Usage Examples

This page documents several simple use cases for you to try out. For full details, see the API Reference, and check out the full class reference for RobotModel.

Loading from a File

You can load a URDF from any .urdf file, as long as you fix the links to be relative or absolute links rather than ROS resource URLs.

>>> import skrobot
>>> robot_model = skrobot.models.urdf.RobotModelFromURDF(urdf_file=skrobot.data.pr2_urdfpath())

Visualization

>>> viewer = skrobot.viewers.TrimeshSceneViewer(resolution=(640, 480))
>>> viewer.add(robot_model)
>>> viewer.show()

If you would like to update renderer:

>>> viewer.redraw()

Accessing Links and Joints

You have direct access to link and joint information.

>>> for link in robot_model.link_list:
...    print(link.name)

>>> for joint in robot_model.joint_list:
...     print(joint.name)

>>> robot_model.l_elbow_flex_joint.joint_angle()
0.0

>>> robot_model.l_elbow_flex_joint.joint_angle(-0.5)
-0.5

>>> robot_model.l_elbow_flex_joint.joint_angle()
-0.5

Inverse Kinematics

This section provides a basic example of inverse kinematics. For comprehensive documentation including axis constraints, batch processing, and advanced features, see Robot Model Tips.

First, set the initial pose. Note that the position of the prismatic joint is in [m] and angles of rotational joints are in [rad].

>>> robot_model.torso_lift_joint.joint_angle(0.05)
>>> robot_model.l_shoulder_pan_joint.joint_angle(60 * 3.14/180.0)
>>> robot_model.l_shoulder_lift_joint.joint_angle(74 * 3.14/180.0)
>>> robot_model.l_upper_arm_roll_joint.joint_angle(70* 3.14/180.0)
>>> robot_model.l_elbow_flex_joint.joint_angle(-120 * 3.14/180.0)
>>> robot_model.l_forearm_roll_joint.joint_angle(20 * 3.14/180.0)
>>> robot_model.l_wrist_flex_joint.joint_angle(-30 * 3.14/180.0)
>>> robot_model.l_wrist_roll_joint.joint_angle(180 * 3.14/180.0)
>>> robot_model.r_shoulder_pan_joint.joint_angle(-60 * 3.14/180.0)
>>> robot_model.r_shoulder_lift_joint.joint_angle(74 * 3.14/180.0)
>>> robot_model.r_upper_arm_roll_joint.joint_angle(-70 * 3.14/180.0)
>>> robot_model.r_elbow_flex_joint.joint_angle(-120 * 3.14/180.0)
>>> robot_model.r_forearm_roll_joint.joint_angle(-20 * 3.14/180.0)
>>> robot_model.r_wrist_flex_joint.joint_angle(-30 * 3.14/180.0)
>>> robot_model.r_wrist_roll_joint.joint_angle(180 * 3.14/180.0)
>>> robot_model.head_pan_joint.joint_angle(0)
>>> robot_model.head_tilt_joint.joint_angle(0)

Next, set move_target and link_list

>>> rarm_end_coords = skrobot.coordinates.CascadedCoords(
...             parent=robot_model.r_gripper_tool_frame,
...             name='rarm_end_coords')
>>> move_target = rarm_end_coords
>>> link_list = [
...     robot_model.r_shoulder_pan_link,
...     robot_model.r_shoulder_lift_link,
...     robot_model.r_upper_arm_roll_link,
...     robot_model.r_elbow_flex_link,
...     robot_model.r_forearm_roll_link,
...     robot_model.r_wrist_flex_link,
...     robot_model.r_wrist_roll_link]

Set target_coords.

>>> target_coords = skrobot.coordinates.Coordinates([0.5, -0.3, 0.7], [0, 0, 0])
>>> robot_model.inverse_kinematics(
...     target_coords,
...     link_list=link_list,
...     move_target=move_target)

For detailed information about inverse kinematics including:

• Axis constraints (rotation_axis and translation_axis parameters)

• Batch inverse kinematics for multiple poses

• Visual examples of different constraint types

• Advanced features and performance optimization

• Common usage patterns

See the comprehensive Robot Model Tips documentation.