SimbodyMatterSubsystem Class Reference

#include <SimbodyMatterSubsystem.h>

Inheritance diagram for SimbodyMatterSubsystem:

Detailed Description

The Simbody low-level multibody tree interface.

Equations represented:

                  qdot = Q u
                  zdot = zdot(t,q,u,z)

      M udot + ~G mult = f(t,q,u,z)
      G udot           = b(t,q,u)

              where

       [P]    [bp]
     G=[V]  b=[bv]  f=T+J*(F-C)
       [A]    [ba]

       pdotdot = P udot - bp(t,q,u) = 0
          vdot = V udot - bv(t,q,u) = 0
 a(t,q,u,udot) = A udot - ba(t,q,u) = 0

                pdot = P u - c(t,q) = 0
                           v(t,q,u) = 0

                             p(t,q) = 0
                               n(q) = 0

where M(q) is the mass matrix, G(q) the acceleration constraint matrix, C(q,u) the coriolis and gyroscopic forces, T is user-applied joint mobility forces, F is user-applied body forces and torques and gravity. J* is the operator that maps spatial forces to joint mobility forces. p() are the holonomic (position) constraints, v() the non-holonomic (velocity) constraints, and a() the acceleration-only constraints, which must be linear, with A the coefficient matrix for a(). pdot, pdotdot are obtained by differentiation of p(), vdot by differentiation of v(). P=partial(pdot)/partial(u) (yes, that's u, not q), V=partial(v)/partial(u). (We can get partial(p)/partial(q) when we need it as P*Q^-1.) n(q) is the set of quaternion normalization constraints, which exist only at the position level and are uncoupled from everything else.

We calculate the constraint multipliers like this: G M^-1 ~G mult = G udot0 - b, udot0=M^-1 f using the pseudo inverse of G M^-1 ~G to give a least squares solution for mult: mult = pinv(G M^-1 ~G)(G M^-1 f - b). Then the real udot is udot = udot0 - udotC, with udotC = M^-1 ~G mult. Note: M^-1* is an O(N) operator that provides the desired result; it *does not* require forming or factoring M.

NOTE: only the following constraint matrices have to be formed and factored:

 *    [G M^-1 ~G]   to calculate multipliers (square, symmetric: LDL' if
 *                  well conditioned, else pseudoinverse)
 *
 *    [P Q^-1]      for projection onto position manifold (pseudoinverse)
 *
 *    [P;V]         for projection onto velocity manifold (pseudoinverse)
 *                  (using Matlab notation meaning rows of P over rows of V)
 *

When working in a weighted norm with weights W on the state variables and weights T (1/tolerance) on the constraint errors, the matrices we need are actually [Tp PQ^1 Wq^1], [Tpv [P;V] Wu^-1], etc. with T and W diagonal weighting matrices. These can then be used to find least squares solutions in the weighted norms.

In many cases these matrices consist of decoupled blocks which can be solved independently; we try to take advantage of that whenever possible to solve a set of smaller systems rather than one large one. Also, in the majority of biosimulation applications we are likely to have only holonomic (position) constraints, so there is no V or A and G=P is the whole story.

Public Member Functions

SimbodyMatterSubsystem ()

Create a tree containing only the ground body (body 0).

SimbodyMatterSubsystem (MultibodySystem &)

~SimbodyMatterSubsystem ()

SimbodyMatterSubsystem (const SimbodyMatterSubsystem &ss)

SimbodyMatterSubsystem & operator= (const SimbodyMatterSubsystem &ss)

bool getShowDefaultGeometry () const

Get whether default decorative geometry is displayed for bodies in this system.

void setShowDefaultGeometry (bool show)

Set whether default decorative geometry is displayed for bodies in this system.

Real calcSystemMass (const State &s) const

Calculate the total system mass.

Vec3 calcSystemMassCenterLocationInGround (const State &s) const

Return the location r_OG_C of the system mass center C, measured from the ground origin OG, and expressed in Ground.

MassProperties calcSystemMassPropertiesInGround (const State &s) const

Return total system mass, mass center location measured from the Ground origin, and system inertia taken about the Ground origin, expressed in Ground.

Inertia calcSystemCentralInertiaInGround (const State &s) const

Return the system inertia matrix taken about the system center of mass, expressed in Ground.

Vec3 calcSystemMassCenterVelocityInGround (const State &s) const

Return the velocity V_G_C = d/dt r_OG_C of the system mass center C in the Ground frame G, expressed in G.

Vec3 calcSystemMassCenterAccelerationInGround (const State &s) const

Return the acceleration A_G_C = d^2/dt^2 r_OG_C of the system mass center C in the Ground frame G, expressed in G.

SpatialVec calcSystemMomentumAboutGroundOrigin (const State &s) const

Return the momentum of the system as a whole (angular, linear) measured in the ground frame, taken about the ground origin and expressed in ground.

MobilizedBodyIndex adoptMobilizedBody (MobilizedBodyIndex parent, MobilizedBody &child)

const MobilizedBody & getMobilizedBody (MobilizedBodyIndex) const

MobilizedBody & updMobilizedBody (MobilizedBodyIndex)

const MobilizedBody::Ground & getGround () const

MobilizedBody::Ground & updGround ()

MobilizedBody::Ground & Ground ()

ConstraintIndex adoptConstraint (Constraint &)

const Constraint & getConstraint (ConstraintIndex) const

Constraint & updConstraint (ConstraintIndex)

void calcAcceleration (const State &, const Vector &mobilityForces, const Vector_< SpatialVec > &bodyForces, Vector &udot, Vector_< SpatialVec > &A_GB) const

This is the primary dynamics operator.

void calcAccelerationIgnoringConstraints (const State &, const Vector &mobilityForces, const Vector_< SpatialVec > &bodyForces, Vector &udot, Vector_< SpatialVec > &A_GB) const

This operator is similar to calcAcceleration but ignores the effects of acceleration constraints.

void calcMInverseV (const State &, const Vector &v, Vector &MinvV, Vector_< SpatialVec > &A_GB) const

This operator calculates M^-1 v where M is the system mass matrix and v is a supplied vector with one entry per mobility.

void calcSpatialKinematicsFromInternal (const State &, const Vector &v, Vector_< SpatialVec > &Jv) const

Requires realization through Stage::Position.

void calcInternalGradientFromSpatial (const State &, const Vector_< SpatialVec > &dEdR, Vector &dEdQ) const

Requires realization through Stage::Position.

Real calcKineticEnergy (const State &) const

Requires realization through Stage::Velocity.

void calcTreeEquivalentMobilityForces (const State &, const Vector_< SpatialVec > &bodyForces, Vector &mobilityForces) const

Accounts for applied forces and centrifugal forces produced by non-zero velocities in the State.

void calcQDot (const State &s, const Vector &u, Vector &qdot) const

Must be in Stage::Position to calculate qdot = Q(q)*u.

void calcQDotDot (const State &s, const Vector &udot, Vector &qdotdot) const

Must be in Stage::Velocity to calculate qdotdot = Q(q)*udot + Qdot(q,u)*u.

void multiplyByQMatrix (const State &s, bool transposeMatrix, const Vector &in, Vector &out) const

Must be in Stage::Position to calculate out_q = Q(q)*in_u (e.g., qdot=Q*u) or out_u = ~Q*in_q.

void multiplyByQMatrixInverse (const State &s, bool transposeMatrix, const Vector &in, Vector &out) const

Must be in Stage::Position to calculate out_u = QInv(q)*in_q (e.g., u=QInv*qdot) or out_q = ~QInv*in_u.

void calcMobilizerReactionForces (const State &s, Vector_< SpatialVec > &forces) const

Calculate the mobilizer reaction force generated by each MobilizedBody.

int getNBodies () const

The number of bodies includes all rigid bodies, massless bodies and ground but not particles.

int getNConstraints () const

This is the total number of defined constraints, each of which may generate more than one constraint equation.

int getNParticles () const

TODO: total number of particles.

int getNMobilities () const

The sum of all the mobilizer degrees of freedom.

int getTotalQAlloc () const

The sum of all the q vector allocations for each joint.

int getTotalMultAlloc () const

This is the sum of all the allocations for constraint multipliers, one per acceleration constraint equation.

void setUseEulerAngles (State &, bool) const

For all mobilizers offering unrestricted orientation, decide what method we should use to model their orientations.

bool getUseEulerAngles (const State &) const

int getNQuaternionsInUse (const State &) const

void setMobilizerIsPrescribed (State &, MobilizedBodyIndex, bool) const

bool isMobilizerPrescribed (const State &, MobilizedBodyIndex) const

bool isUsingQuaternion (const State &, MobilizedBodyIndex) const

QuaternionPoolIndex getQuaternionPoolIndex (const State &, MobilizedBodyIndex) const

AnglePoolIndex getAnglePoolIndex (const State &, MobilizedBodyIndex) const

void setConstraintIsDisabled (State &, ConstraintIndex constraint, bool) const

bool isConstraintDisabled (const State &, ConstraintIndex constraint) const

void convertToEulerAngles (const State &inputState, State &outputState) const

Given a State which is modeled using quaternions, convert it to a representation based on Euler angles and store the result in another state.

void convertToQuaternions (const State &inputState, State &outputState) const

Given a State which is modeled using Euler angles, convert it to a representation based on quaternions and store the result in another state.

const SpatialVec & getCoriolisAcceleration (const State &, MobilizedBodyIndex) const

const SpatialVec & getTotalCoriolisAcceleration (const State &, MobilizedBodyIndex) const

const SpatialVec & getGyroscopicForce (const State &, MobilizedBodyIndex) const

const SpatialVec & getCentrifugalForces (const State &, MobilizedBodyIndex) const

const SpatialMat & getArticulatedBodyInertia (const State &s, MobilizedBodyIndex) const

const Vector_< Vec3 > & getAllParticleLocations (const State &) const

const Vector_< Vec3 > & getAllParticleVelocities (const State &) const

const Vec3 & getParticleLocation (const State &s, ParticleIndex p) const

const Vec3 & getParticleVelocity (const State &s, ParticleIndex p) const

Vector & updAllParticleMasses (State &s) const

void setAllParticleMasses (State &s, const Vector &masses) const

Vector_< Vec3 > & updAllParticleLocations (State &) const

Vector_< Vec3 > & updAllParticleVelocities (State &) const

Vec3 & updParticleLocation (State &s, ParticleIndex p) const

Vec3 & updParticleVelocity (State &s, ParticleIndex p) const

void setParticleLocation (State &s, ParticleIndex p, const Vec3 &r) const

void setParticleVelocity (State &s, ParticleIndex p, const Vec3 &v) const

void setAllParticleLocations (State &s, const Vector_< Vec3 > &r) const

void setAllParticleVelocities (State &s, const Vector_< Vec3 > &v) const

const Vector & getAllParticleMasses (const State &) const

TODO: not implemented yet; particles must be treated as rigid bodies for now.

const Vector_< Vec3 > & getAllParticleAccelerations (const State &) const

const Vec3 & getParticleAcceleration (const State &s, ParticleIndex p) const

void addInStationForce (const State &, MobilizedBodyIndex bodyB, const Vec3 &stationOnB, const Vec3 &forceInG, Vector_< SpatialVec > &bodyForcesInG) const

Apply a force to a point on a body (a station).

void addInBodyTorque (const State &, MobilizedBodyIndex, const Vec3 &torqueInG, Vector_< SpatialVec > &bodyForcesInG) const

Apply a torque to a body.

void addInMobilityForce (const State &, MobilizedBodyIndex, MobilizerUIndex which, Real f, Vector &mobilityForces) const

Apply a scalar joint force or torque to an axis of the indicated body's mobilizer.

bool projectQConstraints (State &s, Real consAccuracy, const Vector &yWeights, const Vector &ooTols, Vector &yErrest, System::ProjectOptions) const

This is a solver you can call after the State has been realized to stage Position.

bool projectUConstraints (State &s, Real consAccuracy, const Vector &yWeights, const Vector &ooTols, Vector &yErrest, System::ProjectOptions) const

This is a solver you can call after the State has been realized to stage Velocity.

const SimbodyMatterSubsystemRep & getRep () const

SimbodyMatterSubsystemRep & updRep ()

Public Attributes

SimbodyMatterSubsystem

Subsystem

Constructor & Destructor Documentation

SimbodyMatterSubsystem ( )

Create a tree containing only the ground body (body 0).

SimbodyMatterSubsystem ( MultibodySystem & ) [explicit]

~SimbodyMatterSubsystem ( ) [inline]

SimbodyMatterSubsystem ( const SimbodyMatterSubsystem & ss ) [inline]

Member Function Documentation

SimbodyMatterSubsystem& operator= ( const SimbodyMatterSubsystem & ss ) [inline]

References Subsystem::operator=().

bool getShowDefaultGeometry ( ) const

Get whether default decorative geometry is displayed for bodies in this system.

void setShowDefaultGeometry ( bool show )

Set whether default decorative geometry is displayed for bodies in this system.

Real calcSystemMass ( const State & s ) const

Calculate the total system mass.

Required stage: Stage::Instance

Vec3 calcSystemMassCenterLocationInGround ( const State & s ) const

Return the location r_OG_C of the system mass center C, measured from the ground origin OG, and expressed in Ground.

Required stage: Stage::Position

MassProperties calcSystemMassPropertiesInGround ( const State & s ) const

Return total system mass, mass center location measured from the Ground origin, and system inertia taken about the Ground origin, expressed in Ground.

Required stage: Stage::Position

Inertia calcSystemCentralInertiaInGround ( const State & s ) const

Return the system inertia matrix taken about the system center of mass, expressed in Ground.

Required stage: Stage::Position

Vec3 calcSystemMassCenterVelocityInGround ( const State & s ) const

Return the velocity V_G_C = d/dt r_OG_C of the system mass center C in the Ground frame G, expressed in G.

Required stage: Stage::Velocity

Vec3 calcSystemMassCenterAccelerationInGround ( const State & s ) const

Return the acceleration A_G_C = d^2/dt^2 r_OG_C of the system mass center C in the Ground frame G, expressed in G.

Required stage: Stage::Acceleration

SpatialVec calcSystemMomentumAboutGroundOrigin ( const State & s ) const

Return the momentum of the system as a whole (angular, linear) measured in the ground frame, taken about the ground origin and expressed in ground.

(The linear component is independent of the "about" point.)

Required stage: Stage::Velocity

MobilizedBodyIndex adoptMobilizedBody	(	MobilizedBodyIndex	parent,
		MobilizedBody &	child
	)

const MobilizedBody& getMobilizedBody ( MobilizedBodyIndex ) const

MobilizedBody& updMobilizedBody ( MobilizedBodyIndex )

const MobilizedBody::Ground& getGround ( ) const

MobilizedBody::Ground& updGround ( )

MobilizedBody::Ground& Ground ( ) [inline]

ConstraintIndex adoptConstraint ( Constraint & )

const Constraint& getConstraint ( ConstraintIndex ) const

Constraint& updConstraint ( ConstraintIndex )

void calcAcceleration	(	const State &	,
		const Vector &	mobilityForces,
		const Vector_< SpatialVec > &	bodyForces,
		Vector &	udot,
		Vector_< SpatialVec > &	A_GB
	)			const

This is the primary dynamics operator.

It takes a state which has been realized to the Dynamics stage, a complete set of forces to apply, and returns the accelerations that result. Only the forces supplied here, and those resulting from centrifugal effects, affect the results. Everything in the matter subsystem is accounted for including velocities and acceleration constraints, which will always be satisified as long as the constraints are consistent. If the position and velocity constraints aren't already satisified in the State, these accelerations are harder to interpret physically, but they will still be calculated and the acceleration constraints will still be satisified. No attempt will be made to satisfy position and velocity constraints, or even to check whether they are statisfied. This is an O(n*nc^2) operator worst case where all nc constraint equations are coupled. Requires prior realization through Stage::Dynamics.

void calcAccelerationIgnoringConstraints	(	const State &	,
		const Vector &	mobilityForces,
		const Vector_< SpatialVec > &	bodyForces,
		Vector &	udot,
		Vector_< SpatialVec > &	A_GB
	)			const

This operator is similar to calcAcceleration but ignores the effects of acceleration constraints.

The supplied forces and velocity-induced centrifugal effects are properly accounted for, but any forces that would have resulted from enforcing the contraints are not present. This is an O(N) operator. Requires prior realization through Stage::Dynamics.

void calcMInverseV	(	const State &	,
		const Vector &	v,
		Vector &	MinvV,
		Vector_< SpatialVec > &	A_GB
	)			const

This operator calculates M^-1 v where M is the system mass matrix and v is a supplied vector with one entry per mobility.

If v is a set of mobility forces f, the result is a generalized acceleration (udot=M^-1 f). Only the supplied vector is used, and M depends only on position states, so the result here is not affected by velocities in the State. However, this fast O(N) operator requires that the Dynamics stage operators are already available, so the State must be realized to Stage::Dynamics even though velocities are ignored. Requires prior realization through Stage::Dynamics.

void calcSpatialKinematicsFromInternal	(	const State &	,
		const Vector &	v,
		Vector_< SpatialVec > &	Jv
	)			const

Requires realization through Stage::Position.

void calcInternalGradientFromSpatial	(	const State &	,
		const Vector_< SpatialVec > &	dEdR,
		Vector &	dEdQ
	)			const

Requires realization through Stage::Position.

Real calcKineticEnergy ( const State & ) const

Requires realization through Stage::Velocity.

void calcTreeEquivalentMobilityForces	(	const State &	,
		const Vector_< SpatialVec > &	bodyForces,
		Vector &	mobilityForces
	)			const

Accounts for applied forces and centrifugal forces produced by non-zero velocities in the State.

Returns a set of mobility forces which replace both the applied bodyForces and the centrifugal forces. Requires prior realization through Stage::Dynamics.

void calcQDot	(	const State &	s,
		const Vector &	u,
		Vector &	qdot
	)			const

Must be in Stage::Position to calculate qdot = Q(q)*u.

void calcQDotDot	(	const State &	s,
		const Vector &	udot,
		Vector &	qdotdot
	)			const

Must be in Stage::Velocity to calculate qdotdot = Q(q)*udot + Qdot(q,u)*u.

void multiplyByQMatrix	(	const State &	s,
		bool	transposeMatrix,
		const Vector &	in,
		Vector &	out
	)			const

Must be in Stage::Position to calculate out_q = Q(q)*in_u (e.g., qdot=Q*u) or out_u = ~Q*in_q.

Note that one of "in" and "out" is always "q-like" while the other is "u-like", but which is which changes if the matrix is transposed. Note that the transposed operation here is the same as multiplying by Q on the right, with the Vectors viewed as RowVectors instead. This is an O(N) operator since Q is block diagonal.

void multiplyByQMatrixInverse	(	const State &	s,
		bool	transposeMatrix,
		const Vector &	in,
		Vector &	out
	)			const

Must be in Stage::Position to calculate out_u = QInv(q)*in_q (e.g., u=QInv*qdot) or out_q = ~QInv*in_u.

Note that one of "in" and "out" is always "q-like" while the other is "u-like", but which is which changes if the matrix is transposed. Note that the transposed operation here is the same as multiplying by QInv on the right, with the Vectors viewed as RowVectors instead. This is an O(N) operator since QInv is block diagonal.

void calcMobilizerReactionForces	(	const State &	s,
		Vector_< SpatialVec > &	forces
	)			const

Calculate the mobilizer reaction force generated by each MobilizedBody.

This is the constraint force that would be required to make the system move in the same way if that MobilizedBody were converted to a Free body. A mobilizer exerts equal and opposite reaction forces on the parent and child bodies. This method reports the force on the child body. The force is applied at the origin of the outboard frame M, and expressed in the ground frame.

The State must have been realized to Stage::Acceleration to use this method.

int getNBodies ( ) const

The number of bodies includes all rigid bodies, massless bodies and ground but not particles.

Bodies and their inboard mobilizers have the same number since they are grouped together as a MobilizedBody MobilizedBody numbering starts with ground at 0 with a regular labeling such that children have higher body numbers than their parents. Mobilizer 0 is meaningless (or I suppose you could think of it as the weld joint that attaches ground to the universe), but otherwise mobilizer n is the inboard mobilizer of body n.

int getNConstraints ( ) const

This is the total number of defined constraints, each of which may generate more than one constraint equation.

int getNParticles ( ) const

TODO: total number of particles.

int getNMobilities ( ) const

The sum of all the mobilizer degrees of freedom.

This is also the length of the state variable vector u and the mobility forces array.

int getTotalQAlloc ( ) const

The sum of all the q vector allocations for each joint.

There may be some that are not in use for particular modeling options.

int getTotalMultAlloc ( ) const

This is the sum of all the allocations for constraint multipliers, one per acceleration constraint equation.

void setUseEulerAngles	(	State &	,
		bool
	)			const

For all mobilizers offering unrestricted orientation, decide what method we should use to model their orientations.

Choices are: quaternions (best for dynamics), or rotation angles (1-2-3 Euler sequence, good for optimization). TODO: (1) other Euler sequences, (2) allow settable zero rotation for Euler sequence, with convenient way to say "this is zero".

bool getUseEulerAngles ( const State & ) const

int getNQuaternionsInUse ( const State & ) const

void setMobilizerIsPrescribed	(	State &	,
		MobilizedBodyIndex	,
		bool
	)			const

bool isMobilizerPrescribed	(	const State &	,
		MobilizedBodyIndex
	)			const

bool isUsingQuaternion	(	const State &	,
		MobilizedBodyIndex
	)			const

QuaternionPoolIndex getQuaternionPoolIndex	(	const State &	,
		MobilizedBodyIndex
	)			const

AnglePoolIndex getAnglePoolIndex	(	const State &	,
		MobilizedBodyIndex
	)			const

void setConstraintIsDisabled	(	State &	,
		ConstraintIndex	constraint,
		bool
	)			const

bool isConstraintDisabled	(	const State &	,
		ConstraintIndex	constraint
	)			const

void convertToEulerAngles	(	const State &	inputState,
		State &	outputState
	)			const

Given a State which is modeled using quaternions, convert it to a representation based on Euler angles and store the result in another state.

void convertToQuaternions	(	const State &	inputState,
		State &	outputState
	)			const

Given a State which is modeled using Euler angles, convert it to a representation based on quaternions and store the result in another state.

const SpatialVec& getCoriolisAcceleration	(	const State &	,
		MobilizedBodyIndex
	)			const

const SpatialVec& getTotalCoriolisAcceleration	(	const State &	,
		MobilizedBodyIndex
	)			const

const SpatialVec& getGyroscopicForce	(	const State &	,
		MobilizedBodyIndex
	)			const

const SpatialVec& getCentrifugalForces	(	const State &	,
		MobilizedBodyIndex
	)			const

const SpatialMat& getArticulatedBodyInertia	(	const State &	s,
		MobilizedBodyIndex
	)			const

const Vector_<Vec3>& getAllParticleLocations ( const State & ) const

const Vector_<Vec3>& getAllParticleVelocities ( const State & ) const

const Vec3& getParticleLocation	(	const State &	s,
		ParticleIndex	p
	)			const `[inline]`

const Vec3& getParticleVelocity	(	const State &	s,
		ParticleIndex	p
	)			const `[inline]`

Vector& updAllParticleMasses ( State & s ) const

void setAllParticleMasses	(	State &	s,
		const Vector &	masses
	)			const `[inline]`

Vector_<Vec3>& updAllParticleLocations ( State & ) const

Vector_<Vec3>& updAllParticleVelocities ( State & ) const

Vec3& updParticleLocation	(	State &	s,
		ParticleIndex	p
	)			const `[inline]`

Vec3& updParticleVelocity	(	State &	s,
		ParticleIndex	p
	)			const `[inline]`

void setParticleLocation	(	State &	s,
		ParticleIndex	p,
		const Vec3 &	r
	)			const `[inline]`

void setParticleVelocity	(	State &	s,
		ParticleIndex	p,
		const Vec3 &	v
	)			const `[inline]`

void setAllParticleLocations	(	State &	s,
		const Vector_< Vec3 > &	r
	)			const `[inline]`

void setAllParticleVelocities	(	State &	s,
		const Vector_< Vec3 > &	v
	)			const `[inline]`

const Vector& getAllParticleMasses ( const State & ) const

TODO: not implemented yet; particles must be treated as rigid bodies for now.

const Vector_<Vec3>& getAllParticleAccelerations ( const State & ) const

const Vec3& getParticleAcceleration	(	const State &	s,
		ParticleIndex	p
	)			const `[inline]`

void addInStationForce	(	const State &	,
		MobilizedBodyIndex	bodyB,
		const Vec3 &	stationOnB,
		const Vec3 &	forceInG,
		Vector_< SpatialVec > &	bodyForcesInG
	)			const

Apply a force to a point on a body (a station).

Provide the station in the body frame, force in the ground frame. Must be realized to Position stage prior to call.

void addInBodyTorque	(	const State &	,
		MobilizedBodyIndex	,
		const Vec3 &	torqueInG,
		Vector_< SpatialVec > &	bodyForcesInG
	)			const

Apply a torque to a body.

Provide the torque vector in the ground frame.

void addInMobilityForce	(	const State &	,
		MobilizedBodyIndex	,
		MobilizerUIndex	which,
		Real	f,
		Vector &	mobilityForces
	)			const

Apply a scalar joint force or torque to an axis of the indicated body's mobilizer.

bool projectQConstraints	(	State &	s,
		Real	consAccuracy,
		const Vector &	yWeights,
		const Vector &	ooTols,
		Vector &	yErrest,
		System::ProjectOptions
	)			const

This is a solver you can call after the State has been realized to stage Position.

It will project the Q constraints along the error norm so that getQConstraintNorm() <= consAccuracy, and will project out the corresponding component of yErrest so that yErrest's Q norm is reduced. Returns true if it does anything at all to State or yErrest.

bool projectUConstraints	(	State &	s,
		Real	consAccuracy,
		const Vector &	yWeights,
		const Vector &	ooTols,
		Vector &	yErrest,
		System::ProjectOptions
	)			const

This is a solver you can call after the State has been realized to stage Velocity.

It will project the U constraints along the error norm so that getUConstraintNorm() <= consAccuracy, and will project out the corresponding component of yErrest so that yErrest's U norm is reduced. Returns true if it does anything at all to State or yErrest.

const SimbodyMatterSubsystemRep& getRep ( ) const

SimbodyMatterSubsystemRep& updRep ( )

Member Data Documentation

SimbodyMatterSubsystem

Subsystem

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

SimbodyMatterSubsystem.h


Public Member Functions
	SimbodyMatterSubsystem ()
	Create a tree containing only the ground body (body 0).
	SimbodyMatterSubsystem (MultibodySystem &)
	~SimbodyMatterSubsystem ()
	SimbodyMatterSubsystem (const SimbodyMatterSubsystem &ss)
SimbodyMatterSubsystem &	operator= (const SimbodyMatterSubsystem &ss)
bool	getShowDefaultGeometry () const
	Get whether default decorative geometry is displayed for bodies in this system.
void	setShowDefaultGeometry (bool show)
	Set whether default decorative geometry is displayed for bodies in this system.
Real	calcSystemMass (const State &s) const
	Calculate the total system mass.
Vec3	calcSystemMassCenterLocationInGround (const State &s) const
	Return the location r_OG_C of the system mass center C, measured from the ground origin OG, and expressed in Ground.
MassProperties	calcSystemMassPropertiesInGround (const State &s) const
	Return total system mass, mass center location measured from the Ground origin, and system inertia taken about the Ground origin, expressed in Ground.
Inertia	calcSystemCentralInertiaInGround (const State &s) const
	Return the system inertia matrix taken about the system center of mass, expressed in Ground.
Vec3	calcSystemMassCenterVelocityInGround (const State &s) const
	Return the velocity V_G_C = d/dt r_OG_C of the system mass center C in the Ground frame G, expressed in G.
Vec3	calcSystemMassCenterAccelerationInGround (const State &s) const
	Return the acceleration A_G_C = d^2/dt^2 r_OG_C of the system mass center C in the Ground frame G, expressed in G.
SpatialVec	calcSystemMomentumAboutGroundOrigin (const State &s) const
	Return the momentum of the system as a whole (angular, linear) measured in the ground frame, taken about the ground origin and expressed in ground.
MobilizedBodyIndex	adoptMobilizedBody (MobilizedBodyIndex parent, MobilizedBody &child)
const MobilizedBody &	getMobilizedBody (MobilizedBodyIndex) const
MobilizedBody &	updMobilizedBody (MobilizedBodyIndex)
const MobilizedBody::Ground &	getGround () const
MobilizedBody::Ground &	updGround ()
MobilizedBody::Ground &	Ground ()
ConstraintIndex	adoptConstraint (Constraint &)
const Constraint &	getConstraint (ConstraintIndex) const
Constraint &	updConstraint (ConstraintIndex)
void	calcAcceleration (const State &, const Vector &mobilityForces, const Vector_< SpatialVec > &bodyForces, Vector &udot, Vector_< SpatialVec > &A_GB) const
	This is the primary dynamics operator.
void	calcAccelerationIgnoringConstraints (const State &, const Vector &mobilityForces, const Vector_< SpatialVec > &bodyForces, Vector &udot, Vector_< SpatialVec > &A_GB) const
	This operator is similar to calcAcceleration but ignores the effects of acceleration constraints.
void	calcMInverseV (const State &, const Vector &v, Vector &MinvV, Vector_< SpatialVec > &A_GB) const
	This operator calculates M^-1 v where M is the system mass matrix and v is a supplied vector with one entry per mobility.
void	calcSpatialKinematicsFromInternal (const State &, const Vector &v, Vector_< SpatialVec > &Jv) const
	Requires realization through Stage::Position.
void	calcInternalGradientFromSpatial (const State &, const Vector_< SpatialVec > &dEdR, Vector &dEdQ) const
	Requires realization through Stage::Position.
Real	calcKineticEnergy (const State &) const
	Requires realization through Stage::Velocity.
void	calcTreeEquivalentMobilityForces (const State &, const Vector_< SpatialVec > &bodyForces, Vector &mobilityForces) const
	Accounts for applied forces and centrifugal forces produced by non-zero velocities in the State.
void	calcQDot (const State &s, const Vector &u, Vector &qdot) const
	Must be in Stage::Position to calculate qdot = Q(q)*u.
void	calcQDotDot (const State &s, const Vector &udot, Vector &qdotdot) const
	Must be in Stage::Velocity to calculate qdotdot = Q(q)udot + Qdot(q,u)u.
void	multiplyByQMatrix (const State &s, bool transposeMatrix, const Vector &in, Vector &out) const
	Must be in Stage::Position to calculate out_q = Q(q)in_u (e.g., qdot=Qu) or out_u = ~Q*in_q.
void	multiplyByQMatrixInverse (const State &s, bool transposeMatrix, const Vector &in, Vector &out) const
	Must be in Stage::Position to calculate out_u = QInv(q)in_q (e.g., u=QInvqdot) or out_q = ~QInv*in_u.
void	calcMobilizerReactionForces (const State &s, Vector_< SpatialVec > &forces) const
	Calculate the mobilizer reaction force generated by each MobilizedBody.
int	getNBodies () const
	The number of bodies includes all rigid bodies, massless bodies and ground but not particles.
int	getNConstraints () const
	This is the total number of defined constraints, each of which may generate more than one constraint equation.
int	getNParticles () const
	TODO: total number of particles.
int	getNMobilities () const
	The sum of all the mobilizer degrees of freedom.
int	getTotalQAlloc () const
	The sum of all the q vector allocations for each joint.
int	getTotalMultAlloc () const
	This is the sum of all the allocations for constraint multipliers, one per acceleration constraint equation.
void	setUseEulerAngles (State &, bool) const
	For all mobilizers offering unrestricted orientation, decide what method we should use to model their orientations.
bool	getUseEulerAngles (const State &) const
int	getNQuaternionsInUse (const State &) const
void	setMobilizerIsPrescribed (State &, MobilizedBodyIndex, bool) const
bool	isMobilizerPrescribed (const State &, MobilizedBodyIndex) const
bool	isUsingQuaternion (const State &, MobilizedBodyIndex) const
QuaternionPoolIndex	getQuaternionPoolIndex (const State &, MobilizedBodyIndex) const
AnglePoolIndex	getAnglePoolIndex (const State &, MobilizedBodyIndex) const
void	setConstraintIsDisabled (State &, ConstraintIndex constraint, bool) const
bool	isConstraintDisabled (const State &, ConstraintIndex constraint) const
void	convertToEulerAngles (const State &inputState, State &outputState) const
	Given a State which is modeled using quaternions, convert it to a representation based on Euler angles and store the result in another state.
void	convertToQuaternions (const State &inputState, State &outputState) const
	Given a State which is modeled using Euler angles, convert it to a representation based on quaternions and store the result in another state.
const SpatialVec &	getCoriolisAcceleration (const State &, MobilizedBodyIndex) const
const SpatialVec &	getTotalCoriolisAcceleration (const State &, MobilizedBodyIndex) const
const SpatialVec &	getGyroscopicForce (const State &, MobilizedBodyIndex) const
const SpatialVec &	getCentrifugalForces (const State &, MobilizedBodyIndex) const
const SpatialMat &	getArticulatedBodyInertia (const State &s, MobilizedBodyIndex) const
const Vector_< Vec3 > &	getAllParticleLocations (const State &) const
const Vector_< Vec3 > &	getAllParticleVelocities (const State &) const
const Vec3 &	getParticleLocation (const State &s, ParticleIndex p) const
const Vec3 &	getParticleVelocity (const State &s, ParticleIndex p) const
Vector &	updAllParticleMasses (State &s) const
void	setAllParticleMasses (State &s, const Vector &masses) const
Vector_< Vec3 > &	updAllParticleLocations (State &) const
Vector_< Vec3 > &	updAllParticleVelocities (State &) const
Vec3 &	updParticleLocation (State &s, ParticleIndex p) const
Vec3 &	updParticleVelocity (State &s, ParticleIndex p) const
void	setParticleLocation (State &s, ParticleIndex p, const Vec3 &r) const
void	setParticleVelocity (State &s, ParticleIndex p, const Vec3 &v) const
void	setAllParticleLocations (State &s, const Vector_< Vec3 > &r) const
void	setAllParticleVelocities (State &s, const Vector_< Vec3 > &v) const
const Vector &	getAllParticleMasses (const State &) const
	TODO: not implemented yet; particles must be treated as rigid bodies for now.
const Vector_< Vec3 > &	getAllParticleAccelerations (const State &) const
const Vec3 &	getParticleAcceleration (const State &s, ParticleIndex p) const
void	addInStationForce (const State &, MobilizedBodyIndex bodyB, const Vec3 &stationOnB, const Vec3 &forceInG, Vector_< SpatialVec > &bodyForcesInG) const
	Apply a force to a point on a body (a station).
void	addInBodyTorque (const State &, MobilizedBodyIndex, const Vec3 &torqueInG, Vector_< SpatialVec > &bodyForcesInG) const
	Apply a torque to a body.
void	addInMobilityForce (const State &, MobilizedBodyIndex, MobilizerUIndex which, Real f, Vector &mobilityForces) const
	Apply a scalar joint force or torque to an axis of the indicated body's mobilizer.
bool	projectQConstraints (State &s, Real consAccuracy, const Vector &yWeights, const Vector &ooTols, Vector &yErrest, System::ProjectOptions) const
	This is a solver you can call after the State has been realized to stage Position.
bool	projectUConstraints (State &s, Real consAccuracy, const Vector &yWeights, const Vector &ooTols, Vector &yErrest, System::ProjectOptions) const
	This is a solver you can call after the State has been realized to stage Velocity.
const SimbodyMatterSubsystemRep &	getRep () const
SimbodyMatterSubsystemRep &	updRep ()
Public Attributes
	SimbodyMatterSubsystem
	Subsystem