Getting Started Tutorials - MechDesigner > Tutorial 2A: Four-bar Kinematic-Chains > Step 2.2: Add a Motion FB; Kinematic Vectors

Motion from MotionDesigner

When we connect a Linear-Motion FB to a Motion-Dimension FB, (see Step 1.6) the Motion-Part rotates with uniform angular velocity.

A Gearing FB can change the angular velocity.

However, Parts in packaging machines frequently have complex motions.

You can design complex motions in MotionDesigner.

You use a Motion FB to link a complex motion in MotionDesigner to a Motion-Part in the model.

Objective of this Step

1.Control how a Part moves with a Motion FB.

2.Show the Kinematic-Vectors for a Point.

Summary of this Step

1.Delete the Gearing FB between the Linear-Motion FB and the Motion-Dimension FB.

2.Add a Motion FB to the graphics-area.

3.Connect a wire from the Linear-Motion FB to the Motion FB and from the Motion-FB to the Motion-Dimension FB.

4.Edit a Point to show its Kinematic Vectors.

5.Edit the scale (length) of the Kinematic Vectors.

You should also complete MotionDesigner Tutorials 2 and Tutorial 3 to change the motion design.

Video of this Step

Add a Motion FB

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STEP 1: Delete the Gearing FB

1.Right-click the Gearing FB in the graphics-area.

2.Click Delete element in the shortcut-menu.

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STEP 2: Add a Motion FB

1.Click Kinematic FB toolbar> Add Motion FB

2.Click in the graphics-area.

The Motion FB is now in the graphics-area.

We automatically link for you the motion in the left-most Motion name-tab to the Motion FB.

To link a different motion, you must edit the Motion FB.

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STEP 3: Connect wires between the Function-Blocks

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 output-connector of the Motion FB to the input-connector of the Motion-Dimension FB.

In the image, there is wire and wire between the FBs.

STEP 4: Cycle the kinematic-chain

1.Press ALT+C on your keyboard.

The Rocker moves with the default motion (left-most tab in MotionDesigner).

As the MMA increases from 0 to 360, the Rocker cycles by one motion.

More details:

When you cycle the model with Run menu > Cycle (or use the ALT+C key combination on your keyboard.

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

Therefore, the input to the Motion FB is equal to the MMA.

The input to the Motion FB corresponds to the X-axis of the motion that is in the left-most Motion name-tab of MotionDesigner.

The corresponding output from the Motion FB is equal to the Y-axis of the same motion.

The output from the Motion FB is the input to the Motion-Dimension FB.

Thus, the Motion-Part (Rocker) moves with the motion that is in the left-most Motion name-tab of MotionDesigner when you use Run menu (or toolbar) > Cycle.

Instant Analysis: Kinematic Vectors

MechDesigner calculates the Position, Velocity, and Acceleration of all Points* at all times.

* Points, start-Points, end-Points, and center-Points.

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STEP 1: Add a Line to the Coupler

Edit the Coupler Part:

1.Double-click the Part-Outline of the Coupler. The Part-Editor opens.

2.Part-Editor: Click Geometry toolbar > Add Line | Drag in the graphics-area to add the Line

3.Part-Editor: Geometry toolbar > Add dimensions and Add constraints to locate the Line.

4.Part-Editor: Double-click the new Line to close the Part-Editor.

You can see the Line in the Coupler.

Point Properties dialog

STEP 2: Show the Velocity and Acceleration Vectors:

1.Double-click the Point Red-14-3 that is at the end of the Line in the Coupler

The Point Properties dialog opens.

2.Click the Kinematic-Vectors separator

3.Enable Show Velocity Vector and Show Acceleration Vector

4.Click the icon to close the dialog.

Change the scale of the Vectors in the graphics-area.

Vector Scale buttons

V corresponds to the Velocity-Vectors

A corresponds to the Acceleration-Vectors

1.Click the up-button to increase the length of the vector

1.Click the down-button to decrease the length of the vector

About the Velocity and Acceleration Vectors

•They show when the Point is moving relative to the Mechanism-Plane

•Their lengths are proportional to the instantaneous Velocity and Acceleration of the Point.

•Their magnitudes are at the arrowhead of each vector

•Their colors can be changed in Application Settings > Colors tab > Graphic separator

•Their values and lengths change at each machine-step - see Machine Settings dialog > Number-of-Steps

Notes

If necessary, to see vectors more clearly, change the color of the Background, the Velocity Vector, and/or the Acceleration Vector.

See Edit menu >Application Settings > Graphics tab > Display Colors separator > Background / Velocity Vector/ Acceleration Vector