Motion-Dimension FB

Summary of Motion-Dimension FB

Use a Motion-Dimension FB to identify a Part you want to move with a specified motion.

Each Motion-Dimension FB may specify:

An Angle between two Lines that are in different Parts and the Line's Point joined with a Pin-Joint - a Part becomes a Rocker.

- or -

A Distance between two Points [at the end of two different Lines] that are in different Parts, and the Lines joined with a Slide-Joint - a Part becomes a Slider.

Rockers and Sliders are said to be Motion-Parts.

Add and Edit Motion-Dimension FB



Kinematics FB toolbar > Motion-Dimension FB [Right-side of Graphic-Area]


Add menu > Add Motion-Dimension FB

'Add Motion-Dimension FB' : to add this element, you must select 3 elements.

For detailed information see: Add Motion-Dimension FB.



STEP 1: Add the Motion-Dimension FB to the graphic-area

1.Single-Click the Kinematics FB toolbar > Motion-Dimension FB

The Command-Manager starts. You must select three elements: a Joint and the two sketch-elements.

The Rules are difficult to describe in full. Thus, see Add Motion-Dimension FB for more details.

In summary, select, either a:

Pin-Joint, then a Line in each Part that it joined with the Pin-Joint. One Part is kinematically-defined

or a

Slide-Joint, then a Point at the end of each Line and Part that is joined with the Slide-Joint. One Part is kinematically-defined.


STEP 2: Open the Motion-Dimension FB dialog-box:

1.Double-click the Motion-Dimension FB in the graphic-area or Assembly-Tree

Note:The Motion-Dimension FB icons in the graphic-area are different to the icon in the Kinematics FB toolbar:


Motion-Dimension FB for a Rocker


Motion-Dimension FB for a Slider

- or -

The Motion-Dimension FB dialog-box


1s-red Base-Value: in the image, the Base-Value is '75'

This is the 'constant' contribution to the output of the Motion-Dimension

The linear or angular value given to the Motion-Part when a wire is not connected to the input of the FB.

2s Motion-Value: (motion-value at its input-connector) in the image, the Motion-Value is '9.15992104

This is the 'motion contribution' to the output of the Motion-Dimension.
It is the motion-value at the input-connector of the Motion-Dimension FB.
The 'Motion-Value' regulates the position of the Motion-Part relative to the Base-Value.

2s Base-Value + Motion-Value

The actual motion-value given to the position of the Motion-Part
It is the output of the Motion-Dimension.
It is the total of Base-Value + Motion-Value


5s Negate Motion-Values: Option to multiply the Motion-Values by -1.

Mirror the motion-values relative to the Base-Value. Click the

Positive Motion-Values check box [default], or
Negative Motion-Values check-box

6s Negate Base-Values: Option to multiply the Base-Value by –1.

Mirror the start-position of the Motion-Part. Click:

Positive Base-Value check box [default], or
Negative Base-Values check-box


The Positive direction of the Motion-Dimension.

When the Motion-Dimension specifies an Angle [Rocker]:

The Positive direction is always the 'counter-clockwise' angle from the 'Fixed Part' to the 'Motion-Part'

When the Motion-Dimension specifies a Distance [Slider]:

The Positive direction is a function of the positive direction of the Lines that you use in the Slide-Joint. There is an arrowhead at the start of one of Lines in the Sliding-Joint that indicates its positive direction.

See Positive Direction of Sliders

Tutorial and Reference Help Files for MechDesigner and MotionDesigner 13.2 + © Machine, Mechanism, Motion and Cam Design Software by PSMotion Ltd