# How to change surface velocity direction?

**URL:** <https://tech-community.robotics.abb.com/t/how-to-change-surface-velocity-direction/10334>\
**Category:** RobotStudio\
**Created:** [August 24, 2021, 9:10am UTC](https://tech-community.robotics.abb.com/t/how-to-change-surface-velocity-direction/10334 "2021-08-24T09:10:34Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![jegea](https://avatars.discourse-cdn.com/v4/letter/j/f14d63/32.png) [@jegea](https://tech-community.robotics.abb.com/u/jegea)\
**Post date:** [August 24, 2021, 9:10am UTC](https://tech-community.robotics.abb.com/t/how-to-change-surface-velocity-direction/10334/1 "2021-08-24T09:10:34Z")

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Hi all,  
I would like to change the direction of the velocity surface during the simulation. I know you can start or stop the surface movement with the physics control block, but I can’t change to move it forward and backward.

Is it possible? Can anybody help me?

Regards

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<div class="post-metadata">

**Author:** ![MartinB](https://avatars.discourse-cdn.com/v4/letter/m/aeb1de/32.png) [@MartinB](https://tech-community.robotics.abb.com/u/MartinB)\
**Post date:** [December 17, 2021, 2:12pm UTC](https://tech-community.robotics.abb.com/t/how-to-change-surface-velocity-direction/10334/2 "2021-12-17T14:12:02Z")

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You can change the surface velocity of the physics control block. Eg forward +100 mm/s, backwards -100 mm/s. You could use a random number generator with tight min/max: min 99,99 max 100. Will be rounded to nearest INT.