Posts by Roboformer

Hello everyone,

I would like to take this opportunity to promote/share a piece of software that was developed as part of a research project at the Chair of Production Systems at the Ruhr University Bochum. This is a Matlab/Simulink programme that uses measured data from a force-torque sensor and the stiffness curvess of the robot joints to calculate and control the displacement of the tool as a result of process forces in real time. This is done on an external computer. The corresponding network traffic is handled by the programme. In addition, the software contains the functionality to adjust a process force in any alternating direction. Instructions, the stiffness curves of a KR600 and sample programmes are included in the download: https://zenodo.org/records/14414081

The following programmes and packages were used for the implementation:
KRC4 V8.3.26
RobotSensorInterface 3.3.2
Matlab 2020a (Simulink Desktop Real-Time, SimScape)

The software was originally developed for use in robot-based incremental sheet metal forming (Roboforming) (https://www.youtube.com/watch?v=r9PAVOrt_co). The controllers are optimised for high process forces of 2000 +/- 500 N and slow movement speeds (20 mm/s). While the calculation of the process force-induced displacement is independent of this, the controllers must be re-parameterised for other processes. A scientific publication describing the approach in detail can be found here: https://link.springer.com/article/10.1007/s11740-021-01052-4.

In the validation experiments, the same positioning accuracies were measured during a forming process as in moving through the air. The status of force control described in the publication no longer corresponds to the current software and can be ignored.

The software is licenced under CC BY 4.0 and can be used freely for any application.

Questions can be sent here or to Dennis Möllensiep (moellensiep@lps.rub.de).

CAM in Solidworks is the light version of the addin CAMWorks. We have ordered a custom postprocessor for Kuka of their local distributor years ago.

Hi,

the files have to be in the following path:

C:\KRC\ROBOTER\Config\User\Common\SensorInterface

It seems that I implemented the offset externally in Matlab. Sorry.

Quote from colmc

This is how i would like to have the configuration of the FTtask, but this gets deleted if someone presses save on the KUKA pendant

You could create a new RSI program and basically copy all your FTCtrl blocks into it. Therefore, it does not get overwritten. The downside is that you can't edit it in the FTCtrl menu. Only directly in the RSI.

Quote from colmc

without the IIR filters before the ZeroGrav function, the output of the function is centered at zero.

I haven't encountered this problem but could you apply the filtering instead to the output of ZeroGrav?

If this doesn't work, I've build a simple custum function to center the output at zero at the start of the program. I could search for it.

Hat der Laptop eine (virtuelle) IP im gleichen Subnet?

RSIBad heißt, dass der Roboter keine oder eine falsch konfigurierte Antwort vom Laptop bekommt.

Sofern du nur Daten an den Laptop senden möchtest und nicht aktiv regeln, kannst du in der RSI-XML-Datei OnlySend auf True stellen. Dann erwartet RSI kein Antwortsignal und bricht nicht sofort ab.

Hi,

I did some research regarding stiffness compensation and some more or less basic force control. Unfortunately you have to obtain them experimentally. If you have a KR600 you could use my published data. Perhaps this might also contain other useful information for your force controller:

Real-time stiffness compensation and force control of cooperating robots in robot-based double sided incremental sheet forming - Production Engineering

In robot-based incremental sheet forming, the forming robot is displaced due to the forming forces and the comparable low stiffness. As the forming forces can…

link.springer.com

From my experience, stiffness compensation isn't necessarily needed for force control. The big challenge is to find the right control parameters which requires extensive and tedious testing.

The only case where you need stiffness compensation und force control simultaniously is when you have big transversal forces to your desired force direction. In this case your point of contact is distorted without stiffness compensation.

Good luck with you implementation.

Re you using Relative or Absolute mode?

Did you set the correction limits inside RSI Visual with the object AXISCORRMON?

Your RSI files must be stored in this folder:

C:\KRC\ROBOTER\Config\User\Common\SensorInterface

Are they there?

Taken from the RSI 3.1 documentation.

You set Onlysend to False in the XML. Therefore, the RSI expects an answer that it does not get. You might want to set it to True to test the communication in atleast one direction.

What is the distance between the points of the LIN-movement? We've encountered a similar problem using small increments.

I guess you don't need them if you don't know what they are. Just delete them in send and receive.

You need to change MaxRotAngle in Poscorr and Poscorrmon

By default the maximum total position adjustment is limited to 6mm. You can use the poscorrmon object in RSIVisual to extend the limit.

How does the XML look? Is OnlySend false?

Have you checked if both FT-Sensors have the same default IP? That might be the problem here. You can connect them directly to a computer and acces them via the web browser to change the IPs.

Afterwards you have to change the IPs of the FT6D_SEN Blocks in your RSI application.

With ForceTorqueControl comes a program called LoadDataDetection. I have never used it for its intended purpose but based on the name it might do the trick.