the path. The HVE Path Follower is further described in Chapters 4 and 16 of the legacy manual.

Assigning Driver Controls¶

The HVE vehicle model is controlled by driver inputs. The available driver controls are:

Throttle Table
Brake Table
Steering Table
Gear Selection Table
HVE Path Follower
Wheel Data

Steering, Throttle, Brake, Path Follower, and Gear Selection driver controls are available for simulation models; only Wheel Data controls are available for reconstruction models.

To supply a vehicle's driver controls, you must first select a vehicle, then choose Driver Controls from the Set-up menu (updated: the 2006 manual says "from the Edit menu" here, but driver controls are on the Set-up menu — Set-up, Driver Controls..., Ctrl+D). There are two ways to select a vehicle:

Choosing from the list of vehicles in the Event Editor
Clicking on the vehicle in the Event Viewer (this also displays its current Position/Velocity dialog)

NOTE: Because trailers do not appear in the list of vehicles in the Event Editor, to apply Driver Controls to a trailer, you must click on the trailer.

After the vehicle is selected, use the Driver Controls option to choose the desired method. The various methods are described below. (See also the code-verified Driver Controls reference.)

Throttle Table — The Throttle Table allows you to provide tractive effort at each drive wheel on the selected vehicle. Data are entered using a table. Three options are available:

Percent Wide-Open-Throttle vs time
Percent Available Friction vs time
Tractive Effort vs time

Figure 2-11: The Throttle Table allows the user to enter a table of tractive effort vs time. The Percent Wide-Open-Throttle option is shown.

The availability of these options is dependent upon the selected calculation model. For example, if the simulation is not capable of using the HVE Vehicle's engine model, the Percent of Wide-open Throttle option is not available.

Brake Table — The Brake Table allows you to provide longitudinal braking force at each wheel of the selected vehicle. Data are entered using a table. Three options are available:

Pedal Force vs time
Percent Available Friction vs time
Braking Force vs time

Figure 2-12: The Brake Table allows the user to enter a table of braking force vs time. The Pedal Force option is shown.

Again, the availability of these options is dependent upon the selected calculation model. For example, if the simulation is not capable of using the HVE Vehicle's brake system model, the Pedal Force option is not available.

Steer Table — The Steer Table allows you to provide steer angles at each steerable axle for the selected vehicle. Data are entered using a table. Two options are available:

Steering Wheel Angle vs time
Tire Angle vs time

Figure 2-13: The Steer Table allows the user to enter a table of steer angles vs time for each steerable axle. The At Steering Wheel option is shown.

Gear Table — The Gear Table allows the user to provide the current gear selection for both the transmission and differential (differential gear selection only applies if the selected vehicle's differential has more than one gear ratio). Data are entered using a special table, as shown in Figure 2-14.

The Gear Table option is used for backing a vehicle, as well as changing its forward gear selection. The Gear Table option is available only if the current simulation model can use the gear information (some simulation models do not allow tractive effort in reverse). Thus, use of the Gear Table also requires that the simulation uses the HVE Engine Model.

Figure 2-14: The Gear Table allows the user to enter a table of gear selections vs time. This table is only available for simulations which include an engine model, and requires that the current Throttle Table uses the Percent Wide-open Throttle method.

HVE Path Follower — The HVE Path Follower dialog allows the user to define a 3-D vehicle path using target positions. Using this path, the simulation model determines the steering, throttle and braking driver inputs required to cause the vehicle to follow the path.

The HVE Path Follower dialog includes options for path following by Required Steering or Required Torque. If target velocities are entered, the Speed Follower option is enabled. Finally, a Driver Filter option is available that allows simulation of the effects of driver physical characteristics on the ability to follow a path.

The HVE Path Follower dialog is shown in Figure 2-15. A detailed description of the HVE Path Follower is provided in Chapter 4 (Event Set-up) and Chapter 16 (HVE Event Model) of the legacy manual.

NOTE: The Torque Method and Speed Follower options were not enabled as of the 2006 manual.

Figure 2-15: The HVE Path Follower dialog — Driver Data page (Driver Start Time, Driver Sample Interval, Driver Preview Time, Path Error Null Distance, Driver Comfort Level).

Wheel Data — The Wheel Data dialog is used for reconstruction models. It differs from the other driver control tables in that its values are fixed, rather than time-dependent, because reconstructions do not calculate in the time domain.

The Wheel Data dialog allows the user to enter the wheel lock-up (sometimes called percent of available friction) and steer angle for each wheel on the selected vehicle. You can also enter the total lock-up for pre-impact braking, and click on a check box to select a different calculation method for handling rotating and spinning vehicles between impact and rest (Rot/Lat Skidding). A typical Wheel Data dialog is shown in Figure 2-16.

Figure 2-16: The Wheel Data dialog is used by reconstruction models that use constant wheel forces and steer angles.

Assigning a Vehicle Damage Profile¶

You can assign a damage profile to the selected vehicle. To supply a damage profile, you must first select a vehicle, then choose Damage Profiles from the Set-up menu. (This option will be unavailable if the selected reconstruction or simulation model does not allow user-entered damage profiles.) A typical Damage Profiles dialog is shown in Figure 2-17.

The damage profile defines the location and character of vehicle damage by allowing the user to specify:

the width of the damaged surface
the depth of crush at up to 10 equally-spaced intervals along the damage width
the location of the center of damage relative to the vehicle's CG
the principal direction of force (PDOF)

This information is initially provided in the form of a Collision Deformation Classification, or CDC (see SAE J224 [6.3]) which HVE uses to assign the default damage profile. The user can then over-ride the default values by replacing the assigned data (see Figure 2-17).

HVE uses the damage profile to calculate and display the Equivalent Energy Speed, or EES [2.26, 6.4]. The default value is set equal to the Total Delta-V (see below). The user may over-ride the default EES by clicking on the EES radio button and entering the desired value.

Damage Results¶

The Damage Data dialog uses the damage profile and stiffness coefficients to calculate the following results:

Delta-V — Change in velocity during the collision. Total, forward and lateral components are displayed.
Damage Energy — Unconserved energy during the collision.
Peak Force — The peak force during the collision.

NOTE: The Damage Profiles dialog calculates the delta-V for a vehicle striking a barrier, not another vehicle! To determine the delta-V during impact with another vehicle requires information about the other vehicle. Use EDCRASH or a similar program for such an analysis.

NOTE: Actually, EDCRASH performs the above analysis on both vehicles, then apportions the delta-V according to the total damage energy and respective vehicle masses.

Figure 2-17: The Damage Data dialog — CDC, PDOF, Use Newton's 3rd Law, Impulse Center, EES/Damage Profile basis, Damage Profile zones, Width, Offset, crush locations and depths, Delta-V Total/Long./Lat., Damage Energy, Peak Force, A Stiff... and B Stiff... buttons.

See also: Damage Data reference.

Stiffness Coefficients¶

The selected vehicle's stiffness coefficients are normally used for damage-based calculation methods. Choosing A Stiffness or B Stiffness displays a dialog showing the current stiffness values for each crush zone. These coefficients are initially assigned by the Vehicle Editor when the vehicle is created. These original coefficients may be replaced by user-entered values for each crush zone (see Figure 2-18).

Figure 2-18: A and B Stiffness Coefficients dialogs allow the user to enter stiffness coefficients for the selected vehicle, per crush zone, with an "All Same As Zone 1" shortcut.

See also: A Stiffness and B Stiffness dialog references.

Assigning a Collision Pulse¶

A collision pulse is the motion vs time history during impact that defines the vehicle's motion during impact. If the current simulation model is an occupant simulation, the user must supply a collision pulse to the selected vehicle. Also, some vehicle simulations can include a collision pulse.

To supply a collision pulse, first select a vehicle, then choose Collision Pulse from the Set-up menu. (This option will be unavailable if the selected reconstruction or simulation model does not use a collision pulse.)

The collision pulse is provided in the form of a table of linear and angular motion inputs (e.g., accelerations) at specified times (see Figure 2-19). Because the collision pulse normally lasts 100 to 200 milliseconds, the timestep is usually very small, on the order of 0.001 to 0.01 seconds.

Figure 2-19: The Collision Pulse dialog — Total Acceleration vs. Time graph, Pulse Data Source and Pulse Type option lists, table of Forward/Lateral/Vertical/Roll/Pitch/Yaw accelerations vs time, with Apply, Print, Factors, New, Open, Save As and Options buttons.

Pulse Data Source¶

The collision pulse data may be assigned in a user-entered table or the data may be transferred automatically from a previously run event (e.g., EDSMAC4). The user determines the source of the collision pulse data using the Pulse Data Source option list.

User-entered Collision Pulse — A user-entered collision pulse is defined by direct table entry of time and associated accelerations. Collision pulses are actually stored in a file; the default collision pulse filename is 'Untitled'. The current table may be saved and opened for use in another event or case. Save and Open buttons in the Collision Pulse dialog are used for this purpose.

Event-defined Collision Pulse — HVE keeps track of all previously executed events that produced a collision pulse. If the selected vehicle was used in one or more of those events, those event names will be accessible by clicking the Pulse Data Source option list. By selecting one of these events, the collision pulse table is automatically loaded using the selected event's output tracks. The table uses the output timestep from the source event.

NOTE: HVE will display a warning message if the timestep assigned by the event is too large.

If the source event (e.g., EDSMAC4) is changed and rerun, the data it supplies to the collision pulse table will be different. Therefore, if the user reruns the occupant simulation the results will be different because they reflect the changes to the source event.

Pulse Type¶

Four types of collision pulses are allowed:

Position vs Time
Velocity vs Time
Acceleration vs Time
Force/Moment vs Time

The current calculation method determines which, if any, methods are selectable.

Collision Pulse Factors¶

The individual linear and angular components of the collision pulse may be increased or decreased using the Pulse Factors dialog (see Figure 2-20). The Collision Pulse Factors provide a convenient way to assess changes in the vehicle and/or occupant response due to an increase or decrease in collision force components.

Figure 2-20: The Collision Pulse In-use Factors dialog — Forward, Lateral, Vertical, Roll, Pitch and Yaw amplification factors.

Collision Pulse Options¶

The Collision Pulse Options dialog allows the user to focus on a particular portion of the collision pulse. This feature is useful because a rollover simulation may require the entire pulse, while a collision simulation only requires that portion during which the acceleration is greater than some threshold acceleration (normally 1 g). The pulse is edited by supplying a threshold acceleration and a starting time that specifies that portion of interest for the entire pulse.

If the current pulse type is Force/Moment, the user can specify the vehicle-fixed coordinates for the point of application of the force on the vehicle.

Figure 2-21: The Collision Pulse Options dialog — Threshold Accel, Tstart, Impulse Center coordinates.

See also: Collision Pulse, Pulse Factors and Pulse Options references.

Vehicle Mesh¶

The Mesh dialog is used for changing the attributes of the mesh (3-D geometry) for the selected vehicle. Vertices within the Weld Distance share the same vertex coordinates. Clicking on Tessellate and then entering a Maximum Side Length ensures that no side of any triangle is longer than the entered value. Identifying the watertightness provides quality information about the mesh. These options are useful for DyMESH and other simulation models employing a deformable mesh.

The Mesh dialog is also used for assigning Inter-vehicle Friction and Restitution (this option takes on various forms, depending on the selected physics model).

To assign Mesh data, first select a vehicle, then choose Vehicle Mesh from the Set-up menu (this option is unavailable if the current reconstruction or simulation model does not use the Mesh Options dialog). The Mesh dialog will be displayed as shown in Figure 2-22.

Figure 2-22: The Vehicle Mesh Options dialog — Vertex Weld Distance, Tessellate/Max Side Length, Is Mesh Water Tight? (Yes/No/Unknown), Mesh Groups included in damage (Body, Glass, Chrome, Trim, Lights, Interior, Other), and Inter-Vehicle friction/relaxation length vs each other object.

Assigning Payloads¶

You can assign a payload to the selected vehicle. To supply a payload, you must first select a vehicle, then choose Payload from the Set-up menu. See Figure 2-23. (This option will be unavailable if the selected reconstruction or simulation model does not allow vehicle payloads.)

The addition of a payload causes HVE to update the earth-fixed position of the vehicle's center of gravity. In addition, the physics model may also automatically alter the inertial properties and weight distribution of the selected vehicle.

NOTE: This behavior is physics model-dependent.

Figure 2-23: The Payload Data dialog — Payload Exists, CG Coordinates (x,y,z), Weight, Mass, Rotational Inertia (Roll, Pitch, Yaw).

See also: Payload dialog reference.

Wheel Data Options (Set-up, Wheels)¶

The Wheels dialog (Set-up menu, Wheels...) contains four tabbed pages: Blow-out, Damage, Brake and Tire-Terrain. (See also the code-verified Wheels dialog reference.)

HVE Tire Blow-out Model¶

The selected vehicle may incur a tire blow-out during an event. The HVE Tire Blow-out Model™ allows the user to study the transient effects of a loss of inflation pressure on vehicle handling and behavior during an event.

The Tire Blow-out dialog (see Figure 2-24) allows the user to select one or more tire locations and specify the time and duration of the blow-out(s), as well as the various factors used for the tire blow-out simulation. Some simulations can determine when the blow-out is to occur; this feature is activated by clicking the AutoStart check box. This option replaces the user-entered Start Time.

Figure 2-24: The Tire Blow-out dialog — Axle No, Side, Location (Inner/Outer), Tire is Blown, Auto Start, Start Time, Duration, Stiffness Factor, Rolling Resistance Factor.

Wheel Damage Option¶

The selected vehicle's wheel may be damaged during an event. A damaged wheel affects vehicle handling in several ways: it alters the location of the wheel (thus altering the tire moments and forces acting on the vehicle); it alters the camber and thus may result in different lateral force at a given wheel location; and the wheel may be partially or totally locked up due to damage.

The Wheel Damage dialog (see Figure 2-25) allows the user to select one or more wheel locations and specify the time and duration of the wheel damage(s), the wheel displacement (Δx, Δy, Δz), the change in camber for each wheel and the percentage of wheel lock-up for each wheel. Some simulations can determine when the damage is to occur; this feature is activated by clicking the AutoStart check box. This option replaces the user-entered Start Time.

Figure 2-25: The Wheel Damage dialog — Axle No, Side, Displacement (change in coordinates x, y, z), Change in Camber, Wheel is Damaged, Auto Start, Start Time, Duration, Peak Lock-up Torque, Max No-Damage Force, Deformation Rate, Max Force.

Wheel Brake Option¶

The selected vehicle's wheel may have an improperly adjusted brake, or the brake may be completely failed due to a mechanical malfunction, such as leakage. These factors influence the brake torque at the selected wheel, and thus, the total forces and moments acting on the sprung mass.

The Wheel Brake dialog (see Figure 2-26) allows the user to select one or more wheel locations and specify the initial lining and drum/rotor temperatures, the initial stroke, and the time and duration of the brake failure. Some simulations can automatically assign the time at which the brake failure begins. This option is activated by clicking the AutoStart check box. This option replaces the user-entered Start Time.

The Wheel Brake dialog is particularly useful for studying the degradation in braking on long, down-hill grades.

Figure 2-26: The Wheel Brakes dialog — Axle No, Side, Brake Designer (Initial Lining Temp, Initial Drum Temp, Initial Stroke), Brake Failure (Brake Is Failed, AutoStart, Start Time, Duration, Failure Extent).

Wheel Tire-Terrain Option¶

The selected vehicle may travel over irregular terrain (e.g., a pot hole or curb) or soft soil during an event. The Tire-Terrain dialog allows the user to select from the following tire-terrain models:

Point Contact Model
Radial Spring Model
Sidewall Impact Model
Soft Soil Model

The Wheel Tire-Terrain dialog (see Figure 2-27) allows the user to select one or more wheel locations and then select the appropriate model for the terrain conditions. The dialog also provides access to the parameters used by each of the models. Note that different wheels may use different models. For example, the right front tire might use the Sidewall Impact model, while the left front tire uses the Radial Spring model.

Figure 2-27: The Wheel Tire-Terrain dialog — Axle No, Side, Location, Tire-Terrain Model (Point Contact / Soft Soil / Radial Spring, with Sidewall Impact check box), Radial Spring parameters (Radial Adjustment Increment, Angular Span, Angular Increment, Sidewall Slide Friction Coefficient, Number of Sidewall Springs, per-spring distances and stiffness ratios).

Accelerometers¶

The Accelerometers dialog (see Figure 2-28) allows the user to select up to five vehicle-fixed locations for the placement of accelerometers. These accelerometers allow the user to study the acceleration and velocity change at the specified location. Such studies are useful for determining the collision severity experienced by occupants seated in various positions within the vehicle. Accelerometers are also useful for determining the threshold for airbag deployment for specific airbag sensor locations.

Figure 2-28: The Accelerometer Data dialog — Location (1-5), Device In Use, Coordinates (x, y, z).

Assigning Restraint System Usage¶

The selected vehicle may have belt and/or airbag restraint systems. However, as we all know, just because the vehicle has restraint systems doesn't necessarily mean they are being used!

If the current simulation model is an occupant simulation, you can supply in-use parameters for belt and airbag restraint systems for the selected vehicle. To supply restraint system in-use parameters, you must first select a vehicle, then choose Restraints from the Set-up menu (updated: the 2006 manual says "from the Edit menu"; the current Set-up menu provides a Restraints... submenu with separate Airbags... and Belts... items). (This option will be unavailable if the selected simulation model does not model restraint systems.)

Using the Restraints dialog, you can select from the available restraints and supply appropriate parameters (see Figure 2-29). An individual system (lap belt, shoulder belt or airbag) is available only if the selected vehicle has that system installed at the occupant's seat position.

Figure 2-29: The Belt Restraint System Data dialog — Belt Restraints For (occupant), Belt Segment, Device In Use, Belt Attached To, left/right segment coordinates (i, j, k), Belt Slack.

See also: Belt Restraint Systems and Airbag Systems references.

Assigning Contacts¶

The human model is composed of 15 segments; each segment has up to three contact ellipsoids. The vehicle model has up to 25 contact surface planes. Occupant and pedestrian simulations work by calculating the force between each of these ellipsoids and surface planes at each timestep. It follows that up to 1,125 (15x3x25) sets of force calculations must be performed. Because these force calculations are rather lengthy, execution may be extremely slow.

If it is clear that certain ellipsoid-surface pairs will never come into contact (e.g., interior surface planes during a pedestrian simulation), it makes sense to tell the simulation model to ignore the contact force calculations for these ellipsoid-surface pairs. The Contacts dialog is used for this purpose. This option is only available for human simulation models.

To select and deselect ellipsoid-surface pairs, first select a vehicle, then choose Contacts from the Set-up menu.

The Contacts dialog displays two list boxes: the one on the left contains all the defined human ellipsoids; the one on the right contains all the defined vehicle contact surfaces. To allow or inhibit interaction between ellipsoid-surface pairs, select an ellipsoid then choose the contacts you wish to allow by either selecting or deselecting from the list of contacts (see Figure 2-30). If the current event is an occupant simulation, all the vehicle interior surfaces are initially selected; if the current event is a pedestrian simulation, all the exterior surfaces are selected.

Figure 2-30: The Contact Interactions dialog — Object, Source(s), Target(s), Combined Material Properties, Current Material and Edit... button.

See also: Contacts dialog reference.

Executing Events¶

After an event has been set up, it is ready for execution. For simulation models, this means starting the simulation and watching the Event Viewer to study the interactions between the human(s), vehicle(s) and environment. The goal is to match the simulated trajectories and damage profiles with the measured trajectories and damage. For reconstruction models, this means using the measured path positions and damage profiles to estimate the initial velocities and velocity changes. In either case, event execution is controlled using the Event Controller.

Event Controller¶

The Event Controller is similar to a typical VCR controller in both form and function (see Figure 2-31).

The Event Controller has the following buttons:

Reset — Reinitialize the calculation model for recomputation
Rewind — Return to the start of the simulation
Reverse — Run the simulation backwards
Pause — Pause the simulation
Play — Run the simulation forwards or execute a reconstruction model
Advance To End — Advance to the end of the simulation

Figure 2-31: The Event Controller — Reset/Rewind/Reverse/Pause/Play/Advance buttons, Max Simulation Time, Simulation Timestep, Current Simulation Frame, Event Controller Slider, Current Simulation Time, Output Interval.

The Event Controller also displays the current simulation time and includes a calculation speed control which allows you to slow down execution, if desired, to observe details during calculations.

Use the Event Controller to execute the current event as follows:

Press Play to start the reconstruction or simulation calculations.
Press Pause to pause the calculations.
Make any changes to the event set-up options (e.g., Driver Controls).
Press Reset to re-initialize the calculation model.
Press Play to re-execute the reconstruction or simulation model with the updated driver controls.

NOTE: If Reset is not pressed, any changes to the event set-up options will be ignored.

Choosing Options¶

HVE provides a number of useful options. These options are available from the Options menu. The available options are:

Key Results — A window displaying the current calculation results for each human and vehicle
Coordinate Axes — Display coordinate axis systems on each human, vehicle and environment
Contacts — Display the human ellipsoids and vehicle surfaces used in occupant/pedestrian force calculations
Belt Anchors — Display an icon showing the location of restraint system seat belt anchors installed in each vehicle
Velocity Vectors — Display the current direction of each object's velocity vector
Skidmarks — Display skidmarks resulting from each skidding tire
Targets — Display user-entered target positions as translucent objects

These options are implemented as toggles: you can show and hide these features. These options are described later in this section, as well as in the Menu Reference section of the manual.

(updated: the current Options menu contains a larger set of show toggles — Show Key Results, Show Axes, Show Contacts, Show Belt Anchors, Show Velocity Vectors, Show Skidmarks, Show Tracks, Show CGs, Show CG Paths, Show Accelerometers, Show Accelerometer Paths, Show Position Sequences, Show Targets, Show Connections — plus Create DB, Distance Tool..., Show Path..., and Autoposition. The settings items are Grid..., Units..., Shadows..., Render... (Ctrl+R), Playback..., Simulation Controls... (Ctrl+Y), Calculation Options... (Ctrl+J), DyMESH..., Get Surface Info..., and Preferences... (Ctrl+F). See the Options Menu reference.)

Chapter 2 continues in Part B: Creating Report and Playback Windows.

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