PyKDL and tf with python3 incompatibility

[jacknlliu]

Reference

• does KDL have python3 binding? #115
• tf2_py cannot work with python3 #259
• Allow setting python version #166

[jacknlliu]

PyKDL unit test

from urdf_parser_py.urdf import URDF
import PyKDL as kdl
robot = URDF.from_parameter_server()
root = robot.get_root()
tree=kdl.Tree(root)

output

python3: /home/ros/data/DRL_Platforms/catkin_ws_for_kdl/src/orocos_kinematics_dynamics/python_orocos_kdl/PyKDL/std_string.sip:52: int convertTo_std_string(PyObject*, void**, int*, PyObject*): Assertion `PyUnicode_Check(s)' failed.
Aborted (core dumped)

See orocos/orocos_kinematics_dynamics#59

kdl_utils wiki, please see pykdl_utils.

[sloretz]

FYI ROS Noetic is using upstream python3-pykdl Debian packages.

I opened a couple bugs for this issue:

• https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=956254
• https://bugs.launchpad.net/ubuntu/+source/orocos-kdl/+bug/1871725

If you intend to use this package in Ubuntu Focal, would you mind clicking the "this bug affects me" button on launchpad? IIUC I think that will help get it looked at sooner.