URDF Joints

This example shows how to load a URDF description of a robot, set some joint angles and display relevant frames.

from pytransform3d.urdf import UrdfTransformManager
import pytransform3d.visualizer as pv


COMPI_URDF = """
<?xml version="1.0"?>
  <robot name="compi">
    <link name="linkmount"/>
    <link name="link1"/>
    <link name="link2"/>
    <link name="link3"/>
    <link name="link4"/>
    <link name="link5"/>
    <link name="link6"/>
    <link name="tcp"/>

    <joint name="joint1" type="revolute">
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <parent link="linkmount"/>
      <child link="link1"/>
      <axis xyz="0 0 1.0"/>
    </joint>

    <joint name="joint2" type="revolute">
      <origin xyz="0 0 0.158" rpy="1.570796 0 0"/>
      <parent link="link1"/>
      <child link="link2"/>
      <axis xyz="0 0 -1.0"/>
    </joint>

    <joint name="joint3" type="revolute">
      <origin xyz="0 0.28 0" rpy="0 0 0"/>
      <parent link="link2"/>
      <child link="link3"/>
      <axis xyz="0 0 -1.0"/>
    </joint>

    <joint name="joint4" type="revolute">
      <origin xyz="0 0 0" rpy="-1.570796 0 0"/>
      <parent link="link3"/>
      <child link="link4"/>
      <axis xyz="0 0 1.0"/>
    </joint>

    <joint name="joint5" type="revolute">
      <origin xyz="0 0 0.34" rpy="1.570796 0 0"/>
      <parent link="link4"/>
      <child link="link5"/>
      <axis xyz="0 0 -1.0"/>
    </joint>

    <joint name="joint6" type="revolute">
      <origin xyz="0 0.346 0" rpy="-1.570796 0 0"/>
      <parent link="link5"/>
      <child link="link6"/>
      <axis xyz="0 0 1.0"/>
    </joint>

    <joint name="jointtcp" type="fixed">
      <origin xyz="0 0 0.05" rpy="0 0 0"/>
      <parent link="link6"/>
      <child link="tcp"/>
    </joint>
  </robot>
"""

tm = UrdfTransformManager()
tm.load_urdf(COMPI_URDF)
joint_names = ["joint%d" % i for i in range(1, 7)]
joint_angles = [0, 0.5, 0.5, 0, 0.5, 0]
for name, angle in zip(joint_names, joint_angles):
    tm.set_joint(name, angle)
fig = pv.figure("URDF")
fig.plot_graph(
    tm, "compi", show_frames=True, show_connections=True,
    whitelist=["link%d" % d for d in range(1, 7)], s=0.05)
fig.view_init()
if "__file__" in globals():
    fig.show()
else:
    fig.save_image("__open3d_rendered_image.jpg")