Step 2.2: Add a Motion FB; Motion Vectors

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Step 2.2: Add a Motion FB; Motion Vectors

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 Kinematics-Tree it is a Rocker.

It rotates at the same rate-of-change as the Master-Machine-Angle.

However, Parts in packaging machines frequently have more complex motions - Parts 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 add wires

3.Show the Velocity and Acceleration Vectors for 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 Motion-Part

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


Tutorial 2: STEP 2.1

Add Motion FB

Edit Motion-Dimension FB


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 Selection-Window

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 Gearing-FB

2.Click the Delete in the contextual-menu


STEP 2: Add a Motion FB to the graphic-area

1.Click Add menu > Motion FB

- or -

1.Click Kinematic FB toolbar> Add Motion FB (to the right of the graphic-area).

2.Click in the graphic-area.

The Motion FBRed-14-1b is now in the graphic-area.

The Motion FB links to motion in MotionDesigner.

In the default case, it is linked to the left-most Motion name-tab

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

See How to connect wires between 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 Red-14-2 and wire Red-14-3 between the FBs.

As the MMA increases from 0 to 360, the output from the Linear-Motion FB also increases from 0 to 360, which is now the input to the Motion FB.

0 - 360 become the independent variable for the Motion FB.

The default motion in MotionDesigner has a range from 0 to 360. The output from the Motion FB is now the default motion.

The default motion from MotionDesigner becomes the input to the Motion-Dimension FB.

Thus, the Motion-Part (Rocker) moves when you use Run menu (or toolbar) > Cycle. with the default motion.

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 ALT+C key on your keyboard.

The Rocker moves, with the motion as specified in MotionDesigner. It completes one motion for each cycle (0360) of the Master-Machine-Angle.

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 Coupler, at a random place, and show its velocity and acceleration vectors.


Add a Line to the coupler.

We use the same procedures to edit all Part - we Edit the Part with the Part-Editor. There are many ways you can start the Part-Editor- See Step 1.3

1.Double-click the Part-Outline 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 Geometry toolbar > Add Line, then Drag in the graphic-area to add the Line

3.Add dimensions and Add constraints to specify position of the Line.

4.Close the Part-Editor


Show the Velocity and Acceleration Vectors:

1.Double-click any Point on a Part with 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

3.Click the Show Velocity Vector and Show Acceleration Vector check-boxes

4.Click the OK-tiny-13-17 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 color of the graphic-area to Gray to see the vectors more clearly.

Edit menu >Application Settings > colors tab > Graphic separator > Background button.

About the Velocity and Acceleration Vectors in the graphic-area

Show only when the Point moves relative to the Mechanism-Plane

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 default vector colors are Blue for Velocity, Red for Acceleration

The vectors update their values and length each machine step - see Machine Settings dialog-box > Number-of-Steps