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SimTK::MobilizedBody::Bushing Class Reference

Six mobilities – arbitrary relative motion modeled as x-y-z translation followed by an x-y-z body-fixed Euler angle sequence, though with a singularity when the middle angle is +/- 90 degrees. More...

+ Inheritance diagram for SimTK::MobilizedBody::Bushing:

Public Member Functions

 Bushing ()
 Construct an empty handle that can be assigned to reference any MobilizedBody::Bushing. More...
 
 Bushing (MobilizedBody &parent, const Transform &X_PF, const Body &bodyInfo, const Transform &X_BM, Direction=Forward)
 Create a Bushing mobilizer between an existing parent (inboard) body P and a new child (outboard) body B created by copying the given bodyInfo into a privately-owned Body within the constructed MobilizedBody object. More...
 
 Bushing (MobilizedBody &parent, const Body &bodyInfo, Direction=Forward)
 Abbreviated constructor you can use if the mobilizer frames are coincident with the parent and child body frames. More...
 
BushingsetDefaultInboardFrame (const Transform &X_PF)
 Change the default inboard ("fixed") frame F on the parent body of this mobilizer. More...
 
BushingsetDefaultOutboardFrame (const Transform &X_BM)
 Change the default outboard ("moving") frame M on this mobilized body (that is, on this mobilizer's child body). More...
 
BushingsetDefaultTransform (const Transform &X_FM)
 Override the default pose for this mobilizer. More...
 
Transform getDefaultTransform () const
 Return the default pose for this mobilizer as a Transform. More...
 
BushingaddBodyDecoration (const Transform &X_BD, const DecorativeGeometry &g)
 Add DecorativeGeometry to the privately-owned Body contained in this MobilizedBody, positioned relative to the body's frame. More...
 
BushingaddOutboardDecoration (const Transform &X_MD, const DecorativeGeometry &g)
 Add DecorativeGeometry to the privately-owned Body contained in this MobilizedBody, positioned relative to the mobilizer's M frame on that body. More...
 
BushingaddInboardDecoration (const Transform &X_FD, const DecorativeGeometry &g)
 Add DecorativeGeometry to the parent (inboard) body of this mobilizer, positioned relative to the mobilizer's F frame on the parent body. More...
 
const Vec6getDefaultQ () const
 Obtain the default value for the generalized coordinates q that has been set for this mobilizer. More...
 
BushingsetDefaultQ (const Vec6 &q)
 Set the default value for the generalized coordinates q for this mobilizer. More...
 
const Vec6getQ (const State &state) const
 Obtain the current value for this mobilizer's generalized coordinates q from the given State, which must be realized through Stage::Model (these are state variables). More...
 
const Vec6getQDot (const State &state) const
 Obtain the current value for this mobilizer's generalized coordinate time derivatives qdot from the given State, which must be realized through Stage::Velocity. More...
 
const Vec6getQDotDot (const State &state) const
 Obtain the current value for this mobilizer's generalized coordinate second time derivatives qdotdot from the given State, which must be realized through Stage::Acceleration. More...
 
const Vec6getU (const State &state) const
 Obtain the current value for this mobilizer's generalized speeds u from the given State, which must be realized through Stage::Model (these are state variables). More...
 
const Vec6getUDot (const State &state) const
 Obtain the current value for this mobilizer's generalized accelerations udot (=d/dt u) from the given State, which must be realized through Stage::Acceleration. More...
 
void setQ (State &state, const Vec6 &q) const
 Set new values for this mobilizer's generalized coordinates q in the given state. More...
 
void setU (State &state, const Vec6 &u) const
 Set new values for this mobilizer's generalized speeds u in the given state. More...
 
Advanced/Obscure

Most users won't use these methods.

const Vec6getMyPartQ (const State &state, const Vector &qlike) const
 Given a vector in the System's generalized coordinate basis, extract the six q's belonging to this mobilizer. More...
 
const Vec6getMyPartU (const State &state, const Vector &ulike) const
 Given a vector in the System's generalized speed basis, extract the six u's belonging to this mobilizer. More...
 
Vec6updMyPartQ (const State &state, Vector &qlike) const
 Given a writable vector in the System's generalized coordinate basis, extract a writable reference to the six q's in that vector that belong to this mobilizer. More...
 
Vec6updMyPartU (const State &state, Vector &ulike) const
 Given a writable vector in the System's generalized speed basis, extract a writable reference to the six u's in that vector that belong to this mobilizer. More...
 
- Public Member Functions inherited from SimTK::MobilizedBody
 MobilizedBody ()
 The default constructor provides an empty MobilizedBody handle that can be assigned to reference any type of MobilizedBody. More...
 
 MobilizedBody (MobilizedBodyImpl *r)
 Internal use only. More...
 
void lock (State &state, Motion::Level level=Motion::Position) const
 Lock this mobilizer's position or velocity at its current value, or lock the acceleration to zero, depending on the level parameter. More...
 
void lockAt (State &state, Real value, Motion::Level level=Motion::Position) const
 Lock this mobilizer's q, u, or udot to the given scalar value, depending on level. More...
 
void lockAt (State &state, const Vector &value, Motion::Level level=Motion::Position) const
 Lock this mobilizer's q, u, or udot to the given Vector value, depending on level. More...
 
template<int N>
void lockAt (State &state, const Vec< N > &value, Motion::Level level=Motion::Position) const
 Lock this mobilizer's q, u, or udot to the given Vec<N> value, depending on the level. More...
 
void unlock (State &state) const
 Unlock this mobilizer, returning it to its normal behavior which may be free motion or may be controlled by a Motion object. More...
 
bool isLocked (const State &state) const
 Check whether this mobilizer is currently locked in the given state. More...
 
Motion::Level getLockLevel (const State &state) const
 Returns the lock level if the mobilizer is locked in the given state, otherwise Motion::NoLevel. More...
 
Vector getLockValueAsVector (const State &state) const
 Return the q, u, or udot value at which this mobilizer is locked, depending on the lock level, as a Vector of the appropriate length. More...
 
MobilizedBodylockByDefault (Motion::Level level=Motion::Position)
 Change whether this mobilizer is initially locked. More...
 
bool isLockedByDefault () const
 Check whether this mobilizer is to be locked in the default state. More...
 
Motion::Level getLockByDefaultLevel () const
 Returns the level at which the mobilizer is locked by default, if it is locked by default, otherwise Motion::NoLevel. More...
 
const TransformgetBodyTransform (const State &state) const
 Extract from the state cache the already-calculated spatial configuration X_GB of body B's body frame, measured with respect to the Ground frame and expressed in the Ground frame. More...
 
const RotationgetBodyRotation (const State &state) const
 Extract from the state cache the already-calculated spatial orientation R_GB of body B's body frame x, y, and z axes expressed in the Ground frame, as the Rotation matrix R_GB. More...
 
const Vec3getBodyOriginLocation (const State &state) const
 Extract from the state cache the already-calculated spatial location of body B's body frame origin Bo, measured from the Ground origin Go and expressed in the Ground frame, as the position vector p_GB (== p_GoBo). More...
 
const TransformgetMobilizerTransform (const State &state) const
 At stage Position or higher, return the cross-mobilizer transform X_FM, the body's inboard mobilizer frame M measured and expressed in the parent body's corresponding outboard frame F. More...
 
const SpatialVecgetBodyVelocity (const State &state) const
 Extract from the state cache the already-calculated spatial velocity V_GB of this body's reference frame B, measured with respect to the Ground frame and expressed in the Ground frame. More...
 
const Vec3getBodyAngularVelocity (const State &state) const
 Extract from the state cache the already-calculated inertial angular velocity vector w_GB of this body B, measured with respect to the Ground frame and expressed in the Ground frame. More...
 
const Vec3getBodyOriginVelocity (const State &state) const
 Extract from the state cache the already-calculated inertial linear velocity vector v_GB (more explicitly, v_GBo) of this body B's origin point Bo, measured with respect to the Ground frame and expressed in the Ground frame. More...
 
const SpatialVecgetMobilizerVelocity (const State &state) const
 At stage Velocity or higher, return the cross-mobilizer velocity V_FM, the relative velocity of this body's "moving" mobilizer frame M in the parent body's corresponding "fixed" frame F, measured and expressed in F. More...
 
const SpatialVecgetBodyAcceleration (const State &state) const
 Extract from the state cache the already-calculated spatial acceleration A_GB of this body's reference frame B, measured with respect to the Ground frame and expressed in the Ground frame. More...
 
const Vec3getBodyAngularAcceleration (const State &state) const
 Extract from the state cache the already-calculated inertial angular acceleration vector b_GB of this body B, measured with respect to the Ground frame and expressed in the Ground frame. More...
 
const Vec3getBodyOriginAcceleration (const State &state) const
 Extract from the state cache the already-calculated inertial linear acceleration vector a_GB (more explicitly, a_GBo) of this body B's origin point Bo, measured with respect to the Ground frame and expressed in the Ground frame. More...
 
const SpatialVecgetMobilizerAcceleration (const State &state) const
 TODO: Not implemented yet – any volunteers? At stage Acceleration, return the cross-mobilizer acceleration A_FM, the relative acceleration of body B's "moving" mobilizer frame M in the parent body's corresponding "fixed" frame F, measured and expressed in F. More...
 
const MassPropertiesgetBodyMassProperties (const State &state) const
 Return a reference to this body's mass properties in the State cache. More...
 
const SpatialInertiagetBodySpatialInertiaInGround (const State &state) const
 Return a reference to the already-calculated SpatialInertia of this body, taken about the body's origin (not its mass center), and expressed in the Ground frame. More...
 
Real getBodyMass (const State &state) const
 Return the mass of this body. More...
 
const Vec3getBodyMassCenterStation (const State &state) const
 Return this body's center of mass station (i.e., the vector fixed in the body, going from body origin to body mass center, expressed in the body frame.) The State must have been realized to Stage::Instance or higher. More...
 
const UnitInertiagetBodyUnitInertiaAboutBodyOrigin (const State &state) const
 Return a reference to this body's unit inertia matrix in the State cache, taken about the body origin and expressed in the body frame. More...
 
const TransformgetInboardFrame (const State &state) const
 Return a reference to this mobilizer's frame F fixed on the parent body P, as the fixed Transform from P's body frame to the frame F fixed to P. More...
 
const TransformgetOutboardFrame (const State &state) const
 Return a reference to this MobilizedBody's mobilizer frame M, as the fixed Transform from this body B's frame to the frame M fixed on B. More...
 
void setInboardFrame (State &state, const Transform &X_PF) const
 TODO: not implemented yet. More...
 
void setOutboardFrame (State &state, const Transform &X_BM) const
 TODO: not implemented yet. More...
 
int getNumQ (const State &state) const
 Return the number of generalized coordinates q currently in use by this mobilizer. More...
 
int getNumU (const State &state) const
 Return the number of generalized speeds u currently in use by this mobilizer. More...
 
QIndex getFirstQIndex (const State &state) const
 Return the global QIndex of the first q for this mobilizer; all the q's range from getFirstQIndex() to QIndex(getFirstQIndex()+getNumQ()-1). More...
 
UIndex getFirstUIndex (const State &state) const
 Return the global UIndex of the first u for this mobilizer; all the u's range from getFirstUIndex() to UIndex(getFirstUIndex()+getNumU()-1). More...
 
Motion::Method getQMotionMethod (const State &state) const
 Determine how generalized coordinate q values are being determined. More...
 
Motion::Method getUMotionMethod (const State &state) const
 Determine how generalized speed u values are being determined. More...
 
Motion::Method getUDotMotionMethod (const State &state) const
 Determine how generalized acceleration udot values are being determined. More...
 
Real getOneQ (const State &state, int which) const
 Return one of the generalized coordinates q from this mobilizer's partition of the matter subsystem's full q vector in the State. More...
 
Real getOneU (const State &state, int which) const
 Return one of the generalized speeds u from this mobilizer's partition of the matter subsystem's full u vector in the State. More...
 
Vector getQAsVector (const State &state) const
 Return as a Vector of length getNumQ() all the generalized coordinates q currently in use by this mobilizer, from this mobilizer's partion in the matter subsystem's full q vector in the State. More...
 
Vector getUAsVector (const State &state) const
 Return as a Vector of length getNumU() all the generalized speeds u currently in use by this mobilizer, from this mobilizer's partion in the matter subsystem's full u vector in the State. More...
 
Real getOneQDot (const State &state, int which) const
 Return one of the generalized coordinate derivatives qdot from this mobilizer's partition of the matter subsystem's full qdot vector in the State cache. More...
 
Vector getQDotAsVector (const State &state) const
 Return as a Vector of length getNumQ() all the generalized coordinate derivatives qdot currently in use by this mobilizer, from this mobilizer's partition in the matter subsystem's full qdot vector in the State cache. More...
 
Real getOneUDot (const State &state, int which) const
 Return one of the generalized accelerations udot from this mobilizer's partition of the matter subsystem's full udot vector in the State cache. More...
 
Real getOneQDotDot (const State &state, int which) const
 Return one of the generalized coordinate second derivatives qdotdot from this mobilizer's partition of the matter subsystem's full qdotdot vector in the State cache. More...
 
Vector getUDotAsVector (const State &state) const
 Return as a Vector of length getNumU() all the generalized accelerations udot currently in use by this mobilizer, from this mobilizer's partion in the matter subsystem's full udot vector in the State cache. More...
 
Vector getQDotDotAsVector (const State &state) const
 Return as a Vector of length getNumQ() all the generalized coordinate second derivatives qdotdot currently in use by this mobilizer, from this mobilizer's partion in the matter subsystem's full qdotdot vector in the State cache. More...
 
Vector getTauAsVector (const State &state) const
 Return the generalized forces tau resulting from prescribed (known) acceleration, corresponding to each of this mobilizer's mobilities, as a Vector of length nu=getNumU(). More...
 
Real getOneTau (const State &state, MobilizerUIndex which) const
 Return one of the tau forces resulting from prescribed (known) acceleration, corresponding to one of this mobilizer's mobilities as selected here using the which parameter, numbered from zero to getNumU()-1. More...
 
void setOneQ (State &state, int which, Real v) const
 Set one of the generalized coordinates q to value v, in this mobilizer's partition of the matter subsystem's full q vector in the State. More...
 
void setOneU (State &state, int which, Real v) const
 Set one of the generalized speeds u to value v, in this mobilizer's partition of the matter subsystem's full u vector in the State. More...
 
void setQFromVector (State &state, const Vector &v) const
 Set all of the generalized coordinates q to value v (a Vector of length getNumQ()), in this mobilizer's partition of the matter subsystem's full q vector in the State. More...
 
void setUFromVector (State &state, const Vector &v) const
 Set all of the generalized speeds u to value v (a Vector of length getNumU()), in this mobilizer's partition of the matter subsystem's full u vector in the State. More...
 
void setQToFitTransform (State &state, const Transform &X_FM) const
 Adjust this mobilizer's q's to best approximate the supplied Transform which requests a particular relative orientation and translation between the F "fixed" frame and M "moving" frame connected by this mobilizer. More...
 
void setQToFitRotation (State &state, const Rotation &R_FM) const
 Adjust this mobilizer's q's to best approximate the supplied Rotation matrix which requests a particular relative orientation between the "fixed" frame F and "moving" frame M connected by this mobilizer. More...
 
void setQToFitTranslation (State &state, const Vec3 &p_FM) const
 Adjust this mobilizer's q's to best approximate the supplied position vector which requests a particular offset between the origins of the F "fixed" frame and M "moving" frame connected by this mobilizer, with any q's (rotational or translational) being modified if doing so helps satisfy the request. More...
 
void setUToFitVelocity (State &state, const SpatialVec &V_FM) const
 Adjust this mobilizer's u's (generalized speeds) to best approximate the supplied spatial velocity V_FM which requests the relative angular and linear velocity between the "fixed" and "moving" frames connected by this mobilizer. More...
 
void setUToFitAngularVelocity (State &state, const Vec3 &w_FM) const
 Adjust this mobilizer's u's (generalized speeds) to best approximate the supplied angular velocity w_FM which requests a particular relative angular between the "fixed" and "moving" frames connected by this mobilizer. More...
 
void setUToFitLinearVelocity (State &state, const Vec3 &v_FM) const
 Adjust any of this mobilizer's u's (generalized speeds) to best approximate the supplied linear velocity v_FM which requests a particular velocity for the "moving" frame M origin in the "fixed" frame F on the parent where these are the frames connected by this mobilizer. More...
 
SpatialVec getHCol (const State &state, MobilizerUIndex ux) const
 Expert use only: obtain a column of the hinge matrix H corresponding to one of this mobilizer's mobilities (actually a column of H_PB_G; what Jain calls H* and Schwieters calls H^T). More...
 
SpatialVec getH_FMCol (const State &state, MobilizerUIndex ux) const
 Expert use only: obtain a column of the mobilizer-local hinge matrix H_FM which maps generalized speeds u to cross-mobilizer spatial velocity V_FM via V_FM=H_FM*u. More...
 
Transform findBodyTransformInAnotherBody (const State &state, const MobilizedBody &inBodyA) const
 Return X_AB, the spatial transform giving this body B's frame in body A's frame. More...
 
Rotation findBodyRotationInAnotherBody (const State &state, const MobilizedBody &inBodyA) const
 Return R_AB, the rotation matrix giving this body B's axes in body A's frame. More...
 
Vec3 findBodyOriginLocationInAnotherBody (const State &state, const MobilizedBody &toBodyA) const
 Return the station on another body A (that is, a point measured and expressed in A) that is currently coincident in space with the origin Bo of this body B. More...
 
SpatialVec findBodyVelocityInAnotherBody (const State &state, const MobilizedBody &inBodyA) const
 Return the angular and linear velocity of body B's frame in body A's frame, expressed in body A, and arranged as a SpatialVec. More...
 
Vec3 findBodyAngularVelocityInAnotherBody (const State &state, const MobilizedBody &inBodyA) const
 Return the angular velocity w_AB of body B's frame in body A's frame, expressed in body A. More...
 
Vec3 findBodyOriginVelocityInAnotherBody (const State &state, const MobilizedBody &inBodyA) const
 Return the velocity of body B's origin point in body A's frame, expressed in body A. More...
 
SpatialVec findBodyAccelerationInAnotherBody (const State &state, const MobilizedBody &inBodyA) const
 Return the angular and linear acceleration of body B's frame in body A's frame, expressed in body A, and arranged as a SpatialVec. More...
 
Vec3 findBodyAngularAccelerationInAnotherBody (const State &state, const MobilizedBody &inBodyA) const
 Return the angular acceleration of body B's frame in body A's frame, expressed in body A. More...
 
Vec3 findBodyOriginAccelerationInAnotherBody (const State &state, const MobilizedBody &inBodyA) const
 Return the acceleration of body B's origin point in body A's frame, expressed in body A. More...
 
SpatialVec findMobilizerReactionOnBodyAtMInGround (const State &state) const
 Return the spatial reaction force (moment and force) applied by the mobilizer to body B at the location of the mobilizer frame M (fixed to body B, but not necessarily at the body frame origin), expressed in Ground. More...
 
SpatialVec findMobilizerReactionOnBodyAtOriginInGround (const State &state) const
 Return the spatial reaction force (moment and force) applied by the mobilizer to body B but shifted to the B frame origin, and expressed in Ground. More...
 
SpatialVec findMobilizerReactionOnParentAtFInGround (const State &state) const
 Return the spatial reaction force (moment and force) applied by the mobilizer to the parent (inboard) body P at the location of the inboard "fixed" mobilizer frame F (fixed to body P, but not necessarily at the P frame origin), expressed in Ground. More...
 
SpatialVec findMobilizerReactionOnParentAtOriginInGround (const State &state) const
 Return the spatial reaction force (moment and force) applied by the mobilizer to the parent (inboard) body P at the location of the P frame origin, and expressed in Ground. More...
 
Vec3 findStationLocationInGround (const State &state, const Vec3 &stationOnB) const
 Return the Cartesian (ground) location that is currently coincident with a station (point) S fixed on body B. More...
 
Vec3 findStationLocationInAnotherBody (const State &state, const Vec3 &stationOnB, const MobilizedBody &toBodyA) const
 Given a station S on this body B, return the location on another body A which is at the same location in space. More...
 
Vec3 findStationVelocityInGround (const State &state, const Vec3 &stationOnB) const
 Given a station fixed on body B, return its inertial (Cartesian) velocity, that is, its velocity relative to the Ground frame, expressed in the Ground frame. More...
 
Vec3 findStationVelocityInAnotherBody (const State &state, const Vec3 &stationOnBodyB, const MobilizedBody &inBodyA) const
 Return the velocity of a station S fixed on body B, in body A's frame, expressed in body A. More...
 
Vec3 findStationAccelerationInGround (const State &state, const Vec3 &stationOnB) const
 Given a station fixed on body B, return its inertial (Cartesian) acceleration, that is, its acceleration relative to the ground frame, expressed in the ground frame. More...
 
Vec3 findStationAccelerationInAnotherBody (const State &state, const Vec3 &stationOnBodyB, const MobilizedBody &inBodyA) const
 Return the acceleration of a station S fixed on body B, in another body A's frame, expressed in body A. More...
 
void findStationLocationAndVelocityInGround (const State &state, const Vec3 &locationOnB, Vec3 &locationOnGround, Vec3 &velocityInGround) const
 It is cheaper to calculate a station's ground location and velocity together than to do them separately. More...
 
void findStationLocationVelocityAndAccelerationInGround (const State &state, const Vec3 &locationOnB, Vec3 &locationOnGround, Vec3 &velocityInGround, Vec3 &accelerationInGround) const
 It is cheaper to calculate a station's ground location, velocity, and acceleration together than to do them separately. More...
 
Vec3 findMassCenterLocationInGround (const State &state) const
 Return the Cartesian (ground) location of this body B's mass center. More...
 
Vec3 findMassCenterLocationInAnotherBody (const State &state, const MobilizedBody &toBodyA) const
 Return the point of another body A that is currently coincident in space with the mass center CB of this body B. More...
 
Vec3 findStationAtGroundPoint (const State &state, const Vec3 &locationInG) const
 Return the station (point) S of this body B that is coincident with the given Ground location. More...
 
Vec3 findStationAtAnotherBodyStation (const State &state, const MobilizedBody &fromBodyA, const Vec3 &stationOnA) const
 Return the station (point) on this body B that is coincident with the given station on another body A. More...
 
Vec3 findStationAtAnotherBodyOrigin (const State &state, const MobilizedBody &fromBodyA) const
 Return the station S of this body that is currently coincident in space with the origin Ao of another body A. More...
 
Vec3 findStationAtAnotherBodyMassCenter (const State &state, const MobilizedBody &fromBodyA) const
 Return the station S of this body that is currently coincident in space with the mass center Ac of another body A. More...
 
Transform findFrameTransformInGround (const State &state, const Transform &frameOnB) const
 Return the current Ground-frame pose (position and orientation) of a frame F that is fixed to body B. More...
 
SpatialVec findFrameVelocityInGround (const State &state, const Transform &frameOnB) const
 Return the current Ground-frame spatial velocity V_GF (that is, angular and linear velocity) of a frame F that is fixed to body B. More...
 
SpatialVec findFrameAccelerationInGround (const State &state, const Transform &frameOnB) const
 Return the current Ground-frame spatial acceleration A_GF (that is, angular and linear acceleration) of a frame F that is fixed to body B. More...
 
Vec3 expressVectorInGroundFrame (const State &state, const Vec3 &vectorInB) const
 Re-express a vector expressed in this body B's frame into the same vector in G, by applying only a rotation. More...
 
Vec3 expressGroundVectorInBodyFrame (const State &state, const Vec3 &vectorInG) const
 Re-express a vector expressed in Ground into the same vector expressed in this body B, by applying only rotation. More...
 
Vec3 expressVectorInAnotherBodyFrame (const State &state, const Vec3 &vectorInB, const MobilizedBody &inBodyA) const
 Re-express a vector expressed in this body B into the same vector expressed in body A, by applying only a rotation. More...
 
MassProperties expressMassPropertiesInGroundFrame (const State &state) const
 Re-express this body B's mass properties in Ground by applying only a rotation, not a shift of reference point. More...
 
MassProperties expressMassPropertiesInAnotherBodyFrame (const State &state, const MobilizedBody &inBodyA) const
 Re-express this body B's mass properties in another body A's frame by applying only a rotation, not a shift of reference point. More...
 
SpatialMat calcBodySpatialInertiaMatrixInGround (const State &state) const
 Return the mass properties of body B, measured from and about the B origin Bo, but expressed in Ground and then returned as a Spatial Inertia Matrix. More...
 
Inertia calcBodyCentralInertia (const State &state, MobilizedBodyIndex objectBodyB) const
 Return the central inertia for body B, that is, the inertia taken about body B's mass center Bc, and expressed in B. More...
 
Inertia calcBodyInertiaAboutAnotherBodyStation (const State &state, const MobilizedBody &inBodyA, const Vec3 &aboutLocationOnBodyA) const
 Return the inertia of this body B, taken about an arbitrary point PA of body A, and expressed in body A. More...
 
SpatialVec calcBodyMomentumAboutBodyOriginInGround (const State &state)
 Calculate body B's momentum (angular, linear) measured and expressed in Ground, but taken about the body origin Bo. More...
 
SpatialVec calcBodyMomentumAboutBodyMassCenterInGround (const State &state) const
 Calculate body B's momentum (angular, linear) measured and expressed in Ground, but taken about the body mass center Bc. More...
 
Real calcStationToStationDistance (const State &state, const Vec3 &locationOnBodyB, const MobilizedBody &bodyA, const Vec3 &locationOnBodyA) const
 Calculate the distance from a station PB on body B to a station PA on body A. More...
 
Real calcStationToStationDistanceTimeDerivative (const State &state, const Vec3 &locationOnBodyB, const MobilizedBody &bodyA, const Vec3 &locationOnBodyA) const
 Calculate the time rate of change of distance from a fixed point PB on body B to a fixed point PA on body A. More...
 
Real calcStationToStationDistance2ndTimeDerivative (const State &state, const Vec3 &locationOnBodyB, const MobilizedBody &bodyA, const Vec3 &locationOnBodyA) const
 Calculate the second time derivative of distance from a fixed point PB on body B to a fixed point PA on body A. More...
 
Vec3 calcBodyMovingPointVelocityInBody (const State &state, const Vec3 &locationOnBodyB, const Vec3 &velocityOnBodyB, const MobilizedBody &inBodyA) const
 TODO: not implemented yet – any volunteers? Return the velocity of a point P moving on body B, in body A's frame, expressed in body A. More...
 
Vec3 calcBodyMovingPointAccelerationInBody (const State &state, const Vec3 &locationOnBodyB, const Vec3 &velocityOnBodyB, const Vec3 &accelerationOnBodyB, const MobilizedBody &inBodyA) const
 TODO: not implemented yet – any volunteers? Return the velocity of a point P moving (and possibly accelerating) on body B, in body A's frame, expressed in body A. More...
 
Real calcMovingPointToPointDistanceTimeDerivative (const State &state, const Vec3 &locationOnBodyB, const Vec3 &velocityOnBodyB, const MobilizedBody &bodyA, const Vec3 &locationOnBodyA, const Vec3 &velocityOnBodyA) const
 TODO: not implemented yet – any volunteers? Calculate the time rate of change of distance from a moving point PB on body B to a moving point PA on body A. More...
 
Real calcMovingPointToPointDistance2ndTimeDerivative (const State &state, const Vec3 &locationOnBodyB, const Vec3 &velocityOnBodyB, const Vec3 &accelerationOnBodyB, const MobilizedBody &bodyA, const Vec3 &locationOnBodyA, const Vec3 &velocityOnBodyA, const Vec3 &accelerationOnBodyA) const
 TODO: not implemented yet – any volunteers? Calculate the second time derivative of distance from a moving point PB on body B to a moving point PA on body A. More...
 
const BodygetBody () const
 Return a const reference to the Body contained within this MobilizedBody. More...
 
BodyupdBody ()
 Return a writable reference to the Body contained within this MobilizedBody. More...
 
MobilizedBodysetBody (const Body &)
 Replace the Body contained within this MobilizedBody with a new one. More...
 
int addBodyDecoration (const Transform &X_BD, const DecorativeGeometry &geometry)
 Add decorative geometry specified relative to the new (outboard) body's reference frame B. More...
 
int addBodyDecoration (const DecorativeGeometry &geometry)
 Convenience method for use when the geometry is supplied in the body frame. More...
 
int addOutboardDecoration (const Transform &X_MD, const DecorativeGeometry &geometry)
 Add decorative geometry specified relative to the outboard mobilizer frame M attached to body B. More...
 
int getNumOutboardDecorations () const
 Return the count of decorations added with addOutboardDecoration(). More...
 
const DecorativeGeometrygetOutboardDecoration (int i) const
 Return a const reference to the i'th outboard decoration. More...
 
DecorativeGeometryupdOutboardDecoration (int i)
 Return a writable reference to the i'th outboard decoration. More...
 
int addInboardDecoration (const Transform &X_FD, const DecorativeGeometry &geometry)
 Add decorative geometry specified relative to the inboard mobilizer frame F attached to the parent body P. More...
 
int getNumInboardDecorations () const
 Return the count of decorations added with addInboardDecoration(). More...
 
const DecorativeGeometrygetInboardDecoration (int i) const
 Return a const reference to the i'th inboard decoration. More...
 
DecorativeGeometryupdInboardDecoration (int i)
 Return a writable reference to the i'th inboard decoration. More...
 
MobilizedBodysetDefaultMassProperties (const MassProperties &m)
 If the contained Body can have its mass properties set to the supplied value m its mass properties are changed, otherwise the method fails. More...
 
const MassPropertiesgetDefaultMassProperties () const
 Return the mass properties of the Body stored within this MobilizedBody. More...
 
void adoptMotion (Motion &ownerHandle)
 Provide a unique Motion object for this MobilizedBody. More...
 
void clearMotion ()
 If there is a Motion object associated with this MobilizedBody it is removed; otherwise, nothing happens. More...
 
bool hasMotion () const
 Check whether this MobilizedBody has an associated Motion object. More...
 
const MotiongetMotion () const
 If there is a Motion object associated with this MobilizedBody, this returns a const reference to it. More...
 
MobilizedBodysetDefaultInboardFrame (const Transform &X_PF)
 Change this mobilizer's frame F on the parent body P. More...
 
MobilizedBodysetDefaultOutboardFrame (const Transform &X_BM)
 Change this mobilizer's frame M fixed on this (the outboard) body B. More...
 
const TransformgetDefaultInboardFrame () const
 Return a reference to this mobilizer's default for the frame F fixed on the parent (inboard) body P, as the fixed Transform from P's body frame to the frame F fixed to P. More...
 
const TransformgetDefaultOutboardFrame () const
 Return a reference to this MobilizedBody's default for mobilizer frame M, as the fixed Transform from this body B's frame to the frame M fixed on B. More...
 
 operator MobilizedBodyIndex () const
 This is an implicit conversion from MobilizedBody to MobilizedBodyIndex when needed. More...
 
MobilizedBodyIndex getMobilizedBodyIndex () const
 Return the MobilizedBodyIndex of this MobilizedBody within the owning SimbodyMatterSubsystem. More...
 
const MobilizedBodygetParentMobilizedBody () const
 Return a reference to the MobilizedBody serving as the parent body of the current MobilizedBody. More...
 
const MobilizedBodygetBaseMobilizedBody () const
 Return a reference to this MobilizedBody's oldest ancestor other than Ground, or return Ground if this MobilizedBody is Ground. More...
 
const SimbodyMatterSubsystemgetMatterSubsystem () const
 Obtain a reference to the SimbodyMatterSubsystem which contains this MobilizedBody. More...
 
SimbodyMatterSubsystemupdMatterSubsystem ()
 Obtain a writable reference to the SimbodyMatterSubsystem which contains this MobilizedBody. More...
 
bool isInSubsystem () const
 Determine whether the current MobilizedBody object is owned by a matter subsystem. More...
 
bool isInSameSubsystem (const MobilizedBody &mobod) const
 Determine whether a given MobilizedBody mobod is in the same matter subsystem as the current body. More...
 
bool isSameMobilizedBody (const MobilizedBody &mobod) const
 Determine whether a given MobilizedBody mobod is the same MobilizedBody as this one. More...
 
bool isGround () const
 Determine whether this body is Ground, meaning that it is actually body 0 of some matter subsytem, not just that its body type is Ground. More...
 
int getLevelInMultibodyTree () const
 Return this body's level in the tree of bodies, starting with ground at 0, bodies directly connected to ground at 1, bodies directly connected to those at 2, etc. More...
 
MobilizedBodycloneForNewParent (MobilizedBody &parent) const
 Create a new MobilizedBody which is identical to this one, except that it has a different parent (and consequently might belong to a different MultibodySystem). More...
 
Real getOneFromQPartition (const State &state, int which, const Vector &qlike) const
 This utility selects one of the q's (generalized coordinates) associated with this mobilizer from a supplied "q-like" Vector, meaning a Vector which is the same length as the Vector of q's for the containing matter subsystem. More...
 
RealupdOneFromQPartition (const State &state, int which, Vector &qlike) const
 This utility returns a writable reference to one of the q's (generalized coordinates) associated with this mobilizer from a supplied "q-like" Vector, meaning a Vector which is the same length as the Vector of q's for the containing matter subsystem. More...
 
Real getOneFromUPartition (const State &state, int which, const Vector &ulike) const
 This utility selects one of the u's (generalized speeds) associated with this mobilizer from a supplied "u-like" Vector, meaning a Vector which is the same length as the Vector of u's for the containing matter subsystem. More...
 
RealupdOneFromUPartition (const State &state, int which, Vector &ulike) const
 This utility returns a writable reference to one of the u's (generalized speeds) associated with this mobilizer from a supplied "u-like" Vector, meaning a Vector which is the same length as the Vector of u's for the containing matter subsystem. More...
 
void applyOneMobilityForce (const State &state, int which, Real f, Vector &mobilityForces) const
 This utility adds in the supplied generalized force f (a scalar) to the appropriate slot of the supplied mobilityForces Vector, which is a "u-like" Vector. More...
 
void convertQForceToUForce (const State &state, const Array_< Real, MobilizerQIndex > &fq, Array_< Real, MobilizerUIndex > &fu) const
 Given a generalized force in the q-space of this mobilizer, convert it to the equivalent generalized mobility force (u-space force). More...
 
void applyBodyForce (const State &state, const SpatialVec &spatialForceInG, Vector_< SpatialVec > &bodyForcesInG) const
 This utility adds in the supplied spatial force spatialForceInG (consisting of a torque vector, and a force vector to be applied at the current body's origin) to the appropriate slot of the supplied bodyForcesInG Vector. More...
 
void applyBodyTorque (const State &state, const Vec3 &torqueInG, Vector_< SpatialVec > &bodyForcesInG) const
 This utility adds in the supplied pure torque torqueInG to the appropriate slot of the supplied bodyForcesInG Vector. More...
 
void applyForceToBodyPoint (const State &state, const Vec3 &pointInB, const Vec3 &forceInG, Vector_< SpatialVec > &bodyForcesInG) const
 This utility adds in the supplied force forceInG applied at a point pointInB to the appropriate slot of the supplied bodyForcesInG Vector. More...
 
- Public Member Functions inherited from SimTK::PIMPLHandle< MobilizedBody, MobilizedBodyImpl, true >
bool isEmptyHandle () const
 Returns true if this handle is empty, that is, does not refer to any implementation object. More...
 
bool isOwnerHandle () const
 Returns true if this handle is the owner of the implementation object to which it refers. More...
 
bool isSameHandle (const MobilizedBody &other) const
 Determine whether the supplied handle is the same object as "this" PIMPLHandle. More...
 
void disown (MobilizedBody &newOwner)
 Give up ownership of the implementation to an empty handle. More...
 
PIMPLHandlereferenceAssign (const MobilizedBody &source)
 "Copy" assignment but with shallow (pointer) semantics. More...
 
PIMPLHandlecopyAssign (const MobilizedBody &source)
 This is real copy assignment, with ordinary C++ object ("value") semantics. More...
 
void clearHandle ()
 Make this an empty handle, deleting the implementation object if this handle is the owner of it. More...
 
const MobilizedBodyImpl & getImpl () const
 Get a const reference to the implementation associated with this Handle. More...
 
MobilizedBodyImpl & updImpl ()
 Get a writable reference to the implementation associated with this Handle. More...
 
int getImplHandleCount () const
 Return the number of handles the implementation believes are referencing it. More...
 

Additional Inherited Members

- Public Types inherited from SimTK::MobilizedBody
enum  Direction {
  Forward = 0,
  Reverse = 1
}
 Constructors can take an argument of this type to indicate that the mobilizer is being defined in the reverse direction, meaning from the outboard (child) body to the inboard (parent) body. More...
 
typedef Pin Torsion
 Synonym for Pin mobilizer. More...
 
typedef Pin Revolute
 Synonym for Pin mobilizer. More...
 
typedef Slider Prismatic
 Synonym for Slider mobilizer. More...
 
typedef Translation Cartesian
 Synonym for Translation mobilizer. More...
 
typedef Translation CartesianCoords
 Synonym for Translation mobilizer. More...
 
typedef BendStretch PolarCoords
 Synonym for BendStretch mobilizer. More...
 
typedef Ball Orientation
 Synonym for Ball mobilizer. More...
 
typedef Ball Spherical
 Synonym for Ball mobilizer. More...
 
- Public Types inherited from SimTK::PIMPLHandle< MobilizedBody, MobilizedBodyImpl, true >
typedef PIMPLHandle
< MobilizedBody,
MobilizedBodyImpl, PTR > 
HandleBase
 
typedef HandleBase ParentHandle
 
- Protected Member Functions inherited from SimTK::PIMPLHandle< MobilizedBody, MobilizedBodyImpl, true >
 PIMPLHandle ()
 The default constructor makes this an empty handle. More...
 
 PIMPLHandle (MobilizedBodyImpl *p)
 This provides consruction of a handle referencing an existing implementation object. More...
 
 PIMPLHandle (const PIMPLHandle &source)
 The copy constructor makes either a deep (value) or shallow (reference) copy of the supplied source PIMPL object, based on whether this is a "pointer semantics" (PTR=true) or "object (value) semantics" (PTR=false, default) class. More...
 
 ~PIMPLHandle ()
 Note that the destructor is non-virtual. More...
 
PIMPLHandleoperator= (const PIMPLHandle &source)
 Copy assignment makes the current handle either a deep (value) or shallow (reference) copy of the supplied source PIMPL object, based on whether this is a "pointer sematics" (PTR=true) or "object (value) semantics" (PTR=false, default) class. More...
 
void setImpl (MobilizedBodyImpl *p)
 Set the implementation for this empty handle. More...
 
bool hasSameImplementation (const MobilizedBody &other) const
 Determine whether the supplied handle is a reference to the same implementation object as is referenced by "this" PIMPLHandle. More...
 

Detailed Description

Six mobilities – arbitrary relative motion modeled as x-y-z translation followed by an x-y-z body-fixed Euler angle sequence, though with a singularity when the middle angle is +/- 90 degrees.

Use MobilizedBody::Free for a similar six-dof joint that is free of singularities.

The six generalized coordinates q are defined q={qx,qy,qz,px,py,pz} where the first three coordinates are the rotation angles and the last three are the Cartesian translations. Note that we follow the usual Simbody convention of having the rotational coordinates precede the translational ones; that does not imply any particular order of operations. In fact, as a sequence this mobilizer should be thought of as first translating the M frame by a vector p_FM=[px,py,pz] (expressed in F), then reorienting M about its new origin location using the rotation angles. In the reference configuration where q=0, the F and M frames are aligned and their origins coincident (Mo=Fo). The convention used here exactly matches the convention used by the force element Force::LinearBushing which infers an identical set of coordinates to express the relative pose of its two connected frames (also called F and M).

The first three generalized coordinates q should be interpreted as a series of rotation angles in radians: q[0]=qx is a rotation about the Mx (=Fx) axis, then q[1]=qy is a rotation about the now-rotated My axis, and then q[2]=qz is a rotation about the now twice-rotated Mz axis. These rotations do not affect the location of M's origin point Mo. The generalized speeds u for the Bushing mobilizer are just the time derivatives of the generalized coordinates, that is, u=qdot={qxdot,qydot,qzdot,vx,vy,vz}, where qxdot=d/dt qx, etc. and v_FM=[vx,vy,vz]=d/dt p_FM is the velocity of Mo measured and expressed in frame F. Note that this is different than the choice of generalized speeds used for MobilizedBody::Free, where the angular velocity vector w_FM is used as the three rotational generalized speeds instead of Euler angle derivatives. (Euler angle derivatives are not the same as angular velocity, except when q=0.)

While this mobilizer provides arbitrary orientation, the Euler angle derivatives are singular when q[1] (qy, the middle rotation) is near +/- Pi/2. That means you should not attempt to do any dynamics in that configuration; if you can't be sure the motion will remain away from that region, you should use a MobilizedBody::Free instead, which uses quaternions to ensure singularity-free rotation.

Here is another way to describe the meaning of a Bushing mobilizer: except for the ordering of the generalized coordinates, a Bushing between frames F on parent body P and frame M on child body B is exactly equivalent to a translation (Cartesian) mobilizer between F and a massless body B0, followed by a series of three pin joints using two massless intermediate bodies B1 and B2. The first pin joint rotates about the common B0x(=Fx) and B1x axes. The second rotates about the common B1y and B2y axes. The last one rotates about the common B2z and Mz axes. Other than performance (which is somewhat better if you use the Bushing since there are fewer bodies), the translation+pins+intermediate bodies system generates exactly the same mobility as the Bushing, but with coordinates q={px,py,pz,qx,qy,qz} (flipped from the Bushing coordinate ordering).

See also
Force::LinearBushing, MobilizedBody::Free, MobilizedBody::Gimbal

Constructor & Destructor Documentation

Construct an empty handle that can be assigned to reference any MobilizedBody::Bushing.

SimTK::MobilizedBody::Bushing::Bushing ( MobilizedBody parent,
const Transform X_PF,
const Body bodyInfo,
const Transform X_BM,
Direction  = Forward 
)

Create a Bushing mobilizer between an existing parent (inboard) body P and a new child (outboard) body B created by copying the given bodyInfo into a privately-owned Body within the constructed MobilizedBody object.

Specify the mobilizer frames F fixed to parent P and M fixed to child B.

See also
MobilizedBody for a diagram and explanation of terminology.
SimTK::MobilizedBody::Bushing::Bushing ( MobilizedBody parent,
const Body bodyInfo,
Direction  = Forward 
)

Abbreviated constructor you can use if the mobilizer frames are coincident with the parent and child body frames.

Member Function Documentation

Bushing& SimTK::MobilizedBody::Bushing::setDefaultInboardFrame ( const Transform X_PF)
inline

Change the default inboard ("fixed") frame F on the parent body of this mobilizer.

The supplied frame is given as a Transform from the parent body's frame P and replaces the F frame specified in the constructor. This is a topological change, meaning that you must call realizeTopology() again if you call this method.

Bushing& SimTK::MobilizedBody::Bushing::setDefaultOutboardFrame ( const Transform X_BM)
inline

Change the default outboard ("moving") frame M on this mobilized body (that is, on this mobilizer's child body).

The supplied frame is given as a Transform from the child body's frame B and replaces the M frame specified in the constructor. This is a topological change, meaning that you must call realizeTopology() again if you use this method.

Bushing& SimTK::MobilizedBody::Bushing::setDefaultTransform ( const Transform X_FM)
inline

Override the default pose for this mobilizer.

Normally the default is q=0, meaning that the F and M frames are aligned. Here you can provide a Transform giving the default pose of the mobilizer's M frame in the parent body's F frame. The given orientation will be converted to a body fixed x-y-z Euler sequence; the given position vector will be used directly. Those six values will be used to set the default values for the generalized coordinates q that will appear in a State that has just been created by a realizeTopology() call. This is a topological change, meaning that you must call realizeTopology() again if you use this method.

Transform SimTK::MobilizedBody::Bushing::getDefaultTransform ( ) const
inline

Return the default pose for this mobilizer as a Transform.

See setDefaultTransform() for more information.

Bushing& SimTK::MobilizedBody::Bushing::addBodyDecoration ( const Transform X_BD,
const DecorativeGeometry g 
)
inline

Add DecorativeGeometry to the privately-owned Body contained in this MobilizedBody, positioned relative to the body's frame.

Bushing& SimTK::MobilizedBody::Bushing::addOutboardDecoration ( const Transform X_MD,
const DecorativeGeometry g 
)
inline

Add DecorativeGeometry to the privately-owned Body contained in this MobilizedBody, positioned relative to the mobilizer's M frame on that body.

Bushing& SimTK::MobilizedBody::Bushing::addInboardDecoration ( const Transform X_FD,
const DecorativeGeometry g 
)
inline

Add DecorativeGeometry to the parent (inboard) body of this mobilizer, positioned relative to the mobilizer's F frame on the parent body.

const Vec6& SimTK::MobilizedBody::Bushing::getDefaultQ ( ) const

Obtain the default value for the generalized coordinates q that has been set for this mobilizer.

The value is returned as a Vec6 but note that the rotational part (first three elements) of the returned quantity is not a vector; it is a body fixed x-y-z Euler angle sequence in radians. The last three elements are a position vector p_FM. The default is q=0 unless overridden.

See also
getDefaultTransform()
Bushing& SimTK::MobilizedBody::Bushing::setDefaultQ ( const Vec6 q)

Set the default value for the generalized coordinates q for this mobilizer.

The value is given as a Vec6 but note that the supplied quantity is not a pair of vectors; it is a body fixed x-y-z Euler angle sequence in radians, followed by a position vector in the last three elements. The default is q=0 unless overridden.

See also
setDefaultTransform()
const Vec6& SimTK::MobilizedBody::Bushing::getQ ( const State state) const

Obtain the current value for this mobilizer's generalized coordinates q from the given State, which must be realized through Stage::Model (these are state variables).

const Vec6& SimTK::MobilizedBody::Bushing::getQDot ( const State state) const

Obtain the current value for this mobilizer's generalized coordinate time derivatives qdot from the given State, which must be realized through Stage::Velocity.

These are the three Euler angle time derivatives followed by the three measure numbers of the velocity vector v_FM giving the velocity of M's origin Mo taken in the F frame. For the Bushing mobilizer, qdot has the same numerical values as the generalized speeds u, but unlike u, qdot is not a state variable.

const Vec6& SimTK::MobilizedBody::Bushing::getQDotDot ( const State state) const

Obtain the current value for this mobilizer's generalized coordinate second time derivatives qdotdot from the given State, which must be realized through Stage::Acceleration.

These are Euler angle second time derivatives followed by the three measure numbers of the vector a_FM giving the acceleration of M's origin Mo taken in the F frame. For the Bushing mobilizer, qdotdot=udot.

const Vec6& SimTK::MobilizedBody::Bushing::getU ( const State state) const

Obtain the current value for this mobilizer's generalized speeds u from the given State, which must be realized through Stage::Model (these are state variables).

For the Bushing joint, these are the time derivatives of q, that is, u=qdot.

const Vec6& SimTK::MobilizedBody::Bushing::getUDot ( const State state) const

Obtain the current value for this mobilizer's generalized accelerations udot (=d/dt u) from the given State, which must be realized through Stage::Acceleration.

For the Bushing joint, these are the time derivatives of qdot, that is, udot=qdotdot.

void SimTK::MobilizedBody::Bushing::setQ ( State state,
const Vec6 q 
) const

Set new values for this mobilizer's generalized coordinates q in the given state.

This invalidates Stage::Position and above. The new value is given as a Vec6, but is interpreted as a body fixed x-y-z Euler angle sequence in radians, followed by the three measure numbers of the position vector p_FM giving the location of the M frame origin Mo measured from and expressed in the F frame.

See also
MobilizedBody::setQToFitTransform()
void SimTK::MobilizedBody::Bushing::setU ( State state,
const Vec6 u 
) const

Set new values for this mobilizer's generalized speeds u in the given state.

This invalidates Stage::Velocity and above. The new value is given as a Vec6, but is interpreted as the time derivatives of a body fixed x-y-z Euler angle sequence in radians/time (not an angular velocity!), followed by the three measure numbers of the velocity vector v_FM giving the velocity of the M frame origin Mo measured and expressed in the F frame. For the Bushing mobilizer, these are just the time derivatives of the generalized coordinates q, that is, u=qdot.

See also
MobilizedBody::setUToFitVelocity()
const Vec6& SimTK::MobilizedBody::Bushing::getMyPartQ ( const State state,
const Vector qlike 
) const

Given a vector in the System's generalized coordinate basis, extract the six q's belonging to this mobilizer.

const Vec6& SimTK::MobilizedBody::Bushing::getMyPartU ( const State state,
const Vector ulike 
) const

Given a vector in the System's generalized speed basis, extract the six u's belonging to this mobilizer.

Vec6& SimTK::MobilizedBody::Bushing::updMyPartQ ( const State state,
Vector qlike 
) const

Given a writable vector in the System's generalized coordinate basis, extract a writable reference to the six q's in that vector that belong to this mobilizer.

Vec6& SimTK::MobilizedBody::Bushing::updMyPartU ( const State state,
Vector ulike 
) const

Given a writable vector in the System's generalized speed basis, extract a writable reference to the six u's in that vector that belong to this mobilizer.


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