﻿ Kinematic Analysis Tools: Instant Values

# Tutorial 2B: Kinematic Tools

## Kinematic Analysis Tools

We use these tools to show kinematic values at any angle of the machine cycle and Master-Machine-Angle[MMA].

We can also plot the kinematic values for a complete machine cycle, with a Graph FB.

#### Tool 1: Element Properties dialog-box

This dialog-box shows the Element's Properties. The values are at the Master-Machine-Angle [MMA]. You can move the model to any MMA while this dialog is open.

Elements that have Element Properties are:

 • Wire, Part, Pin-Joint, Slide-Joint, 2D-Cam, Part-Outline, Line, Circle, Arc, Point, Gear-Pair, Function-Blocks...

To open the Element Properties dialog-box:

In the graphic-area:

 1 Hover above the element so that it becomes Red. Do not click the element.
 2 CTRL key down + Click the element

The 'Element-Properties dialog is now open.

The two steps above are frequently described as one step: 'Hover+CTRL+Click'.

Notes:

 • If you Hover+CTRL+Click more than one element, the Element Properties dialog-box may not open.

Element Properties dialog box for a Point

Element Properties dialog for a Point : see image above. [The properties for different elements are different.

In the image above, we looking at the 'Element's Properties of a Point'.

At the top of the dialog-box, you can see the

 • Element's Name [Point19],
 • Element's Part [Part3], and
 • Element's Mechanism [Mechanism].

In this case, we are looking at the Element Properties of 'Point19', which is a child to 'Part3', which is a child to 'Mechanism'

Point Property:

In the case of a Point, the properties are:

 • 'Part Pos': the Point's vector position within the coordinate-system of the Part.
 • 'Mech Pos': the Point's vector position within the coordinate-system of the Mechanism-Editor.
 • 'Glob Position': the Point's vector position within the coordinate-system of the Model-Editor.
 • 'Velocity', 'Acceleration':
 o i , j : the magnitude of the vector's Velocity and Acceleration , in the X and Y directions, respectively.
 o |n| : the total magnitude of the vector's Velocity and Acceleration
 o Θ :  the direction of the vector's Velocity and Acceleration . ['0' is the X-axis direction of the Mechanism-Plane].

'V' indicates they are 'vector' values.

 Tool 2: Trace-Points

The Trace-Point shows the path of a Point on the Mechanism-Plane for a complete machine cycle.

Other terms for a Trace-Point are: 'locus', 'curve', and sometime a 'coupler curve'.

It is only possible to show a Trace-Point of a Point when the:

 • Part is a kinematically-defined chain, or as a Green Part-Outline.
 • Point actually moves relative to the Mechanism-Plane.

You can show any number of Trace-Points.

To show a Trace-Point:

 1 Click Add Trace-Point in the Mechanism Local Toolbar
 2 Click a Point that is a child to a Part in a kinematically-defined chain
 3 Click OK in the Command-Manager

Do 1-3 again for other Points that belong to the same or different Parts.

NOTES: SELECT-ELEMENTS DIALOG-BOX

When there are coincident Points, the Select Elements dialog-box opens.

 1 Click a Point in the Select Elements dialog-box
 2 Click OK to close the Select Elements dialog-box
 3 Click OK in the Command-Manager

Do 1-3 again for other Points. Even in the same Part.

When the Points are in the same Part, or they are made coincident with a Pin-Joint, then the Point you select is not important.

To delete a Trace-Point

 1 Click the Trace-Point in the graphic-area so that it becomes RED, and also shows in the Selection-Window
 2 Click the 'delete' button on your keyboard,

- or -

 2 Right-click the Point in the Selection-Window
 3 Click 'Delete' in the contextual menu

Note: If the Point:

 1 ...is a Point sketch-element (and not a Point that is start-Point, end-Point, centre-Point of another sketch-element)
 2 ...is, also, not constrained with a dimension or constraint in the Part-Editor
 3 ...is, also, a Trace-Point...

...then, you can drag the Point in the Mechanism-Editor and watch the Trace-Point update.

The Point must satisfy ALL of 1 ,2 & 3 before it is possible to drag the point.

 Tool 3: Kinematic Vectors: Velocity and Acceleration

To show Velocity and Acceleration vectors from a Point as the Point moves in the graphic-area.

To Show or Hide Velocity and Acceleration Vectors:

In the graphic-area:

 1 Double-click a Point on a Part that has a Green Part-Outline

The Point: Vectors and Position dialog-box opens.

 2 Click the Show or Hide Vectors separator bar
 3 Click the Show Velocity Vector or Show Acceleration Vector, or both, check boxes
 4 Click the OK button 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.

Note 1: If necessary, change the colour of the graphic-area to Dark Grey to see the vectors more clearly.

Application Settings > Colours tab > Graphic Colors > Background button. .

Note 2:

 • You can double-click a velocity or acceleration vector to open this dialog-box.
 • Cycle (shortcut Alt+C, [C for R13+]) to see the vectors.

About the Velocity and Acceleration Vectors in the graphic-area

 • They 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 in WHITE!
 • The colour of each is Blue for Velocity, Red for Acceleration
 • Update values and length each step as in the Machine Settings dialog-box.

To 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 many need to repeat this many times.

 Top-Tip - make the vectors very short to see only the magnitude of the motion-values near to the Point.

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