Vehicle - Platform - Terrain
(VPT)
Models Library

Intro-

A variety of related platform-oriented models were created on previous projects. These have been integrated into a single collection, called the VPT library, for Vehicle-Platform-Terrain (VPT) models. The models enable network models to be integrated with mission-level scenarios to provide realistic and dynamic network traffic, as well as to assess networking quality impacts on mission success.

WinFrame-VPT-3D-Viewer

Background

The Vehicle-Platform-Terrain (VPT) models library of CSIM contains several simple elements for modeling operational scenarios and/or engagements between various kinds of entities or platforms. The elements may be imbued with strategy logic and initial status and capabilities, such as and special strengths. Scenarios may be quickly studied by snapping down the objects into their initial positions, and letting the simulation unfold. The models are composable, extensible, and are highly re-usable for many purposes.

This document will describe the VPT models and how to use them. The VPT models form a base set which can either be used as-is through parameterization, or further evolved into more extensive models of specific systems.

The VPT models leverage CSIM's unified simulation environment to simplify the construction of new models, as well as for increased simulation composability, efficiency, scalability, and compatibility to other levels of modeling. Being based on a general purpose simulator, it has received broad use with commensurate testing and validation.

Independent World Models for Each Agent
Of particular interest is the maintenance of different views of information access. VPT contains models of sensor capabilities, as well as sensor information sharing. For example, actual truth state, versus knowledge as perceived from other units.

Distinct purposes of VPT are to study evolved behaviors, or the emergence of improved strategies and behaviors through evolutionary computing paradigms.

The VPT models are located under $CSIM_MODEL_LIBS/VPT. Several example scenario simulations are also included under the examples sub-directory.

Although the models are useful as-is, they are also considered as examples for how to model vehicle and platform scenarios. The base models can be extended or simplified as needed. They are constructed in an object-oriented top-down fashion. New vehicle models can be added by inheriting the base class model definition, and adding to it.

To use these models, include (by-reference) $CSIM_MODEL_LIBS/VPT/Library.sim in your top-level diagram.

World Models

Inherent in the VPT is the concept of a World Model for each entity. It reflects the state of information that each entity holds about other entities. With this model, the position or existence of neighboring objects can be fuzzied, denied, or spoofed.

Terrain Data Base

To support the multi-platform modeling, a simplified terrain database with access functions provide information about visual and RF contact between any pair of platforms, as well as traversability, based on platform x,y,z locations. Terrain conditions are described as real values for traversability and RF propagation. In this way, effects such as foliage, urban structures, interference sources, or mountains can be abstracted. Two versions of the RF propagation map are available: a standard grid-based version, and a more efficient polygon-based version. The polgon version integrated propagation loss across regions of arbitrary shape, dimension, and precision. In practice, it can produce results which are more accurate than could be obtained from very fine grids, but while co0nsuming minimal computation, especially for mixtures of urban and open terrain.

A round-earth model is combined with arbitrary elevation data. Data can be accepted from a variety for formats, such as DTED or NASA geological database. The VPT terrain model is simpler and more abstract than earlier terrain models. It is based on a simple eclipsing and propagation grid. Each grid square contains a pair of values for traversabilty and RF propagation loss per unit distance. The grid vertices (or lines) specify an xyz elevation value.

Weather Model

VPT contains a simplified weather model that can describe obscuration conditions over the terrain, as well as wind conditions for dispersant plume modeling. The dispersant plume model predicts spread versus time.

Advanced Visualizations

The following pictures represent images captured from last year's CSIM simulation projects, including PCA (DARPA-Tech demo) UAV over ground terrain, Drexel U. / Lockheed Martin / ACIN Autonomous Communicating Robots / Sensors for FCS, and MANet.