Two ABS algorithms are currently implemented in the HVE simulation environment. These are the Tire Slip algorithm and the HVE Bosch Version 1 algorithm. Tire Slip - This is a simple and straight-forward ABS algorithm. Its design is based on the fundamental goal of an ABS system, which is to maintain tire slip in the vicinity of peak friction coefficient. It is generally applicable to any type of vehicle (passenger car, truck, etc). HVE Bosch Version 1 Algorithm - The HVE Bosch Version 1 ABS algorithm is based on the information provided in Bosch technical literature. The algorithm is based on wheel spin acceleration and a critical tire slip threshold. The Bosch ABS system is used on many US and foreign passenger cars.

To further enhance the results from an ABS simulation, HVE now includes a new method for displaying tire marks. In the new method, the opacity of a tire mark is varied according to the current vertical tire load (heavier tire loads produce darker marks), the percentage of longitudinal tire slip and the percentage of lateral tire slip (increased slip produces darker marks). In addition, a set of weighting coefficients determines the opacity of tire marks during combined braking and steering. Since the vast majority of vehicles are now fitted with ABS, the new HVE ABS model is an important new feature, especially for simulating pre-impact braking and loss of control.

More detailed information about the HVE ABS Simulation Model is available in SAE 2002-01-0559, "A Simulation Model for Vehicle Braking Systems Fitted with ABS".

The HVE Brake Designer model incorporates advanced features, such as the effect of sliding speed and temperature on lining friction. The model also includes the capability to study brake fade characteristics, such as that which occurs to trucks on long downhill grades. Parameters defining physical, performance and material properties of brake components are fully user-editable.

Values for brake factor, actuation factor and brake torque ratio are calculated by the HVE Brake Designer. Initial values are based on the environment's ambient temperature and zero sliding velocity at the pad/rotor (or drum/lining) interface. During a vehicle dynamic simulation, the appropriate brake factor and brake torque ratio are based on the current brake internal temperature and sliding velocity calculated by the simulation. Outputs from HVE-compatible vehicle dynamics simulation models using the HVE Brake Designer include brake torque, brake stroke, brake pressure, brake piston force, drum/rotor temperature and lining temperature.

DyMESH is useful for all collision simulations, and is especially useful for underride, or any crash where three-dimensional collision dynamics are present. All types of vehicles (passenger car, truck, trailer, dolly, barrier) may be involved in any number of simultaneous collisions. Using the HVE simulation environment, vehicle deformation is visualized as it is calculated during collision simulations. Researchers can compare simulated damage against actual damage from staged collisions or real world crashes as a means to validate their simulation results. Because the vehicle mesh typically includes several thousand nodes, HVE displays the resulting damage with great resolution.

Detailed validation results can be found in SAE 1999-01-0104, "The DyMESH Method for Three-Dimensional Multi-Vehicle Collision Simulation" and SAE 2000-01-0844, "Validation of DyMESH for Vehicles vs. Barrier Collisions" and also SAE 2004-01-1207, "Validation of the SIMON Model for Vehicle Handling and Collision Simulation - Comparison of Results with Experiments and Other Models".

The HVE Driver Model has four components: Path Generator, General Parameters, Driver Descriptors, Driver Neuro-Muscular Filter. The path generator uses up to eight 3-D positions and orientations to define the attempted path. The path is constructed from a 3-D spline curve passing through each user-specified location and tangent to the roll, pitch and yaw orientations for each location. The general parameters provide control over the Driver Model algorithm. Control parameters include driver starting time, driver sample interval, driver preview distance, allowable path error, and initial steering wheel angle. The driver descriptors describe how the operator attempts to control the vehicle. These parameters include the driver preview distance (the point ahead of the vehicle where the driver is actually looking and presumably wants to go), driver comfort level (lateral acceleration), maximum steering wheel velocity, steer correction rate and steer correction damping. The driver neuro-muscular filter represents a mathematical model of the human operator in man-machine performance. The model used in HVE was derived from the model described by McRuer, et al (1965) as published in the NASA Bioastronautics Databook (NASA SP-3006). The model includes an effective time delay representing the time required to read, interpret and decide upon the appropriate control motion, the lead time representing a ratio of the weight the driver attributes to the displayed velocity compared to the displayed position, and the time lag representing the amount of data smoothing the driver applies to his external stimuli. These parameters correspond to the first-order effects of the neurological and muscular systems of a human driver.

More detailed information about the HVE Driver Model is available in SAE 2000-01-1313, "The Simulation of Driver Inputs Using a Vehicle Driver Model".

To study transient effects, the HVE Tire Blow-out Model operates in the time domain (i.e., the dependent parameters are varied according to time). By far, the greatest effect of reduced inflation is on cornering stiffness, camber stiffness, radial tire stiffness and rolling resistance. Therefore, these parameters were made the dependent parameters in the blow-out model. The dependent parameters are varied using linear interpolation, starting at the initiation time and lasting over the blow-out duration. The dependent parameters are multiplied (stiffness values) and divided (rolling resistance) by user-entered blow-out factors to create the blown tire properties.

More detailed information about the HVE Tire Blow-out Model is available in SAE 980221, "3-Dimensional Simulation of Vehicle Response to Tire Blow-outs".