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:
Collaboration diagram for chrono::vehicle::ChTire:

Public Types

enum  CollisionType { SINGLE_POINT, FOUR_POINTS, ENVELOPE }
 

Public Member Functions

 ChTire (const std::string &name)
 
void SetStepsize (double val)
 Set the value of the integration step size for the underlying dynamics (if applicable). 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. More...
 
virtual double GetRadius () const =0
 Get the tire radius.
 
virtual double GetMass () const =0
 Get the tire mass. More...
 
virtual double ReportMass () const
 Report the tire mass. More...
 
virtual ChVector GetInertia () const =0
 Get the tire moments of inertia. More...
 
virtual TerrainForce ReportTireForce (ChTerrain *terrain) const =0
 Report the tire force and moment. 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.
 
virtual void Initialize (std::shared_ptr< ChWheel > wheel)
 Initialize this tire subsystem by associating it to an existing wheel subsystem. More...
 
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
 ChPart (const std::string &name)
 Construct a vehicle subsystem with the specified name. More...
 
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.
 
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.
 
void SetContactFrictionCoefficient (float friction_coefficient)
 Set coefficient of friction. More...
 
void SetContactRestitutionCoefficient (float restitution_coefficient)
 Set coefficient of restitution. More...
 
void SetContactMaterialProperties (float young_modulus, float poisson_ratio)
 Set contact material properties. More...
 
void SetContactMaterialCoefficients (float kn, float gn, float kt, float gt)
 Set contact material coefficients. More...
 
float GetCoefficientFriction () const
 Get coefficient of friction for contact material.
 
float GetCoefficientRestitution () const
 Get coefficient of restitution for contact material.
 
float GetYoungModulus () const
 Get Young's modulus of elasticity for contact material.
 
float GetPoissonRatio () const
 Get Poisson ratio for contact material.
 
float GetKn () const
 Get normal stiffness coefficient for contact material.
 
float GetKt () const
 Get tangential stiffness coefficient for contact material.
 
float GetGn () const
 Get normal viscous damping coefficient for contact material.
 
float GetGt () const
 Get tangential viscous damping coefficient for contact material.
 
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 ChVector 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 ChVector<> &moments, const ChVector<> &products, const ChMatrix33<> &vehicle_rot, const ChMatrix33<> &body_rot)
 Utility function for transforming inertia tensors between centroidal frames. More...
 

Protected Member Functions

void CalculateKinematics (double time, const WheelState &wheel_state, const ChTerrain &terrain)
 Calculate kinematics quantities based on the given state of the associated wheel body. More...
 
double GetOffset () const
 Get offset from spindle center. More...
 
virtual TerrainForce GetTireForce () const =0
 Get the tire force and moment. More...
 
- Protected Member Functions inherited from chrono::vehicle::ChPart
virtual void Create (const rapidjson::Document &d)
 Create a vehicle subsystem from JSON data. More...
 

Static Protected Member Functions

static bool DiscTerrainCollision (const ChTerrain &terrain, const ChVector<> &disc_center, const ChVector<> &disc_normal, double disc_radius, ChCoordsys<> &contact, double &depth)
 Perform disc-terrain collision detection. More...
 
static bool DiscTerrainCollision4pt (const ChTerrain &terrain, const ChVector<> &disc_center, const ChVector<> &disc_normal, double disc_radius, double width, ChCoordsys<> &contact, double &depth, double &camber_angle)
 Perform disc-terrain collision detection considering the curvature of the road surface. More...
 
static bool DiscTerrainCollisionEnvelope (const ChTerrain &terrain, const ChVector<> &disc_center, const ChVector<> &disc_normal, double disc_radius, const ChFunction_Recorder &areaDep, ChCoordsys<> &contact, double &depth)
 Collsion algorithm based on a paper of J. More...
 
static void ConstructAreaDepthTable (double disc_radius, ChFunction_Recorder &areaDep)
 Utility function to construct a loopkup table for penetration depth as function of intersection area, for a given tire radius. More...
 
- Static Protected Member Functions inherited from chrono::vehicle::ChPart
static void ExportBodyList (rapidjson::Document &jsonDocument, std::vector< std::shared_ptr< ChBody >> bodies)
 Export the list of bodies to the specified JSON document.
 
static void ExportShaftList (rapidjson::Document &jsonDocument, std::vector< std::shared_ptr< ChShaft >> shafts)
 Export the list of shafts to the specified JSON document.
 
static void ExportJointList (rapidjson::Document &jsonDocument, std::vector< std::shared_ptr< ChLink >> joints)
 Export the list of joints to the specified JSON document.
 
static void ExportCouplesList (rapidjson::Document &jsonDocument, std::vector< std::shared_ptr< ChShaftsCouple >> couples)
 Export the list of shaft couples to the specified JSON document.
 
static void ExportMarkerList (rapidjson::Document &jsonDocument, std::vector< std::shared_ptr< ChMarker >> markers)
 Export the list of markers to the specified JSON document.
 
static void ExportLinSpringList (rapidjson::Document &jsonDocument, std::vector< std::shared_ptr< ChLinkTSDA >> springs)
 Export the list of translational springs to the specified JSON document.
 
static void ExportRotSpringList (rapidjson::Document &jsonDocument, std::vector< std::shared_ptr< ChLinkRotSpringCB >> springs)
 Export the list of rotational springs to the specified JSON document.
 
static void ExportBodyLoadList (rapidjson::Document &jsonDocument, std::vector< std::shared_ptr< ChLoadBodyBody >> loads)
 Export the list of body-body loads to the specified JSON document.
 

Protected Attributes

std::shared_ptr< ChWheelm_wheel
 associated wheel subsystem
 
double m_stepsize
 tire integration step size (if applicable)
 
CollisionType m_collision_type
 method used for tire-terrain collision
 
- Protected Attributes inherited from chrono::vehicle::ChPart
std::string m_name
 subsystem name
 
bool m_output
 specifies whether or not output is generated for this subsystem
 
float m_friction
 contact coefficient of friction
 
float m_restitution
 contact coefficient of restitution
 
float m_young_modulus
 contact material Young modulus
 
float m_poisson_ratio
 contact material Poisson ratio
 
float m_kn
 normal contact stiffness
 
float m_gn
 normal contact damping
 
float m_kt
 tangential contact stiffness
 
float m_gt
 tangential contact damping
 

Friends

class ChWheel
 

Constructor & Destructor Documentation

◆ ChTire()

chrono::vehicle::ChTire::ChTire ( const std::string &  name)
Parameters
[in]namename of this tire system

Member Function Documentation

◆ CalculateKinematics()

void chrono::vehicle::ChTire::CalculateKinematics ( double  time,
const WheelState wheel_state,
const ChTerrain terrain 
)
protected

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

Parameters
[in]timecurrent time
[in]wheel_statecurrent state of associated wheel body
[in]terrainreference to the terrain system

◆ ConstructAreaDepthTable()

void chrono::vehicle::ChTire::ConstructAreaDepthTable ( double  disc_radius,
ChFunction_Recorder 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 ( const ChTerrain terrain,
const ChVector<> &  disc_center,
const ChVector<> &  disc_normal,
double  disc_radius,
ChCoordsys<> &  contact,
double &  depth 
)
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]terrainreference to terrain system
[in]disc_centerglobal location of the disc center
[in]disc_normaldisc normal, expressed in the global frame
[in]disc_radiusdisc radius
[out]contactcontact coordinate system (relative to the global frame)
[out]depthpenetration depth (positive if contact occurred)

◆ DiscTerrainCollision4pt()

bool chrono::vehicle::ChTire::DiscTerrainCollision4pt ( const ChTerrain terrain,
const ChVector<> &  disc_center,
const ChVector<> &  disc_normal,
double  disc_radius,
double  width,
ChCoordsys<> &  contact,
double &  depth,
double &  camber_angle 
)
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]terrainreference to terrain system
[in]disc_centerglobal location of the disc center
[in]disc_normaldisc normal, expressed in the global frame
[in]disc_radiusdisc radius
[in]widthtire width
[out]contactcontact coordinate system (relative to the global frame)
[out]depthpenetration depth (positive if contact occurred)
[out]camber_angletire camber angle

◆ DiscTerrainCollisionEnvelope()

bool chrono::vehicle::ChTire::DiscTerrainCollisionEnvelope ( const ChTerrain terrain,
const ChVector<> &  disc_center,
const ChVector<> &  disc_normal,
double  disc_radius,
const ChFunction_Recorder areaDep,
ChCoordsys<> &  contact,
double &  depth 
)
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]terrainreference to terrain system
[in]disc_centerglobal location of the disc center
[in]disc_normaldisc normal, expressed in the global frame
[in]disc_radiusdisc radius
[in]areaDeplookup table to calculate depth from intersection area
[out]contactcontact coordinate system (relative to the global frame)
[out]depthpenetration depth (positive if contact occurred)

◆ EstimateInertia()

ChVector 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_widthtire width [mm]
aspect_ratioaspect ratio: height to width [percentage]
rim_diameterrim diameter [in]
tire_massmass of the tire [kg]
t_factortread to sidewall thickness factor

◆ GetCamberAngle()

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

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

The return value is in radians. (positive sign = upper side tipping to the left, negative sign = upper side tipping to the right)

◆ GetInertia()

◆ GetLongitudinalSlip()

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

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

(positive sign = driving, negative sign = breaking)

◆ GetMass()

◆ GetOffset()

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

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

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

The return value is in radians. (positive sign = left turn, negative sign = 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. 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.

◆ Initialize()

void chrono::vehicle::ChTire::Initialize ( std::shared_ptr< ChWheel wheel)
virtual

Initialize this tire subsystem by associating it to an existing wheel subsystem.

The tire mass and inertia are used to increment those of the associated suspension spindle body.

◆ ReportMass()

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

Report the tire mass.

Certain tire models (e.g. those based on FEA) must return 0 in GetMass() so that the tire mass is not double counted in the underlying mechanical system. For reporting purposes, use this function instead.

Reimplemented in chrono::vehicle::ChDeformableTire.

◆ 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.

Implemented in chrono::vehicle::ChDeformableTire, chrono::vehicle::ChPacejkaTire, chrono::vehicle::ChTMeasyTire, chrono::vehicle::ChPac02Tire, chrono::vehicle::ChRigidTire, chrono::vehicle::ChFialaTire, chrono::vehicle::ChLugreTire, and chrono::vehicle::ChPac89Tire.

◆ SetCollisionType()

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

Set the collision type for tire-terrain interaction.

Default: SINGLE_POINT

◆ SetStepsize()

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

Set the value of the integration step size for the underlying dynamics (if applicable).

Default value: 1ms.

◆ Synchronize()

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

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

Parameters
[in]timecurrent time
[in]terrainreference to the terrain system