controlling a RG6 gripper with a onrobot URcap

[libishm1]

Hi everyone,

I’m working with an OnRobot RG6 gripper using the official OnRobot URCap.The gripper works perfectly when programmed directly on the PolyScope pendant, no issues there.

However, I’m running into trouble when trying to load custom URScripts generated by the Robots plugin in Grasshopper.

In my custom script, I’ve included the OnRobot initialization blocks and I’m calling the gripper using: on_return = rg_grip(9.1, 36.0, tool_index = 0, blocking = True, depth_comp = False, popupmsg = True)rg_payload_set(mass = 0.0, tool_index = 0, use_guard = True) to open the gripper and close the gripper in the custom commands for the pick locations respectively,

These commands are placed in the appropriate pick/hold sections.

What works

The program3.script file exported from the UR pendant runs correctly.

The RG6 responds reliably inside a URP program.

What does NOT work

The custom URScript from Grasshopper fails to load, even though it includes the same initialization logic.

The robot reports an installation-related error before execution begins.

I have attached the UR robot script generated by the robot pendant as program3.script for reference. Also, the custom script generated by me from grasshopper,

Has anyone successfully integrated GH Robots, while maintai

ning RG6 functionality or similar grippers.

Reference - [(1770) UR Robot Grippers and UR Caps in Grasshopper - YouTube] (https://www.youtube.com/watch?v=9ENygL6V1Ao)

any help is appreciated,
! error_message
files.zip

Thanks in advance,

[LoyWeiWin]

Maybe try this instead (with the "custom mode") function? and the change the weight of the end effector using the "create tool" function rather than hard code it? Hopefully this helps.

[libishm1]

At the moment, the URCap does not allow direct input in the standard URScript format. Because of this limitation, I had to embed a small URScript program directly in the PolyScope pendant and load it from there. To make this workable, I reverse-engineered the URCap’s internal script structure and wrote a small Python utility to reformat my generated code so it matches what the URCap expects.

This workflow is still a work in progress, but the reformatted script does execute correctly on the robot. That said, there are unresolved issues—most notably, the gripper rotates during the pick and place motions themselves rather than during the transition between them.

This reflects the current state of progress from last year. I’ll update this as the workflow evolves. I’m also curious whether there is a simpler or more robust way to make the URCap work seamlessly with the Robots plugin, without needing this intermediate reformatting step.

[visose]

If you leave an em dash behind its even more obvious 😄

[libishm1]

I seemed to have missed that 😄, I used copilot to reformat my original text, and also ChatGPT for code completion.