modelWeakRevolute
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 a modification of the Revolute block in the Mechanics.MultiBody.Joints package
of the Modelica Standard Library
Copyright © 1998-2016, Modelica Association and DLR.
Block for modeling a revolute joint with a weak constraint. Most Modelica joints introduce strong constraints, i.e. the position of the two frames must be exactly equal. In reality, such strong constraints can cause binding in systems with multiple joints and cause systems to have kinematic loops. This joint overcomes these problems by using a weak formulation of the joint constraints.
Model extends the WeakSpherical joint and adds rotational stiffness to constrained rotations.
One needs to pay attention and be careful with angle definitions when used in conjunction with rotational springs because phi is determined as a function of R_rel, therefore angle branching occurs at phi = pi and -pi.
Copyright © 2018
ATA ENGINEERING, INC.
ALL RIGHTS RESERVED
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | useAxisFlange | false | = true, if axis flange is enabled |
| Boolean | rotateAboutX | false | = true, if rotating about X axis relative to frame_a |
| Boolean | rotateAboutY | false | = true, if rotating about Y axis relative to frame_a |
| Boolean | rotateAboutZ | true | = true, if rotating about Z axis relative to frame_a |
| Boolean | animation | true | = true, if animation shall be enabled (show axis as cylinder) |
| SI.TranslationalSpringConstant | c_pos_constraint | 1.0e6 | Spring constant for positional constraint |
| SI.RotationalSpringConstant | c_rot_constraint | 1.0e6 | Spring constant for rotational constraint |
| SI.RotationalSpringConstant | d_rot_constraint | 100.0 | Spring constant for rotational constraint |
| Animation › if animation = true | |||
| SI.Distance | cylinderLength | world.defaultJointLength | Length of cylinder representing the joint axis |
| SI.Distance | cylinderDiameter | world.defaultJointWidth | Diameter of cylinder representing the joint axis |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Mechanics.Rotational.Interfaces.Flange_a | axis | 1-dim. rotational flange that drives the joint | |
| Modelica.Mechanics.Rotational.Interfaces.Flange_b | support | 1-dim. rotational flange of the drive support (assumed to be fixed in the world frame, NOT in the joint) | |
| 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 |
|---|---|---|---|
| Modelica.Mechanics.MultiBody.Types.Color | cylinderColor | Modelica.Mechanics.MultiBody.Types.Defaults.JointColor | Color of cylinder representing the joint axis |
| Modelica.Mechanics.MultiBody.Types.SpecularCoefficient | specularCoefficient | world.defaultSpecularCoefficient | Reflection of ambient light (= 0: light is completely absorbed) |
| WeakSpherical | weakSpherical | ||
| Visualizers.Advanced.Shape | cylinder | ||
| Modelica.Mechanics.Rotational.Components.SpringDamper | spring1 | ||
| Modelica.Mechanics.Rotational.Components.SpringDamper | spring2 |