Description

Definition of a single-tire test rig.

#include <ChTireTestRig.h>

Public Member Functions
	ChTireTestRig (std::shared_ptr< ChWheel > wheel, std::shared_ptr< ChTire > tire, ChSystem *system)

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

void	SetNormalLoad (double load)
	Set desired normal load (default: 0 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	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	SetTerrainSCM (double Bekker_Kphi, double Bekker_Kc, double Bekker_n, double Mohr_cohesion, double Mohr_friction, double Janosi_shear, double terrain_length=10)
	Enable use of SCM terrain. Specify SCM soil parameters. More...

void	SetTerrainRigid (double friction, double restitution, double Young_modulus, double terrain_length=10)
	Enable use of rigid terrain. Specify contact material properties. More...

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

void	SetTimeDelay (double delay)
	Set time delay before releasing the wheel (default: 0s).

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

void	Initialize (double long_slip, double base_speed=1)
	Initialize the rig system for a simulation with given longitudinal slip. More...

void	GetSuggestedCollisionSettings (double &collision_envelope, ChVector< int > &collision_bins) const
	Get suggested collision settings. More...

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

double	GetTotalMass () const
	Get total rig mass.

double	GetAppliedLoad () const
	Get applied load on rig (to enforce specified normal load, taking into account the masses of all components).

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

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

TerrainForce	ReportTireForce () const
	Get the current tire forces.

Constructor & Destructor Documentation

◆ ChTireTestRig()

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

Parameters

wheel	wheel subsystem
tire	tire subsystem
system	containing mechanical system

Member Function Documentation

◆ GetSuggestedCollisionSettings()

void chrono::vehicle::ChTireTestRig::GetSuggestedCollisionSettings	(	double &	collision_envelope,
		ChVector< int > &	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() [1/2]

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

Initialize the rig system.

This version uses all motion functions as specified by the user. It is the user's responsibility to set these up for a meaningful test.

◆ Initialize() [2/2]

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

Initialize the rig system for a simulation with given longitudinal slip.

This version overrides the motion functions for the carrier longitudinal slip and for the wheel angular speed to enfore the specified longitudinal slip 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.

◆ 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.

◆ 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()

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

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 dimensions 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]

◆ SetTerrainRigid()

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

Enable use of rigid terrain. Specify contact material properties.

Parameters

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

◆ 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	terrain_length = `10`
	)

Enable use of SCM terrain. Specify SCM soil parameters.

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)
terrain_length	length 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

Public Member Functions

Constructor & Destructor Documentation

◆ ChTireTestRig()

Member Function Documentation

◆ GetSuggestedCollisionSettings()

◆ Initialize() [1/2]

◆ Initialize() [2/2]

◆ SetAngSpeedFunction()

◆ SetLongSpeedFunction()

◆ SetTerrainGranular()

◆ SetTerrainRigid()

◆ SetTerrainSCM()