Description

Base class for a tire system.

A tire subsystem is a force element. It is passed position and velocity information of the wheel body and it produces ground reaction forces and moments to be applied to the wheel body.

#include <ChTire.h>

Inheritance diagram for chrono::vehicle::ChTire:

[legend]

Collaboration diagram for chrono::vehicle::ChTire:

[legend]

Public Types
enum	CollisionType { SINGLE_POINT, FOUR_POINTS, ENVELOPE }
	Collision detection type. More...

enum	ContactSurfaceType { NODE_CLOUD, TRIANGLE_MESH }
	Contact surface type. More...

Public Member Functions
void	SetStepsize (double val)
	Set the integration step size for the underlying dynamics (default: 1ms). More...

double	GetStepsize () const
	Get the current value of the integration step size.

void	SetCollisionType (CollisionType collision_type)
	Set the collision type for tire-terrain interaction (default: SINGLE_POINT). More...

void	SetContactSurfaceType (ContactSurfaceType type, double dim=0.01, int collision_family=13)
	Set the contact surface type (default: NODE_CLOUD). More...

void	SetPressure (double pressure)
	Set the internal tire pressure [Pa] (default: 0). More...

double	GetPressure () const
	Get the internal tire pressure [Pa].

virtual double	GetRadius () const =0
	Get the tire radius.

virtual double	GetWidth () const =0
	Get the tire width.

virtual double	GetTireMass () const =0
	Return the tire mass.

virtual ChVector3d	GetTireInertia () const =0
	Return the tire moments of inertia (in the tire centroidal frame).

virtual TerrainForce	ReportTireForce (ChTerrain *terrain) const =0
	Report the tire force and moment. More...

virtual TerrainForce	ReportTireForceLocal (ChTerrain *terrain, ChCoordsys<> &tire_frame) const =0
	Get the tire force and moment expressed in the tire frame. More...

double	GetSlipAngle () const
	Return the tire slip angle calculated based on the current state of the associated wheel body. More...

double	GetLongitudinalSlip () const
	Return the tire longitudinal slip calculated based on the current state of the associated wheel body. More...

double	GetCamberAngle () const
	Return the tire camber angle calculated based on the current state of the associated wheel body. More...

virtual double	GetDeflection () const
	Report the tire deflection.

const std::string &	GetMeshFilename () const
	Get the name of the Wavefront file with tire visualization mesh. More...

std::shared_ptr< ChWheel >	GetWheel () const
	Get the associated wheel. More...

virtual void	Initialize (std::shared_ptr< ChWheel > wheel)
	Initialize this tire subsystem by associating it to an existing wheel subsystem.

virtual void	Synchronize (double time, const ChTerrain &terrain)
	Update the state of this tire system at the current time. More...

virtual void	Advance (double step)
	Advance the state of this tire by the specified time step.

Public Member Functions inherited from chrono::vehicle::ChPart
const std::string &	GetName () const
	Get the name identifier for this subsystem.

void	SetName (const std::string &name)
	Set the name identifier for this subsystem.

virtual std::string	GetTemplateName () const =0
	Get the name of the vehicle subsystem template.

bool	IsInitialized () const
	Return flag indicating whether or not the part is fully constructed.

double	GetMass () const
	Get the subsystem mass. More...

const ChFrame &	GetCOMFrame () const
	Get the current subsystem COM frame (relative to and expressed in the subsystem's reference frame). More...

const ChMatrix33 &	GetInertia () const
	Get the current subsystem inertia (relative to the subsystem COM frame). More...

const ChFrame &	GetTransform () const
	Get the current subsystem position relative to the global frame. More...

void	SetVisualizationType (VisualizationType vis)
	Set the visualization mode for this subsystem.

virtual void	AddVisualizationAssets (VisualizationType vis)
	Add visualization assets to this subsystem, for the specified visualization mode.

virtual void	RemoveVisualizationAssets ()
	Remove all visualization assets from this subsystem.

virtual void	SetOutput (bool state)
	Enable/disable output for this subsystem.

bool	OutputEnabled () const
	Return the output state for this subsystem.

virtual void	ExportComponentList (rapidjson::Document &jsonDocument) const
	Export this subsystem's component list to the specified JSON object. More...

virtual void	Output (ChVehicleOutput &database) const
	Output data for this subsystem's component list to the specified database.

Static Public Member Functions
static ChVector3d	EstimateInertia (double tire_width, double aspect_ratio, double rim_diameter, double tire_mass, double t_factor=2)
	Utility function for estimating the tire moments of inertia. More...

Static Public Member Functions inherited from chrono::vehicle::ChPart
static ChMatrix33	TransformInertiaMatrix (const ChVector3d &moments, const ChVector3d &products, const ChMatrix33<> &vehicle_rot, const ChMatrix33<> &body_rot)
	Utility function for transforming inertia tensors between centroidal frames. More...

Protected Member Functions
	ChTire (const std::string &name)
	Construct a tire subsystem with given name.

void	CalculateKinematics (const WheelState &wheel_state, const ChCoordsys<> &tire_frame)
	Calculate kinematics quantities based on the given state of the associated wheel body. More...

double	GetOffset () const
	Get offset from spindle center. More...

virtual double	GetAddedMass () const =0
	Get the mass added to the associated spindle body. More...

virtual ChVector3d	GetAddedInertia () const =0
	Get the inertia added to the associated spindle body. More...

virtual TerrainForce	GetTireForce () const =0
	Get the tire force and moment. More...

std::shared_ptr< ChVisualShapeTriangleMesh >	AddVisualizationMesh (const std::string &mesh_file_left, const std::string &mesh_file_right)
	Add mesh visualization to the body associated with this tire (a wheel spindle body). More...

Protected Member Functions inherited from chrono::vehicle::ChPart
	ChPart (const std::string &name)
	Construct a vehicle subsystem with the specified name.

virtual void	InitializeInertiaProperties ()=0
	Initialize subsystem inertia properties. More...

virtual void	UpdateInertiaProperties ()=0
	Update subsystem inertia properties. More...

void	AddMass (double &mass)
	Add this subsystem's mass. More...

void	AddInertiaProperties (ChVector3d &com, ChMatrix33<> &inertia)
	Add this subsystem's inertia properties. More...

virtual void	Create (const rapidjson::Document &d)
	Create a vehicle subsystem from JSON data. More...

void	ExportBodyList (rapidjson::Document &jsonDocument, std::vector< std::shared_ptr< ChBody >> bodies) const
	Export the list of bodies to the specified JSON document.

void	ExportShaftList (rapidjson::Document &jsonDocument, std::vector< std::shared_ptr< ChShaft >> shafts) const
	Export the list of shafts to the specified JSON document.

void	ExportJointList (rapidjson::Document &jsonDocument, std::vector< std::shared_ptr< ChLink >> joints) const
	Export the list of joints to the specified JSON document.

void	ExportCouplesList (rapidjson::Document &jsonDocument, std::vector< std::shared_ptr< ChShaftsCouple >> couples) const
	Export the list of shaft couples to the specified JSON document.

void	ExportMarkerList (rapidjson::Document &jsonDocument, std::vector< std::shared_ptr< ChMarker >> markers) const
	Export the list of markers to the specified JSON document.

void	ExportLinSpringList (rapidjson::Document &jsonDocument, std::vector< std::shared_ptr< ChLinkTSDA >> springs) const
	Export the list of translational springs to the specified JSON document.

void	ExportRotSpringList (rapidjson::Document &jsonDocument, std::vector< std::shared_ptr< ChLinkRSDA >> springs) const
	Export the list of rotational springs to the specified JSON document.

void	ExportBodyLoadList (rapidjson::Document &jsonDocument, std::vector< std::shared_ptr< ChLoadBodyBody >> loads) const
	Export the list of body-body loads to the specified JSON document.

Static Protected Member Functions
static bool	DiscTerrainCollision (CollisionType method, const ChTerrain &terrain, const ChVector3d &disc_center, const ChVector3d &disc_normal, double disc_radius, double width, const ChFunctionInterp &areaDep, ChCoordsys<> &contact, double &depth, float &mu)
	Perform disc-terrain collision detection, using the specified method. More...

static void	ConstructAreaDepthTable (double disc_radius, ChFunctionInterp &areaDep)
	Utility function to construct a loopkup table for penetration depth as function of intersection area, for a given tire radius. More...

static bool	DiscTerrainCollision1pt (const ChTerrain &terrain, const ChVector3d &disc_center, const ChVector3d &disc_normal, double disc_radius, ChCoordsys<> &contact, double &depth, float &mu)
	Perform disc-terrain collision detection. More...

static bool	DiscTerrainCollision4pt (const ChTerrain &terrain, const ChVector3d &disc_center, const ChVector3d &disc_normal, double disc_radius, double width, ChCoordsys<> &contact, double &depth, float &mu)
	Perform disc-terrain collision detection considering the curvature of the road surface. More...

static bool	DiscTerrainCollisionEnvelope (const ChTerrain &terrain, const ChVector3d &disc_center, const ChVector3d &disc_normal, double disc_radius, double width, const ChFunctionInterp &areaDep, ChCoordsys<> &contact, double &depth, float &mu)
	Collsion algorithm based on a paper of J. More...

Static Protected Member Functions inherited from chrono::vehicle::ChPart
static void	RemoveVisualizationAssets (std::shared_ptr< ChPhysicsItem > item)
	Erase all visual shapes from the visual model associated with the specified physics item (if any).

static void	RemoveVisualizationAsset (std::shared_ptr< ChPhysicsItem > item, std::shared_ptr< ChVisualShape > shape)
	Erase the given shape from the visual model associated with the specified physics item (if any).

Protected Attributes
std::shared_ptr< ChWheel >	m_wheel
	associated wheel subsystem

double	m_stepsize
	tire integration step size (if applicable)

double	m_pressure
	internal tire pressure

CollisionType	m_collision_type
	method used for tire-terrain collision

ContactSurfaceType	m_contact_surface_type
	type of contact surface model (node cloud or mesh)

double	m_contact_surface_dim
	contact surface dimension (node radius or mesh thickness)

int	m_collision_family
	collision family for this tire

std::string	m_vis_mesh_file
	name of OBJ file for visualization of this tire (may be empty)

double	m_slip_angle

double	m_longitudinal_slip

double	m_camber_angle

Protected Attributes inherited from chrono::vehicle::ChPart
std::string	m_name
	subsystem name

bool	m_initialized
	specifies whether ot not the part is fully constructed

bool	m_output
	specifies whether or not output is generated for this subsystem

std::shared_ptr< ChPart >	m_parent
	parent subsystem (empty if parent is vehicle)

double	m_mass
	subsystem mass

ChMatrix33	m_inertia
	inertia tensor (relative to subsystem COM)

ChFrame	m_com
	COM frame (relative to subsystem reference frame)

ChFrame	m_xform
	subsystem frame expressed in the global frame

Friends
class	ChWheel

class	ChWheeledVehicle

class	ChWheeledTrailer

Member Enumeration Documentation

◆ CollisionType

enum chrono::vehicle::ChTire::CollisionType

strong

Collision detection type.

Used by tire models that perform their own terrain collision detection.

◆ ContactSurfaceType

enum chrono::vehicle::ChTire::ContactSurfaceType

strong

Contact surface type.

Used by tire models that rely on the underlying Chrono collision detection.

Member Function Documentation

◆ AddVisualizationMesh()

std::shared_ptr< ChVisualShapeTriangleMesh > chrono::vehicle::ChTire::AddVisualizationMesh	(	const std::string &	mesh_file_left,
		const std::string &	mesh_file_right
	)

protected

Add mesh visualization to the body associated with this tire (a wheel spindle body).

The two meshes are assumed to be specified with respect to a frame with origin at the center of the tire and Y axis pointing towards the outside. This function uses one of the two provided OBJ files, depending on the side on which the tire is mounted. The name of the output mesh shape is set to be the stem of the input filename.

◆ CalculateKinematics()

void chrono::vehicle::ChTire::CalculateKinematics	(	const WheelState &	wheel_state,
		const ChCoordsys<> &	tire_frame
	)

protected

Calculate kinematics quantities based on the given state of the associated wheel body.

Parameters

[in]	wheel_state	current state of associated wheel body
[in]	tire_frame	tire contact frame

◆ ConstructAreaDepthTable()

void chrono::vehicle::ChTire::ConstructAreaDepthTable	(	double	disc_radius,
		ChFunctionInterp &	areaDep
	)

staticprotected

Utility function to construct a loopkup table for penetration depth as function of intersection area, for a given tire radius.

The return map can be used in DiscTerrainCollisionEnvelope.

◆ DiscTerrainCollision()

bool chrono::vehicle::ChTire::DiscTerrainCollision	(	CollisionType	method,
		const ChTerrain &	terrain,
		const ChVector3d &	disc_center,
		const ChVector3d &	disc_normal,
		double	disc_radius,
		double	width,
		const ChFunctionInterp &	areaDep,
		ChCoordsys<> &	contact,
		double &	depth,
		float &	mu
	)

staticprotected

Perform disc-terrain collision detection, using the specified method.

Parameters

[in]	method	tire-terrain collision detection method
[in]	terrain	reference to terrain system
[in]	disc_center	global location of the disc center
[in]	disc_normal	disc normal, expressed in the global frame
[in]	disc_radius	disc radius
[in]	width	tire width
[in]	areaDep	lookup table to calculate depth from intersection area
[out]	contact	contact coordinate system (relative to the global frame)
[out]	depth	penetration depth (positive if contact occurred)
[out]	mu	coefficient of friction at contact

◆ DiscTerrainCollision1pt()

bool chrono::vehicle::ChTire::DiscTerrainCollision1pt	(	const ChTerrain &	terrain,
		const ChVector3d &	disc_center,
		const ChVector3d &	disc_normal,
		double	disc_radius,
		ChCoordsys<> &	contact,
		double &	depth,
		float &	mu
	)

staticprotected

Perform disc-terrain collision detection.

This utility function checks for contact between a disc of specified radius with given position and orientation (specified as the location of its center and a unit vector normal to the disc plane) and the terrain system associated with this tire. It returns true if the disc contacts the terrain and false otherwise. If contact occurs, it returns a coordinate system with the Z axis along the contact normal and the X axis along the "rolling" direction, as well as a positive penetration depth (i.e. the height below the terrain of the lowest point on the disc).

Parameters

[in]	terrain	reference to terrain system
[in]	disc_center	global location of the disc center
[in]	disc_normal	disc normal, expressed in the global frame
[in]	disc_radius	disc radius
[out]	contact	contact coordinate system (relative to the global frame)
[out]	depth	penetration depth (positive if contact occurred)
[out]	mu	coefficient of friction at contact

◆ DiscTerrainCollision4pt()

bool chrono::vehicle::ChTire::DiscTerrainCollision4pt	(	const ChTerrain &	terrain,
		const ChVector3d &	disc_center,
		const ChVector3d &	disc_normal,
		double	disc_radius,
		double	width,
		ChCoordsys<> &	contact,
		double &	depth,
		float &	mu
	)

staticprotected

Perform disc-terrain collision detection considering the curvature of the road surface.

The surface normal is calculated based on 4 different height values below the wheel center. The effective height is calculated as average value of the four height values. This utility function checks for contact between a disc of specified radius with given position and orientation (specified as the location of its center and a unit vector normal to the disc plane) and the terrain system associated with this tire. It returns true if the disc contacts the terrain and false otherwise. If contact occurs, it returns a coordinate system with the Z axis along the contact normal and the X axis along the "rolling" direction, as well as a positive penetration depth (i.e. the height below the terrain of the lowest point on the disc).

Parameters

[in]	terrain	reference to terrain system
[in]	disc_center	global location of the disc center
[in]	disc_normal	disc normal, expressed in the global frame
[in]	disc_radius	disc radius
[in]	width	tire width
[out]	contact	contact coordinate system (relative to the global frame)
[out]	depth	penetration depth (positive if contact occurred)
[out]	mu	coefficient of friction at contact

◆ DiscTerrainCollisionEnvelope()

bool chrono::vehicle::ChTire::DiscTerrainCollisionEnvelope	(	const ChTerrain &	terrain,
		const ChVector3d &	disc_center,
		const ChVector3d &	disc_normal,
		double	disc_radius,
		double	width,
		const ChFunctionInterp &	areaDep,
		ChCoordsys<> &	contact,
		double &	depth,
		float &	mu
	)

staticprotected

Collsion algorithm based on a paper of J.

Shane Sui and John A. Hirshey II: "A New Analytical Tire Model for Vehicle Dynamic Analysis" presented at 2001 MSC User Meeting

Parameters

[in]	terrain	reference to terrain system
[in]	disc_center	global location of the disc center
[in]	disc_normal	disc normal, expressed in the global frame
[in]	disc_radius	disc radius
[in]	width	tire width
[in]	areaDep	lookup table to calculate depth from intersection area
[out]	contact	contact coordinate system (relative to the global frame)
[out]	depth	penetration depth (positive if contact occurred)
[out]	mu	coefficient of friction at contact

◆ EstimateInertia()

ChVector3d chrono::vehicle::ChTire::EstimateInertia	(	double	tire_width,
		double	aspect_ratio,
		double	rim_diameter,
		double	tire_mass,
		double	t_factor = `2`
	)

static

Utility function for estimating the tire moments of inertia.

The tire is assumed to be specified with the common scheme (e.g. 215/65R15) and the mass of the tire (excluding the wheel) provided.

Parameters

tire_width	tire width [mm]
aspect_ratio	aspect ratio: height to width [percentage]
rim_diameter	rim diameter [in]
tire_mass	mass of the tire [kg]
t_factor	tread to sidewall thickness factor

◆ GetAddedInertia()

virtual ChVector3d chrono::vehicle::ChTire::GetAddedInertia ( ) const

protectedpure virtual

Get the inertia added to the associated spindle body.

Certain tires (e.g., those FEA-based) have their own physical representation and hence do not add mass and inertia to the spindle body. All others increment the spindle body moments of inertia by the amount reported by this function.

Implemented in chrono::vehicle::ChDeformableTire, and chrono::vehicle::ChRigidTire.

◆ GetAddedMass()

virtual double chrono::vehicle::ChTire::GetAddedMass ( ) const

protectedpure virtual

Get the mass added to the associated spindle body.

Certain tires (e.g., those FEA-based) have their own physical representation and hence do not add mass and inertia to the spindle body. All others increment the spindle body mass by the amount repoirted by this function.

Implemented in chrono::vehicle::ChDeformableTire, and chrono::vehicle::ChRigidTire.

◆ GetCamberAngle()

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

inline

Return the tire camber angle calculated based on the current state of the associated wheel body.

Note that this is a "dynamic" or "effective" camber angle, defined as the angle of the wheel from a plane normal to the current tire contact patch. The return value is in radians. A positive value corresponds to the upper side tipping to the left, while a negative value indicates the upper side tipping to the right.

◆ GetLongitudinalSlip()

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

inline

Return the tire longitudinal slip calculated based on the current state of the associated wheel body.

A positive value corresponds to a driving wheel, while a negative sign indicates braking.

◆ GetMeshFilename()

const std::string& chrono::vehicle::ChTire::GetMeshFilename ( ) const

inline

Get the name of the Wavefront file with tire visualization mesh.

An empty string is returned if no mesh was specified.

◆ GetOffset()

double chrono::vehicle::ChTire::GetOffset ( ) const

inlineprotected

Get offset from spindle center.

This queries the associated wheel, so it must be called only after the wheel was initialized.

◆ GetSlipAngle()

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

inline

Return the tire slip angle calculated based on the current state of the associated wheel body.

The return value is in radians with a positive sign for a left turn and a negative sign for a right turn.

◆ GetTireForce()

virtual TerrainForce chrono::vehicle::ChTire::GetTireForce ( ) const

protectedpure virtual

Get the tire force and moment.

This represents the output from this tire system that is passed to the vehicle system. The return application point, force, and moment are assumed to be expressed in the global reference frame. Typically, the vehicle subsystem will pass the tire force to the appropriate suspension subsystem which applies it as an external force on the wheel body. NOTE: tire models that rely on underlying Chrono functionality (e.g., the Chrono contact system or Chrono constraints) must always return zero forces and moments, else tire forces are double counted.

Implemented in chrono::vehicle::ChDeformableTire, chrono::vehicle::ChRigidTire, and chrono::vehicle::ChForceElementTire.

◆ GetWheel()

std::shared_ptr<ChWheel> chrono::vehicle::ChTire::GetWheel ( ) const

inline

Get the associated wheel.

Note that a tire is associated with a wheel only during initialization.

◆ ReportTireForce()

virtual TerrainForce chrono::vehicle::ChTire::ReportTireForce ( ChTerrain * terrain ) const

pure virtual

Report the tire force and moment.

This function can be used for reporting purposes or else to calculate tire forces in a co-simulation framework. The return application point, force, and moment are assumed to be expressed in the global reference frame.

Implemented in chrono::vehicle::ChDeformableTire, chrono::vehicle::ChRigidTire, and chrono::vehicle::ChForceElementTire.

◆ ReportTireForceLocal()

virtual TerrainForce chrono::vehicle::ChTire::ReportTireForceLocal	(	ChTerrain *	terrain,
		ChCoordsys<> &	tire_frame
	)		const

pure virtual

Get the tire force and moment expressed in the tire frame.

The tire frame has its origin in the contact patch, the X axis in the tire heading direction and the Z axis in the terrain normal at the contact point. If the tire is not in contact, the tire frame is not set and the function returns zero force and moment.

Implemented in chrono::vehicle::ChDeformableTire, chrono::vehicle::ChRigidTire, and chrono::vehicle::ChForceElementTire.

◆ SetCollisionType()

void chrono::vehicle::ChTire::SetCollisionType ( CollisionType collision_type )

inline

Set the collision type for tire-terrain interaction (default: SINGLE_POINT).

Derived classes (concrete tire models) may or may not use this setting.

◆ SetContactSurfaceType()

void chrono::vehicle::ChTire::SetContactSurfaceType	(	ContactSurfaceType	type,
		double	dim = `0.01`,
		int	collision_family = `13`
	)

Set the contact surface type (default: NODE_CLOUD).

'dim' represents the radius of a collision sphere (for NODE_CLOUD) or the mesh thickness (for TRIANGLE_MESH). Derived classes (concrete tire models) may or may not use this setting.

◆ SetPressure()

void chrono::vehicle::ChTire::SetPressure ( double pressure )

inline

Set the internal tire pressure [Pa] (default: 0).

Derived classes (concrete tire models) may or may not use this setting.

◆ SetStepsize()

void chrono::vehicle::ChTire::SetStepsize ( double val )

inline

Set the integration step size for the underlying dynamics (default: 1ms).

Derived classes (concrete tire models) may or may not use this setting.

◆ Synchronize()

virtual void chrono::vehicle::ChTire::Synchronize	(	double	time,
		const ChTerrain &	terrain
	)

inlinevirtual

Update the state of this tire system at the current time.

A derived class should also set the current slip, longitudinal slip, and camber angle.

Reimplemented in chrono::vehicle::ChPac02Tire, chrono::vehicle::ChTMeasyTire, chrono::vehicle::ChTMsimpleTire, chrono::vehicle::ChPac89Tire, chrono::vehicle::ChRigidTire, and chrono::vehicle::ChFialaTire.

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

/builds/uwsbel/chrono/src/chrono_vehicle/wheeled_vehicle/ChTire.h
/builds/uwsbel/chrono/src/chrono_vehicle/wheeled_vehicle/ChTire.cpp

Description

Public Types

Public Member Functions

Static Public Member Functions

Protected Member Functions

Static Protected Member Functions

Protected Attributes

Friends

Member Enumeration Documentation

◆ CollisionType

◆ ContactSurfaceType

Member Function Documentation

◆ AddVisualizationMesh()

◆ CalculateKinematics()

◆ ConstructAreaDepthTable()

◆ DiscTerrainCollision()

◆ DiscTerrainCollision1pt()

◆ DiscTerrainCollision4pt()

◆ DiscTerrainCollisionEnvelope()

◆ EstimateInertia()

◆ GetAddedInertia()

◆ GetAddedMass()

◆ GetCamberAngle()

◆ GetLongitudinalSlip()

◆ GetMeshFilename()

◆ GetOffset()

◆ GetSlipAngle()

◆ GetTireForce()

◆ GetWheel()

◆ ReportTireForce()

◆ ReportTireForceLocal()

◆ SetCollisionType()

◆ SetContactSurfaceType()

◆ SetPressure()

◆ SetStepsize()

◆ Synchronize()