(Experimental – API will change – use at your own risk) Define a sphere on each of two bodies. More...

Inheritance diagram for SimTK::SphereSphereContact:

Public Member Functions
	SphereSphereContact (MobilizedBody &mobod_F, const Vec3 &defaultCenterOnF, Real defaultRadiusOnF, MobilizedBody &mobod_B, const Vec3 &defaultCenterOnB, Real defaultRadiusOnB, Real minCOR, Real mu_s, Real mu_d, Real mu_v)

bool	disable (State &state) const override
	Disable the normal and friction constraints if they were enabled. More...

bool	enable (State &state) const override
	Enable the normal and friction constraints if they were disabled. More...

bool	isEnabled (const State &state) const override
	Return true if this contact is enabled. More...

Vec3	whereToDisplay (const State &state) const override
	This returns a point in the ground frame at which you might want to say the constraint is "located", for purposes of display only. More...

Real	getPerr (const State &state) const override
	Return the position error for the contact constraint (usually a signed distance function). More...

Real	getVerr (const State &state) const override
	Return the time derivative of the contact constraint position error. More...

Real	getAerr (const State &state) const override
	Return the time derivative of the contact constraint velocity error. More...

Real	calcEffectiveCOR (const State &state, Real defaultCaptureSpeed, Real defaultMinCORSpeed, Real impactSpeed) const override
	Returns the effective coefficient of restitution (COR) for this contact, given an impact speed (a nonnegative scalar). More...

bool	hasFriction (const State &state) const override
	Returns `true` if there is a friction constraint associated with this contact constraint. More...

Vec2	getSlipVelocity (const State &state) const override

Real	calcEffectiveCOF (const State &state, Real defaultTransitionSpeed, Real slipSpeed) const override
	Returns the effective coefficient of friction mu for this contact, given a relative slip speed (a nonnegative scalar). More...

MultiplierIndex	getContactMultiplierIndex (const State &s) const override
	Return the multiplier index Simbody assigned for the unilateral contact constraint (for contact, this is the normal constraint). More...

void	getFrictionMultiplierIndices (const State &s, MultiplierIndex &ix_x, MultiplierIndex &ix_y) const override
	If hasFriction(), this method returns the multipliers used for the x- and y-direction friction constraints. More...

Public Member Functions inherited from SimTK::UnilateralContact
	UnilateralContact (int sign=1)
	The base class constructor allows specification of the sign convention to be used with this constraint. More...

virtual	~UnilateralContact ()

Real	getSignConvention () const
	Report the sign convention (1 or -1) supplied at construction. More...

virtual bool	isProximal (const State &state, Real ptol) const
	Given the position constraint tolerance currently in use, is this contact close enough to contacting that we should treat it as though it is in contact? Normally we just see if sign*perr <= tol, but individual contacts can override this if they want to do some scaling. More...

virtual Vec3	getPositionInfo (const State &state) const
	TODO: kludge needed because we're misusing existing constraints. More...

virtual void	setInstanceParameter (State &state, const Vec3 &pos) const
	TODO: kludge to set instance parameters on internal constraints; this should be the same Vec3 you got from getPositionInfo(). More...

void	setMyIndex (UnilateralContactIndex cx)

UnilateralContactIndex	getMyIndex () const

Detailed Description

(Experimental – API will change – use at your own risk) Define a sphere on each of two bodies.

This constraint will prevent interpenetration of those spheres, and provide for frictional forces when they are in contact. The resulting contact is parameterized by a coefficient of restitution for impacts in the plane normal direction, and by coefficients of friction for frictional forces in the plane.

Constructor & Destructor Documentation

◆ SphereSphereContact()

SimTK::SphereSphereContact::SphereSphereContact	(	MobilizedBody &	mobod_F,
		const Vec3 &	defaultCenterOnF,
		Real	defaultRadiusOnF,
		MobilizedBody &	mobod_B,
		const Vec3 &	defaultCenterOnB,
		Real	defaultRadiusOnB,
		Real	minCOR,
		Real	mu_s,
		Real	mu_d,
		Real	mu_v
	)

Member Function Documentation

◆ disable()

bool SimTK::SphereSphereContact::disable ( State & state ) const

inlineoverridevirtual

Disable the normal and friction constraints if they were enabled.

Return true if we actually had to disable something.

Implements SimTK::UnilateralContact.

◆ enable()

bool SimTK::SphereSphereContact::enable ( State & state ) const

inlineoverridevirtual

Enable the normal and friction constraints if they were disabled.

Return true if we actually had to enable something.

Implements SimTK::UnilateralContact.

◆ isEnabled()

bool SimTK::SphereSphereContact::isEnabled ( const State & state ) const

inlineoverridevirtual

Return true if this contact is enabled.

Implements SimTK::UnilateralContact.

◆ whereToDisplay()

Vec3 SimTK::SphereSphereContact::whereToDisplay ( const State & state ) const

overridevirtual

This returns a point in the ground frame at which you might want to say the constraint is "located", for purposes of display only.

Implements SimTK::UnilateralContact.

◆ getPerr()

Real SimTK::SphereSphereContact::getPerr ( const State & state ) const

overridevirtual

Return the position error for the contact constraint (usually a signed distance function).

You have to apply the sign convention to interpret this properly.

Implements SimTK::UnilateralContact.

◆ getVerr()

Real SimTK::SphereSphereContact::getVerr ( const State & state ) const

inlineoverridevirtual

Return the time derivative of the contact constraint position error.

You have to apply the sign convention to interpret this properly.

Implements SimTK::UnilateralContact.

◆ getAerr()

Real SimTK::SphereSphereContact::getAerr ( const State & state ) const

inlineoverridevirtual

Return the time derivative of the contact constraint velocity error.

You have to apply the sign convention to interpret this properly.

Implements SimTK::UnilateralContact.

◆ calcEffectiveCOR()

Real SimTK::SphereSphereContact::calcEffectiveCOR	(	const State &	state,
		Real	defaultCaptureSpeed,
		Real	defaultMinCORSpeed,
		Real	impactSpeed
	)		const

inlineoverridevirtual

Returns the effective coefficient of restitution (COR) for this contact, given an impact speed (a nonnegative scalar).

For a given pair of contacting materials this is typically a function of just the impact speed, but it could also depend on the time and configuration in state, which should be realized through Stage::Position. The given default impact speed thresholds (also nonnegative) are used to calculate the COR unless this Contact overrides those.

Implements SimTK::UnilateralContact.

◆ hasFriction()

bool SimTK::SphereSphereContact::hasFriction ( const State & state ) const

inlineoverridevirtual

Returns true if there is a friction constraint associated with this contact constraint.

If so, calcEffectiveCOF() must be overridden.

Reimplemented from SimTK::UnilateralContact.

◆ getSlipVelocity()

Vec2 SimTK::SphereSphereContact::getSlipVelocity ( const State & state ) const

inlineoverridevirtual

Reimplemented from SimTK::UnilateralContact.

◆ calcEffectiveCOF()

Real SimTK::SphereSphereContact::calcEffectiveCOF	(	const State &	state,
		Real	defaultTransitionSpeed,
		Real	slipSpeed
	)		const

inlineoverridevirtual

Returns the effective coefficient of friction mu for this contact, given a relative slip speed (a nonnegative scalar).

For a given pair of contacting materials this is typically a function of just the slip speed, but it could also depend on the time and configuration in state, which should be realized through Stage::Position. The given default slip-to-roll transition speed threshold (also nonnegative) is used to calculate mu unless this Contact overrides it with its own transition speed.

Reimplemented from SimTK::UnilateralContact.

◆ getContactMultiplierIndex()

MultiplierIndex SimTK::SphereSphereContact::getContactMultiplierIndex ( const State & state ) const

overridevirtual

Return the multiplier index Simbody assigned for the unilateral contact constraint (for contact, this is the normal constraint).

If the constraint is not enabled, there is no multiplier and the returned index will be invalid.

Implements SimTK::UnilateralContact.

◆ getFrictionMultiplierIndices()

void SimTK::SphereSphereContact::getFrictionMultiplierIndices	(	const State &	state,
		MultiplierIndex &	ix_x,
		MultiplierIndex &	ix_y
	)		const

overridevirtual

If hasFriction(), this method returns the multipliers used for the x- and y-direction friction constraints.

If no friction, or if this constraint is disabled, the returned values are invalid.

Reimplemented from SimTK::UnilateralContact.

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

ConditionalConstraint.h

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ SphereSphereContact()

Member Function Documentation

◆ disable()

◆ enable()

◆ isEnabled()

◆ whereToDisplay()

◆ getPerr()

◆ getVerr()

◆ getAerr()

◆ calcEffectiveCOR()

◆ hasFriction()

◆ getSlipVelocity()

◆ calcEffectiveCOF()

◆ getContactMultiplierIndex()

◆ getFrictionMultiplierIndices()