CHOMP Motion Planner

Mrinal Kalakrishnan, one of three motion planning interns here at Willow Garage, is finishing up his summer project and returning to the University of Southern California. Mrinal has been working on a smooth motion planning and control pipeline for the PR2, introducing a new approach to object manipulation  The key component of this work was the implementation of CHOMP (Covariant Hamiltonian Optimization and Motion Planning), a motion planner developed at CMU and Intel Research. You can find this implementation in the chomp_motion_planner package for ROS.

Mrinal chose to implement this motion planner on the PR2 because CHOMP's method of planning away from obstacles produces very smooth, natural-looking movements. You can see in the video that the PR2's arm trajectory is rather fluid and avoids unusual or awkward joint angles. The animation shows the arm optimizing the trajectory away from the bookshelf, while maintaining a smooth motion plan.  Mrinal's work with CHOMP allowed for informative comparisons to be made with the two other motion planners being researched and implemented here, ompl and sbpl_arm_planner.  All three motion planners use the same interface, making switches between the three systems very simple.

In addition to his work with CHOMP, Mrinal wrote the distance_field package for ROS which performs 3-D obstacle inflation to generate a cost-map for arm planners. He also wrote spline_smoother, a library of algorithms which can convert a set of waypoints, as typically generated by motion planners, into a smooth spline trajectory suitable for execution on a robot.

Below is Mrinal's end-of-summer presentation, where you can find additional details about his work here at Willow Garage.

Mrinal Kalakrishnan: CHOMP Motion Planner on Scribd (Download PDF from ROS.org)