Connecting rigid bodies with spherical joints

[shamilmamedov]

Hi everyone. I am trying to model a serial chain robot consisting of rigid bodies connected via spherical joints. There is no way to select spherical joint in URDF even though Pinocchio supports spherical joints. Would it be possible to create URDF with revolute joints and then change it to spherical in Pinocchio after building the model using buildModelFromUrdf(urdf)? Is there a better way to create such a robot?

[jcarpent]

I would recommend building this robot programmaticaly, following this example:
https://github.com/stack-of-tasks/pinocchio/blob/9719bdc0d3dc330df1ef53a080602c675b352a05/examples/simulation-pendulum.py

[shamilmamedov]

Thank you for quick reply! Quick related question: can I implement universal joint using JointModelComposite?

[jcarpent]

Yes, indeed. We plan to add it to Pinocchio soon.