# Measurement of forces - movel

**URL:** <https://forum.universal-robots.com/t/measurement-of-forces-movel/10323>\
**Category:** URScript\
**Created:** [November 26, 2020, 10:46am UTC](https://forum.universal-robots.com/t/measurement-of-forces-movel/10323 "2020-11-26T10:46:27Z")\
**Posts on this page:** 3\
**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 26, 2020, 10:46am UTC](https://forum.universal-robots.com/t/measurement-of-forces-movel/10323/1 "2020-11-26T10:46:27Z")

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Hi all,  
@ajp  
I am trying to write a code that initiates a robot above a surface and then slowly descends till reaching contact until a force in the z-direction reaches 2N, which causes the loop to stop.

The issue I am having is, that once i initialize movel the loop is not going to continue running, instead it waits till movel finished its task and only then allows the loop to continue.  
**Any solutions?**

_ **How to let the loop which collects data from sensor run, while in the same time let the robot move to the desired location?** _

Here is my code

```
F_start = FT_sensor.force_moment_feedback().reshape(6, 1)
dist = 0.01
start = np.array([0.0000, -0.6732, 0.15768, -0.0425, 3.1233, 0.0983])
end = np.array([0.0000, -0.6732, 0.1483-dist, -0.0425, 3.1233, 0.0983])
robot.movel(start)
j = 0
fx = []
fy = []
fz = []
while True:

    print(FT_sensor.force_moment_feedback().reshape(6, 1)[2]-F_start[2])
    j += 1
    real_force = FT_sensor.force_moment_feedback().reshape(6, 1)-F_start
    fx.append(real_force[0])
    fy.append(real_force[1])
    fz.append(real_force[2])

    robot.movel(end, a=0.05, v=0.002)

    if np.abs(FT_sensor.force_moment_feedback().reshape(6, 1)[2]-F_start[2]) > 2.0:
        robot.stopl()
        print(np.abs(FT_sensor.force_moment_feedback().reshape(6, 1)[2]-F_start[2]))
        print("inner loop broken")
        break

robot.movel(start)
```

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<div class="post-metadata">

**Author:** ![anon59108369](https://avatars.discourse-cdn.com/v4/letter/a/f05b48/32.png) [@anon59108369](https://forum.universal-robots.com/u/anon59108369)\
**Post date:** [November 28, 2020, 5:02pm UTC](https://forum.universal-robots.com/t/measurement-of-forces-movel/10323/2 "2020-11-28T17:02:47Z")

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Help will be greatly appreciated 🙂

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<div class="post-metadata">

**Author:** ![ajp](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.universal-robots.com/ajp/32/471_2.png) [@ajp](https://forum.universal-robots.com/u/ajp)\
**Post date:** [November 30, 2020, 3:07am UTC](https://forum.universal-robots.com/t/measurement-of-forces-movel/10323/3 "2020-11-30T03:07:55Z")

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There’s an option under while and if statements in Polyscope called “check expression continuously”, which creates a thread to monitor the value (in this case z force) while the loop is running. I’d make a simple program in polyscope using it then look at how it works in the polyscope generated script program to see how it works.