Simbody  3.5
SimTK::SpherePlaneContact Class Reference

(Experimental -- API will change -- use at your own risk) Define a sphere on one body that cannot penetrate a plane attached to another body. More...

+ Inheritance diagram for SimTK::SpherePlaneContact:

List of all members.

Public Member Functions

 SpherePlaneContact (MobilizedBody &planeBodyB, const UnitVec3 &normal_B, Real height, MobilizedBody &followerBodyF, const Vec3 &point_F, Real radius, 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.
bool enable (State &state) const override
 Enable the normal and friction constraints if they were disabled.
bool isEnabled (const State &state) const override
 Return true if this contact is enabled.
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.
Real getPerr (const State &state) const override
 Return the position error for the contact constraint (usually a signed distance function).
Real getVerr (const State &state) const override
 Return the time derivative of the contact constraint position error.
Real getAerr (const State &state) const override
 Return the time derivative of the contact constraint velocity error.
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).
bool hasFriction (const State &state) const override
 Returns true if there is a friction constraint associated with this contact constraint.
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).
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).
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.

Detailed Description

(Experimental -- API will change -- use at your own risk) Define a sphere on one body that cannot penetrate a plane attached to another body.

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

SimTK::SpherePlaneContact::SpherePlaneContact ( MobilizedBody planeBodyB,
const UnitVec3 normal_B,
Real  height,
MobilizedBody followerBodyF,
const Vec3 point_F,
Real  radius,
Real  minCOR,
Real  mu_s,
Real  mu_d,
Real  mu_v 
)

Member Function Documentation

bool SimTK::SpherePlaneContact::disable ( State state) const [inline, override, virtual]

Disable the normal and friction constraints if they were enabled.

Return true if we actually had to disable something.

Implements SimTK::UnilateralContact.

bool SimTK::SpherePlaneContact::enable ( State state) const [inline, override, virtual]

Enable the normal and friction constraints if they were disabled.

Return true if we actually had to enable something.

Implements SimTK::UnilateralContact.

bool SimTK::SpherePlaneContact::isEnabled ( const State state) const [inline, override, virtual]

Return true if this contact is enabled.

Implements SimTK::UnilateralContact.

Vec3 SimTK::SpherePlaneContact::whereToDisplay ( const State state) const [override, virtual]

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.

Real SimTK::SpherePlaneContact::getPerr ( const State state) const [override, virtual]

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.

Real SimTK::SpherePlaneContact::getVerr ( const State state) const [inline, override, virtual]

Return the time derivative of the contact constraint position error.

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

Implements SimTK::UnilateralContact.

Real SimTK::SpherePlaneContact::getAerr ( const State state) const [inline, override, virtual]

Return the time derivative of the contact constraint velocity error.

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

Implements SimTK::UnilateralContact.

Real SimTK::SpherePlaneContact::calcEffectiveCOR ( const State state,
Real  defaultCaptureSpeed,
Real  defaultMinCORSpeed,
Real  impactSpeed 
) const [inline, override, virtual]

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.

bool SimTK::SpherePlaneContact::hasFriction ( const State state) const [inline, override, virtual]

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

If so, calcEffectiveCOF() must be overridden.

Reimplemented from SimTK::UnilateralContact.

Vec2 SimTK::SpherePlaneContact::getSlipVelocity ( const State state) const [inline, override, virtual]

Reimplemented from SimTK::UnilateralContact.

Real SimTK::SpherePlaneContact::calcEffectiveCOF ( const State state,
Real  defaultTransitionSpeed,
Real  slipSpeed 
) const [inline, override, virtual]

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.

MultiplierIndex SimTK::SpherePlaneContact::getContactMultiplierIndex ( const State state) const [override, virtual]

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.

void SimTK::SpherePlaneContact::getFrictionMultiplierIndices ( const State state,
MultiplierIndex ix_x,
MultiplierIndex ix_y 
) const [override, virtual]

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:
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