Getting Started Tutorials - MechDesigner > Tutorial 2C: Kinematic Tools

Kinematic Analysis Tools

You can plot kinematic values of for one or more machine cycles with a Graph FB.

You can also kinematic values at a machine-angle.

Tool 1: Element-Properties dialog

The Element Properties dialog is a list of kinematic values for an element at the Master-Machine-Angle.

Elements that have Element-Properties are:

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

GST-2C-A-ELEMENT-PROPERTIES

To show the Elements Properties dialog:

Before MD16.1.370

In the graphics-area:

CTRL + CLICK one element

The Element-Properties dialog is now open.

Note:

The Element-Properties dialog does not open if you CTRL+Click more than one element.

After MD 16-1-370

When you move your mouse above an element in the graphics-area, the Element's Properties ALSO show in the Feedback Area > Extended Hints box

Element-Properties dialog-box : Point

Example:

Element-Properties of a Point.

In this case, the Element-Properties are of Point212', which is a child to Part36, which is a child to a mechanism with the name RRP.

Properties of a Point

•Part Pos: the Point's vector position in the Part's coordinate-system

•Mech Pos: the Point's vector position in the Mechanism-Editor's coordinate-system

•Glob Pos: the Point's vector position in the Model-Editor's coordinate-system

•Velocity, Acceleration:

oi , j : Velocity and Acceleration, in the X-axis and Y-axis directions, respectively.

o|n| : the magnitude of the Velocity and Acceleration

oΘ : the direction of the Velocity and Acceleration . ('0' is the X-axis direction of the Mechanism-Plane)

V indicates vector values.

Tool 2: Trace-Points

A Trace-Point is the path of a Point on the Mechanism-Plane for one machine-cycle.

You can add many Trace-Point at one time.

1.Click Kinematic-elements toolbar > Add Trace-Point

2.Click a Point* in the graphics-area

3.Click in the Command-Manager

Do 1-3 again to show the Trace-Point of other Points.

* Point, start-Point, end-Point, and Center-Point

To Drag a Point in the graphics-area of the Mechanism-Editor:

As a rule, you cannot drag sketch-elements in the Mechanism-Editor.

There is one exception to the rule when you do these 3 steps.

STEP 1: In the Part-Editor:

The exception does not apply to a start-Point, end-Point, or center-Point.

1.Do Geometry toolbar > Add Point sketch-element

2.Click the graphics-area

Do not add to the Point a constraint or dimension.

3.Close the Part-Editor

STEP 2: In the Mechanism-Editor:

1.Do Kinematic-elements toolbar > Add Trace-Point

2.Select the Point

3.Click in the Command-Manager.

STEP 3: In the Mechanism-Editor:

1.Drag the Point with the Trace-Point, slowly.

Video : Add Trace-Point

Tool 3: Kinematic Vectors: Velocity and Acceleration

You can show the Kinematic-Vectors of a Point* with the Point Properties dialog.

* Point, start-Point, end-Point, center-Point, Motion-Point.

STEP 1: Select the Point

In the graphics-area:

1.Double-click a Point* that is a child to a Part that is kinematically defined.

Use Filters toolbar> Points if it is difficult to double-click a Point*.

The Point Properties dialog is open.

STEP 2: Enable the Velocity and or Acceleration Vectors

In the Point Properties dialog:

1.Click Kinematic-Vectors

2.Enable Show Velocity Vector

3.Enable Show Acceleration Vector

4.Click to close the dialog.

Do 1-5 again to show or hide Kinematic Vectors of different Points

Velocity and Acceleration Vectors in the graphics-area

•The Vectors show when the Point moves relative to the Mechanism-Plane

•The length of the vectors are proportional to the Point's instantaneous Velocity and Acceleration.

•The magnitude of the vectors are at the arrowhead of each vector

•The color (default) of the vectors are Velocity, Acceleration

•The vectors update their values and length each Machine-Step

Scope

Enable, to show the Vectors relative to the:

•Local xyz axes - the axes of the Mechanism-Editor (default), or

•Global XYZ axes - the axes of the Model-Editor

Velocity Vector Options

Enable, to show the:

•Magnitude of the Velocity Vector (default), OR

•X component of the Velocity Vector, OR

•Y component of the Velocity Vector, OR

•z component of the Velocity Vector.

Note 1:

If necessary, change the color of the Vectors to see the Vectors and their kinematic-values more clearly - see Application Settings > Graphics tab > Display colors

Velocity and Acceleeration Vectors from a Point.

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

Use the Vector Scale buttons at the below the graphics-area.

Force, Torque, Velocity, Acceleration Buttons to scale the vectors.

Velocity and Acceleration buttons.

To change the length of vectors:

1.Click the up/down button to increase/decrease the length of the vector.

Tool 4: Instant Radar Scale

DO NOT USE UNTIL FURTHER NOTICE.

To show the Dimensional Instant Radar Scale:

In the graphics-area:

ALT+Click

The Instant-Scale shows next to your mouse-pointer.

As you zoom-in or zoom-out the scale also auto-scales.

There are 10 concentric circles.

There are two thick circles, which show the actual dimension value at their radii.

•Inner Dark Circle (50.000 in the image) is circle #5

•Outer Dark Circle (100.000 in the image) is circle #10

Linearly interpolate the dimensions for the other circles.

Note: If the numbers have too may zeros, the inner number overwrites the outer number.

You should reduce the number of digits. To reduce the number of zeros: Application-Settings > Number-Format.

Tool 5: Kinematics-Tree - Dyad is Solved, will Break, is Broken?

MechDesigner compiles Parts and Joints into dyads.

Dyads have two(2) Parts and three(3) Joints.

You may find that the two Parts assemble correctly when you add the last joints.

But, when you cycle your model, you may find that Parts cannot assemble at all points in the machine-cycle.

The Kinematics-Tree indicates to you whether the dyads can assemble or not.

The Kinematics-Tree uses symbols to indicate three KINEMATIC STATES.

KINEMATIC-STATE 1

- There is a kinematic solution for the Kinematic-Chain at all points in the machine-cycle.

KINEMATIC-STATE 2

- There is not a kinematic solution at all points in the machine-cycle.

KINEMATIC-STATE 3

- There is not a kinematic solution at this instant in the machine-cycle.