Curved Regular Grid Road

The idea of a CRG road is to give reference, split the road, or store road information at grid points, as shown in the Regular Grid in the below image. The Curved Regular Grid was developed since the Regular Grid does not bend. This contains a Center Reference Line (bold line) and other lines parallel to this, separated by a distance.

The CRG file contains the definition of the curved reference line. This requires you to specify the points along the line, which when joined creates the curved reference line. Along with the points, the heading angle phi is required at each point.

The points along the curved reference line are provided as multiples of a value called u increment. v increment and u increment, when clubbed together, will help in traversing across the length and width of the entire grid.


Figure 1. CRG

CRG File Definitions

Z-ARRAY
z(nu, nv) Height values at grid points (may contain NaNs)
U-AXIS (REFERENCE LINE)
ubeg Start coordinate (default: 0.00m)
uend End coordinate
V-AXIS (ORTHOGONAL TO REFERENCE LINE)
vmin, vmax V value at right/left edge of road (equally spaced v-axis), or
v(nv) Variably spaced v-axis
PHI (HEADING ANGLE)
p One phi value for straight reference line, or
p(nu-1) phi values between reference line points. Distance between these points is (uend-ubeg) / (nu-1).
R0 (REFERENCE LINE ORIGIN)
(x0, y0) Inertial coordinates (default (0, 0))

See the Sample Road Data Files topic to view a CRG file sample.

For the latest developments please visit OpenCRG.

Usage

A .crg file can be directly provided to the Auto Tire auto entity by browsing for the .crg file in the dialog box.


Figure 2.

If the you want to add more information to the crg road like friction etc. you need to provide the .crg file through an .rdf.

In this case, a .crg file has to be referenced through an .rdf file as shown below. The ROAD_TYPE term should be given as .crg. In the parameters block, the path to the .crg road file needs to be specified. It can accommodate relative and absolute paths. 
$---------------------------------------------------MODEL
[MODEL]
PROPERTY_FILE_FORMAT    = 'USER'
FUNCTION_NAME = 'mbdtire::ROAD_ALTAIR'
METHOD             	= '2D'
ROAD_TYPE           = 'crg'
$------------------------------------------------------------PARAMETERS
[PARAMETERS]
 MU                      = 1.0
 CRG_ROADFILE            = '.\CRG.crg'

The road is also supported by CD, CTI, MF_SWIFT and FIALA Tires. CD Tire requires the crg file path directly. All other tires requiere the crg file path to be mentioned in an rdf.