Use Motions from MotionDesigner
In Step 1.6, the model is a Part that rotates with 'constant angular velocity' - the term we use for it is a Crank. In the it is referred to as a Rocker.
It rotates at the same rate-of-change as the .
However, Parts in packaging machines frequently have more complex motions - Part do not only rotate continuously.
We must use a Motion FB to link a Motion in MotionDesigner to the Motion-Part in the model.
Objective of this Step
|1.||Move a Part with a motion that is more complex than 'constant angular velocity' |
|2.||Delete a FB and and add 'wires' |
|3.||Show the Velocity and Acceleration Vectors of a Point|
Summary of this Step
|1.||Delete the wire between the Linear-Motion FB and the Motion-Dimension FB |
|2.||Add a Motion FB to the graphic-area. |
The Motion FB links a motion that is in MotionDesigner to the
Note: The Motion-Part is the Part whose motion is defined by the Motion-Dimension FB.
|3.||Connect a wire between the Linear-Motion FB and the Motion FB|
|4.||Connect a wire between the Motion FB and the Motion-Dimension FB|
|5.||Edit the Motion-Dimension FB.|
|6.||Edit a Point to show its Velocity and Acceleration Vectors.|
You should also complete MotionDesigner Tutorials 2 and Tutorial 3 to change the motion design.
Video of this Step
Move the 'Motion-Part' with a Motion FB
| STEP 1: ||Delete the Gearing FB [or wire]|
To delete the Gearing FB [or a wire that connects two FBs].
|1.||Click the FB [or wire] one time. |
The FB [or wire] element shows in the
|2.||Right-click the FB [or wire] element in the Selection-Window.|
|3.||Click 'Delete Element' in the contextual-menu.|
- or -
|1.||Click the FB [or wire] in the graphic-area so that it become red |
|2.||Click the 'delete' key on your keyboard.|
- or - [see left]
|1.||Hover + Right-Click the FB [or wire] |
|2.||Click the 'Delete' command in the contextual-menu|
| STEP 2: ||Add a Motion FB to the graphic-area |
|2.||Click to the right of the graphic-area.|
|3.||Click in the graphic-area.|
The Motion FB is now in the graphic-area.
It will be linked to the default, or left-most motion name-tab in MotionDesigner.
Note: To link the Motion FB to a different motion name-tab, edit the Motion FB to select a different motion. We will review the Motion FB dialog-box later.
| STEP 3: ||Connect wires between the FBs |
|1.||Drag a wire from the output-connector of the Linear-Motion FB to the input-connector of the Motion FB. |
|2.||Drag a wire from the Motion FB to the Motion-Dimension FB.|
In the image, there is wire and wire between the FBs.
As the MMA changes from 0 to 360, the output from the Linear-Motion FB also changes from 0 to 360.
0 - 360 become the 'independent variable' for the Motion FB. . This means, the output - the 'Y-axis - becomes a function of the input.
The Motion is designed with a cycle of 0 -360. The output is the Motion in MotionDesigner.
The motion from MotionDesigner becomes the input to the Motion-Dimension FB
Thus, the Motion-Part [Rocker] moves when you use .
The Motion FB, in the default case, links the Motion that is in the 'left-most' motion-tab, in MotionDesigner.
| STEP 4: ||Cycle the kinematic-chain with the 'C' key on your keyboard.|
The Rocker moves, with the motion as specified in MotionDesigner. It completes one motion for each cycle [0 – 360] of the .
Instant Analysis: Velocity and Acceleration
We are about to demonstrate that MechDesigner calculates the Position, Velocity and Acceleration of all Points at all times.
We will add a new Line to the , at a random place, and show its velocity and acceleration vectors.
Add the Line to the coupler.
We use the same procedures to edit the coupler as to edit any Part - we 'Edit the Part with the Part-Editor'. There are many ways you can start the Part-Editor.
[See Step 1.3. to review how to edit the Base-Part, or see How to Edit a Part for other options - there are many!]
|1.||Double-click the of the coupler Part |
The Part-Editor opens. Note: the axes have the same alignment in the Part-Editor and the Mechanism-Editor.
|2.||Click , then a Line' in the graphic-area |
|3.||Use dimensions and constraints to specify the Line's position.|
Show the Velocity and Acceleration Vectors:
|1.||Double-click a Point on a Part that has a Green Part-Outline - all of the Parts have Green Part-Outlines |
The Point: Vectors and Position dialog-box opens - see image.
|2.||Click the Show or Hide Vectors separator to expand that section of the dialog-box|
|3.||Click the Show Velocity Vector or Show Acceleration Vector, or the two, check boxes|
|4.||Click the icon, to close the dialog-box.|
Do 1-3 again to show the kinematic vectors of different Points, or to hide vectors for those Points that show vectors.
Scale the vectors
You can stretch or shrink the length of the vectors. Click the Velocity and the Acceleration (Accel.) buttons in the Feedback-Area.
|1.||Click the up-button to increase the length of the vectors |
- or -
|1.||Click the down-button to decrease the length of the vectors |
You may need to click the button many times.
If necessary, change the colour of the graphic-area to Grey to see the vectors more clearly.
About the Velocity and Acceleration Vectors in the graphic-area
|•||Show when the Point moves relative to the |
|•||Their length is proportional to the Point's instantaneous Velocity and Acceleration.|
|•||The magnitude of the vectors shows at the arrowhead of each vector|
|•||The vector colours are Blue for Velocity, Red for Acceleration |
|•||The vectors update their values and length each machine step - see Machine Settings dialog-box.|