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Step 1.5: Add and Edit a Motion-Dimension FB

Contents

IMPORTANT: Background to this Step.

Part's have two states

•	Unsolved Parts are not kinematically-defined. They have Blue Part-Outlines

•	Solved Parts are kinematically-defined. They have Green Part-Outlines

To be useful, the Part must be solved.

The state of the Part after STEP 1.4 is unsolved.

We will change its state to solved in this step of the tutorial.

Note:

To edit the default colours:

Application Settings > Graphics tab > Display Colours > Part Solved to Green and Part Unsolved to Blue.

Objective of this Step

To change the state of the Part to solved.

The Part becomes kinematically-defined.

Summary of this Step

Add a Motion-Dimension FB to a Part that is joined to another Part 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

•	Add a Motion-Dimension FB

•	Edit a Motion-Dimension FB

STEP 1:

Click:
Kinematic-FB toolbar > Motion-Dimension FB
- or -
Add menu > Add Motion-Dimension FB

GA-AddMotionDim-0

In the Command-Manager, we must select three elements

We must select the three elements in the correct order (in sequence):

Pin-Joint

Solved-Line

Free Line

Command Manager ready for selections

Click the elements in the image above

Pin-Joint - see Step 1.4

Line in the Base-Part - see Step 1.3.

Line is a child to the Base-Part. The Line is a solved-line because the Base-Part is a kinematically-defined Part.

Line radiates (is a 'ray') from the Pin-Joint

CAD-Line along the centre of the Added-Part - see Step 1.2

CAD-Line is a child to the Added-Part. The CAD-Line is a free-line because the Added-Part is a Free Part .

CAD-Line radiates (is a 'ray') from the Pin-Joint

Commandd Manager with selections

STEP 2:

Click

in the Command-Manager.
or
Right-Click in the Graphic-Area - recommended short-cut.

The Motion-Dimension FB is now in the graphic-area.

GA-MotionDimRocker_FBmenu

The Motion-Dimension FB element has two features in the graphic-area:

Function-Block

Motion-Dimension Line - the arrowhead is the positive (increasing) direction of the motion-value.

Note: There are two different mouse-actions:

To move the FB

To move the Motion-Dimension

Function-Block :	Hover(FB) + DRAG
Motion-Dimension Line :	CTRL + Hover(FB) + DRAG

Hover(FB)= move your mouse above the FB icon.

DRAG = Mouse-Button-Down, and move your mouse-pointer, Mouse-Button-Up

Notes:

•	The colour of the Part-Outline is has changed from Blue to Green. Parts with Green Part-Outlines are kinematically-defined Part.

•	The design of the icon in the graphic-area is different to the icon in the Motion-Dimension FB in the Kinematic-FB toolbar.

•	Its design is similar to a Pin-Joint, which is to help you see that the Motion-Dimension FB specifies the angle of a Part.

To edit the Part's initial position, we must edit its Base-Value parameter in the Motion-Dimension dialog-box.

Motion-Dimension FB dialog-box

1.	Double-click the Motion-Dimension FB in the graphic-area or see How to open a dialog-box.

In the Motion-Dimension dialog-box:

Edit:

o	Base-Value

The angle of the Motion-Dimension when a wire is not connected to the input-connector of the Motion-Dimension FB.

- or -

o	Base-Value + Motion Value

The current positional value of the Motion-Part

It is sometimes more useful to edit the current positional value than to edit its Base-Value.

Directions

It is possible to 'negate' the sense of the Base-Value and the Motion-Values

Notes:

There are two parts to the Motion-Dimension in the graphic-area:

There is the FB Icon and the Dimension.

To move the:

•	Icon: Hover(FB) + Drag the Function-Block

•	Dimension: CTRL + Hover(FB) + Drag the Function-Block

The Part, Pin-Joint and Motion-Dimension are the elements that make a Rocker. A Rocker is a Motion-Part.
If you explore the Kinematics-Tree, you can see the three elements that you need to give the Rocker kinematic-element.
Kinematic-Tree with Elements for a Rocker		Part
		Pin-Joint
		Mot-Dim Rocker

•	Degrees-of-Freedom (DOF) The number of coordinates that you need to specify the position and orientation of a Part.

•

Mobility

o	Mobility = Degrees-of-Freedom – Number of Motion-Dimensions

•	Motion-Parts:

o	Rocker: a Part joined with a Pin-Joint to a kinematically-defined Part. The angle of the Rocker is given by a Motion-Dimension FB.

o	Slider: a Part joined with a Slide-Joint to a kinematically-defined Part. The position of the Slider is given by a Motion-Dimension FB.

•	Kinematically-Defined Part: a Part that is a child to a kinematically-defined chain

•	Kinematically-Defined Chain: a kinematic-chain that has Mobility equal to Zero.

•	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.

•	3 – 2 – 1 = 0 ( DOFs )

Tutorials and Reference Help Files for MechDesigner and MotionDesigner 14.2 + © Machine, Cam, Mechanism, and Motion Design Software by PSMotion Ltd