Step 1.5: Add and Edit a Motion-Dimension FB
Contents
IMPORTANT: Background to this Step.
Part's have two states
| • | Unsolved, also called Free-Parts, an not kinematically-defined. |
| • | Solved, also called kinematically-defined Parts. |
The state of the Part after STEP 1.4 is unsolved. With a little skill, you can drag the Part-Outline about the Pin-Joint. It has one degree-of-freedom. When the Part is unsolved, we do not know where to find the Part.
Objective of this Step
To change the state of the Part to solved, so that it becomes a kinematically-defined Part.
We introduce the Motion-Dimension and its Motion-Dimension Function-Block [FB].
The Part-Outline will change from a Blue to Green [as default colours to indicate its state.
Summary of this Step
Add a Motion-Dimension FB to a Part joined with a Pin-Joint.
Edit the Part's start position.
Note: we can also add a Motion-Dimension FB to a Slide-Joint - See Tutorial Step 2.5
Video
 |
Tutorial 1: Step 1.5
|
A: Add a Motion-Dimension FB to a Part
|
|
||||||||
|
The Command-Manager opens starts a dialog. You need to select three elements from the graphic-area. We must a select three elements in the correct order:
|
||||||||
 Command Manager ready for selections  Commandd Manager with selections |
Click, in order, refer to elements
Line Line
Added-Part is a Free Part . The CAD-Line along its centre is a child to the Added-Part. Line The order you click the elements is important:
Note: The numbers that append [at the end of] the Element-name. The numbers become greater as you add more elements with the same name. |
||||||||
|
The Motion-Dimension FB has two features in the graphic-area:
CTRL+Drag to move the motion-value in the graphic-area.
You can drag the icon. |
||||||||
Notes:
|
|||||||||
Edit the Part's initial position.
To edit the Part's initial position, we must edit its Base-Value parameter in the Motion-Dimension FB dialog-box. |
|||||||||||
 Motion-Dimension FB dialog-box |
For example: Double-click the Motion-Dimension FB in the graphic-area [See How to open a dialog-box]. See also: How to open a dialog-box. Use Motion-Dimension FB dialog-box to:
- or -
It is sometimes useful to edit its current positional value rather than its Base-Value. The Base-Value... ... is the angle of the Joint when there is not a wire at the input-connector of the Motion-Dimension FB. ... is the 'offset' of to the Line in the Motion-Parts from the Line in the 'solved' Part. Directions It is possible to 'negate' the sense of the 'Base-Value' and the 'Motion-Values'. [I rarely use these options, I use a Gearing FB]. Notes: There are two Parts to the Motion-Dimension FB in the graphic-area: Icon and the Dimension. To move the:
|
||||||||||
The Kinematics Tree
The Part, Pin-Joint and Motion-Dimension are the elements that make a Rocker. A Rocker is one of the two Motion-Parts. |
||
If you explore the Kinematics-Tree, you can see the three elements for the Rocker: |
||
 Kinematic-Tree with Elements for a Rocker |
|
Part |
|
Pin-Joint |
|
|
Mot-Dim Rocker |
|
Important Kinematic Terms
Some terminology: See also Basic Kinematics for more information.
A Completely Free-Part has three degrees-of-freedom (on a Plane) A Pin-Joint removes two degrees-of-freedom. A Motion-Dimension removes one degree-of-freedom. |