Edit the Start of a Traditional Motion-Laws

A Traditional Motion-Law allows you to specify a position at its start and its end, but not a velocity, acceleration, or jerk. The velocity and acceleration values are usually zero.

See Standard or Traditional Segments

Here, we show you how to edit the Position at the Start of a Traditional Motion-Law.

We consider the two cases:

Case 1: The Previous-Segment is also Traditional Motion-Law.

and

Case 2: The Previous-Segment is a Dwell Motion-Law - which is a special case of a Traditional Motion-Law.

VIDEO OF THIS TUTORIAL

How to...

Edit the Start of a Traditional Motion-Law

tog_minusCase 1: The Previous Segment is also a Traditional Motion-Law

Motion Graphs of Traditional Motion Laws

Motion Graphs of Traditional Motion Laws

 

 

In the image to the left, the:

1s-red Selected-Segment (RED) is a Modified-Trapezoidal - a 'Traditional Motion-Law'.

2s Previous-Segment is a Modified-Sinusoid - this is also a 'Traditional Motion-Law'.

To edit the 'End of the Modified-Sinusoid' / 'Start of the Modified-Trapezoid' Motion-Law:

1.Click the Modified-Trapezoid Segment1s-red  - so that it becomes the Selected-Segment
2.Click the Blend-Point and Segment toolbar > Start Blend-Point Editor icon
Start Blend-Point Editor

Start Blend-Point Editor

Position Values in the Blend-Point Editor

Position Values in the Blend-Point Editor

In the Y-axis Values separator of the Blend-Point Editor

3.Make sure the Specify End Position Control-Button is active 3s
4.Make sure the Match Control-Button is active 4s
5.Edit the End-Position5s with the Spin-Box tool, or use you keyboard to enter a new motion value.

The Position at the end of the Modified-Sinusoid Segment changes to the motion-value you enter in the Position data-box.

Question:

Why are the Velocity, Acceleration, and Jerk Control Buttons disabled?

Answer:

You cannot edit them. The motion derivatives are fully defined by the mathematical function that specifies the Modified-Sinusoid segment. The Velocity and Acceleration values are zero. The Jerk is another value.

tog_minusCase 2: The Previous Segment is a Dwell Motion-Law

Tut5-PreSeg-Dwell

Let's see what is in the Blend-Point Editor when the Modified Trapezoid motion-law is the Selected-Segment.

1.Click the Modified-Trapezoid Segment1s-red  - so that it becomes the Selected-Segment
2.Click the Blend-Point and Segment toolbar > Start Blend-Point Editor icon
Start Blend-Point Editor

Start Blend-Point Editor

Tut5-BPE-PreSegDwell

In the Y-axis Values separator of the Blend-Point Editor

3.The Specify End Position Control-Button is Grey 3s Thus you cannot select it!

This is because the End Position of the Previous-Segment, when the Previous-Segment is a DWELL, and the Match Control-Button is active also, can ONLY be specified at the start of the DWELL.

When the Match Control-Button is active, you cannot edit the Start Position of the Selected-Segment. This is because, nearly always, the Position motion-values 'flow' from one segment to the next so that there is not a position discontinuity.

To edit the end of the Dwell Segment you must the Start Position of the Dwell Segment. Thus:

1.Select the Dwell Segment

The Dwell Segment becomes the Red Selected-Segment.

Make sure the Match Control-Button is active

2.Edit the End-Position [of the Previous-Segment]

This becomes Start-Position of the Dwell Segment ...

... which automatically becomes the End-Position of the Dwell Segment [logically, it must] ...

... which becomes the the Start-Position of the Modified-Traditional segment.

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