# Synchronous Motion with A Linear Axis

**URL:** <https://forum.universal-robots.com/t/synchronous-motion-with-a-linear-axis/9079>\
**Category:** URScript\
**Created:** [October 8, 2020, 4:42pm UTC](https://forum.universal-robots.com/t/synchronous-motion-with-a-linear-axis/9079 "2020-10-08T16:42:06Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![anon4832633](https://avatars.discourse-cdn.com/v4/letter/a/8baadc/32.png) [@anon4832633](https://forum.universal-robots.com/u/anon4832633)\
**Post date:** [October 8, 2020, 4:42pm UTC](https://forum.universal-robots.com/t/synchronous-motion-with-a-linear-axis/9079/1 "2020-10-08T16:42:06Z")

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I will do synchronous motion with a linear slider with servo motor but I could not decide the most suitable urscript function. In my opinion, servoj is suitable but also movep seems me appropriate for trajectory without calculations of orientation and position interpolations. Which motion function gives the best performance for synchronous movement?

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**Author:** ![Ebbe](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.universal-robots.com/ebbe/32/1413_2.png) [@Ebbe](https://forum.universal-robots.com/u/Ebbe)\
**Post date:** [October 13, 2020, 1:30pm UTC](https://forum.universal-robots.com/t/synchronous-motion-with-a-linear-axis/9079/2 "2020-10-13T13:30:21Z")

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Hi @anon4832633,

It also depends if the synchronization shall be an addition to a user programmed movement. Like the conveyor tracking.  
If that is the case I would go for the conveyor tracking functionality that will give you the option to add a one axis offset or use the online path offset functionality on the e-series. That will give you the ability to offset in all 6 degrees of freedom.

If that is not the case. The _speedl_ function is also an option.

I am not sure the is just one simple answer to the “best performance”. How do you define that? In all cases it will be depended on the stimuli you want to track.

Ebbe

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<div class="post-metadata">

**Author:** ![anon4832633](https://avatars.discourse-cdn.com/v4/letter/a/8baadc/32.png) [@anon4832633](https://forum.universal-robots.com/u/anon4832633)\
**Post date:** [October 14, 2020, 1:37pm UTC](https://forum.universal-robots.com/t/synchronous-motion-with-a-linear-axis/9079/3 "2020-10-14T13:37:59Z")

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Hi @Ebbe,  
Thanks for reply. Maybe, I did not explain clearly my problem. Nowadays I don’t have robot when i get a robot i will try the motion functions because I asked this kind of question. I will weld workpiece attached 2 external axis. I will add a linear axis at the base of the robot, and I have 2 external axis that move workpiece , and robot tool will follow workpiece motion. In my opinion, speedl and movep functions are related with speed controlling so when I use these functions I could not exactly catch workpiece motion because I cannot catch poses related with acceleration of robot tool(lagging may happen). If I use servoj function, I can control tool pose any time and external 2 axis servo motors will be followed according to servoj command timing. Am I wrong?