Absolute value F/T sensor - UR10e

Technical Questions
1

Hello,

Is it possible to get the absolute value of the F/T sensor ?
The F/T sensor is reseted (zero) as soon a I run a program, whatever the mass attached to the flange.

What I would like is to get the absolute force applied on the F/T sensor.
If I add a 2kg part on the flange when the robot is stopped, i would like to see the 2kg it when I start the program (the payload is the same in both cases).

Thank you for your help

Florent.

2

Are you sure the sensor is reset automatically every time you run a program? I’ve noticed the force mode template on the teaching pendant does indeed reset the ft sensor automatically, but if you avoid using it then the sensor shouldn’t be reset unless you manually call zero_ftsensor(). You will have to write your force mode commands via URScript to avoid using the Force Mode Template.

You can then get the readings by following the instructions on this page https://www.universal-robots.com/articles/ur/programming/get-force-and-torque-values-in-tool-coordinate-system/

3

Hello,

Thank you for the information.

I made some tests and I confirm that the F/T sensor is resetted every time I run the program.
I would like to disable this behaviour and get the raw value of the F/T sensor.
I will help me a lot for my measurement tests.

4

Hello,

I encountered the same situation when I used UR16e. I noticed that the F/T sensor is reset whenever I run any local program. When UR is powered on, the sensor is also reset.

I would like the sensor to retain its values when I start a local program. If I can get the absolute value of the F/T sensor, it will also solve my problem.

Could you please help me about this problem? @Ebbe @ajp

Thanks!

5

Hello,

I contacted the UR10 support for this need.
There is no build in function to get the absolute values of the Force/Torque sensor under Polyscope.

The only way is to use rtde variable : ft_raw_wrench
I make some tests and it worked. I received on a distant computer by rtde the raw /absolute values of the sensor. Do not worry to see huge huge offsets for each axis.
For my need it was sufficient, it was for remote monitoring.

To retrieve the value of ft_raw_wrench variable under polyscope, i assume we would need to use a python program (with rtde connection to get values and write values on registers) running

  • under a python daemon in local (on the robot)
  • or an external computer.

For the first case we have to use the urcap sdk. I have never do that…seems complex. Is there a tutorial to install a python daemon ?
For the second, with an external computer we will decrease in reliability and robot independence.

Do you see others options ?

6

Thanks for your reply! I think your answer can solve my problem. @florent.monbrun

In most cases, I control the robot remotely, but sometimes I need to use DI to start a local program which will reset the F/T sensor unexpectedly. So I think the simplest way is to avoid the F/T sensor reset when the local program launches.