Wrong sign for R1 torso pitch joint - Githubissues

robotology / cer

Contains SW specific to the R1 robots

GNU General Public License v2.0

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Wrong sign for R1 torso pitch joint #121

Closed randaz81 closed 3 years ago

randaz81 commented 3 years ago

We noticed that on the R1 robot (*) the torso pitch joint encoder value is positive when the torso is bent backward. This is not correct, according to several different sources:

on the redmine project, on the kinematics page, it is clearly stated the value is positive when the torso is bent forward. I am reporting the relevant picture at the bottom of this issue.
the urdf file is built according to the redmine specs, so this is ok. And ROS kinematics is built according to this file.
on the gazebo simulator, the value is positive when the torso is bent forward.

For these reasons, we are going to open a PR on https://github.com/robotology/robots-configuration to fix the sign of the encoder.

(* verified on SN000 and SN003)

CERKinematicTree

pattacini commented 3 years ago

Good catch @randaz81 👍🏻

I'm afraid that the tripod plugin used by the motor control needs to be carefully revised then.

pattacini commented 3 years ago

I'll have a look at this the next week, most likely.

DatSpace commented 3 years ago

I saw the commit changes the encoder pitch direction for all the robots. Is it verified that the pitch is wrong on the other ones as well ? Just in case.

pattacini commented 3 years ago

Hi @DatSpace

All R1 share the same kinematics of the torso.

pattacini commented 3 years ago

In particular, the change impacts all those modules reading/controlling the equivalent joint of the torso. IK modules instead shouldn't be impacted as they do deal with the physical torso, meaning straight with the 3 elongations.

pattacini commented 3 years ago

I'll have a look at this the next week, most likely.

There's no way I can be on that as said earlier any time soon, unfortunately. At any rate, for the reason above, I feel confident to close the issue and get back quickly to it if needed.