# Control based on force\_mode

**URL:** <https://forum.universal-robots.com/t/control-based-on-force-mode/9843>\
**Category:** URScript\
**Created:** [November 10, 2020, 4:26pm UTC](https://forum.universal-robots.com/t/control-based-on-force-mode/9843 "2020-11-10T16:26:18Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![anon59108369](https://avatars.discourse-cdn.com/v4/letter/a/f05b48/32.png) [@anon59108369](https://forum.universal-robots.com/u/anon59108369)\
**Post date:** [November 10, 2020, 4:26pm UTC](https://forum.universal-robots.com/t/control-based-on-force-mode/9843/1 "2020-11-10T16:26:18Z")

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Hi,  
I am trying to implement an impedance control, but for now only in free-space (to test if it works).

**How it works:**

1. Find Xm (impedance model position)
2. Based on Xm calculate the wrench which should cause the robot to move in a way which causes it to be close to the Xm
3. The calculated wrench is feed into `force_mode` which suppose to cause it to reach the desired goal.

The issue I am having is that even though the Xm does reach the final goal (as can be seen on the graph) meaning I do obtain the required impedance model position. The wrench which is a function of xm doesn’t cause the robot to move in a similar manner to that of xm.  
This can be seen in the above graph: Xm (impedance model), Xr(actual TCP position) , X0 (goal)

_ **Question: Many control laws can be written in a form that creates a wrench and cause the robot to reach the desired goal position. I am just unsure where the issue might be, and why when I feed the wrench into force\_mode it doesn’t cause the robot to move to the desired location. I think it is an issue with the robot and therefore any hints would help a lot** _

 ![image](https://us1.discourse-cdn.com/flex020/uploads/universal_robots/original/2X/f/f3c0676158fd6bedda696a46c28168147b619343.png)