Description

Deformable terrain model.

This class implements a deformable terrain based on the Soil Contact Model. Unlike RigidTerrain, the vertical coordinates of this terrain mesh can be deformed due to interaction with ground vehicles or other collision shapes.

#include <SCMDeformableTerrain.h>

Inheritance diagram for chrono::vehicle::SCMDeformableTerrain:

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Collaboration diagram for chrono::vehicle::SCMDeformableTerrain:

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Classes
class	SoilParametersCallback
	Class to be used as a callback interface for location-dependent soil parameters. More...

Public Types
enum	DataPlotType { PLOT_NONE, PLOT_LEVEL, PLOT_LEVEL_INITIAL, PLOT_SINKAGE, PLOT_SINKAGE_ELASTIC, PLOT_SINKAGE_PLASTIC, PLOT_STEP_PLASTIC_FLOW, PLOT_PRESSURE, PLOT_PRESSURE_YELD, PLOT_SHEAR, PLOT_K_JANOSI, PLOT_IS_TOUCHED, PLOT_ISLAND_ID, PLOT_MASSREMAINDER }

Public Member Functions
	SCMDeformableTerrain (ChSystem *system)
	Construct a default SCMDeformableSoil. More...

void	SetPlane (ChCoordsys<> mplane)
	Set the plane reference. More...

void	SetSoilParameters (double Bekker_Kphi, double Bekker_Kc, double Bekker_n, double Mohr_cohesion, double Mohr_friction, double Janosi_shear, double elastic_K, double damping_R)
	Set the properties of the SCM soil model. More...

void	SetBulldozingFlow (bool mb)
	Enable/disable the creation of soil inflation at the side of the ruts (bulldozing effects).

bool	GetBulldozingFlow () const

void	SetBulldozingParameters (double mbulldozing_erosion_angle, double mbulldozing_flow_factor=1.0, int mbulldozing_erosion_n_iterations=3, int mbulldozing_erosion_n_propagations=10)
	Set parameters controlling the creation of side ruts (bulldozing effects). More...

void	SetAutomaticRefinement (bool mr)
	Enable/disable dynamic mesh refinement. More...

bool	GetAutomaticRefinement () const

void	SetAutomaticRefinementResolution (double mr)
	Set the resolution for automatic mesh refinement (specified in meters). More...

double	GetAutomaticRefinementResolution () const

void	SetTestHighOffset (double moff)
	Set the vertical level up to which collision is tested (relative to the reference level at the sample point). More...

double	GetTestHighOffset () const

void	SetPlotType (DataPlotType mplot, double mmin, double mmax)
	Set the color plot type for the soil mesh. More...

void	SetColor (ChColor color)
	Set visualization color. More...

void	SetTexture (const std::string tex_file, float tex_scale_x=1, float tex_scale_y=1)
	Set texture properties. More...

void	EnableMovingPatch (std::shared_ptr< ChBody > body, const ChVector<> &point_on_body, double dimX, double dimY)
	Enable moving patch an set parameters (default: disabled). More...

void	RegisterSoilParametersCallback (SoilParametersCallback *cb)
	Specify the callback object to set the soil parameters at given (x,y) locations. More...

virtual double	GetHeight (double x, double y) const override
	Get the terrain height at the specified (x,y) location.

virtual chrono::ChVector	GetNormal (double x, double y) const override
	Get the terrain normal at the specified (x,y) location.

virtual float	GetCoefficientFriction (double x, double y) const override
	Get the coefficient of friction at the specified (x,y) location. More...

const ChCoordsys &	GetPlane () const
	Get the current reference plane. The SCM terrain patch is in the (x,y) plane with normal along the Z axis.

const std::shared_ptr< ChTriangleMeshShape >	GetMesh () const
	Get the underlyinh triangular mesh.

void	Initialize (double height, double sizeX, double sizeY, int divX, int divY)
	Initialize the terrain system (flat). More...

void	Initialize (const std::string &mesh_file)
	Initialize the terrain system (mesh). More...

void	Initialize (const std::string &heightmap_file, const std::string &mesh_name, double sizeX, double sizeY, double hMin, double hMax)
	Initialize the terrain system (height map). More...

TerrainForce	GetContactForce (std::shared_ptr< ChBody > body) const
	Return the current cumulative contact force on the specified body (due to interaction with the SCM terrain).

void	PrintStepStatistics (std::ostream &os) const
	Print timing and counter information for last step.

Public Member Functions inherited from chrono::vehicle::ChTerrain
virtual void	Synchronize (double time)
	Update the state of the terrain system at the specified time.

virtual void	Advance (double step)
	Advance the state of the terrain system by the specified duration.

void	RegisterFrictionFunctor (FrictionFunctor *functor)
	Specify the functor object to provide the coefficient of friction at given (x,y) locations.

Additional Inherited Members
Protected Attributes inherited from chrono::vehicle::ChTerrain
FrictionFunctor *	m_friction_fun
	functor for location-dependent coefficient of friction

Constructor & Destructor Documentation

◆ SCMDeformableTerrain()

chrono::vehicle::SCMDeformableTerrain::SCMDeformableTerrain ( ChSystem * system )

Construct a default SCMDeformableSoil.

The user is responsible for calling various Set methods before Initialize.

Parameters

[in] system pointer to the containing multibody system

Member Function Documentation

◆ EnableMovingPatch()

void chrono::vehicle::SCMDeformableTerrain::EnableMovingPatch	(	std::shared_ptr< ChBody >	body,
		const ChVector<> &	point_on_body,
		double	dimX,
		double	dimY
	)

Enable moving patch an set parameters (default: disabled).

If enabled, ray-casting is performed only for the SCM vertices that are within the specified range (dimX, dimY) of the given point on the specified reference body.

Parameters

[in]	body	monitored body
[in]	point_on_body	patch center, relative to body
[in]	dimX	patch X dimension
[in]	dimY	patch Y dimension

◆ GetCoefficientFriction()

float chrono::vehicle::SCMDeformableTerrain::GetCoefficientFriction	(	double	x,
		double	y
	)		const

overridevirtual

Get the coefficient of friction at the specified (x,y) location.

This coefficient of friction value may be used by certain tire models to modify the tire characteristics, but it will have no effect on the interaction of the terrain with other objects (including tire models that do not explicitly use it). For SCMDeformableTerrain, this function defers to the user-provided functor object of type ChTerrain::FrictionFunctor, if one was specified. Otherwise, it returns the constant value of 0.8.

Implements chrono::vehicle::ChTerrain.

◆ Initialize() [1/3]

void chrono::vehicle::SCMDeformableTerrain::Initialize	(	const std::string &	heightmap_file,
		const std::string &	mesh_name,
		double	sizeX,
		double	sizeY,
		double	hMin,
		double	hMax
	)

Initialize the terrain system (height map).

The initial undeformed mesh is provided via the specified BMP file as a height map

Parameters

[in]	heightmap_file	filename for the height map (BMP)
[in]	mesh_name	name of the mesh asset
[in]	sizeX	terrain dimension in the X direction
[in]	sizeY	terrain dimension in the Y direction
[in]	hMin	minimum height (black level)
[in]	hMax	maximum height (white level)

◆ Initialize() [2/3]

void chrono::vehicle::SCMDeformableTerrain::Initialize ( const std::string & mesh_file )

Initialize the terrain system (mesh).

The initial undeformed mesh is provided via a Wavefront .obj file.

Parameters

[in] mesh_file filename of the input mesh (.OBJ file in Wavefront format)

◆ Initialize() [3/3]

void chrono::vehicle::SCMDeformableTerrain::Initialize	(	double	height,
		double	sizeX,
		double	sizeY,
		int	divX,
		int	divY
	)

Initialize the terrain system (flat).

This version creates a flat array of points.

Parameters

[in]	height	terrain height
[in]	sizeX	terrain dimension in the X direction
[in]	sizeY	terrain dimension in the Y direction
[in]	divX	number of divisions in the X direction
[in]	divY	number of divisions in the Y direction

◆ RegisterSoilParametersCallback()

void chrono::vehicle::SCMDeformableTerrain::RegisterSoilParametersCallback ( SoilParametersCallback * cb )

Specify the callback object to set the soil parameters at given (x,y) locations.

To use constant soil parameters throughout the entire patch, use SetSoilParameters.

◆ SetAutomaticRefinement()

void chrono::vehicle::SCMDeformableTerrain::SetAutomaticRefinement ( bool mr )

Enable/disable dynamic mesh refinement.

If enabled, additional points are added under contact patches, up to the desired resolution.

◆ SetAutomaticRefinementResolution()

void chrono::vehicle::SCMDeformableTerrain::SetAutomaticRefinementResolution ( double mr )

Set the resolution for automatic mesh refinement (specified in meters).

The mesh is refined, as needed, until the largest side of a triangle reaches trhe specified resolution. Triangles out of contact patches are not refined.

◆ SetBulldozingParameters()

void chrono::vehicle::SCMDeformableTerrain::SetBulldozingParameters	(	double	mbulldozing_erosion_angle,
		double	mbulldozing_flow_factor = `1.0`,
		int	mbulldozing_erosion_n_iterations = `3`,
		int	mbulldozing_erosion_n_propagations = `10`
	)

Set parameters controlling the creation of side ruts (bulldozing effects).

Parameters

mbulldozing_erosion_angle	angle of erosion of the displaced material (in degrees!)
mbulldozing_flow_factor	growth of lateral volume respect to pressed volume
mbulldozing_erosion_n_iterations	number of erosion refinements per timestep
mbulldozing_erosion_n_propagations	number of concentric vertex selections subject to erosion

◆ SetColor()

void chrono::vehicle::SCMDeformableTerrain::SetColor ( ChColor color )

Set visualization color.

Parameters

[in] color color of the visualization material

◆ SetPlane()

void chrono::vehicle::SCMDeformableTerrain::SetPlane ( ChCoordsys<> mplane )

Set the plane reference.

By default, the reference plane is horizontal with Z up (ISO vehicle reference frame). To set as Y up, call SetPlane(ChCoordys(VNULL, Q_from_AngX(-CH_C_PI_2)));

◆ SetPlotType()

void chrono::vehicle::SCMDeformableTerrain::SetPlotType	(	DataPlotType	mplot,
		double	mmin,
		double	mmax
	)

Set the color plot type for the soil mesh.

When a scalar plot is used, also define the range in the pseudo-color colormap.

◆ SetSoilParameters()

void chrono::vehicle::SCMDeformableTerrain::SetSoilParameters	(	double	Bekker_Kphi,
		double	Bekker_Kc,
		double	Bekker_n,
		double	Mohr_cohesion,
		double	Mohr_friction,
		double	Janosi_shear,
		double	elastic_K,
		double	damping_R
	)

Set the properties of the SCM soil model.

These parameters are described in: "Parameter Identification of a Planetary Rover Wheel-Soil Contact Model via a Bayesian Approach", A.Gallina, R. Krenn et al. Note that the original SCM model does not include the K and R coefficients. A very large value of K and R=0 reproduce the original SCM.

Parameters

Bekker_Kphi	Kphi, frictional modulus in Bekker model
Bekker_Kc	Kc, cohesive modulus in Bekker model
Bekker_n	n, exponent of sinkage in Bekker model (usually 0.6...1.8)
Mohr_cohesion	Cohesion in, Pa, for shear failure
Mohr_friction	Friction angle (in degrees!), for shear failure
Janosi_shear	J , shear parameter, in meters, in Janosi-Hanamoto formula (usually few mm or cm)
elastic_K	elastic stiffness K, per unit area, [Pa/m] (must be larger than Kphi)
damping_R	vertical damping R, per unit area [Pa s/m] (proportional to vertical speed)

◆ SetTestHighOffset()

void chrono::vehicle::SCMDeformableTerrain::SetTestHighOffset ( double moff )

Set the vertical level up to which collision is tested (relative to the reference level at the sample point).

Since the contact is unilateral, this could be zero. However, when computing bulldozing flow, one might also need to know if in the surrounding there is some potential future contact: so it might be better to use a positive value (but not higher than the max. expected height of the bulldozed rubble, to avoid slowdown of collision tests).

◆ SetTexture()

void chrono::vehicle::SCMDeformableTerrain::SetTexture	(	const std::string	tex_file,
		float	tex_scale_x = `1`,
		float	tex_scale_y = `1`
	)

Set texture properties.

Parameters

[in]	tex_file	texture filename
[in]	tex_scale_x	texture scale in X
[in]	tex_scale_y	texture scale in Y

The documentation for this class was generated from the following files:

/builds/uwsbel/chrono/src/chrono_vehicle/terrain/SCMDeformableTerrain.h
/builds/uwsbel/chrono/src/chrono_vehicle/terrain/SCMDeformableTerrain.cpp

Description

Classes

Public Types

Public Member Functions

Additional Inherited Members

Constructor & Destructor Documentation

◆ SCMDeformableTerrain()

Member Function Documentation

◆ EnableMovingPatch()

◆ GetCoefficientFriction()

◆ Initialize() [1/3]

◆ Initialize() [2/3]

◆ Initialize() [3/3]

◆ RegisterSoilParametersCallback()

◆ SetAutomaticRefinement()

◆ SetAutomaticRefinementResolution()

◆ SetBulldozingParameters()

◆ SetColor()

◆ SetPlane()

◆ SetPlotType()

◆ SetSoilParameters()

◆ SetTestHighOffset()

◆ SetTexture()