Motion Control and Motor Drives

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Limit Switches and Contour Moves.

 I am developing a 4 axis contour motion system and need to know how to handle if one of the axis activate a limit switch.  Does the activated axis have to be moved off the switch so the contour move can continue or can you move it off with a co-ordinated contour move?

 

Configuraton

 

LabVIEW 2013 SP1

Softmotion 2013

cRIO Crate

NI 9514 C Series Servo Drive Interface with Encoder Feedback (all 4 axis_

 

Paul

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Can you explain with a little more detail or provide a diagram of what you are trying to acheive? 

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The controller that I am developing is a four-axis inspection delivery tool. It is made up with a vertical pole that can be moved up and down and rotate. At end of the pole there is an "arm" that can be raised and lowered; the arm can also rotate +/-45 degrees. What I want to do is to move 2 to 3 axis simultaneously so the tool end can travel along set paths. For example if the tool end is to move horizontally, the arm has to be raised (rotated) while the overall tool is lowered. To calculate the coordinated time path of each axis, I use an inverse kinematic calculation that creates a table of positions (for each axis) with the set time interval, thus the use of multi-axis contour move.

 

The problem that I am worried about but have not had a chance to test, is what happens when on the axis activate a limit switch, say for example the tools vertical upper or lower travel limits. With standard single axis point-to-point movement, you can always command to travel off the limit (but not through it) but it is not clear what will happen when using contour moves (single or multiple-axis). Thus the question, how to handle, when one of the axis of a coordinated contour move motion activates a limit switch.


Cheers


Paul

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