Question regarding robot experiments

[fbottarel]

Hi @arsalan-mousavian, and thanks for making the code public!

I have a simple question regarding the robot experiments (as shown in the videos). I am trying to use some of the grasps generated by this approach to grasp some simple objects off a table with our Franka arm, and I' m wondering how you guys implemented the finger movement in the grasp evaluation you have shown. According to my experience, the Franka library only exposes a grasp command (which tends to squish soft objects). In your videos, however, the force applied during the grasp does not seem to be very large (e.g. it does not squish the boxes or the mustard bottle). Did you guys develop a custom force controller for the fingers, or did you just use whatever comes with libfranka and franka_ros?

Thanks in advance!

[arsalan-mousavian]

Hi @fbottarel, we don't have any force controller but would really like to have one. So if you develop force controller for franka please share it publicly. I think it's going to be very useful.

At the time, we prompted the user for entering the force before moving the robot. for boxes we used 40N and for Mustard we used 70N. These days we just set the force to 70N for all the objects. It's not a perfect solution but it's better than asking the user to enter the amount of force.

[fbottarel]

Thank you @arsalan-mousavian for the swift response. Unfortunately, the libfranka API does not allow for direct control of the gripper fingers in terms of force/torque, there are only "non-realtime" commands very similar to how ROS actions work. For this specific purpose, in the lab I'm working at we are looking forward to switch out the Franka hand for a gripper that allows for that sort of thing.

On a side note: is a 40N/70N sufficient to grab boxes without squishing them? It seems quite large to me!