WOLFRAM SYSTEMMODELER

JointSSR

Spherical - spherical - revolute joint aggregation with mass (no constraints, no potential states)

Diagram

Wolfram Language

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Click for copyable input
SystemModel["Modelica.Mechanics.MultiBody.Joints.Assemblies.JointSSR"]
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Information

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

This component consists of a spherical joint 1 at frame_a, a revolute joint at frame_b and a spherical joint 2 which is connected via rod 1 to the spherical joint 1 and via rod 2 to the revolute joint, see the default animation in the following figure (the axes vectors are not part of the default animation):

model Joints.Assemblies.JointSSR

Besides an optional point mass in the middle of rod 1, this joint aggregation has no mass and no inertia, and introduces neither constraints nor potential state variables. It should be used in kinematic loops whenever possible since the non-linear system of equations introduced by this joint aggregation is solved analytically (i.e., a solution is always computed, if a unique solution exists).

An additional frame_ib is present. It is fixed in rod 2 connecting the revolute and the spherical joint at the side of the revolute joint that is connected to this rod (= rod2.frame_a = revolute.frame_a).

An additional frame_im is present. It is fixed in rod 2 connecting the revolute and the spherical joint at the side of spherical joint 2 that is connected to this rod (= rod2.frame_b). It is always parallel to frame_ib.

The easiest way to define the parameters of this joint is by moving the MultiBody system in a reference configuration where all frames of all components are parallel to each other (alternatively, at least frame_b and frame_ib of the JointSSR joint should be parallel to each other when defining an instance of this component).

Connectors (6)

frame_a

Type: Frame_a

Description: Coordinate system fixed to the component with one cut-force and cut-torque

frame_b

Type: Frame_b

Description: Coordinate system fixed to the component with one cut-force and cut-torque

frame_ib

Type: Frame_b

Description: Coordinate system at origin of frame_b fixed at connecting rod of spherical and revolute joint

frame_im

Type: Frame_b

Description: Coordinate system at origin of spherical joint in the middle fixed at connecting rod of spherical and revolute joint

axis

Type: Flange_a

Description: 1-dim. rotational flange that drives the revolute joint

bearing

Type: Flange_b

Description: 1-dim. rotational flange of the drive bearing of the revolute joint

Parameters (14)

animation

Value: true

Type: Boolean

Description: = true, if animation shall be enabled

showMass

Value: true

Type: Boolean

Description: = true, if point mass on rod 1 shall be shown (provided animation = true and rod1Mass > 0)

rod1Length

Value:

Type: Length (m)

Description: Distance between the origins of the two spherical joints

rod1Mass

Value: 0

Type: Mass (kg)

Description: Mass of rod 1 (= point mass located in middle of rod connecting the two spherical joints)

n_b

Value: {0, 0, 1}

Type: Axis ()

Description: Axis of revolute joint fixed and resolved in frame_b

rRod2_ib

Value: {1, 0, 0}

Type: Position[3] (m)

Description: Vector from origin of frame_ib to spherical joint in the middle, resolved in frame_ib

phi_offset

Value: 0

Type: Angle_deg (°)

Description: Relative angle offset of revolute joint (angle = phi(t) + from_deg(phi_offset))

phi_guess

Value: 0

Type: Angle_deg (°)

Description: Select the configuration such that at initial time |phi(t0) - from_deg(phi_guess)| is minimal

sphereDiameter

Value: world.defaultJointLength

Type: Diameter (m)

Description: Diameter of the spheres representing the two spherical joints

rod1Diameter

Value: sphereDiameter / Types.Defaults.JointRodDiameterFraction

Type: Diameter (m)

Description: Diameter of rod 1 connecting the two spherical joints

rod2Diameter

Value: rod1Diameter

Type: Diameter (m)

Description: Diameter of rod 2 connecting the revolute joint and spherical joint 2

revoluteDiameter

Value: world.defaultJointWidth

Type: Diameter (m)

Description: Diameter of cylinder representing the revolute joint

revoluteLength

Value: world.defaultJointLength

Type: Distance (m)

Description: Length of cylinder representing the revolute joint

checkTotalPower

Value: false

Type: Boolean

Description: = true, if total power flowing into this component shall be determined (must be zero)

Components (6)

world

Type: World

Description:

revolute

Type: RevoluteWithLengthConstraint

Description:

rod1

Type: SphericalSpherical

Description:

rod2

Type: FixedTranslation

Description:

relativePosition

Type: RelativePosition

Description:

position_b

Type: Constant[3]

Description: