# Robot takes shortest path rather than avoiding joint limit

**URL:** <https://forum.universal-robots.com/t/robot-takes-shortest-path-rather-than-avoiding-joint-limit/816>\
**Category:** Technical Questions\
**Tags:** robot-motion\
**Created:** [May 26, 2017, 10:24am UTC](https://forum.universal-robots.com/t/robot-takes-shortest-path-rather-than-avoiding-joint-limit/816 "2017-05-26T10:24:04Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![anon52467762](https://avatars.discourse-cdn.com/v4/letter/a/f14d63/32.png) [@anon52467762](https://forum.universal-robots.com/u/anon52467762)\
**Post date:** [May 26, 2017, 10:24am UTC](https://forum.universal-robots.com/t/robot-takes-shortest-path-rather-than-avoiding-joint-limit/816/1 "2017-05-26T10:24:04Z")

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i use UR10  
UR software version:3.3.4.310(Dec 06 2016)  
s/n:2016303598

if current robot base TCP pose is  
x=-349.43mm  
y=132.91mm  
z=348.32mm

[RPY degree]  
rx=179.75  
ry=2.92  
**rz=-83.84**

if target rz in RPY degree is 91.716.others pose remain,then wrist3 would **turn clockwise** to target rz pose

alternate current robot base TCP pose is  
x=-349.43mm  
y=132.91mm  
z=348.32mm

[RPY degree]  
rx=179.75  
ry=2.92  
**rz=-98.33**

now,the target rz in RPY degree remain 91.716,then wrist3 would turn in **anti-clockwise** until hit joint limit.

How to avoid this issue?

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<div class="post-metadata">

**Author:** ![anon29830848](https://avatars.discourse-cdn.com/v4/letter/a/e36b37/32.png) [@anon29830848](https://forum.universal-robots.com/u/anon29830848)\
**Post date:** [May 26, 2017, 12:10pm UTC](https://forum.universal-robots.com/t/robot-takes-shortest-path-rather-than-avoiding-joint-limit/816/2 "2017-05-26T12:10:19Z")

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It sounds like your issue is the same as the problem described here:

> [@Cartesian linear move can "wind up" the wrist](http://forum.universal-robots.com/t/cartesian-linear-move-can-wind-up-the-wrist/418/13):
>
> After some more working around the problem, I’m not so sure this is actually a very useful approach. My assumption was that the long rotation would prevent hitting joint limits. However, in some cases we actually had to rotate in the same direction as the short path, but an additional 2\*pi. I’m not so sure that this can easily be fixed in movel() without making the robot movement rather unpredictable. So, we did manage to detect what rotation should prevent hitting the wrist3 limit in our setu…

There are some suggested workarounds there you can take a look at.

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<div class="post-metadata">

**Author:** ![anon52467762](https://avatars.discourse-cdn.com/v4/letter/a/f14d63/32.png) [@anon52467762](https://forum.universal-robots.com/u/anon52467762)\
**Post date:** [May 29, 2017, 2:09am UTC](https://forum.universal-robots.com/t/robot-takes-shortest-path-rather-than-avoiding-joint-limit/816/3 "2017-05-29T02:09:03Z")

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I have a look now,thank

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<div class="post-metadata">

**Author:** ![system](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.universal-robots.com/system/32/1_2.png) [@system](https://forum.universal-robots.com/u/system)\
**Post date:** [January 19, 2021, 6:52pm UTC](https://forum.universal-robots.com/t/robot-takes-shortest-path-rather-than-avoiding-joint-limit/816/4 "2021-01-19T18:52:59Z")

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