What is the best way to perform relative arm manipulation in cartesian frame

Hi Pollen Team

I had a quick question regarding some manipulations that we are trying to do with the robot. We are basically trying to move from a waypoint to a goal pose, but the goal pose is dynamic in nature, we tried using the forward and inverse kinematics functions provided through the sdk but that landed us no where as we kept having issues with the robot either being unable to compute the inverse kinematics to find joint values to use goto() or the robot was unable to go to goal pose. We tried using translate_by() function to just add some offsets from the waypoint and move there but that just led to inaccurate and jerky motion. We also tried to use the get_translate_by() to generate forward kinematics matrix to get to a certain offset from the waypoint but that also resulted in robot being unable to move to goal pose errors. Can you point us in the right direction here ?

To recap the problem : We just want to move from a known pose to another x,y,z position with a similar orientation

Hi @jinpeimatsuda

If you want to move from a known pose to another position with the same orientation, you were indeed right to use the translate_by function. I’m surprised that it didn’t work well. Could you send us the code you used and a video showing what happens on the robot so we can get a better idea? Maybe the goal pose is nearby the arm limits, or are you encountering a singularity?

For more information, you can also refer to the documentation if you haven’t already done so : Master Reachy 2 Arm Kinematics: Coordinate Systems, Forward and Inverse Kinematics

Best,
Claire

Hey @Claire

Thank you so much for the prompt response, I’ve attached the code here and added the video too. I don’t think we are encountering singularity. We verified moving to spots very close to target pose using goto commands and we are able to get there. Please let me know if the team has any ideas on how to work through this issue

Best
Akash