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Diffdrive plugin: How to use it?

asked 2013-05-29 11:42:54 -0600

gazer gravatar image

updated 2013-05-29 11:43:14 -0600

Hi all

I am looking to mimic the erratics robot tutorial, and includ and use the diffdrive plugin, for the purpose of moving the robot (without navigation). How do I do that?

Where should I start?

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answered 2013-05-29 17:13:30 -0600

gazer gravatar image

I got it... But I still need to understand how to precisely using it. I got the plugin to work. Any guidelines would be very helpful. Thank you all!

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Hi! What exactly do you need to know. I didn't do the tutorial (maybe you can link that). But I have a robot base, that uses a ros plugin to receive cmd_vel commands and set the values through pid's to the wheel joints.

Christoph gravatar imageChristoph ( 2013-06-04 11:44:18 -0600 )edit

Hi. now I have been able to move the base using the cmd_vel command. Are you able to move to a specific location specified in the x, y,z coordinate?

gazer gravatar imagegazer ( 2013-06-06 12:33:28 -0600 )edit

Hi! I am using ros gmapping and move base packages (nodes) with rviz to move my robot. There I use the 2D Nav Goal to mark a target location. Move base then creates a path to the target and sends cmd vel commands.

Christoph gravatar imageChristoph ( 2013-06-07 05:12:58 -0600 )edit

good job! but my navigation stack isn't working... it moves in circle without advancing to the goal...... How smooth is yours?

gazer gravatar imagegazer ( 2013-06-13 19:23:06 -0600 )edit

I didn’t do any tests so far, but the movement looks quiet ok. I let rviz show me the local and the global plan (actual route path) and you can see how the local plan and the robot movement tries to reach/follow the global route.

Christoph gravatar imageChristoph ( 2013-06-14 04:55:07 -0600 )edit

nice.... would you mind to share which robot simulator package are you using? I have tried the erratic robot, turtle bot and I have trouble in launching them in gazebo. The reason I ask because I want to see how the navigation stack works for the other robot, and then I will follow their setup for my own robot. thank you very much!

gazer gravatar imagegazer ( 2013-06-14 16:27:06 -0600 )edit

Hey! I created my own robot from the scratch (SDF description) and then followed the tutorials for ROS based plugins. I then subscribed to the cmd_vel topic. For the base I have to publish my odometry data as a tf message as well as an odom message because the ROS move_base node needs both forms. For the ROS gmapping node I need to publish my joint states (of the wheels) as a JointState message. That is more a general explanation. I use no other simulation packages.

Christoph gravatar imageChristoph ( 2013-06-18 12:35:00 -0600 )edit

what a beast! could I ask you two questions. For the "/odom" frame, it's fixed right? And also for the local planner params setting, the global frame id is should be "/odom", the robot_base frame id should be "/base_link" (or base_footprint depending on the setup)?

gazer gravatar imagegazer ( 2013-06-18 17:22:54 -0600 )edit

if you have time, do you mind to explain why local planner params use "/odom" as globalframeid, while the global planner params use "/map" as the globalframeid, thank you!

gazer gravatar imagegazer ( 2013-06-18 17:24:02 -0600 )edit

I am not quiet sure about that point. Our real robot already used the move\_base node, so all I had to do was to use the same launch files and send the needed tf and odom messages. But I will ask my team mates about this point next week to get a usefull answer. As far as I understand the node and as I can see in rviz, you get two different routes to the desired goal, where the local r tries to follow the global. The global path just uses the fixed global map, while odom also uses actual data ???

Christoph gravatar imageChristoph ( 2013-06-21 07:37:59 -0600 )edit
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Asked: 2013-05-29 11:42:54 -0600

Seen: 1,379 times

Last updated: May 29 '13