Spherical

Spherical cut joint and translational directions may be constrained or released

    Spherical

Library

Modelica/Mechanics/MultiBody/Joints/Constraints

Description

This model does not use explicit variables e.g. state variables in order to describe the relative motion of frame_b with to respect to frame_a, but defines kinematic constraints between the frame_a and frame_b. The forces and torques at both frames are then evaluated in such a way that the constraints are satisfied. Sometimes this type of formulation is also called an implicit joint in literature.

As a consequence of the formulation the relative kinematics between frame_a and frame_b cannot be initialized.

In particular in complex multibody systems with closed loops this may help to simplify the system of non-linear equations. Please compare the translation log using the classical joint formulation and the alternative formulation used here in order to check whether this fact applies to the particular system under consideration.

In systems without closed loops the use of this implicit joint does not make sense or may even be disadvantageous.

See the subpackage Examples.Constraints for testing the joint.

Parameters

Spherical_0

NameLabelDescriptionData TypeValid Values

mo_x_locked

x_locked

= true: constraint force in x-direction, resolved in frame_a

Scalar

true
false

mo_y_locked

y_locked

= true: constraint force in y-direction, resolved in frame_a

Scalar

true
false

mo_z_locked

z_locked

= true: constraint force in z-direction, resolved in frame_a

Scalar

true
false

mo_animation

animation

= true, if animation shall be enabled (show sphere)

Scalar

true
false

mo_sphereDiameter

sphereDiameter

Diameter of sphere representing the spherical joint

Scalar

mo_sphereColor

sphereColor

Color of sphere representing the spherical joint

Vector of size 3

mo_specularCoefficient

specularCoefficient

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

Scalar

Ports

NameTypeDescriptionIO TypeNumber

frame_a

implicit

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

input

1

frame_b

implicit

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

output

1