Prioritized Inverse Kinematics ROS

Prioritized Inverse Kinematics ROS library pik_ros.

The PIK solver gives a solution to the prioritized positional inverse kinematics problem: selecting joint positions that result in optimizing a number of prioritized tasks for different links in the kinematic chain.

In the image bellow you can see examples with following priorities:

• spraying_frame position, shown with a blue sphere
• spraying_frame approach axis orientation, shown with a blue arrow
• forearm_link position, shown with a purple sphere

PIK ROS solver uses sequential prioritized optimization, where PtscEigen is used for prioritized optimization, and MoveIt is used for the robot model data and Jacobian calculation.

🖥️ Using the library

⚙️ Dependencies

This project depends on ROS, MoveIt and PtscEigen.

⚙️ Build

Clone to your catkin workspace and build with

catkin build pik_ros

Usage example

//Include the library header 
#include <PikRos.hpp>

//Construct the Pik object 
PikRos::Pik my_pik( nh,                           //ros node handle
                    "my_robot_name",              //namespace for robot description
                    "my_joint_model_group_name",  //for MoveIt
                    settings);                    //PikRos::Settings object

//Define a vector of tasks, with descending priorities 
//IkTask constructor takes arguments: (task_type, frame, desired_value)
std::vector<PikRos::IkTask> ik_tasks{ 
  PikRos::IkTask( PikRos::FRAME_POSITION, "spraying_frame", desired_tool_position ), 
  PikRos::IkTask( PikRos::FRAME_APPROACH_AXIS, "spraying_frame", desired_approach_vector ),
  PikRos::IkTask( PikRos::FRAME_POSITION, "forearm_link", desired_elbow_position ) 
};

// Solve problem
Eigen::VectorXd q = my_pik.solve( ik_tasks, q_initial_guess );

Including the library in your ROS project

Find the pik_ros pacakage in your CMakeLists.txt file:

find_package( catkin REQUIRED COMPONENTS 
              pik_ros 
              ... )

And link the catkin libraries:

target_link_libraries( your_target_name 
                       ${catkin_LIBRARIES}
                       ... )

For a complete usage example see kinova_gen3_pik_examples

Available Tasks

Priorities are given to the solver as a vector of PikRos::IkTask objects, with descending priorities.

PikRos::IkTaskType describes a particular task type given to the solver. Available task types are:

• FRAME_POSITION - Frame position task, has a value of [x, y, z]^T in meters
• FRAME_ORIENTATION - Frame orientation task, has a quaternion value [w, x, y, z]^T
• FRAME_POSE - Frame pose task, a combination of FRAME_POSITION and FRAME_ORIENTATION tasks
• FRAME_APPROACH_AXIS - Frame approach axis task, has a value of a 3D vector [x, y, z]^T

Citing

If you use this code in a scholarly work, please consider citing our paper:

@misc{https://doi.org/10.48550/arxiv.2307.00302,
  doi = {10.48550/ARXIV.2307.00302},
  url = {https://arxiv.org/abs/2307.00302},
  author = {Vatavuk,  Ivo and Kovačić,  Zdenko},
  keywords = {Robotics (cs.RO),  FOS: Computer and information sciences,  FOS: Computer and information sciences},
  title = {Constrained Prioritized 3T2R Task Control for Robotic Agricultural Spraying},
  publisher = {arXiv},
  year = {2023},
  copyright = {arXiv.org perpetual,  non-exclusive license}
}

📝 License

Materials in this repository are distributed under the following license:

All software is licensed under the BSD 3-Clause License.