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...

struct	TerrainPatchSize
	Terrain patch dimensions. More...

class	WheelBCECreationCallback
	Callback interface for user-defined wheel/tire BCE markers (CRM terrain only). More...

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

enum	TerrainType { SCM, RIGID, CRG, GRANULAR, CRM, NONE }
	Terrain type.

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).

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 TerrainPatchSize &size, const TerrainParamsRigid &params)
	Enable use of rigid terrain.

void	SetTerrainRigid (const TerrainPatchSize &size, double friction, double restitution, double Young_modulus)
	Enable use of rigid terrain. More...

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

void	SetTerrainSCM (const TerrainPatchSize &size, double Bekker_Kphi, double Bekker_Kc, double Bekker_n, double Mohr_cohesion, double Mohr_friction, double Janosi_shear, double grid_spacing=0.125)
	Enable use of SCM terrain. More...

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

void	SetTerrainGranular (const TerrainPatchSize &size, double radius, double density, double friction, double cohesion, double Young_modulus)
	Enable use of granular terrain. More...

void	SetTerrainCRM (const TerrainPatchSize &size, const TerrainParamsCRM &params)
	Enable use of CRM terrain. More...

void	SetTerrainCRM (const TerrainPatchSize &size, double spacing, double density, double Young_modulus, double friction, double cohesion)
	Enable use of CRM terrain. More...

void	RegisterWheelBCECreationCallback (std::shared_ptr< WheelBCECreationCallback > callback)
	Register a user callback for specifying wheel/tire BCE markers (CRM terrain only).

void	SetWheelActiveBox (const ChVector3d &size)
	Set size of the active box associated with the tire (CRM terrain only). More...

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

double	GetTimeDelay () const
	Get time delay after which mesurements are calculated. More...

bool	OutputEnabled () const
	Check if kinematic and kinetic quantities are collected. More...

void	Initialize (Mode mode, double drop_speed=0.1)
	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	GetNormalLoad () const
	Get the normal load.

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...

double	GetLongitudinalSlip () const
	Get current tire longitudinal slip. More...

double	GetSlipAngle () const
	Get current tire slip angle. More...

double	GetCamberAngle () const
	Get current tire camber angle. More...

std::shared_ptr< ChSpindle >	GetSpindle () const
	Get the spindle object.

std::shared_ptr< ChLinkMotorLinearSpeed >	GetMotorCarrier () const
	Get the linear motor used to actuate the carrier.

std::shared_ptr< ChLinkMotorRotationSpeed >	GetMotorWheel () const
	Get the rotation motor used to actuate the wheel.

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

◆ GetCamberAngle()

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

Get current tire camber angle.

This value is calculated from the current spindle normal direction.

◆ 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.

◆ GetLongitudinalSlip()

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

Get current tire longitudinal slip.

This value is calculated from the horizontal speed of the spindle body and its angular rotation speed.

◆ GetSlipAngle()

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

Get current tire slip angle.

This value is calculated from the current spindle normal direction.

◆ 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

◆ GetTimeDelay()

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

inline

Get time delay after which mesurements are calculated.

After the drop phase (TEST mode only), this value is set to the input time delay increased by the wheel drop time. Before the drop phase is completed, this function returns the input time delay.

◆ Initialize()

void chrono::vehicle::ChTireTestRig::Initialize	(	Mode	mode,
		double	drop_speed = `0.1`
	)

Initialize the rig system.

It is the user's responsibility to set the operation mode and motion functions in a consistent way. In TEST mode, the wheel is lowered onto the terrain with a speed equal to drop_speed.

◆ OutputEnabled()

bool chrono::vehicle::ChTireTestRig::OutputEnabled ( ) const

inline

Check if kinematic and kinetic quantities are collected.

This function returns true only in TEST mode once the motion functions are activated.

◆ 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.

◆ SetTerrainCRM() [1/2]

void chrono::vehicle::ChTireTestRig::SetTerrainCRM	(	const TerrainPatchSize &	size,
		const TerrainParamsCRM &	params
	)

Enable use of CRM terrain.

The terrain subsystem is modelled through continuum with CRM.

◆ SetTerrainCRM() [2/2]

void chrono::vehicle::ChTireTestRig::SetTerrainCRM	(	const TerrainPatchSize &	size,
		double	spacing,
		double	density,
		double	Young_modulus,
		double	friction,
		double	cohesion
	)

Enable use of CRM terrain.

Parameters

size	terrain patch size
spacing	SPH particle spacing
density	material density
Young_modulus	material Young's modulus
friction	material internal friction
cohesion	material internal cohesion

◆ SetTerrainGranular() [1/2]

void chrono::vehicle::ChTireTestRig::SetTerrainGranular	(	const TerrainPatchSize &	size,
		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.

◆ SetTerrainGranular() [2/2]

void chrono::vehicle::ChTireTestRig::SetTerrainGranular	(	const TerrainPatchSize &	size,
		double	radius,
		double	density,
		double	friction,
		double	cohesion,
		double	Young_modulus
	)

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.

Parameters

size	terrain patch size
radius	particle radius [m]
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]

◆ SetTerrainRigid()

void chrono::vehicle::ChTireTestRig::SetTerrainRigid	(	const TerrainPatchSize &	size,
		double	friction,
		double	restitution,
		double	Young_modulus
	)

Enable use of rigid terrain.

Specify contact material properties and patch dimensions.

Parameters

size	terrain patch size
friction	coefficient of friction
restitution	coefficient of restitution
Young_modulus	contact material Young's modulus [Pa]

◆ SetTerrainSCM()

void chrono::vehicle::ChTireTestRig::SetTerrainSCM	(	const TerrainPatchSize &	size,
		double	Bekker_Kphi,
		double	Bekker_Kc,
		double	Bekker_n,
		double	Mohr_cohesion,
		double	Mohr_friction,
		double	Janosi_shear,
		double	grid_spacing = `0.125`
	)

Enable use of SCM terrain.

Specify SCM soil parameters and patch dimensions.

Parameters

size	terrain patch size
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

◆ SetTimeDelay()

void chrono::vehicle::ChTireTestRig::SetTimeDelay ( double delay )

inline

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

In TEST mode, this delay is measured after the wheel bottom point reaches the terrain height.

◆ SetWheelActiveBox()

void chrono::vehicle::ChTireTestRig::SetWheelActiveBox ( const ChVector3d & size )

Set size of the active box associated with the tire (CRM terrain only).

The default size is based on the tire AABB inflated by 25%.

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

◆ GetCamberAngle()

◆ GetDBP()

◆ GetLongitudinalSlip()

◆ GetSlipAngle()

◆ GetSuggestedCollisionSettings()

◆ GetTimeDelay()

◆ Initialize()

◆ OutputEnabled()

◆ SetAngSpeedFunction()

◆ SetConstantLongitudinalSlip()

◆ SetLongSpeedFunction()

◆ SetTerrainCRM() [1/2]

◆ SetTerrainCRM() [2/2]

◆ SetTerrainGranular() [1/2]

◆ SetTerrainGranular() [2/2]

◆ SetTerrainRigid()

◆ SetTerrainSCM()

◆ SetTimeDelay()

◆ SetWheelActiveBox()