Description

Definition of a single-tire test rig.

#include <ChTireTestRig.h>

Classes
struct	TerrainParamsGranular
	Granular terrain patch parameters. More...

struct	TerrainParamsRigid
	Rigid terrain patch parameters. More...

struct	TerrainParamsSCM
	SCM terrain patch parameters. More...

Public Types
enum	Mode { Mode::SUSPEND, Mode::DROP, Mode::TEST }
	Tire test rig operation mode. More...

Public Member Functions
	ChTireTestRig (std::shared_ptr< ChWheel > wheel, std::shared_ptr< ChTire > tire, ChSystem *system)
	Construct a tire test rig within the specified system. More...

void	SetGravitationalAcceleration (double grav)
	Set gravitational acceleration (default: 9.81 m/s2).

void	SetNormalLoad (double load)
	Set desired normal load (default: 1000 N).

double	GetNormalLoad (double load) const
	Get the normal load.

void	SetCamberAngle (double camber)
	Set camber angle (default: 0 rad).

void	SetLongSpeedFunction (std::shared_ptr< ChFunction > funct)
	Specify rig carrier longitudinal speed as function of time (default: none). More...

void	SetAngSpeedFunction (std::shared_ptr< ChFunction > funct)
	Specify wheel angular speed as function of time (default: none). More...

void	SetSlipAngleFunction (std::shared_ptr< ChFunction > funct)
	Specify wheel slip angle as function of time (default: constant value 0 rad).

void	SetConstantLongitudinalSlip (double long_slip, double base_speed=1)
	Specify a constant given longitudinal slip. More...

void	SetTireCollisionType (ChTire::CollisionType coll_type)
	Set collision type for tire-terrain interaction (default: SINGLE_POINT).

void	SetTireStepsize (double step)
	Set the time step for advancing tire dynamics (default: 1e-3 s).

void	SetTireVisualizationType (VisualizationType vis)
	Set visualization type for the tire (default: PRIMITIVES).

void	SetTerrainRigid (const TerrainParamsRigid &params)
	Enable use of rigid terrain.

void	SetTerrainRigid (double friction, double restitution, double Young_modulus, double terrain_length=10, double terrain_width=1)
	Enable use of rigid terrain. More...

void	SetTerrainSCM (const TerrainParamsSCM &params)
	Enable use of SCM terrain.

void	SetTerrainSCM (double Bekker_Kphi, double Bekker_Kc, double Bekker_n, double Mohr_cohesion, double Mohr_friction, double Janosi_shear, double grid_spacing=0.125, double terrain_length=10, double terrain_width=1)
	Enable use of SCM terrain. More...

void	SetTerrainGranular (const TerrainParamsGranular &params)
	Enable use of granular terrain. More...

void	SetTerrainGranular (double radius, unsigned int num_layers, double density, double friction, double cohesion, double Young_modulus, double terrain_width=1)
	Enable use of granular terrain. More...

void	SetTerrainCRM (const TerrainParamsCRM &params)
	Enable use of CRM terrain.

void	SetTerrainCRM (double radius, double density, double cohesion, double terrain_length=10, double terrain_width=1, double terrain_depth=0.2)

void	SetTimeDelay (double delay)
	Set time delay before applying motion functions (default: 0 s).

void	Initialize (Mode mode)
	Initialize the rig system. More...

void	GetSuggestedCollisionSettings (double &collision_envelope, ChVector3i &collision_bins) const
	Get suggested collision settings. More...

void	Advance (double step)
	Advance system state by the specified time step.

double	GetMass () const
	Get total rig mass.

std::shared_ptr< ChTerrain >	GetTerrain () const
	Get a handle to the underlying terrain subsystem.

const ChVector3d &	GetPos () const
	Get current carrier body position.

TerrainForce	ReportTireForce () const
	Get the current tire forces.

double	GetDBP () const
	Return current drawbar-pull value. More...

Member Enumeration Documentation

◆ Mode

enum chrono::vehicle::ChTireTestRig::Mode

strong

Tire test rig operation mode.

Enumerator
SUSPEND	suspended tire (locked spindle)
DROP	tire drop test
TEST	normal tire test

Constructor & Destructor Documentation

◆ ChTireTestRig()

chrono::vehicle::ChTireTestRig::ChTireTestRig	(	std::shared_ptr< ChWheel >	wheel,
		std::shared_ptr< ChTire >	tire,
		ChSystem *	system
	)

Construct a tire test rig within the specified system.

Parameters

wheel	wheel subsystem
tire	tire subsystem
system	containing mechanical system

Member Function Documentation

◆ GetDBP()

double chrono::vehicle::ChTireTestRig::GetDBP ( ) const

Return current drawbar-pull value.

This is the reaction force in the linear motor used to enforce the specified rig longitudinal speed.

◆ GetSuggestedCollisionSettings()

void chrono::vehicle::ChTireTestRig::GetSuggestedCollisionSettings	(	double &	collision_envelope,
		ChVector3i &	collision_bins
	)		const

Get suggested collision settings.

These values are meaningful only when using granular terrain and Chrono::Multicore.

Parameters

collision_envelope	suggested envelope based on particle radius
collision_bins	suggested number of bins for broad-pahse collision detection

◆ Initialize()

void chrono::vehicle::ChTireTestRig::Initialize ( Mode mode )

Initialize the rig system.

It is the user's responsibility to set the operation mode and motion functions in a consistent way.

◆ SetAngSpeedFunction()

void chrono::vehicle::ChTireTestRig::SetAngSpeedFunction ( std::shared_ptr< ChFunction > funct )

Specify wheel angular speed as function of time (default: none).

If a function is not specified, the wheel is not actuated.

◆ SetConstantLongitudinalSlip()

void chrono::vehicle::ChTireTestRig::SetConstantLongitudinalSlip	(	double	long_slip,
		double	base_speed = `1`
	)

Specify a constant given longitudinal slip.

This version overrides the motion functions for the carrier longitudinal slip and for the wheel angular speed to enforce the specified longitudinalslip value. A positive slip value indicates that the wheel is spinning. A negative slip value indicates that the wheel is sliding (skidding); in particular, s=-1 indicates sliding without rotation.

◆ SetLongSpeedFunction()

void chrono::vehicle::ChTireTestRig::SetLongSpeedFunction ( std::shared_ptr< ChFunction > funct )

Specify rig carrier longitudinal speed as function of time (default: none).

If a function is not specified, the carrier is not actuated.

◆ SetTerrainGranular() [1/2]

void chrono::vehicle::ChTireTestRig::SetTerrainGranular ( const TerrainParamsGranular & params )

Enable use of granular terrain.

The terrain subsystem consists of identical spherical particles initialized in layers. A moving-patch option is used, with the patch length set based on the tire dimensions.

◆ SetTerrainGranular() [2/2]

void chrono::vehicle::ChTireTestRig::SetTerrainGranular	(	double	radius,
		unsigned int	num_layers,
		double	density,
		double	friction,
		double	cohesion,
		double	Young_modulus,
		double	terrain_width = `1`
	)

Enable use of granular terrain.

Specify contact material properties. The terrain subsystem consists of identical spherical particles initialized in layers. A moving-patch option is used, with the patch length set based on the tire dimensions.

Parameters

radius	particle radius [m]
num_layers	number of layers for initial particle creation
density	particle material density [kg/m3]
friction	inter-particle coefficient of friction
cohesion	inter-particle cohesion pressure [Pa]
Young_modulus	particle contact material Young's modulus [Pa]
terrain_width	width of terrain patch

◆ SetTerrainRigid()

void chrono::vehicle::ChTireTestRig::SetTerrainRigid	(	double	friction,
		double	restitution,
		double	Young_modulus,
		double	terrain_length = `10`,
		double	terrain_width = `1`
	)

Enable use of rigid terrain.

Specify contact material properties and patch dimensions.

Parameters

friction	coefficient of friction
restitution	coefficient of restitution
Young_modulus	contact material Young's modulus [Pa]
terrain_length	length of terrain patch [m]
terrain_width	width of terrain patch

◆ SetTerrainSCM()

void chrono::vehicle::ChTireTestRig::SetTerrainSCM	(	double	Bekker_Kphi,
		double	Bekker_Kc,
		double	Bekker_n,
		double	Mohr_cohesion,
		double	Mohr_friction,
		double	Janosi_shear,
		double	grid_spacing = `0.125`,
		double	terrain_length = `10`,
		double	terrain_width = `1`
	)

Enable use of SCM terrain.

Specify SCM soil parameters and patch dimensions.

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 [Pa], for shear failure
Mohr_friction	Friction angle [degrees], for shear failure
Janosi_shear	shear parameter J [m], (usually a few mm or cm)
grid_spacing	SCM grid spacing
terrain_length	length of terrain patch
terrain_width	width of terrain patch

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

/builds/uwsbel/chrono/src/chrono_vehicle/wheeled_vehicle/test_rig/ChTireTestRig.h
/builds/uwsbel/chrono/src/chrono_vehicle/wheeled_vehicle/test_rig/ChTireTestRig.cpp

Description

Classes

Public Types

Public Member Functions

Member Enumeration Documentation

◆ Mode

Constructor & Destructor Documentation

◆ ChTireTestRig()

Member Function Documentation

◆ GetDBP()

◆ GetSuggestedCollisionSettings()

◆ Initialize()

◆ SetAngSpeedFunction()

◆ SetConstantLongitudinalSlip()

◆ SetLongSpeedFunction()

◆ SetTerrainGranular() [1/2]

◆ SetTerrainGranular() [2/2]

◆ SetTerrainRigid()

◆ SetTerrainSCM()