Melodic on Ubuntu 18.04 Simulation in gazebo I created a urdf for my robot and I can get the robot to spawn in gazebo. The robot is imbalanced but I wanted to get try and get the robot to move before I started fixing the balancing issues. The plug-in I'm using is libgazeborosdiff_drive.so I've tried publishing from the command line using this input

rostopic pub /cmdvel geometrymsgs/Twist "linear: x: 0.0 y: 0.0 z: 0.0 angular: x: 0.0 y: 0.0 z: 1.0" -r 10

The robot just stays in one spot. The next part is my .urdf code

<?xml version="1.0"?>

${updaterate} <leftjoint>leftwheeljoint rightwheeljoint 0.5 0.1 1. 20 50.0 cmdvel odom <odometryframe>odom box

640 480 R8G8B8 0.1 100 gaussian 0.0 0.01 30.0 file://camera.yaml true 0.0 true camera imageraw camerainfo camera_link

Am I correct in assuming that I have to publish twist commands to the /cmd_vel topic to get this robot to move? I've tried the official ros resources but I'm new to programming so everything is hard for me to understand.