Chapter 16 — Event Model Definition

The HVE Event Editor is a fully 3-dimensional environment for executing human and vehicle dynamics models. Both reconstruction-type (i.e., backwards calculating) and simulation-type (i.e., forwards calculating or predictive) models are accommodated. The HVE Event Editor inherently uses 3-D visualization to provide feedback to the user; that is, all the motion calculated by the model is displayed in HVE's 3-D Event Viewer and may be visualized from any perspective. Numeric results are displayed in viewers called Key Results windows.

The HVE execution environment has an open architecture: users may choose to execute commercially available reconstructions and simulations or develop their own. Any HVE-compatible reconstruction or simulation model may be executed. The details of writing HVE-compatible reconstruction and simulation models are provided in the HVE Developer's Toolkit references.

Overview

The HVE Event Editor is used for setting up and executing reconstructions and simulations involving the selected humans, vehicles and environment. The Event Model thus requires two basic definitions:

• Event set-up definitions for all inputs required by an HVE-compatible reconstruction or simulation model
• Event output track definitions for all outputs produced by the reconstruction or simulation model

This chapter provides these definitions, beginning with a general overview of the HVE execution environment.

General Overview

Figure 16-1: HVE system environment, showing the Human, Vehicle, Environment, Event and Playback Editors.

A block diagram for the HVE execution environment is shown in Figure 16-1. The basic components of this environment are:

• Human Editor — Creates and manages all the humans used in the current case.
• Vehicle Editor — Creates and manages all the vehicles used in the current case.
• Environment Editor — Creates and manages the current environment.
• Event Editor — Creates and manages all the events in the current case.
• Playback Editor — Manages all the output from each event and allows the user to specify various forms of output.

A more detailed review of the Event Editor reveals it performs the following functions:

• Loads the selected objects (humans and/or vehicles) into the current event
• Adds the requested event set-up parameters (position, velocity, vehicle damage, etc.)
• Executes the event
• Stores the program output

The event set-up definition provides the exact format for the parameters passed to the calculation model as input. The output track definition provides the exact format for the parameters produced by the calculation model and stored by the event as output. The remainder of this chapter provides the details of the event set-up and output track definitions.

Event Set-up Parameters

Event set-up parameters are selected from the HVE Set-up menu (see Chapter 4). The following options are available:

• Position/Velocity
• Driver Controls (Throttle, Brakes, Steering, Gear Selection, HVE Driver path follower, Wheel Data and — where supported — Lights)
• Vehicle Damage (Damage Profile)
• Vehicle Payload
• Collision Pulse
• Mesh
• Wheels (Blow-out, Damage, Tire-Terrain and Brakes)
• Accelerometers
• Human vs. Vehicle Contacts
• Belt and Airbag Restraint Systems Usage

Position/Velocity

The Position/Velocity Event Set-up parameters are defined in Table 16-1.

Table 16-1: Position/Velocity Event Set-up Parameters

Parameter	Units (US / SI)	Description
X or x, Y or y, Z or z	in / cm or ft / m *	Linear distance from earth-fixed origin (vehicles and human pedestrians) or vehicle-fixed origin (human occupants)
Roll, Pitch, Yaw	deg	Angular displacement about the vehicle-fixed z, y and x axes (in that order) or human segment-fixed z, y and x axes (again, the order is important). For trailers and human segments other than the pelvis, these angles are articulation angles relative to the upstream vehicle or human segment.
Fwd, Lat, Vert velocity	in/sec, mph / km/h *	Linear velocity components in the vehicle-fixed or human segment-fixed forward, lateral and vertical directions
Roll, Pitch, Yaw velocity	deg/sec	Angular velocities about the vehicle-fixed z, y and x axes or human segment-fixed z, y and x axes. For trailers and human segments other than the pelvis, these are articulation velocities relative to the upstream segment.

* Vehicle units (in / cm; mph / km/h) for human occupants; environment units (ft / m; mph / km/h) for human pedestrians and vehicles.

Position and velocity may be assigned for the current human or vehicle. The following positions and velocities may be assigned:

• Initial
• Begin Perception
• Begin Braking
• Impact
• Separation
• Point-on-curve
• End-of-rotation
• Final/Rest

The position(s) and velocities required by a reconstruction or simulation model vary from model to model. In general, simulation-type models require only initial positions and velocities. Reconstruction-type models normally require positions at impact and rest. However, all the above positions may be entered for any model. The reconstruction or simulation model knows which positions are actually used by the model. Positions which are entered but not used are called target positions because they provide visual feedback to the user regarding how close the simulated path matches the desired path.

NOTE: Target humans and vehicles are translucent, to distinguish them from positions which are used by the model.

When a human or vehicle is selected for positioning, its Position/Velocity dialog is displayed. The Position/Velocity dialog allows the user to enter the position and velocity according to the following procedures.

Positioning Unit Vehicles

Single vehicles, and the tow vehicle of vehicle-trailer combinations, are positioned relative to the earth-fixed coordinate system. X, Y, Z linear positions and roll, pitch, yaw orientations may be entered. Total velocity and sideslip angle are entered. Vertical velocity may be entered for 3-D models. The forward (U) and lateral (V) velocity are auto-computed from the total velocity, sideslip angle and vertical velocity, but remain editable; editing U, V or the sideslip angle recomputes the other components. (updated)

Positioning Trailers

Trailers and dollies are positioned relative to the vehicle pulling them; thus only relative roll, pitch and yaw positions and velocities are required.

NOTE: Trailer and dolly names are not displayed in the selected objects list. To select a trailer or dolly for event set-up (positioning, driver controls, etc.), click on the desired object in the Event Viewer.

Positioning Human Occupants

Human occupants are positioned using the CG of the pelvis segment, and are positioned relative to the vehicle-fixed coordinate system. x, y, z linear positions and roll, pitch, yaw orientations of the pelvis may be entered. i, j, k linear velocities and roll, pitch, yaw angular velocities are entered relative to the pelvis segment's local coordinate system.

Positioning Human Pedestrians

Human pedestrians are positioned using the CG of the pelvis segment, and are positioned relative to the earth-fixed coordinate system. X, Y, Z linear positions and roll, pitch, yaw orientations of the pelvis may be entered. i, j, k linear velocities and roll, pitch, yaw angular velocities are entered relative to the pelvis segment's local coordinate system.

For both human occupants and pedestrians, segments other than the pelvis are positioned using joint articulation angles relative to the upstream (i.e., closer to the pelvis) adjoining segment; thus only relative roll, pitch and yaw positions and velocities are required.

NOTE: 2-D, yaw-plane models do not use Z, roll or pitch information. HVE will automatically make these fields non-user-editable and calculate the values using AutoPosition.

Deleting Human and Vehicle Positions

Human and vehicle positions may be deleted from an event. This is done simply by selecting the undesired human or vehicle in the viewer, then choosing Delete from the Edit menu.

NOTE: If no object is selected before choosing Delete, you will be asked if you want to delete the entire event! Therefore, you must first select a human or vehicle before choosing Delete from the Edit menu.

Rotation Direction

According to the SAE coordinate system, rotation direction is defined using the right-hand rule. Thus, positive rotation is clockwise about a given axis. For example, looking down on the X-Y plane from above, a vehicle turning right will have a positive rotation direction.

It follows that the coordinate system convention has implications when entering a sequence of positions (e.g., Impact, Separation, Rest). When two successive positions are entered, the direction of rotation is defined by the difference in the heading angles. For example, if the heading angle at impact, Ψ_imp, is 35 degrees and the heading angle at rest, Ψ_rest, is 80 degrees, then the difference from impact to rest is Ψ_rest - Ψ_imp = 80 - 35 = +45 degrees. The positive sign indicates the direction of rotation from impact to rest is positive (i.e., clockwise). In general, any rotation direction is defined as follows:

ΔΨ = Ψ(n) − Ψ(n−1)

where

Symbol	Meaning
n	a position in a sequence of positions (e.g., rest)
n−1	the previous position in a sequence of positions (e.g., impact)

If ΔΨ is positive, the direction is clockwise; if ΔΨ is negative, the direction is counter-clockwise. The above applies to roll and pitch rotations as well as yaw (heading angle) rotations.

NOTE: This definition is especially important to EDVAP/EDCRASH users. In those earlier programs, the direction of rotation was entered directly by the user as Clockwise, Counter-clockwise or None. In HVE, the direction of rotation is not entered directly; it is determined as shown above.

Figure 16-2: Examples of rotation direction for various position sequences.

Driver Controls

The Driver Control Event Set-up parameters are defined in Tables 16-2 through 16-6. Driver controls may be selected for the current vehicle. The available driver controls are:

• Throttle
• Brakes
• Steering
• Gear Selection
• HVE Driver (Path Follower)
• Wheel Data
• Lights (updated: a Lights page is available when the calculation method supports light systems and the vehicle has lights defined)

The Driver Controls dialog is a tabbed property sheet; the pages that appear depend on the capabilities of the current event's calculation method and on the selected vehicle. For the current page-by-page reference, see Driver Controls. The Driver Controls options are described below.

Throttle

The Throttle Table Event Set-up parameters are defined in Table 16-2.

Table 16-2: Throttle Table Event Set-up Parameters

Parameter	Units (US / SI)	Description
Time	sec	Time associated with the current level of throttle input
Throttle Input	%/100, lb / N or %/100	Current value for throttle input

Throttle controls are available for simulations, and are used to accelerate the vehicle. Three methods of throttle control tables are available (see also the Throttle page):

• Wide-open Throttle (Percent WOT) — This method allows the user to enter a table of throttle position versus time. The resulting table determines how much engine power is applied. An entry of 100 percent applies a drive torque associated with 100 percent of the current vehicle's engine power at the current engine speed. (updated: this option engages the vehicle's engine and drivetrain data.)

NOTE: This method is available only if the current simulation includes an engine model with the ability to calculate drive torque according to the current engine speed and throttle position. A Gear Table must also be supplied.

• Tractive Effort — This method allows the user to enter a table of tractive effort (total force accelerating the vehicle) versus time. The resulting table determines how much accelerating force is applied at each drive wheel.

NOTE: The Tractive Effort Table only allows entries at drive wheels, as specified by the Vehicle Information dialog.

• Percent Available Friction — This method allows the user to enter a table of available tractive effort (percentage of total available frictional force accelerating the vehicle) versus time. The resulting table determines how much accelerating force is applied at each drive wheel. The calculations are performed by the simulation model, which multiplies the entered value by the currently available tire friction and vertical tire load.

NOTE: The Percent Available Friction Table only allows entries at drive wheels, as specified by the Vehicle Information dialog.

Brakes

The Brake Table Event Set-up parameters are defined in Table 16-3.

Table 16-3: Brake Table Event Set-up Parameters

Parameter	Units (US / SI)	Description
Time	sec	Time associated with the current level of brake input
Brake Input	lb / N or %/100	Current value for brake input

Brake controls are available for simulations. Three methods are available (see also the Brake page):

• Pedal Force (called "At Pedal" in the legacy edition) — This method allows the user to enter a table of brake pedal force versus time. The resulting table determines how much brake torque is applied at each wheel. The brake torque at each wheel is the product of the entered table value, master cylinder ratio, proportioning rate and wheel torque ratio. (updated: this is the only option that engages the vehicle's brake system — and Brake Designer — data.)

NOTE: The Pedal Force option is available only if the current simulation includes a brake model with the ability to calculate brake torque according to the brake system parameters and brake pedal force.

• Brake Force — This method allows the user to enter a table of brake force (total force decelerating the vehicle) versus time. The resulting table determines how much decelerating force is applied at each wheel.
• Percent Available Friction — This method allows the user to enter a table of available braking force (percentage of total available frictional force braking the vehicle) versus time. The resulting table determines how much brake force is applied at each wheel. The calculations are performed by the simulation model, which multiplies the entered value by the currently available tire friction and vertical tire load.

Steering

The Steer Table Event Set-up parameters are defined in Table 16-4.

Table 16-4: Steer Table Parameters

Parameter	Units (US / SI)	Description
Time	sec	Time associated with the current level of steer input
Steer Input	deg	Current value for steer input

Steering controls are available for simulations. Two methods are available:

• At Steering Wheel — This method allows the user to enter a table of steering wheel angle versus time. The entered value is divided by the axle's steering gear ratio to determine the nominal steer angle at the tire.

NOTE: The actual steer angle of an individual tire may be affected by roll steer and/or toe-in. The inclusion of these parameters is simulation-dependent.

• At Axle — This method allows the user to enter a table of steer angle at each tire of a steerable axle. The entered value is applied directly to the tire, and is unaffected by any roll steer or toe-in.

(updated: the current Steer page also provides a Use Ackermann Steering check box — when checked, the simulation applies Ackermann geometry to the steer angles, so that the inside and outside tires of a steerable axle are steered through slightly different angles. See the Steer page.)

Gear Selection

The Gear Selection Table Event Set-up parameters are defined in Table 16-5.

Table 16-5: Gear Selection Table Event Set-up Parameters

Parameter	Units (US / SI)	Description
Time	sec	Time associated with the current gear shift
Gear Selection	n/a	Current gear number for transmission or differential

The Gear Selection dialog is available for simulations. This dialog allows the user to enter a table of gear selection versus time. Separate tables may be entered for the transmission and differential.

NOTE: This option is available only if the current Throttle Method is Wide-open Throttle.

The dialog has a user-selectable option for transmission and differential.

NOTE: The differential option is available only if the selected vehicle has more than one differential ratio.

HVE Driver (Path Follower)

The HVE Path Follower — presented in the current version as the HVE Driver page — allows the user to define a 3-D path using target positions. Using this path, the simulation model determines the steering, throttle and braking inputs required to make the vehicle follow the path. The HVE Path Follower Event Set-up parameters are defined in Table 16-6.

(updated: the current HVE Driver page offers two driver-model versions, Ver. 1 and Ver. 2, selected by radio buttons enabled when Use Path Follower is checked, and a Path Source selector — Position/Velocity dialog positions, or a path table (reserved). See the HVE Driver page.)

The HVE Path Follower includes several features, some required and some optional. These features are:

• Path Generator (required) — user-defined path positions (e.g., Initial, Begin Braking, etc.) to define the attempted path
• General Parameters (required) — user-entered parameters required for HVE Path Follower operation
• Method (required) — user-entered parameters defining how the correction is accomplished
• Speed Follower (optional) — user-entered velocities at each path position are used to define an attempted speed at each point on the path
• Neuro-muscular Filter (optional) — user-entered parameters that define driver physiological capabilities

Path Generator

A primary input to a path follower is the procedure used to define the attempted path. The HVE Path Follower uses up to eight user-defined path positions (see Event Set-up, Assigning Positions). These positions and orientations are used as nodes in a 3-D spline path (see Figure 16-3). It is this spline path that the vehicle attempts to follow.

General Parameters

The basic parameters required for use of the HVE Path Follower are the path (described above), Start Time and Sample Interval, Preview Distance (the point ahead of the vehicle where the driver is actually looking and presumably wants to go), the Allowable Path Error and the level of Lateral Acceleration acceptable to the driver. (updated: the current Driver tab specifies the preview point by a Driver Preview Time (sec) together with a Driver Minimum Preview Distance (ft) used at low speeds, plus a Path Error Null Distance, a Max Speed Error and a Driver Comfort Level (g); see the HVE Driver page.)

Method

Two methods are available in the HVE Path Follower. These are:

• Variable Steering — The path correction is accomplished by means of a steering correction. In this case, the user supplies an Initial Steer Angle, Maximum Steering Wheel Velocity, Steering Correction Factor and Steer Damping.
• Variable Torque — The path correction is accomplished by means of a torque application at the steerable wheels. In this case, the user supplies an Initial Steering Wheel Torque, Maximum Steering Wheel Torque, Torque Correction Factor and Torque Damping.

NOTE: (updated) The Variable Torque option is currently disabled in the user interface; Variable Steering is the available path follower method.

Table 16-6: HVE Path Follower Parameters

Parameter	Units (US / SI)	Description
Start Time	sec	Simulation time for start of path follower
Sample Time	sec	Time increment for path sampling
Driver Preview Distance	ft / m	Distance ahead of vehicle where driver is looking (updated: entered via Driver Preview Time and Minimum Preview Distance in the current dialog)
Max Path Error	ft / m	Allowable distance from desired path to point projected ahead of vehicle at the Driver Preview Distance
Max Lat Accel	g	Driver's limit for comfortable lateral acceleration
Path Follower Method	—	Method used to accomplish path following (Variable Steer or Torque)
Initial Steer Angle	deg	Steering wheel angle at Driver Start Time
Max Steer Velocity	deg/sec	Limit on steering wheel angular velocity
Steer Correction Factor	deg/ft / deg/m	Amount of steering correction per unit of path error
Steer Correction Damping	deg-sec/ft / deg-sec/m	Damping, used to limit steering activity
Initial Steering Torque	in-lb / N-m	Steering wheel torque at Driver Start Time
Max Steering Torque	in-lb / N-m	Limit on steering wheel torque
Torque Correction Factor	in-lb/ft / N-m/m	Amount of steering torque correction per unit of path error
Torque Damping	in-lb-sec/ft / N-m-sec/m	Damping, used to limit steering activity
Max Speed Error	mph / km/h	Allowable difference between current speed and desired speed
Max Throttle Pedal	%/100	Maximum allowable pedal position
Max Brake Pedal	lb / N	Maximum allowable pedal force
Driver Lag Time	sec	Neuro-muscular filter lag time
Driver Lead Time	sec	Neuro-muscular filter lead time
Driver Time Delay	sec	Neuro-muscular filter time delay

Speed Follower

The speed follower option attempts to maintain the required speed, as established by the user-entered velocities at each path position (if a velocity for any path position is not entered, an error message will be issued and the method will abort). In addition, the user supplies an Allowable Speed Error, Maximum Throttle Application and Maximum Brake Pedal Force.

Figure 16-3: The HVE Path Follower uses up to eight user-assigned positions to define a 3-D path. Intermediate path positions are determined using a 3-D spline.

NOTE: (updated) The legacy edition stated that the Speed Follower option was not implemented. The Speed follower is implemented in the current version: user-entered velocities at each path position define an attempted speed at each point on the path, and the driver model applies throttle and brake pedal inputs to achieve those speeds. See the Speed Follower page.

Neuro-muscular Filter

The neuro-muscular filter from the original HVOSM VD-2 model has been included in the HVE Path Follower. Originally developed for NASA, the neuro-muscular filter represents a simplified model of the physiological operator which incorporates a Time Delay, Lead Time and Lag Time. These parameters correspond to the first-order effects of the neurological and muscular systems of a human driver. (See the Filter page.)

To use the HVE Path Follower, first you must assign at least two path positions for the vehicle, then perform the following steps:

1. Choose Driver Controls from the Set-up menu.
2. Choose the HVE Driver (Path Follower) page. The HVE Path Follower parameters will be displayed.
3. Assign the desired HVE Path Follower parameters.
4. Press OK when the desired parameters are assigned.

Wheel Data

The Wheel Data Event Set-up parameters are defined in Table 16-7.

Table 16-7: Wheel Data Event Set-up Parameters

Parameter	Units (US / SI)	Description
Pre-impact Drag Factor	%/100	Linear deceleration rate from Begin Braking to Impact
Percent Friction	%/100	Constant percent of available friction at each wheel used to decelerate the vehicle between impact and rest
Steer Angle	deg	Constant steer angle at each wheel

The Wheel Data dialog is available for reconstruction models. This dialog allows the user to enter the following information:

• Pre-impact Deceleration Rate (Drag Factor) — The entered value is multiplied by the gravitational constant to determine the total vehicle deceleration between the user-entered Begin Braking and Impact positions. This value is relevant only if the user has supplied a Begin Braking position for the current vehicle.
• Rotation/Lateral Skidding Checkbox — This checkbox may be used by reconstruction models to trigger special calculations for spinning vehicles.

NOTE: Spinning vehicles have tire forces which vary, resulting in a variable deceleration rate between impact and rest!

• Percent Available Friction used at each wheel — The entered value represents the percentage of the available friction force used in longitudinal braking at each wheel during the post-impact phase.
• Steer Angle at each wheel — The entered value is used to determine the steer angle at each wheel. This angle is assumed to remain constant, and applies only during the post-impact phase.

Damage Profile

The Damage Profile Event Set-up parameters are defined in Table 16-8.

Table 16-8: Damage Profile Event Set-up Parameters

Parameter	Units (US / SI)	Description
CDC	(none)	Collision Deformation Classification, 7-character damage code describing location and character of damage
PDOF	deg	Principal Direction Of Force, the direction of the collision impulse (same as direction of delta-V)
Impulse Center	in / cm	Vehicle-fixed x,y coordinates of the impulse center
EES	mph / km/h	Equivalent Energy Speed, the barrier impact speed required to cause the observed vehicle damage
Width	in / cm	Total width of damage
Offset	in / cm	Longitudinal or lateral distance from the CG to the center of the damage profile
Crush Depth	in / cm	Measured depth of crush at up to 10 points along the damage profile
A Stiffness	lb/in / N/cm	Force per unit of damage width required to initiate measurable damage (for each crush zone)
B Stiffness	lb/in² / N/cm²	Force per unit of crush depth per unit of damage width required to cause the measured damage (for each crush zone)

The Damage Profile dialog allows the user to enter a damage profile for the selected vehicle. The damage profile is obtained by post-crash inspection of the vehicle, and provides a significant amount of useful information about the collision, including:

• Damage Energy
• Peak Force
• Linear and angular velocity change
• Principal Direction of Force (PDOF)

This information, in turn, can be used to help estimate impact speed and collision severity.

CDC

HVE's Damage Profile dialog asks the user for a Collision Deformation Classification (CDC), a seven-character damage code describing the vehicle damage. The CDC is an SAE Recommended Practice, and is defined in SAE J224, portions of which are included in the HVE Help Index.

The entered CDC is used to define a default PDOF and damage profile, which includes damage width, depth and location. The default data provided by the CDC are used to fill in the fields in the Damage Profile dialog. The resulting delta-V, damage energy and peak force are calculated and displayed in the dialog.

NOTE: The calculated values define what would happen if the current vehicle struck a rigid barrier, not another vehicle! To determine what would happen during a collision with another vehicle requires information about the second vehicle (in particular, its mass and damage energy).

The specific damage profile parameters are defined below.

PDOF

Simply stated, the PDOF is the direction of the impulse. This, of course, has physical significance, because the direction of the impulse is the same as the direction of the delta-V. In fact, because the damage analysis has no way of computing the forward and lateral components of the delta-V, the user-entered PDOF is used for this purpose.

NOTE: If scene data are entered, the PDOF can often be calculated. This serves as an excellent cross-check on the user-entered value.

The PDOF is assigned by the CDC as the closest hour angle (or clock direction), as shown in Figure 16-5. Each hour equals 30 degrees. The Damage Profile dialog displays the resulting PDOF in degrees. It may be edited by the user.

Use Newton's 3rd Law

Some reconstruction programs (e.g., EDCRASH) are able to calculate the PDOF of one vehicle in a two-vehicle collision based on the impact heading angles and the PDOF of the other vehicle. Clicking on the Use Newton's 3rd Law check box executes that option.

NOTE: You can only choose this option for one of the vehicles; if you choose this option for both vehicles (or the other vehicle is a barrier), the program will normally display an error message.

Impulse Center

The Impulse Center X,Y coordinates define the vehicle-fixed location through which the PDOF acts. The default impulse center is calculated by summing moments and forces for each zone (see Damage Profile Zones, below) in the damage profile. These coordinates are user-editable.

NOTE: Once edited by the user, further changes to the damage profile data (width, crush depths, offset) will no longer affect the displayed values for the impulse center.

Basis

After entering a CDC, HVE calculates a default damage profile, delta-V and other damage-related information. This provides the starting point for damage-based calculations. The results may be further refined by editing either the EES or the Damage Profile.

NOTE: Whether the reconstruction program uses the damage profile or EES is program-dependent.

EES

If the Basis is EES (Equivalent Energy Speed), the default value for EES is assigned from the total delta-V (initially calculated from the CDC). The EES may then be user-edited.

Damage Profile Zones

When the Basis is Damage Profile, the damage data may be edited, causing the delta-V, Damage Energy and Peak Force to be updated. This method also allows the user to edit the A and B stiffness coefficients that are used in the calculations (see below). The Damage Profiles drop-down list allows the user to select the number of Crush Zones (and therefore, the number of Crush Depths) in the damage profile.

NOTE: See also Crush Zones and Crush Depths, later in this section.

Damage Width

The Damage Width is the width of the damaged region (see Figure 16-4). The default value assigned by the CDC does not include induced damage (non-contact damage adjacent to the area of actual contact with another vehicle). In most cases, the user should include induced damage if the goal is to estimate delta-V.

Damage Offset

The Damage Offset is simply the longitudinal or lateral distance from the CG to the midpoint of the damage profile (see Figure 16-4).

Crush Depths

A table of crush depths defines the shape of the damage profile. Up to 10 equally spaced crush depths may be provided along the total damage width, as shown in Figure 16-4.

Figure 16-4: Damage Profile examples.

Stiffness Coefficients

The damage analysis requires empirical coefficients determined by crash tests. These coefficients are called stiffness coefficients, because they define the structural stiffness of the vehicle. Two coefficients are provided:

• A Coefficient — The A coefficient has units of force per unit of damage width, and defines the force necessary to begin crushing the vehicle's exterior.
• B Coefficient — The B coefficient has units of force per unit of crush depth per unit of damage width, and defines the linear spring rate of the vehicle's exterior.

Given values for A and B, the crush force per unit of damage width is assumed to have a linear relationship with crush depth. Figure 16-6 shows this relationship. The A and B coefficients are provided in the A Stiffness and B Stiffness dialogs, respectively (see Menu Reference, Set-up menu). The A Stiffness and B Stiffness dialogs allow the user to assign equal coefficients for every zone or vary the coefficients from zone to zone.

Crush Zones

The area between any two crush depth measurements is called a crush zone; thus the number of crush zones will always be one less than the number of entered crush depths, as shown in Figure 16-4.

Obviously, the actual stiffness of a vehicle varies according to the structure absorbing the crush, especially on the side of a vehicle, where one area, such as the quarter panel, contains unsupported sheet metal, while another area, such as a wheel, might be quite rigid. A separate set of A and B coefficients may be assigned to each crush zone.

NOTE: The A and B coefficients are not independent from each other; one should never be adjusted without adjusting the other. In addition, the percentage of adjustment should be the same for both the A and B stiffness coefficients.

Figure 16-5: The default PDOF is assigned by its clock direction (12, 01, 02, etc.) in the first two characters of the CDC.

Figure 16-6: Force vs. Crush characteristics.

Mesh

The Vehicle Mesh Event Set-up parameters are defined in Table 16-9.

Table 16-9: Mesh Event Set-up Parameters

Parameter	Units (US / SI)	Description
Maximum Side Length	in / cm	Determines the longest side of a polygon
Inter-vehicle Friction	—	Inter-vehicle friction coefficient for the selected pair of vehicles
Relaxation Length	%/100	Determines the amount of reduction in displacement vector

The Vehicle Mesh Event Set-up options are:

• Tessellate — The user enters a value for the maximum length of a side for any triangle in the vehicle mesh. Each triangle is then re-evaluated and any side longer than the specified value is again halved until all sides of every triangle are no larger than the specified Maximum Side Length.
• Inter-Vehicle Friction — The user specifies the inter-vehicle friction for the selected pair of vehicles (or vehicle body and environment) in a vehicle simulation.
• Relaxation Length — This value represents the amount (as a percentage of deformation) of reduction in vertex displacement.

Payload

The Payload Event Set-up parameters are defined in Table 16-10.

Table 16-10: Payload Event Set-up Parameters

Parameter	Units (US / SI)	Description
x, y, z coordinates	in / cm	x, y and z distances from the vehicle CG to the Payload CG
Weight	lb / N	Payload weight
Rotational Inertia	lb-sec²-in / kg-m²	Payload rotational inertia about its x, y and z axes

The Payload dialog allows the user to assign a payload to the selected vehicle. The payload may be any object which adds inertia to a vehicle that is not accounted for in the vehicle's inertial properties. Examples include cargo and occupants.

The availability of these fields is dependent on the reconstruction or simulation model. For example, a 2-D model will not ask the user for roll or pitch inertia because they aren't required. Some models do not allow a lateral payload offset, so the y-coordinate is not requested.

The vehicle's center of gravity shifts when a payload is added. Therefore, HVE will calculate and update the earth-fixed coordinates of the vehicle's CG. The new X, Y, Z coordinates are displayed in the Position/Velocity dialog. This same updating of the vehicle CG location occurs when occupants are added. Refer to the User's Manual for the specific calculation model to see if it supports automatic repositioning of the vehicle CG when occupants are added to the vehicle.

Collision Pulse

The Collision Pulse Event Set-up parameters are defined in Table 16-11.

Table 16-11: Collision Pulse Event Set-up Parameters

Parameter	Units (US / SI)	Description
Pulse Type	—	Type of collision pulse (Position, Velocity, Acceleration, or Force/Moment)
Longitudinal, Lateral and Vertical linear motion	in / cm, mph / km/h, g or lb / N	Vehicle-fixed components of the linear motion
Roll, Pitch, Yaw angular motion	deg, deg/sec, deg/sec² or ft-lb / N-m	Angular motion about the vehicle's roll, pitch and yaw axes
Pulse Factors	%/100	Multipliers for individual directions
Threshold Acceleration	g	Minimum total linear acceleration required for inclusion in the collision pulse
Tstart	sec	Event time at which the collision pulse begins
Impulse Center x, y, z	in / cm	Vehicle-fixed coordinates of the impulse center (Force/Moment pulse type only)

The Collision Pulse parameters define the acceleration vs. time response of a vehicle. The collision pulse is used for occupant simulations.

The Pulse Factors are a convenient way to evaluate the outcome by reducing or increasing the acceleration(s) by a user-defined percentage.

Setting the Threshold Acceleration allows the user to specify a minimum acceleration for the collision pulse. The table begins only after the acceleration reaches this minimum value and ends after the acceleration drops below this value.

Tstart specifies the time at which the collision pulse begins. Setting Tstart to a non-zero value allows the user to choose only a portion of the collision pulse, if desired.

Impulse Center x, y, z specifies the vehicle-fixed coordinates for the point of application of the force in a Force/Moment collision pulse table.

Wheels

The Wheels Event Set-up options are:

• Tire Blow-out — Parameters that activate the HVE Tire Blow-out Model, a time-dependent variation in tire properties.
• Wheel Damage — Parameters that allow the time-dependent relocation of wheels and wheel lock-up, as from a collision.
• Brakes — Parameters that model the slack adjusters and lining and drum temperatures.
• Tire-Terrain — Parameters that model tire-terrain interaction.

The Wheel Event Set-up parameters are defined in Table 16-12.

Table 16-12: Wheel Editing Event Set-up Parameters

Parameter	Units (US / SI)	Description
Axle Number	—	Axle index (1, 2 or 3)
Side	—	Side index (Right or Left)
Location	—	Tire location index (Inner or Outer)
Tire Is Blown	—	Flag indicating the tire is blown
AutoStart	—	Flag indicating the start time is set by the simulation
Start Time	sec	Simulation time at which blow-out or wheel displacement starts
Duration	sec	Duration over which air loss or wheel displacement occurs
Stiffness Factor	—	Multiplier for tire stiffness parameters
Rolling Resistance Factor	—	Multiplier for tire rolling resistance
Change in Coordinates	in / cm	Vehicle-fixed wheel displacement distance
Change in Camber	deg	Vehicle-fixed wheel camber change angle
Percent Peak Lock-up Torque	%/100	Percentage of nominal torque required to lock the wheel
Initial Lining Temp	deg F / deg C	Temperature of the brake lining at the start of the simulation
Initial Drum Temp	deg F / deg C	Temperature of the brake drum at the start of the simulation
Adjuster Slack	in / cm	Slack adjuster stroke before brake torque begins

Table 16-12: Wheel Editing Event Set-up Parameters (continued — Tire-Terrain)

Parameter	Units (US / SI)	Description
Axle Number	—	Axle index (1, 2 or 3)
Side	—	Side index (Right or Left)
Location	—	Tire location index (Inner or Outer)
Tire-Terrain Model	—	Tire-Terrain Model option
Sidewall Impact	—	Flag indicating the Sidewall Impact option is to be used
Radial Adjustment Increment	in / cm	Incremental change in radial spring length used in the spring force calculation
Angular Span	deg	Sweep angle for radial springs
Angular Increment	deg	Angular increment between radial springs
Sidewall Slide Friction Coefficient	—	Tire sidewall slide friction coefficient
Number of Sidewall Springs	—	Number of sidewall springs attached to each radial spring
Spring Number	—	Spring index
Spring Radial Dist from Wheel Center	in / cm	Radial distance from the wheel center to the current lateral spring
Spring Lateral Dist to Wheel Center	in / cm	Distance from the tire centerline plane to the tire sidewall for the current spring
Sidewall Spring Stiffness Ratio	—	Ratio of sidewall spring stiffness to radial spring stiffness
Spring Saturation Deflection	in / cm	Maximum allowable deflection for the current sidewall spring

Accelerometers

The Accelerometers Event Set-up parameters are defined in Table 16-13.

Table 16-13: Accelerometers Event Set-up Parameters

Parameter	Units (US / SI)	Description
Device Number	—	Device selector number
Device Is Used	—	Flag indicating the selected device is in use
x-coord, y-coord, z-coord	in / cm	Vehicle-fixed coordinates of the accelerometer

Simulations can report the local velocity and acceleration for each of up to five vehicle-fixed accelerometer locations.

• Device Number is the index for the specified accelerometer.
• The Device Is Used check box is used to activate the specified accelerometer.
• x, y, z-coordinates are the vehicle-fixed coordinates for the specified accelerometer.

Contacts

The Contacts Event Set-up parameters are defined in Table 16-14.

Table 16-14: Contact Event Set-up Parameters

Parameter	Units (US / SI)	Description
Source Segment	n/a	Name of the source segment (may be either a human ellipsoid or a vehicle contact surface)
Target Segment	n/a	Name of the target segment (may be either a human ellipsoid or a vehicle contact surface)
Material Name	—	User-editable material name
Constant	lb / N	Force required to initiate deflection
Linear Stiffness	lb/in / N/cm	Linear material deformation coefficient
Quadratic Stiffness	lb/in² / N/cm²	Quadratic material deformation coefficient
Cubic Stiffness	lb/in³ / N/cm³	Cubic material deformation coefficient
Damping Constant	lb-sec/in / N-sec/m	Material velocity-dependent deformation constant
Friction Constant	—	Inter-segment friction coefficient
Maximum Force	lb / N	Force at which the 3rd-order force-deflection relationship is abandoned
Maximum Deflection	in / cm	Deflection at which the 3rd-order force-deflection relationship is abandoned
Unloading Slope	lb/in / N/cm	Linear unloading slope beginning at maximum deflection
Max Defl/Timestep	in / cm	Logical distance defining the amount of deformation allowed during one timestep (used to define front/back)
Edge Constant	—	Force reduction coefficient for edges

The Contacts parameters are used by occupant and pedestrian simulations. The Contacts dialog allows the user to display all human ellipsoid vs. vehicle contact surface pairs and deselect them, if desired.

The purpose of deselecting the interaction of a particular ellipsoid vs. contact surface pair is to reduce calculation time by removing irrelevant ellipsoid vs. contact force calculations. For example, it is clear that a pedestrian will not strike the seat bottom cushion, so by removing this (and similar) ellipsoid/contact pairs, the simulation will skip the calculations required to determine their interaction.

Some human simulations use the human ellipsoid material properties and the vehicle contact surface material properties together to define the force vs. deflection relationship for a particular ellipsoid/surface pair. Other human simulations do not use these individual properties; instead they use a single Combined Material property. In that case, the Combined Material Properties dialog is used to assign these properties. The material properties for an ellipsoid/surface pair are defined by first selecting the pair, and then choosing Combined Material in the Contacts dialog. A standard materials dialog is displayed for the selected pair. (See the Contacts dialog page.)

Restraints

The Restraints Event Set-up parameters are defined in Table 16-15.

Table 16-15: Restraint Event Set-up Parameters

Parameter	Units (US / SI)	Description
x, y and z Attachment Coordinates	in / cm	Segment-based x, y, z coordinates for the attachment point of the ends of the right and left belt segments
Belt Slack	in / cm	Belt slack. The amount of displacement between the ends of the belt allowed before creating belt tension (a negative value implies pre-load)
Airbag Begin Fill Time	sec	Simulation time at which the airbag is deployed and begins to fill
Airbag Fill Duration	sec	Length of time during which airbag filling occurs

The Restraints parameters allow the user to provide in-use restraint system parameters for occupant events. For Belt Restraint systems, this means assigning the segment-fixed belt attachment point on the human (the other end of the belt is attached to the vehicle, and is therefore a vehicle parameter assigned in the Vehicle Editor) and belt slack.

NOTE: Most occupant simulators will view negative belt slack as pretensioning.

For Airbag Restraint systems, the in-use factors are deployment time and fill duration.

NOTE: To assign in-use parameters for either the belt or airbag restraint systems requires that a restraint exist at the seated position of the occupant.

NOTE: The seated position of the occupant is assigned using the Human Editor when the human is created.

NOTE: The seat position of each restraint system is assigned using the Vehicle Editor.

Output Track Parameters

The Event output track definition is dependent on object type, Human or Vehicle. Output track results are displayed during Event Mode in Key Results windows and, during Playback Mode, in the Variable Output Table.

Human and Vehicle Output Track Parameters are provided below.

Human Output Tracks

The output tracks for HVE humans are divided into five categories:

• Kinematics
• Joints
• Occupant Contacts
• Belts
• Airbags

The output track parameter definitions for each of these groups are described below. Specific definitions are provided in Tables 16-16 through 16-20.

Kinematics

The Human Segment Kinematics output groups are defined in Table 16-16.

Table 16-16: Human Segment Kinematics Output Track Group Parameters

Parameter	Units (US / SI)	Description
x or X, y or Y, z or Z	in / cm for occupants, ft / m for pedestrians	Coordinates for the center of gravity of each segment, relative to the vehicle-fixed coordinate system (occupants) or earth-fixed coordinate system (pedestrians)
Roll, Pitch, Yaw	deg for occupants, deg for pedestrians	Orientation of each segment, relative to the vehicle-fixed coordinate system (occupants) or earth-fixed coordinate system (pedestrians)
Vtotal, i vel, j vel, k vel	in/sec / km/h	Total, i, j and k velocity of each segment, relative to the vehicle-fixed coordinate system (occupants) or earth-fixed coordinate system (pedestrians)
Roll Vel, Pitch Vel, Yaw Vel	deg/sec	Roll, pitch and yaw velocities of each segment relative to the segment's axis system
Atotal, i acc, j acc, k acc	deg/sec²	Roll, pitch and yaw acceleration of each segment relative to the segment's axis system

The Human Segment Kinematics output tracks define the current position, velocity and acceleration for each human segment.

Joints

The Human Joints output groups are defined in Table 16-17.

Table 16-17: Human Inter-segment Joint Output Track Group Parameters

Parameter	Units (US / SI)	Description
Roll, Pitch, Yaw	deg	Angular orientation of segment relative to the upstream segment's coordinate axis system
FxElastic, FyElastic, FzElastic	lb / N	Segment-fixed joint force components from elasticity
FxDamping, FyDamping, FzDamping	lb / N	Segment-fixed joint force components from damping
FxTotal, FyTotal, FzTotal	lb / N	Segment-fixed total joint force components
MxElastic, MyElastic, MzElastic	in-lb / N-m	Moment about the upstream joint's i, j, k axis system from joint elasticity
MxDamping, MyDamping, MzDamping	in-lb / N-m	Moment about the upstream joint's i, j, k axis system from joint damping
MxTotal, MyTotal, MzTotal	in-lb / N-m	Total moment about the upstream joint's i, j, k axis system from joint torques

The Human Joint output tracks define the current conditions at each joint.

Contacts

The Human Contacts output groups are defined in Table 16-18.

Table 16-18: Human Contacts Output Track Group Parameters

Parameter	Units (US / SI)	Description
x, y, z	in / cm	Contact surface contact coordinates
Deflection	in / cm	Contact surface deflection at x, y, z
F (total)	lb / N	Total contact force
F (normal)	lb / N	Contact surface normal force
F (friction)	lb / N	Contact surface frictional force

The Human Contacts output tracks define the current interaction between each selected human ellipsoid and vehicle contact surface.

NOTE: These are the same values reported in the Vehicle Contacts output tracks.

Belts

The Human Belt Restraints output groups are defined in Table 16-19.

Table 16-19: Human Belt Restraints Output Track Group Parameters

Parameter	Units (US / SI)	Description
Belt Attachment i-coord, j-coord, k-coord	in / cm	The i, j, k segment-fixed coordinates for the belt attachment point
Belt Strain	%/100	Simulated belt strain
Belt Tension	lb / N	Simulated belt tension
Belt Pressure	lb / N	Simulated belt force against the segment

The Human Belt output tracks define the current belt outputs.

Airbags

The Human Airbag Restraints output groups are defined in Table 16-20.

Table 16-20: Human Airbag Restraints Output Track Group Parameters

Parameter	Units (US / SI)	Description
Pressure	psi / kPa	Airbag internal pressure
Radius	in / cm	Airbag radius
Bag Fn	lb / N	Normal contact force between human and airbag
Bag Fmu	lb / N	Friction contact force between airbag and vehicle
Bag x, Bag y, Bag z	in / cm	Human contact point with airbag

The Human Airbag Restraints output tracks define the current interaction between the human occupant and the airbag.

NOTE: These are similar to the values reported in the Vehicle Airbag Restraints output tracks.

Vehicle Output Tracks

The output tracks for HVE vehicles are divided into the following categories:

• Kinematics
• Kinetics
• Accelerometers
• Damage
• Tires
• Wheels
• Connections
• Drivetrain
• Driver Inputs
• Occupant Contacts
• Belts
• Airbags

The output track parameter definitions for each of these groups are described below. Specific definitions are provided in Tables 16-21 through 16-32.

Sprung Mass Kinematics

The Vehicle Sprung Mass Kinematics output groups are defined in Table 16-21.

Table 16-21: Vehicle Sprung Mass Kinematics Output Track Group Parameters

Parameter	Units (US / SI)	Description
X, Y, Z	ft / m	Coordinates of the vehicle center of gravity relative to the earth-fixed coordinate system
Roll, Pitch, Yaw	deg	Orientation of the vehicle-fixed coordinate system relative to the earth-fixed coordinate system (order of rotations is Yaw, Pitch, Roll)
Radius	ft / m	Path radius of the vehicle CG
Nu (Course Angle)	deg	Angle of the total velocity vector relative to the earth-fixed coordinate system
Vtotal, u vel, v vel, w vel	mph / km/h	Total, u (longitudinal), v (side) and w (normal) velocity of the vehicle (see SAE J670e for definitions)
Beta (Sideslip Angle)	deg	arctan(v vel / u vel), angle from the vehicle heading vector to the velocity vector
Roll Velocity, Pitch Velocity, Yaw Velocity	deg/sec	p (roll), q (pitch) and r (yaw) velocity about the vehicle's x, y, z axis system
Atotal, u dot, v dot, w dot, Long Acc, Lat Acc, Vert Acc	g	Total, u, v and w accelerations, and Longitudinal, Lateral and Vertical accelerations (see SAE J670e for definitions)
Roll Acc, Pitch Acc, Yaw Acc	deg/sec²	Roll, pitch and yaw accelerations about the vehicle's x, y, z axis system
Translation KE, Rotation KE, Total KE	ft-lb / Joule	Kinetic energy associated with translation, rotation and their sum

The Vehicle Kinematics output tracks define the current position, velocity and acceleration, and other related parameters, at the current timestep.

Sprung Mass Kinetics

The Vehicle Sprung Mass Kinetics output groups are defined in Table 16-22.

Table 16-22: Vehicle Sprung Mass Kinetics Output Track Group Parameters

Parameter	Units (US / SI)	Description
FxSusp, FySusp, FzSusp	lb / N	Summation of suspension forces at the vehicle CG relative to the vehicle-fixed axis system
MxSusp, MySusp, MzSusp	ft-lb / N-m	Summation of suspension moments about the vehicle CG relative to the vehicle-fixed axis system
FxColl, FyColl, FzColl	lb / N	Summation of collision forces at the vehicle CG relative to the vehicle-fixed axis system
MxColl, MyColl, MzColl	ft-lb / N-m	Summation of collision moments about the vehicle CG relative to the vehicle-fixed axis system
FxAero, FyAero, FzAero	lb / N	Summation of aerodynamic forces at the vehicle CG relative to the vehicle-fixed axis system
MxAero, MyAero, MzAero	ft-lb / N-m	Summation of aerodynamic moments about the vehicle CG relative to the vehicle-fixed axis system
FxConn, FyConn, FzConn	lb / N	Summation of inter-vehicle connection forces at the vehicle CG relative to the vehicle-fixed axis system
MxConn, MyConn, MzConn	ft-lb / N-m	Summation of connection moments about the vehicle CG relative to the vehicle-fixed axis system

The Vehicle Sprung Mass Kinetics output tracks define the forces and moments at the sprung mass CG due to the various sources listed above.

Accelerometers

The Accelerometers Output Group parameters are defined in Table 16-23.

Table 16-23: Vehicle Accelerometers Output Track Group Parameters

Parameter	Units (US / SI)	Description
x, y, z	in / cm	Vehicle-fixed accelerometer coordinates
V-tot, u-vel, v-vel, w-vel	mph / km/h	Accelerometer velocity at x, y, z, resolved according to the vehicle-fixed coordinate system
X-dot, Y-dot, Z-dot	mph / km/h	Accelerometer velocity at x, y, z, resolved according to the earth-fixed coordinate system
Acc-tot, Long Acc, Lat Acc, Vert Acc	g	Accelerometer acceleration at x, y, z
u-dot, v-dot, w-dot	g	Accelerometer acceleration at x, y, z; time derivative of u-vel, v-vel, w-vel

The Accelerometers output tracks define the position, velocity (earth-fixed and vehicle-fixed) and acceleration (earth-fixed and vehicle-fixed) for each installed accelerometer. Up to five accelerometers may be defined (see Event Set-up, Accelerometers).

Damage

The Damage Output Group parameters are defined in Table 16-24.

Table 16-24: Vehicle Damage Output Track Group Parameters

Parameter	Units (US / SI)	Description
Is Damaged	—	Flag indicating the vertex sustained damage since the previous timestep
Vertex ID	—	Vertex number, used for indexing
x, y, z	in / cm	Vertex vehicle-fixed coordinates
Fx, Fy, Fz	lb / N	Vehicle-fixed force components at x, y, z
F0 (surf), F1 (surf), F2 (surf), F3 (surf)	lb / N, lb/in / N/cm, lb/in² / N/cm², lb/in³ / N/cm³	Force-deflection characteristics of the vertex
Mu (surf)	—	Vertex friction multiplier
Fmax (surf)	lb / N	Vertex maximum force characteristic
Fu (surf)	lb/in / N/cm	Vertex unloading linear stiffness

Each vehicle vertex has associated with it the above data. These data are currently not available to the user through the variable output interface.

NOTE: The x, y, z coordinates are used to visualize the damage done to the vehicle exterior.

Tires

The Vehicle Tires output groups are defined in Table 16-25.

Table 16-25: Vehicle Tires Output Track Group Parameters

Parameter	Units (US / SI)	Description
x, y, z	in / cm	Coordinates of the tire contact patch relative to the vehicle-fixed coordinate system (see SAE J670e)
X, Y, Z	ft / m	Coordinates of the tire contact patch relative to the earth-fixed coordinate system (used for drawing tire marks)
Fx', Fy', Fz'	lb / N	Longitudinal, lateral and normal force at the tire contact patch relative to the tire's coordinate axis system
Mx', My', Mz'	in-lb / N-m	Rolling resistance moment, overturning moment and aligning torque relative to the tire's coordinate axis system
Trad	in / cm	Tire loaded radius
LongSlip	%/100	Longitudinal tire slip
LatSlip	deg	Tire slip angle
Inclination Angle	deg	Angle from the tire z-axis to the surface normal
SkidMark	—	Opacity of skidmark (0 = clear; 1 = opaque)
Mu (surf)	—	Friction multiplier of the surface
Nx, Ny, Nz	—	Earth-fixed unit normal of the terrain at X,Y
F0 (surf), F1 (surf), F2 (surf), F3 (surf)	lb / N, lb/in / N/cm, lb/in² / N/cm², lb/in³ / N/cm³	Force-deflection characteristics of the terrain at X,Y
N, Kphi, Kc	none, lb/in^N+1 / N/cm^N+1, lb/in^N+2 / N/cm^N+2	Bekker soil constants for the terrain at X,Y
Moisture	%/100	Moisture content of the terrain at X,Y
Clay	%/100	Clay content of the terrain at X,Y (updated: the Clay track is retained; the terrain Macrotexture parameter was added as an additional track, not as a replacement — see Chapter 13)
Sinkage	ft / m	Soil deformation at X,Y
Fx' plow, Fy' plow	lb / N	Wheel-fixed tire plow force at X,Y
Fx Sidewall, Fy Sidewall, Fz Sidewall	lb / N	Longitudinal, lateral and normal tire sidewall force (sidewall-impact model)
Water Depth	in / cm	Depth of water on the terrain at X,Y
Macrotexture	in / cm	Terrain macrotexture depth at X,Y
Water Mu Mult	—	Friction multiplier applied for the water depth at X,Y
Water RR	—	Rolling-resistance contribution from the water depth at X,Y

Tire-related vehicle output tracks define the conditions at the tire contact patch for each tire.

Wheels

The Vehicle Wheels output groups are defined in Table 16-26.

Table 16-26: Vehicle Wheel Output Track Group Parameters

Parameter	Units (US / SI)	Description
x (wheel), y (wheel), z (wheel)	in / cm	Coordinates of the wheel center with respect to the vehicle-fixed axis system
dz (axle)	in / cm	Vertical axle displacement (solid axles)
phi (axle)	deg	Solid axle vehicle-fixed roll angle
gamma (wheel)	deg	Wheel camber relative to the vehicle-fixed axis system (+ clockwise about an axis parallel to, and in the direction of, the x-axis)
spin (wheel)	deg	Wheel rotation angle about the spin axis
delta (wheel)	deg	Vehicle-fixed wheel steer angle
Vtot (wheel)	mph / km/h	Total earth-fixed velocity at the wheel center
Xvel (wheel)	mph / km/h	Earth-fixed X velocity at the wheel center
Yvel (wheel)	mph / km/h	Earth-fixed Y velocity at the wheel center
Zvel (wheel)	mph / km/h	Earth-fixed Z velocity at the wheel center
vtot (wheel)	mph / km/h	Vehicle-fixed total velocity at the wheel center
u-vel (wheel)	mph / km/h	Vehicle-fixed forward velocity at the wheel center
v-vel (wheel)	mph / km/h	Vehicle-fixed lateral velocity at the wheel center
w-vel (wheel)	mph / km/h	Vehicle-fixed vertical velocity at the wheel center
zdot (axle)	mph / km/h	Solid axle vehicle-fixed vertical velocity
phid (axle)	deg/sec	Solid axle roll velocity
gamma-dot	deg/sec	Wheel camber change rate
Spin Vel (wheel)	deg/sec	Wheel rotational speed about the spin axis
Delta-dot	deg/sec	Wheel steer velocity
A tot, X acc, Y acc, Z acc	g	Wheel center acceleration relative to the earth-fixed coordinate system
Along, Alat, Avert	g	Wheel center acceleration relative to the vehicle-fixed coordinate system
zddot (axle)	g	Solid axle vehicle-fixed vertical acceleration
phidd (axle)	deg/sec²	Solid axle vehicle-fixed angular acceleration
gamma-ddot	deg/sec²	Wheel camber acceleration
Spin Acc	deg/sec²	Wheel spin angular acceleration
Delta-ddot	deg/sec²	Wheel steer angular acceleration
zddot	g	Wheel jounce/rebound acceleration
Fx, Fy, Fz	lb / N	Force at the wheel center with respect to the vehicle-fixed axis system
Mx, Mz	ft-lb / N-m	Wheel moments about the camber and steer axes (see axle Drive/Brake Torque)
dz (susp)	in / cm	Suspension vertical displacement (+ down)
zvel (susp)	mph / km/h	Suspension vertical velocity (+ down)
Fz Susp, Fz Damp, Fz A-P	lb / N	Suspension force components from suspension spring, damping (i.e., shock absorber) and anti-pitch
RollStf	ft-lb / N-m	Auxiliary roll stiffness from anti-sway bar
WheelBrkPress	psi / kPa	Brake pressure at the wheel cylinder
Drive Tq, Brake Tq	ft-lb / N-m	Torque applied about the wheel spin axis
FxDrv (Att), FxBrk (Att)	lb / N	Attempted drive or brake force (from throttle and/or braking inputs)
Brk Stroke	in / cm	Stroke of the wheel cylinder or slack adjuster before brake torque is applied
Brk Press	psi / kPa	Brake fluid pressure (air or hydraulic) at the wheel cylinder or brake chamber
F Piston	lb / N	Force from the piston or slack adjuster on the braking mechanism
T Interface	deg F / deg C	Temperature at the interface between the brake lining and drum
T Drum	deg F / deg C	Brake drum temperature
T Lining	deg F / deg C	Brake lining temperature

The above table defines output tracks for each wheel location. Some are axle-related (choosing the right or left side for these parameters will display the same results). Some parameters are effective at the wheel center, some are at the suspension and some are at the brake.

Inter-vehicle Connections

The Vehicle Inter-vehicle Connections output groups are defined in Table 16-27.

Table 16-27: Vehicle Connections Output Track Group Parameters

Parameter	Units (US / SI)	Description
Roll, Pitch, Yaw	deg	Roll, pitch and yaw orientation relative to the towing vehicle's coordinate system
Roll Vel, Pitch Vel, Yaw Vel	deg/sec	Roll, pitch and yaw articulation velocities relative to the towing vehicle's coordinate system
Rollddot, Pitchddot, Yawddot	deg/sec²	Roll, pitch and yaw articulation accelerations relative to the towing vehicle's coordinate system
Fx, Fy, Fz	lb / N	Connection forces in the vehicle-fixed coordinate system
Mx, My, Mz	ft-lb / N-m	Connection moments in the vehicle-fixed coordinate system

The Inter-vehicle Connections output tracks define the conditions at the connection point between the towing and towed vehicle.

Drivetrain

The Vehicle Drivetrain output groups are defined in Table 16-28.

Table 16-28: Vehicle Drivetrain Output Track Group Parameters

Parameter	Units (US / SI)	Description
Engine speed	RPM	Engine rotational velocity (i.e., RPM)
Power	HP / kW	Engine power
Torque	ft-lb / N-m	Engine torque
Transmission Ratio	—	The current numeric ratio for the transmission
Differential Ratio	—	The current numeric ratio for the differential

The Vehicle Drivetrain output tracks define the current drivetrain conditions.

Driver Controls

The Vehicle Driver Controls output groups are defined in Table 16-29.

Table 16-29: Vehicle Driver Controls Output Track Group Parameters

Parameter	Units (US / SI)	Description
% WOT	%/100	Throttle position, percent of WOT
Brake Force	lb / N	Brake pedal force
Brake Press	psi / kPa	Brake system master cylinder pressure
Trans Gear	—	Transmission gear selection
Diff Gear	—	Differential gear selection
Steer Angle	deg	Steering wheel angle
Steer Ang Vel	deg/sec	Steering wheel angular velocity
Steer Ang Acc	deg/sec²	Steering wheel angular acceleration
Steer Tq	in-lb / N-m	Steering wheel torque
Path X, Path Y	ft / m	Earth-fixed X,Y coordinates of the path used by the HVE Path Follower
Path X Att, Path Y Att	ft / m	Earth-fixed X,Y coordinates of the path at the preview distance
Path Err	ft / m	Distance from the attempted path to the desired path
DX Preview, DY Preview	ft / m	Earth-fixed coordinates of the preview point

The Vehicle Driver Controls output tracks define the current driver inputs. Results from the steer degree of freedom and HVE Path Follower are also included in the Vehicle Driver output group.

Contacts

The Vehicle Contacts output groups are defined in Table 16-30.

Table 16-30: Vehicle Contacts Output Track Group Parameters

Parameter	Units (US / SI)	Description
x, y, z	in / cm	Contact surface contact coordinates
Deflection	in / cm	Contact surface deflection at x, y, z
Ftotal	lb / N	Total contact force
Fnormal	lb / N	Contact surface normal force
Ffriction	lb / N	Contact surface frictional force

The Vehicle Contacts output tracks define the current interaction between each selected human ellipsoid and vehicle contact surface.

NOTE: These are the same values reported in the Human Contacts output tracks.

Belt Restraints

The Vehicle Belt Restraints output groups are defined in Table 16-31.

Table 16-31: Vehicle Belt Restraints Output Track Group Parameters

Parameter	Units (US / SI)	Description
Belt x, Belt y, Belt z	in / cm	Vehicle-fixed belt anchor point coordinates
Belt Azimuth	deg	The angle of the belt in the vehicle-fixed x-y plane
Belt Zenith	deg	The elevation angle of the belt in the vehicle-fixed coordinate system
Belt Strain	%/100	Simulated belt strain
Belt Stretch	in / cm	Simulated belt stretch
Belt Tension	lb / N	Simulated belt tension

The Vehicle Belt output tracks define the current belt forces and stretch.

Airbag Restraints

The Vehicle Airbag Restraints output groups are defined in Table 16-32.

Table 16-32: Vehicle Airbag Restraints Output Track Group Parameters

Parameter	Units (US / SI)	Description
Pressure	psi / kPa	Airbag internal pressure
Radius	in / cm	Airbag radius
Bag Defl	in / cm	Airbag deflection caused by the back-side contact surface
Bag Fn	lb / N	Airbag normal force from the back-side contact surface
Bag Fmu	lb / N	Frictional force between the back-side contact surface and the airbag
Deploy x, Deploy y, Deploy z	in / cm	Airbag vehicle-fixed deployment coordinates

The Vehicle Airbag Restraints output tracks define the current interaction between the human occupant and the airbag.

NOTE: These are similar to the values reported in the Human Airbag Restraints output tracks (see Human Output Tracks, Airbags).

Static Reports

In addition to the time-dependent output track parameters described above, additional output parameters related to the HVE human or vehicle may be monitored. These results are stored in the form of static reports and include:

• Accident History
• Damage Data
• Damage Profile
• Driver Data
• Environment Data
• Event Data
• Human Data
• Injury Data
• Messages
• Momentum Diagram
• Program Data
• Site Drawing
• Vehicle Data

Whereas the event produces human and vehicle output tracks at each output interval, the above static reports are produced only once at the end of the run.

NOTE: There is an important and fundamental difference between the output track definitions and the information displayed in the Static Reports: each available output track parameter is strictly defined by the HVE Event Model. However, the static reports may contain any information the developer of the reconstruction or simulation model chooses to report.

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See also (dialog references): Event Information · Event Setup · Position/Velocity · Driver Controls · Contacts · Inter-vehicle Connections · Simulation Controls

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