Setting different motor speeds


#1

How to set different motor speed with respect to each other?
Eg. One motor running at 0.5 times the speed of the normal (other motor) speed.


#2

You need to publish a cmd_vel message with the motor velocities that you want.

To understand topics look at this:
http://wiki.ros.org/ROS/Tutorials/UnderstandingTopics

To understand more about the cmd_vel message specifically there are lots of references - here is a popular one:

You can do this from the command line using:

rostopic pub

Something like

rostopic pub /cmd_vel geometry_msgs/Twist “linear:
x: 0.5
y: 0.0
z: 0.0
angular:
x: 0.0
y: 0.0
z: 0.0” -r 10

in the alternative

rostopic pub -1 /cmd_vel geometry_msgs/Twist – ‘[2.0, 0.0, 0.0]’ ‘[0.0, 0.0, 1.8]’

Although check the proper topic name (it could be magni_robot/cmd_vel) or something similar. You can look at the list of topics by typing

rostopic list