NVIDIA Jetbot is not moving using /cmd_vel

Question

Hello. I have tried to move real Jetbot using ROS terminal commands, but they do not work.

I'm using remote control with SSH, and the connection is stable when I'm using gmapping and laser_scan_matcher for scanning and saving map. But when I tried to use move_base with rviz, it didn't work on a real robot.

I've used NVIDIA's tutorials on Jupyter Notebook to see if its motors problem, but it actually worked and Jetbot moved using robot.forward/backward etc. commands

Then I used $rostopic echo /cmd_vel to see if /cmd_vel atleast receives messages, I typed in a new terminal

$rostopic pub /cmd_vel geometry_msgs/Twist "linear:
      x: 0.0
      y: 0.0
      z: 0.0
    angular:
      x: 0.0
      y: 0.0
      z: 0.5

and the terminal with echo got the message, still no motor movement.

Can someone please explain why it isn't working? Ubuntu 18.04, ROS melodic

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Originally posted by steven_yakovlev on ROS Answers with karma: 11 on 2022-04-26

Post score: 0

Answer 1

I have found the problem. It appears that my motors do not have encoder, and apparently odometry is needed directly for cmd_vel to work.

In case anyone wonders how to solve this, simply use jetbot_motors/cmd_raw instead of cmd_vel. I've been moving jetbot using move_base from jackal_navigation package, and in move_base.launch file in launch folder I added this line:

<remap from="/cmd_vel" to="/jetbot_motors/cmd_raw"/>

Hope this will help anyone!

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Originally posted by steven_yakovlev with karma: 11 on 2022-05-13

This answer was ACCEPTED on the original site

Post score: 1