Documentation Status

shadow_robot: sr_description | sr_example | sr_gazebo_plugins | sr_hand | sr_hardware_interface | sr_kinematics | sr_mechanism_controllers | sr_mechanism_model | sr_move_arm | sr_movements | sr_robot_msgs | sr_tactile_sensors | sr_utilities

Package Summary

Documented

A specific shadowhand package derived from arm_kinematics, for computing both forward and backward kinematics for the fingers except thumb. Solution is analytic. Developed as an alternative to arm_kinematics that cannot solve coupled joints.

shadow_robot: sr_description | sr_example | sr_gazebo_plugins | sr_hand | sr_hardware_interface | sr_kinematics | sr_mechanism_controllers | sr_mechanism_model | sr_move_arm | sr_movements | sr_robot_msgs | sr_tactile_sensors | sr_utilities

Package Summary

Documented

A specific shadowhand package derived from arm_kinematics, for computing both forward and backward kinematics for the fingers except thumb. Solution is analytic. Developed as an alternative to arm_kinematics that cannot solve coupled joints.

shadow_robot: sr_description | sr_example | sr_gazebo_plugins | sr_hand | sr_hardware_interface | sr_mechanism_controllers | sr_mechanism_model | sr_move_arm | sr_movements | sr_robot_msgs | sr_self_test | sr_tactile_sensors | sr_utilities

Package Summary

Documented

A specific shadowhand package derived from arm_kinematics, for computing both forward and backward kinematics for the fingers except thumb. Solution is analytic. Developed as an alternative to arm_kinematics that cannot solve coupled joints.

Package Summary

Released Continuous integration Documented

A specific shadowhand package derived from arm_kinematics, for computing both forward and backward kinematics for the fingers except thumb. Solution is analytic. Developed as an alternative to arm_kinematics that cannot solve coupled joints.

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Overview

sr_kinematics currently contains a specific analytical inverse kinematics for the shadow_robot hand. Currently, only the 4 fingers have an IK solution, the thumb will come later. The solution takes care of the coupled joint J1/J2 (assuming it is 1:1) and accepts 3D requests (instead of 6D). There is an approximation in this solution.

Detail of the solution

Approximation

The developed IK uses an approximation of the fingertip center to create a virtually simplified 2 links (3 dof) kinematic chain. The method considers the isoceles triangle formed by the coupled joint to solve the inverse kinematics.

  • finger_approximation.png

Limits

  • Because the finger chain (J4+J3+J1/J2) provides only 3 dof, the request only takes the position of the finger tip into account (no requested orientation can be reached).
  • The Little finger joint 5 (inside the palm) is not considered either.
  • IK for the thumb is not solved by the current version.

ROS API

Services

The node proposes the same services and parameters as the arm_kinematics

NOTE that epsilon parameter is used to detect singularities for J4 joint.

Wiki: sr_kinematics (last edited 2011-09-09 17:02:16 by Guillaume Walck)