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How to create an action server for navigation?

asked 2018-10-16 03:37:00 -0600

stevemartin gravatar image

I have created my own robot and already created a 2d map using gmapping with laser. The simple amcl localization is used in rviz (laser - particle filter) and my robot is able to localize in a created pmg map in rviz. Now, I want to send a goal coordinates for my robot for it to navigate within a map and I have created a new package and a new node like following this tutorial: http://wiki.ros.org/navigation/Tutori...

I can see that it waits for the server and when I launch this node, I get the move_base/goal topic but the client just awaits. How can I create this server?

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So you are stuck here I guess:

  while(!ac.waitForServer(ros::Duration(5.0))){
    ROS_INFO("Waiting for the move_base action server to come up");
  }

Is this message showing all the time? Also do you have move_base running?

pavel92 gravatar imagepavel92 ( 2018-10-16 03:50:12 -0600 )edit

You should look into the actionlib doc and also the action lib tutorials to understand the basics of it first.

Delb gravatar imageDelb ( 2018-10-16 03:56:43 -0600 )edit

@pavel92 Yes, it shows every 5 seconds. It is running.

stevemartin gravatar imagestevemartin ( 2018-10-16 04:55:19 -0600 )edit

@Delb I have read that tutorial, in Action Server CPP file, they have included chores::DoDishesGoalConstPtr& goal in void execute. What will be equivalentvent to that in move_base_msgs::MoveBaseAction ?

stevemartin gravatar imagestevemartin ( 2018-10-16 05:20:32 -0600 )edit

You should continue investigating the tutorials it's explained (here). For move_base that should be move_base_msgs::MoveBaseGoalConstPtr& goal

Delb gravatar imageDelb ( 2018-10-16 05:33:02 -0600 )edit

@stevemartin: what sort of robot do you have? A differential drive platform?

If so: unless you want to learn how to write your own action server for this, I would suggest to use one of the available diff drive packages or ros_control plugins. That will save you quite some time.

gvdhoorn gravatar imagegvdhoorn ( 2018-10-16 05:36:09 -0600 )edit

@gvdhoorn Yes, a mobile robot. I can see that the plugin is responsible for the movement and I believe it publishes to /cmd_vel topic. But I was looking for the navigation of my robot. I want to send a goal coordinates and let my robot to navigate to that point (in known map).

stevemartin gravatar imagestevemartin ( 2018-10-16 06:00:12 -0600 )edit

The navigation stack is typically responsible for consuming nav goals and then transforming those into Twist msgs published on cmd_vel topics that ultimately make the robot move.

It's rare for someone to write their own MoveBaseGoal consumer.

gvdhoorn gravatar imagegvdhoorn ( 2018-10-16 06:03:55 -0600 )edit

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answered 2018-11-01 03:29:32 -0600

pavel92 gravatar image

I had the similar situation a while ago when the move_base action server was not coming up. The reason was that move_base and the node where the action client was created were in different namespaces. After they were put in the same namespace the problem was solved.

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Asked: 2018-10-16 03:37:00 -0600

Seen: 281 times

Last updated: Nov 01 '18