modelSphericalSpring

Spherical joint (3 constraints and no potential states, or 3 degrees-of-freedom and 3 states)

Extends from Modelica.Mechanics.MultiBody.Interfaces.PartialTwoFrames (Base model for components providing two frame connectors + outer world + assert to guarantee that the component is connected).

Information

Attribution Notice

This model is an extension of the Spherical block in the Mechanics.MultiBody.Joints package of the Modelica Standard Library
Copyright © 1998-2016, Modelica Association and DLR.

Block for modeling a spherical joint with torsional stiffness in each direction. The torsional stiffness of this joint in all three directions is determined by the constant c.

Parameters

Type	Name	Default	Description
SI.TranslationalSpringConstant	c		Spring constants {rx,ry,rz}
Boolean	animation	false	= true, if animation shall be enabled (show sphere)
Frames.Orientation	R_rel_start	Frames.axesRotations(sequence_start, angles_start, zeros(3))	Orientation object from frame_a to frame_b at initial time
SI.Angle[3]	phi_start	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_rel_start, sequence_angleStates)	Potential angle states at initial time
if animation = true
SI.Distance	sphereDiameter	world.defaultJointLength	Diameter of sphere representing the spherical joint
Initialization
Boolean	angles_fixed	false	= true, if angles_start are used as initial values, else as guess values
SI.Angle[3]	angles_start	{0, 0, 0}	Initial values of angles to rotate frame_a around 'sequence_start' axes into frame_b
Types.RotationSequence	sequence_start	{1, 2, 3}	Sequence of rotations to rotate frame_a into frame_b at initial time
Boolean	w_rel_a_fixed	false	= true, if w_rel_a_start are used as initial values, else as guess values
SI.AngularVelocity[3]	w_rel_a_start	{0, 0, 0}	Initial values of angular velocity of frame_b with respect to frame_a, resolved in frame_a
Boolean	z_rel_a_fixed	false	= true, if z_rel_a_start are used as initial values, else as guess values
SI.AngularAcceleration[3]	z_rel_a_start	{0, 0, 0}	Initial values of angular acceleration z_rel_a = der(w_rel_a)
Advanced
Types.RotationSequence	sequence_angleStates	{1, 2, 3}	Sequence of rotations to rotate frame_a into frame_b around the 3 angles used as states

Connectors

Type	Name	Default	Description
Interfaces.Frame_a	frame_a (from PartialTwoFrames)		Coordinate system a fixed to the component with one cut-force and cut-torque
Interfaces.Frame_b	frame_b (from PartialTwoFrames)		Coordinate system b fixed to the component with one cut-force and cut-torque

Components

Type	Name	Default	Description
Types.Color	sphereColor	Modelica.Mechanics.MultiBody.Types.Defaults.JointColor	Color of sphere representing the spherical joint
Types.SpecularCoefficient	specularCoefficient	world.defaultSpecularCoefficient	Reflection of ambient light (= 0: light is completely absorbed)
SI.Angle[3]	phi		Dummy or 3 angles to rotate frame_a into frame_b
SI.AngularVelocity[3]	phi_d		= der(phi)
SI.AngularAcceleration[3]	phi_dd		= der(phi_d)
SI.AngularVelocity[3]	w_rel		Dummy or relative angular velocity of frame_b with respect to frame_a, resolved in frame_b