No zero_ftsensor() script function

Technical Questions
1

Hello everyone,

I am trying to get some good readings from the F/T sensor of the UR3e, to do so I was advised to call the zero_ftsensor() script function. However, I can’t see to find this function under the scripts tab of the teach panel. I am running the latest software version (5.11.8). Am I missing something? Thanks in advance.

2

You can just type it in within a script node.

Here’s the description from the URScript manual:

** 16.1.63. zero_ftsensor()**
** Zeroes the TCP force/torque measurement from the builtin force/torque sensor by subtracting the**
** current measurement from the subsequent.**
** Note: Function only applicable in G5**

** e-Series 110 Script Manual**

There’s no example,and I haven’t done any messing around with this feature, so I’m not sure exactly how/where it’s used.

3

Thanks for the reply. Unfortunately this does not have an effect. Another thing that got me curious was the wide range of sensor values. With no load attached, they return +/- 5 N, and increase even when applying force to the elbow. This got me thinking that the FT sensor in the tool flange is not delivering the force, but rather it is calculated using the joint currents. I hope i made my problem clear and appreciate any help.

4

Hi,
It might depend on how you are reading the F/T sensor values. If you are using the force() script command it is returning the scalar forces at the TCP (summation of all forces). If you are using get_tcp_force() it returns a 6 element vector, showing X/Y/Z, etc forces. The force() command is going to be more noisy and higher magnitude.

It might help to average the forces using a thread to get rid of the noise.

If none of the above helps then it might be that you have an uncalibrated F/T sensor. Does this problem become more apparent when you rotate wrist 3 while taking readings? IF it does then this is a sign of an uncalibrated F/T sensor. Contact UR service and see what their advice is.

5

Hello,
I am using the get_tcp_force() script function in order to get readings for all axes. Rotating the wrist delivers an even wider range of measurements. Thanks for your help, I am going to contact UR service.