Description

Rigid terrain model.

This class implements a terrain modeled as a rigid shape which can interact through contact and friction with any other bodies whose contact flag is enabled. In particular, this type of terrain can be used in conjunction with a ChRigidTire.

#include <RigidTerrain.h>

Inheritance diagram for chrono::vehicle::RigidTerrain:

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Collaboration diagram for chrono::vehicle::RigidTerrain:

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Classes
class	Patch
	Definition of a patch in a rigid terrain model. More...

Public Types
enum	PatchType { PatchType::BOX, PatchType::MESH, PatchType::HEIGHT_MAP }
	Patch type. More...

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

	RigidTerrain (ChSystem *system, const std::string &filename)
	Construct a RigidTerrain from a JSON specification file. More...

std::shared_ptr< Patch >	AddPatch (std::shared_ptr< ChContactMaterial > material, const ChCoordsys<> &position, double length, double width, double thickness=1, bool tiled=false, double max_tile_size=1, bool visualization=true)
	Add a terrain patch represented by a rigid box. More...

std::shared_ptr< Patch >	AddPatch (std::shared_ptr< ChContactMaterial > material, const ChCoordsys<> &position, const std::string &mesh_file, bool connected_mesh=true, double sweep_sphere_radius=0, bool visualization=true)
	Add a terrain patch represented by a triangular mesh. More...

std::shared_ptr< Patch >	AddPatch (std::shared_ptr< ChContactMaterial > material, const ChCoordsys<> &position, const std::string &heightmap_file, double length, double width, double hMin, double hMax, bool connected_mesh=true, double sweep_sphere_radius=0, bool visualization=true)
	Add a terrain patch represented by a heightmap image. More...

std::shared_ptr< Patch >	AddPatch (std::shared_ptr< ChContactMaterial > material, const ChCoordsys<> &position, const std::vector< ChVector3d > &point_cloud, double length, double width, int unrefined_resolution, int heightmap_resolution, int max_refinements=5, double refine_angle_limit=30, double smoothing_factor=0.25, double max_edge_length=1.0, double sweep_sphere_radius=0.001, bool visualization=true)
	Add a terrain patch drawn from a vector of vectors - refined using the LEPP method. More...

void	Initialize ()
	Initialize all defined terrain patches.

const std::vector< std::shared_ptr< Patch > > &	GetPatches () const
	Get the terrain patches currently added to the rigid terrain system.

void	BindPatch (std::shared_ptr< Patch > patch)
	Bind the visual and collision models of the specified patch. More...

void	RemovePatch (std::shared_ptr< Patch > patch)
	Remove the specified patch.

void	UseLocationDependentFriction (bool val)
	Enable use of location-dependent coefficient of friction in terrain-solid contacts. More...

virtual double	GetHeight (const ChVector3d &loc) const override
	Get the terrain height below the specified location. More...

virtual ChVector3d	GetNormal (const ChVector3d &loc) const override
	Get the terrain normal at the point below the specified location. More...

virtual float	GetCoefficientFriction (const ChVector3d &loc) const override
	Get the terrain coefficient of friction at the point below the specified location. More...

virtual void	GetProperties (const ChVector3d &loc, double &height, ChVector3d &normal, float &friction) const override
	Get all terrain characteristics at the point below the specified location. More...

void	ExportMeshPovray (const std::string &out_dir, bool smoothed=false)
	Export all patch meshes as macros in PovRay include files.

void	ExportMeshWavefront (const std::string &out_dir)
	Export all patch meshes as Wavefront files.

bool	FindPoint (const ChVector3d loc, double &height, ChVector3d &normal, float &friction) const
	Find the terrain height, normal, and coefficient of friction at the point below the specified location. More...

void	SetCollisionFamily (int family)
	Set common collision family for patches. More...

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	RegisterHeightFunctor (std::shared_ptr< HeightFunctor > functor)
	Specify the functor object to provide the terrain height at given locations. More...

void	RegisterNormalFunctor (std::shared_ptr< NormalFunctor > functor)
	Specify the functor object to provide the terrain normal at given locations. More...

void	RegisterFrictionFunctor (std::shared_ptr< FrictionFunctor > functor)
	Specify the functor object to provide the coefficient of friction at given locations.

Additional Inherited Members
Protected Attributes inherited from chrono::vehicle::ChTerrain
std::shared_ptr< HeightFunctor >	m_height_fun
	functor for location-dependent terrain height

std::shared_ptr< NormalFunctor >	m_normal_fun
	functor for location-dependent terrain normal

std::shared_ptr< FrictionFunctor >	m_friction_fun
	functor for location-dependent coefficient of friction

Member Enumeration Documentation

◆ PatchType

enum chrono::vehicle::RigidTerrain::PatchType

strong

Patch type.

Enumerator
BOX	rectangular box
MESH	triangular mesh (from a Wavefront OBJ file)
HEIGHT_MAP	triangular mesh (generated from a gray-scale heightmap image)

Constructor & Destructor Documentation

◆ RigidTerrain() [1/2]

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

Construct a default RigidTerrain.

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

Parameters

[in] system pointer to the containing multibody system

◆ RigidTerrain() [2/2]

chrono::vehicle::RigidTerrain::RigidTerrain	(	ChSystem *	system,
		const std::string &	filename
	)

Construct a RigidTerrain from a JSON specification file.

Parameters

[in]	system	pointer to the containing multibody system
[in]	filename	name of the JSON specification file

Member Function Documentation

◆ AddPatch() [1/4]

std::shared_ptr< RigidTerrain::Patch > chrono::vehicle::RigidTerrain::AddPatch	(	std::shared_ptr< ChContactMaterial >	material,
		const ChCoordsys<> &	position,
		const std::string &	heightmap_file,
		double	length,
		double	width,
		double	hMin,
		double	hMax,
		bool	connected_mesh = `true`,
		double	sweep_sphere_radius = `0`,
		bool	visualization = `true`
	)

Add a terrain patch represented by a heightmap image.

If the image has an explicit gray channel, that value is used as an encoding of height. Otherwise, RGB values are converted to YUV and luminance (Y) is used as height encoding.

Parameters

[in]	material	contact material
[in]	position	patch location and orientation
[in]	heightmap_file	filename for the height map (BMP)
[in]	length	patch length
[in]	width	patch width
[in]	hMin	minimum height (black level)
[in]	hMax	maximum height (white level)
[in]	connected_mesh	use connected contact mesh?
[in]	sweep_sphere_radius	radius of sweep sphere
[in]	visualization	enable/disable construction of visualization assets

◆ AddPatch() [2/4]

std::shared_ptr< RigidTerrain::Patch > chrono::vehicle::RigidTerrain::AddPatch	(	std::shared_ptr< ChContactMaterial >	material,
		const ChCoordsys<> &	position,
		const std::string &	mesh_file,
		bool	connected_mesh = `true`,
		double	sweep_sphere_radius = `0`,
		bool	visualization = `true`
	)

Add a terrain patch represented by a triangular mesh.

The mesh is specified through a Wavefront file and is used for both contact and visualization.

Parameters

[in]	material	contact material
[in]	position	patch location and orientation
[in]	mesh_file	filename of the input mesh (OBJ)
[in]	connected_mesh	use connected contact mesh?
[in]	sweep_sphere_radius	radius of sweep sphere
[in]	visualization	enable/disable construction of visualization assets

◆ AddPatch() [3/4]

std::shared_ptr< RigidTerrain::Patch > chrono::vehicle::RigidTerrain::AddPatch	(	std::shared_ptr< ChContactMaterial >	material,
		const ChCoordsys<> &	position,
		const std::vector< ChVector3d > &	point_cloud,
		double	length,
		double	width,
		int	unrefined_resolution,
		int	heightmap_resolution,
		int	max_refinements = `5`,
		double	refine_angle_limit = `30`,
		double	smoothing_factor = `0.25`,
		double	max_edge_length = `1.0`,
		double	sweep_sphere_radius = `0.001`,
		bool	visualization = `true`
	)

Add a terrain patch drawn from a vector of vectors - refined using the LEPP method.

For each Chvector, x and y represent grid elements and the z value is the height. Usually, 10% to 25% of the heightmap resolution for unrefined_resolution produces good results.

Parameters

[in]	material	contact material
[in]	position	patch location and orientation
[in]	point_cloud	point cloud of height vectors
[in]	length	patch length (m)
[in]	width	patch width (m)
[in]	unrefined_resolution	the starting resolution of the alternating triangle mesh
[in]	heightmap_resolution	resolution of the heightmap to filter the point cloud
[in]	max_refinements	maximum triangle edge length for use in edge refinement
[in]	refine_angle_limit	Normal threshold angle for refinement stop (degrees)
[in]	smoothing_factor	Taubin smoothing degree [0,1]
[in]	max_edge_length	Maximum edge length in Refine Mesh Edges LEPP method
[in]	sweep_sphere_radius	radius of sweep sphere
[in]	visualization	enable/disable construction of visualisation assets

◆ AddPatch() [4/4]

std::shared_ptr< RigidTerrain::Patch > chrono::vehicle::RigidTerrain::AddPatch	(	std::shared_ptr< ChContactMaterial >	material,
		const ChCoordsys<> &	position,
		double	length,
		double	width,
		double	thickness = `1`,
		bool	tiled = `false`,
		double	max_tile_size = `1`,
		bool	visualization = `true`
	)

Add a terrain patch represented by a rigid box.

The patch is constructed such that the center of its top surface (the "driving" surface) is in the x-y plane of the specified coordinate system. If tiled = true, multiple side-by-side boxes are used.

Parameters

[in]	material	contact material
[in]	position	patch location and orientation
[in]	length	patch length
[in]	width	patch width
[in]	thickness	box thickness
[in]	tiled	terrain created from multiple tiled boxes
[in]	max_tile_size	maximum tile size
[in]	visualization	enable/disable construction of visualization assets

◆ BindPatch()

void chrono::vehicle::RigidTerrain::BindPatch ( std::shared_ptr< Patch > patch )

Bind the visual and collision models of the specified patch.

This function should be called for any patches created dynamically during simulation, after the RigidTerrain was initialized.

◆ FindPoint()

bool chrono::vehicle::RigidTerrain::FindPoint	(	const ChVector3d	loc,
		double &	height,
		ChVector3d &	normal,
		float &	friction
	)		const

Find the terrain height, normal, and coefficient of friction at the point below the specified location.

The point on the terrain surface is obtained through ray casting into the terrain contact model. The return value is 'true' if the ray intersection succeeded and 'false' otherwise (in which case the output is set to heigh=0, normal=world vertical, and friction=0.8).

◆ GetCoefficientFriction()

float chrono::vehicle::RigidTerrain::GetCoefficientFriction ( const ChVector3d & loc ) const

overridevirtual

Get the terrain coefficient of friction at the point below the specified location.

This function should return the coefficient of friction at the closest point below the specified location (in the direction of the current world vertical). For RigidTerrain, this function defers to the user-provided functor object of type ChTerrain::FrictionFunctor, if one was specified. Otherwise, it returns the constant value from the appropriate patch, as specified through SetContactFrictionCoefficient. Note that this function may be used by tire models to appropriately 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). See UseLocationDependentFriction.

Reimplemented from chrono::vehicle::ChTerrain.

◆ GetHeight()

double chrono::vehicle::RigidTerrain::GetHeight ( const ChVector3d & loc ) const

overridevirtual

Get the terrain height below the specified location.

This function should return the height of the closest point below the specified location (in the direction of the current world vertical). If a user-provided functor object of type ChTerrain::HeightFunctor is provided, that will take precedence over the internal mechanism for calculating terrain height based on the specified geometry.

Reimplemented from chrono::vehicle::ChTerrain.

◆ GetNormal()

ChVector3d chrono::vehicle::RigidTerrain::GetNormal ( const ChVector3d & loc ) const

overridevirtual

Get the terrain normal at the point below the specified location.

This function should return the normal at the closest point below the specified location (in the direction of the current world vertical). If a user-provided functor object of type ChTerrain::NormalFunctor is provided, that will take precedence over the internal mechanism for calculating terrain normal based on the specified geometry.

Reimplemented from chrono::vehicle::ChTerrain.

◆ GetProperties()

void chrono::vehicle::RigidTerrain::GetProperties	(	const ChVector3d &	loc,
		double &	height,
		ChVector3d &	normal,
		float &	friction
	)		const

overridevirtual

Get all terrain characteristics at the point below the specified location.

This function should return the terrain properties at the closest point below the specified location (in the direction of the current world vertical). This is more efficient than calling GetHeight, GetNormal, and GetCoefficientFriction separately, as it performs a single ray-casting operation (if needed at all).

Reimplemented from chrono::vehicle::ChTerrain.

◆ SetCollisionFamily()

void chrono::vehicle::RigidTerrain::SetCollisionFamily ( int family )

inline

Set common collision family for patches.

Default: 14. Collision is disabled with all other objects in this family.

◆ UseLocationDependentFriction()

void chrono::vehicle::RigidTerrain::UseLocationDependentFriction ( bool val )

inline

Enable use of location-dependent coefficient of friction in terrain-solid contacts.

This assumes that a non-trivial functor (of type ChTerrain::FrictionFunctor) was defined and registered with the terrain subsystem. Enable this only if simulating a system that has contacts with the terrain that must be resolved using the underlying Chrono contact mechanism (e.g., for rigid tires, FEA tires, tracked vehicles). Note that this feature requires a relatively expensive traversal of all contacts at each simulation step. By default, this option is disabled. This function must be called before Initialize.

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

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

Description

Classes

Public Types

Public Member Functions

Additional Inherited Members

Member Enumeration Documentation

◆ PatchType

Constructor & Destructor Documentation

◆ RigidTerrain() [1/2]

◆ RigidTerrain() [2/2]

Member Function Documentation

◆ AddPatch() [1/4]

◆ AddPatch() [2/4]

◆ AddPatch() [3/4]

◆ AddPatch() [4/4]

◆ BindPatch()

◆ FindPoint()

◆ GetCoefficientFriction()

◆ GetHeight()

◆ GetNormal()

◆ GetProperties()

◆ SetCollisionFamily()

◆ UseLocationDependentFriction()