This information is part of the Modelica Standard Library maintained by the Modelica Association.

PointMass

Body used all places of the comparision model with zero inertia tensor

CONNECTORS
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NameTypeDescription
frame_aFrame_aCoordinate system fixed at body
PARAMETERS
NameTypeDefault ValueDescription
animationBooleantrue= true, if animation shall be enabled (show cylinder and sphere)
r_CMPosition[3]Vector from frame_a to center of mass, resolved in frame_a
mMass1Mass of rigid body
I_11Inertia0 (1,1) element of inertia tensor
I_22Inertia0 (2,2) element of inertia tensor
I_33Inertia0 (3,3) element of inertia tensor
I_21Inertia0 (2,1) element of inertia tensor
I_31Inertia0 (3,1) element of inertia tensor
I_32Inertia0 (3,2) element of inertia tensor
angles_fixedBooleanfalse= true, if angles_start are used as initial values, else as guess values
angles_startAngle[3]{0,0,0}Initial values of angles to rotate frame_a around 'sequence_start' axes into frame_b
sequence_startRotationSequence{1,2,3}Sequence of rotations to rotate frame_a into frame_b at initial time
w_0_fixedBooleanfalse= true, if w_0_start are used as initial values, else as guess values
w_0_startAngularVelocity[3]{0,0,0}Initial or guess values of angular velocity of frame_a resolved in world frame
z_0_fixedBooleanfalse= true, if z_0_start are used as initial values, else as guess values
z_0_startAngularAcceleration[3]{0,0,0}Initial values of angular acceleration z_0 = der(w_0)
sphereDiameterDiameterworld.defaultBodyDiameterDiameter of sphere
cylinderDiameterDiametersphereDiameter/Types.Defaults.BodyCylinderDiameterFractionDiameter of cylinder
enforceStatesBooleanfalse = true, if absolute variables of body object shall be used as states (StateSelect.always)
useQuaternionsBooleantrue = true, if quaternions shall be used as potential states otherwise use 3 angles as potential states
sequence_angleStatesRotationSequence{1,2,3} Sequence of rotations to rotate world frame into frame_a around the 3 angles used as potential states
IInertia[3,3][I_11,I_21,I_31;I_21,I_22,I_32;I_31,I_32,I_33]inertia tensor
R_startOrientationModelica.Mechanics.MultiBody.Frames.axesRotations(sequence_start, angles_start, zeros(3))Orientation object from world frame to frame_a at initial time
z_a_startAngularAcceleration[3]Frames.resolve2(R_start, z_0_start)Initial values of angular acceleration z_a = der(w_a), i.e., time derivative of angular velocity resolved in frame_a
Q_startOrientationFrames.to_Q(R_start)Quaternion orientation object from world frame to frame_a at initial time
phi_startAngle[3]if sequence_start[1] == sequence_angleStates[1] and sequence_start[2] == sequence_angleStates[2] and sequence_start[3] == sequence_angleStates[3] then angles_start else Frames.axesRotationsAngles(R_start, sequence_angleStates)Potential angle states at initial time
USED IN EXAMPLES
Modelica.Mechanics.MultiBody.Examples.Elementary.PointGravityWithPointMasses2.SystemWithStandardBodies
For comparison purposes, an equivalent model with Bodies instead of PointMasses