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TDDD48 Automated planning (6 ECTS)

Lab 5B: Motion Planning

Written by Mikael Nilsson.

Introduction

Note: You only have to complete and hand in either lab 5A or 5B.

In this lab you will use a graphical environment to test different motion planning techniques. You will use OMPL, the Open Motion Planning Library, which comes both for integration into existing projects as well as with a graphical interface to visualize planning. More information about OMPL can be found on the OMPL homepage via the link below.

Updates and Known Problems

Any problems discovered during the lab, and any clarifications we make to the lab instructions, will be announced here.

Resources

The following resources are available:

  • OMPL homepage - here you can find all available informaion on OMPL.
  • GUI description - Getting started with the GUI.
  • OMPL primer - this pdf contains a concise introduction to OMPL. It goes through some theory behind motion planning and how to get started with OMPL.

Running OMPL

OMPL is run on the server tipserix. You remote login by typing

ssh -X tipserix 

OMPL is started by executing

/usr/local/bin/ompl_app 

If you want to run OMPL from home you have two options. Either install it locally or run it remote via ssh. We cannot however offer support for these options and hence recommend that you carry out the lab in the PULs. When you start OMPL_app which is the graphical interface of OMPL you will see something like this:

Lab 5B.1: Comparing Planners

Start OMPL_app. In this part we will take a look at some different types of motion planners and compare their approaches. OMPL comes with many resources in the form of maps and robots. For simplicity we will use 2D maps and robots although the gui always renders the image in 3D. To get 2D planning set the "robot_type" to "Rigid body planning (2D)". The mentioned resources are found in

 /home/.../OMPL/omplapp-0.12.2-Source/resources/2D 

Start with choosing a map that you think looks interesting and add a robot to it. Before you can start planning you need to select a start and a goal location.

Now you can choose a planner out of the many existing to get your first plan in OMPL. After a plan is found you can choose to have it animated step by step or shown. You can also show states and edges between states to see which states and paths the planner generated.

For the rest of the lab, select two maps which you think will capture the different aspects of motion planning. Then use the following information to select at least 3 different planners that you run on the same problems. In the report, write which you have chosen and describe how they work in general terms. Also report your findings when it comes to plan quality, generated states and time used by the planner. It is important that you add screenshots to the report so that the lab assistant can follow your reasoning. Note that random planners will generate different plans each time so don't forget to screenshot (alt-print sceen) before you move on. It is also possible and recommended to save the paths for the report.

If the planner takes considerably longer time than allowed by the time limit it may have crashed. To see if a planner is working as intended it may help to use the log window from the tools meny. Unfortunately we have observed that the PRM planner which you know from the lectures often crashes.

Finishing and handing in the results

When you hand in your results:

  • Create a single ZIP file, named fffll111-fffll222-lab5.zip where fffll111 and fffll222 are your login names (assuming you are working in pairs).
  • The ZIP file should contain all pictures and saved plans as well as the report as a simple text file or as a PDF document (no Word or OpenOffice documents, please).
  • Send the ZIP file by e-mail to Mikael Nilsson.

Page responsible: Jonas Kvarnström
Last updated: 2013-05-17