Description

Base class for a semi-trailing arm suspension (non-steerable).

Derived from ChSuspension, but still an abstract base class.

The suspension subsystem is modeled with respect to a right-handed frame, with X pointing towards the front, Y to the left, and Z up (ISO standard). The suspension reference frame is assumed to be always aligned with that of the vehicle. When attached to a chassis, only an offset is provided.

All point locations are assumed to be given for the left half of the suspension and will be mirrored (reflecting the y coordinates) to construct the right side.

#include <ChSemiTrailingArm.h>

Inheritance diagram for chrono::vehicle::ChSemiTrailingArm:

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Collaboration diagram for chrono::vehicle::ChSemiTrailingArm:

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Public Member Functions
	ChSemiTrailingArm (const std::string &name)

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

virtual bool	IsSteerable () const final override
	Specify whether or not this suspension can be steered.

virtual bool	IsIndependent () const final override
	Specify whether or not this is an independent suspension.

virtual void	Initialize (std::shared_ptr< ChChassis > chassis, std::shared_ptr< ChSubchassis > subchassis, std::shared_ptr< ChSteering > steering, const ChVector<> &location, double left_ang_vel=0, double right_ang_vel=0) override
	Initialize this suspension subsystem. More...

virtual void	AddVisualizationAssets (VisualizationType vis) override
	Add visualization assets for the suspension subsystem. More...

virtual void	RemoveVisualizationAssets () override
	Remove visualization assets for the suspension subsystem.

virtual double	GetTrack () override
	Get the wheel track for the suspension subsystem.

std::shared_ptr< ChLinkTSDA >	GetSpring (VehicleSide side) const
	Get a handle to the specified spring element.

std::shared_ptr< ChLinkTSDA >	GetShock (VehicleSide side) const
	Get a handle to the specified shock (damper) element.

virtual ChSuspension::Force	ReportSuspensionForce (VehicleSide side) const override
	Return current suspension forces (spring and shock) on the specified side.

double	GetSpringForce (VehicleSide side) const
	Get the force in the spring element.

double	GetSpringLength (VehicleSide side) const
	Get the current length of the spring element.

double	GetSpringDeformation (VehicleSide side) const
	Get the current deformation of the spring element.

double	GetShockForce (VehicleSide side) const
	Get the force in the shock (damper) element.

double	GetShockLength (VehicleSide side) const
	Get the current length of the shock (damper) element.

double	GetShockVelocity (VehicleSide side) const
	Get the current deformation velocity of the shock (damper) element.

virtual void	LogConstraintViolations (VehicleSide side) override
	Log current constraint violations.

virtual std::shared_ptr< ChBody >	GetAntirollBody (VehicleSide side) const override
	Specify the suspension body on the specified side to attach a possible antirollbar subsystem. More...

void	LogHardpointLocations (const ChVector<> &ref, bool inches=false)
	Log the locations of all hardpoints. More...

Public Member Functions inherited from chrono::vehicle::ChSuspension
const ChVector &	GetRelPosition () const
	Get the location of the suspension subsystem relative to the associated chassis reference frame. More...

std::shared_ptr< ChBody >	GetSpindle (VehicleSide side) const
	Get a handle to the spindle body on the specified side.

std::shared_ptr< ChShaft >	GetAxle (VehicleSide side) const
	Get a handle to the axle shaft on the specified side.

std::shared_ptr< ChLinkLockRevolute >	GetRevolute (VehicleSide side) const
	Get a handle to the revolute joint on the specified side.

const ChVector &	GetSpindlePos (VehicleSide side) const
	Get the global location of the spindle on the specified side.

ChQuaternion	GetSpindleRot (VehicleSide side) const
	Get the orientation of the spindle body on the specified side. More...

const ChVector &	GetSpindleLinVel (VehicleSide side) const
	Get the linear velocity of the spindle body on the specified side. More...

ChVector	GetSpindleAngVel (VehicleSide side) const
	Get the angular velocity of the spindle body on the specified side. More...

double	GetAxleSpeed (VehicleSide side) const
	Get the angular speed of the axle on the specified side.

void	Synchronize ()
	Synchronize this suspension subsystem. More...

void	ApplyAxleTorque (VehicleSide side, double torque)
	Apply the provided motor torque. More...

virtual double	getSpindleRadius () const =0
	Return the radius of the spindle body (visualization only).

virtual double	getSpindleWidth () const =0
	Return the width of the spindle body (visualization only).

virtual std::shared_ptr< ChBody >	GetBrakeBody (VehicleSide side) const
	Specify the body on the specified side for a possible connection to brake subsystem. More...

void	ApplyParkingBrake (bool brake)
	Simple model of a parking brake.

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.

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

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

Protected Types
enum	PointId { SPINDLE, TA_CM, TA_O, TA_I, TA_S, SHOCK_C, SHOCK_A, SPRING_C, SPRING_A, NUM_POINTS }
	Identifiers for the various hardpoints. More...

Protected Member Functions
virtual void	InitializeInertiaProperties () override
	Initialize subsystem inertia properties. More...

virtual void	UpdateInertiaProperties () override
	Update subsystem inertia properties. More...

virtual const ChVector	getLocation (PointId which)=0
	Return the location of the specified hardpoint. More...

virtual double	getCamberAngle () const
	Return the camber angle, in radians (default: 0).

virtual double	getToeAngle () const
	Return the toe angle, in radians (default: 0). More...

virtual double	getSpindleMass () const =0
	Return the mass of the spindle body.

virtual double	getArmMass () const =0
	Return the mass of the trailing arm body.

virtual const ChVector &	getSpindleInertia () const =0
	Return the moments of inertia of the spindle body.

virtual const ChVector &	getArmInertia () const =0
	Return the moments of inertia of the trailing arm body.

virtual double	getAxleInertia () const =0
	Return the inertia of the axle shaft.

virtual double	getArmRadius () const =0
	Return the radius of the trailing arm body (visualization only).

virtual double	getSpringRestLength () const =0
	Return the free (rest) length of the spring element.

virtual std::shared_ptr< ChLinkTSDA::ForceFunctor >	getSpringForceFunctor () const =0
	Return the functor object for spring force.

virtual std::shared_ptr< ChLinkTSDA::ForceFunctor >	getShockForceFunctor () const =0
	Return the functor object for shock force.

virtual std::shared_ptr< ChVehicleBushingData >	getCABushingData () const
	Return stiffness and damping data for the arm bushing. More...

Protected Member Functions inherited from chrono::vehicle::ChSuspension
	ChSuspension (const std::string &name)
	Construct a suspension subsystem with given name.

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

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

void	AddInertiaProperties (ChVector<> &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...

Protected Attributes
std::shared_ptr< ChBody >	m_arm [2]
	trailing arm bodies (left/right)

std::shared_ptr< ChVehicleJoint >	m_revoluteArm [2]
	chassis-arm revolute joints (left/right)

std::shared_ptr< ChLinkTSDA >	m_shock [2]
	spring links (left/right)

std::shared_ptr< ChLinkTSDA >	m_spring [2]
	shock links (left/right)

Protected Attributes inherited from chrono::vehicle::ChSuspension
ChVector	m_rel_loc
	location relative to chassis

std::shared_ptr< ChBody >	m_spindle [2]
	handles to spindle bodies

std::shared_ptr< ChShaft >	m_axle [2]
	handles to axle shafts

std::shared_ptr< ChShaftsBody >	m_axle_to_spindle [2]
	handles to spindle-shaft connectors

std::shared_ptr< ChLinkLockRevolute >	m_revolute [2]
	handles to spindle revolute joints

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

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

Additional Inherited Members
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...

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< ChLinkRSDA >> 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.

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).

Member Enumeration Documentation

◆ PointId

enum chrono::vehicle::ChSemiTrailingArm::PointId

protected

Identifiers for the various hardpoints.

Enumerator
SPINDLE	spindle location (center of mass)
TA_CM	trailing arm, center of mass
TA_O	trailing arm, chassis connection outter
TA_I	trailing arm, chassis connection inner
TA_S	trailing arm, connection to spindle
SHOCK_C	shock, chassis
SHOCK_A	shock, lower control arm
SPRING_C	spring, chassis
SPRING_A	spring, lower control arm

Constructor & Destructor Documentation

◆ ChSemiTrailingArm()

chrono::vehicle::ChSemiTrailingArm::ChSemiTrailingArm ( const std::string & name )

Parameters

[in] name name of the subsystem

Member Function Documentation

◆ AddVisualizationAssets()

void chrono::vehicle::ChSemiTrailingArm::AddVisualizationAssets ( VisualizationType vis )

overridevirtual

Add visualization assets for the suspension subsystem.

This default implementation uses primitives.

Reimplemented from chrono::vehicle::ChSuspension.

◆ GetAntirollBody()

virtual std::shared_ptr<ChBody> chrono::vehicle::ChSemiTrailingArm::GetAntirollBody ( VehicleSide side ) const

inlineoverridevirtual

Specify the suspension body on the specified side to attach a possible antirollbar subsystem.

Return the corresponding trailing arm.

Reimplemented from chrono::vehicle::ChSuspension.

◆ getCABushingData()

virtual std::shared_ptr<ChVehicleBushingData> chrono::vehicle::ChSemiTrailingArm::getCABushingData ( ) const

inlineprotectedvirtual

Return stiffness and damping data for the arm bushing.

Returning nullptr (default) results in using a kinematic revolute joint.

Reimplemented in chrono::vehicle::SemiTrailingArm.

◆ getLocation()

virtual const ChVector chrono::vehicle::ChSemiTrailingArm::getLocation ( PointId which )

protectedpure virtual

Return the location of the specified hardpoint.

The returned location must be expressed in the suspension reference frame.

◆ getToeAngle()

virtual double chrono::vehicle::ChSemiTrailingArm::getToeAngle ( ) const

inlineprotectedvirtual

Return the toe angle, in radians (default: 0).

A positive value indicates toe-in, a negative value indicates toe-out.

Reimplemented in chrono::vehicle::SemiTrailingArm.

◆ Initialize()

void chrono::vehicle::ChSemiTrailingArm::Initialize	(	std::shared_ptr< ChChassis >	chassis,
		std::shared_ptr< ChSubchassis >	subchassis,
		std::shared_ptr< ChSteering >	steering,
		const ChVector<> &	location,
		double	left_ang_vel = `0`,
		double	right_ang_vel = `0`
	)

overridevirtual

Initialize this suspension subsystem.

The suspension subsystem is initialized by attaching it to the specified chassis and (if provided) to the specified subchassis, at the specified location (with respect to and expressed in the reference frame of the chassis). It is assumed that the suspension reference frame is always aligned with the chassis reference frame. Since this suspension is non-steerable, the steering subsystem is always ignored.

Parameters

[in]	chassis	associated chassis subsystem
[in]	subchassis	associated subchassis subsystem (may be null)
[in]	steering	associated steering subsystem (may be null)
[in]	location	location relative to the chassis frame
[in]	left_ang_vel	initial angular velocity of left wheel
[in]	right_ang_vel	initial angular velocity of right wheel

Implements chrono::vehicle::ChSuspension.

◆ InitializeInertiaProperties()

void chrono::vehicle::ChSemiTrailingArm::InitializeInertiaProperties ( )

overrideprotectedvirtual

Initialize subsystem inertia properties.

Derived classes must override this function and set the subsystem mass (m_mass) and, if constant, the subsystem COM frame and its inertia tensor. This function is called during initialization of the vehicle system.

Implements chrono::vehicle::ChPart.

◆ LogHardpointLocations()

void chrono::vehicle::ChSemiTrailingArm::LogHardpointLocations	(	const ChVector<> &	ref,
		bool	inches = `false`
	)

Log the locations of all hardpoints.

The reported locations are expressed in the suspension reference frame. By default, these values are reported in SI units (meters), but can be optionally reported in inches.

◆ UpdateInertiaProperties()

void chrono::vehicle::ChSemiTrailingArm::UpdateInertiaProperties ( )

overrideprotectedvirtual

Update subsystem inertia properties.

Derived classes must override this function and set the global subsystem transform (m_xform) and, unless constant, the subsystem COM frame (m_com) and its inertia tensor (m_inertia). Calculate the current inertia properties and global frame of this subsystem. This function is called every time the state of the vehicle system is advanced in time.