Revolute

Revolute cut-joint and translational directions may be constrained or released

    Revolute

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 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

Revolute_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_n

n

Axis of rotation resolved in frame_a (= same as in frame_b)

Vector of size 3

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

mo_e

e

Unit vector in direction of rotation axis, resolved in frame_a (= same as in frame_b)

Vector of size 3

mo_nnx_a

nnx_a

Arbitrary vector that is not aligned with rotation axis n

Vector of size 3

mo_ey_a

ey_a

Unit vector orthogonal to axis n of revolute joint, resolved in frame_a

Vector of size 3

mo_ex_a

ex_a

Unit vector orthogonal to axis n of revolute joint and to ey_a, resolved in frame_a

Vector of size 3

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