ROS Resources: Documentation | Support | Discussion Forum | Service Status | Q&A answers.ros.org
Ask Your Question
0

How does Dijkstra's algorithms work inside navfn?

asked 2015-02-03 06:49:27 -0500

Mercy gravatar image

updated 2015-02-04 04:53:24 -0500

Hi, I have gone through this and this as well . Can someone explain how the global path planner works in details?

EDIT: According to your suggestion, I have visited NavfnROS and navfn. In navfn_ros.cpp, line number 197 , we have makePlan () method defined which calls calcNavFnDijkstra(true) line 285. This calcNavFnDijkstra(true) is defined here, line number 290. It uses

propNavFnDijkstra(std::max(nx*ny/20,nx+ny),atStart);

00302

00303 // path

00304 int len = calcPath(nx*ny/2);

END

I want to remove only Dijkstra's algorithm; I don't want to change the costmap generation, cell updation, obstacle avoidance

I know what is a potential field, but how it is used here; I have no idea. How does gradient line 989 help us in making the global plan? I am using ROS fuerte.

edit retag flag offensive close merge delete

2 Answers

Sort by » oldest newest most voted
0

answered 2015-02-03 07:07:58 -0500

I suggest you have a look at the source code and then ask more specific questions based on what you discover. There are fortunately many people on ROS Answers who are willing to help others, but very few have the time to write a comprehensive answer to a extremely broad questions like yours.

You're much more likely to get answers to a question like "I have looked into package X's code and do not quite understand what is done in function Y, can someone help me?" than to one like "Please explain the internal workings of package X in detail" (such as your current question above).

edit flag offensive delete link more

Comments

@Stefan, I have updated the question according to your suggestion. Please have a look.

Mercy gravatar imageMercy ( 2015-02-03 08:54:51 -0500 )edit

@Martin thanks. But, currently I have to use that one.

Mercy gravatar imageMercy ( 2015-02-04 05:20:29 -0500 )edit
2

answered 2015-02-04 04:52:44 -0500

If you're using Hydro or later, you could switch to David Lu's global_planner. It has implementations of several algorithms (A*, Dijkstra) and can also emulate the old navfn behavior, if you wish. Looks like the source code is much easier to digest than navfn.

edit flag offensive delete link more

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Question Tools

1 follower

Stats

Asked: 2015-02-03 06:49:27 -0500

Seen: 433 times

Last updated: Feb 04 '15