JointSSR

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

    JointSSR

Library

Modelica/Mechanics/MultiBody/Joints/Assemblies

Description

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).

Parameters

JointSSR_0

NameLabelDescriptionData TypeValid Values

mo_animation

animation

= true, if animation shall be enabled

Scalar

true
false

mo_showMass

showMass

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

Scalar

true
false

mo_rod1Length

rod1Length

Distance between the origins of the two spherical joints

Scalar

mo_rod1Mass

rod1Mass

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

Scalar

mo_n_b

n_b

Axis of revolute joint fixed and resolved in frame_b

Vector of size 3

mo_rRod2_ib

rRod2_ib

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

Vector of size 3

mo_phi_offset

phi_offset

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

Scalar

mo_phi_guess

phi_guess

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

Scalar

JointSSR_1

NameLabelDescriptionData TypeValid Values

mo_sphereDiameter

sphereDiameter

Diameter of the spheres representing the two spherical joints

Scalar

mo_sphereColor

sphereColor

Color of the spheres representing the two spherical joints

Vector of size 3

mo_rod1Diameter

rod1Diameter

Diameter of rod 1 connecting the two spherical joints

Scalar

mo_rod1Color

rod1Color

Color of rod 1 connecting the two spherical joint

Vector of size 3

mo_rod2Diameter

rod2Diameter

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

Scalar

mo_rod2Color

rod2Color

Color of rod 2 connecting the revolute joint and spherical joint 2

Vector of size 3

mo_revoluteDiameter

revoluteDiameter

Diameter of cylinder representing the revolute joint

Scalar

mo_revoluteLength

revoluteLength

Length of cylinder representing the revolute joint

Scalar

mo_revoluteColor

revoluteColor

Color of cylinder representing the revolute joint

Vector of size 3

mo_specularCoefficient

specularCoefficient

Reflection of ambient light (= 0: light is completely absorbed)

Scalar

JointSSR_2

NameLabelDescriptionData TypeValid Values

mo_checkTotalPower

checkTotalPower

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

Scalar

true
false

JointSSR_3

NameLabelDescriptionData TypeValid Values

mo_aux

aux

aux

Structure

mo_aux/fixed

fixed

Cell of scalars

true
false

mo_aux/start

start

Cell of scalars

mo_f_rod

f_rod

f_rod

Structure

mo_f_rod/fixed

fixed

Cell of scalars

true
false

mo_f_rod/start

start

Cell of scalars

mo_totalPower

totalPower

totalPower

Structure

mo_totalPower/fixed

fixed

Cell of scalars

true
false

mo_totalPower/start

start

Cell of scalars

Ports

NameTypeDescriptionIO TypeNumber

frame_a

implicit

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

input

1

frame_b

implicit

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

output

1

frame_ib

implicit

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

output

2

frame_im

implicit

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

output

3

axis

implicit

1-dim. rotational flange that drives the revolute joint

input

2

bearing

implicit

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

output

4