Can I use arduino to subscribe /cmd_vel?
Hello ros forum!
I am new to ros
sorry for my bad english
I follow navigation_tutorial and it seems to work
How can i publish /cmd_vel to my arduino ?
I need to control my little car !
please help!
Asked by Crowdeal on 2019-11-07 09:32:15 UTC
Answers
/cmd_vel is a subscriber itself so you have to publish to it.
provided that you setup everything right, (rosserial), and when you do a rostopic list, you see /cmd_vel in the list of topics, you type
rostopic pub /cmd_vel geometry_msgs/Twist and hit tab, twice it will show:
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: 0.0"
Modify the linear speed, twist.linear.x to be 0.5 for example, and twist.angular.z for the angular speed, for example 0.4 and it will make the robot move in a circle, with speed of 0.5m/s.
Hope this helps, -C.A.
Asked by wintermute on 2019-11-07 10:30:15 UTC
Comments
But i want to know how to publish it to arduino
Asked by Crowdeal on 2019-11-07 22:48:52 UTC
Should i use rosserial?
Asked by Crowdeal on 2019-11-07 22:50:23 UTC
Yes, the above scheme publishes to arduino. /cmd_vel is a subscriber running on the arduino. you publish to it, from anywhere.
For example look at this tutorial: http://wiki.ros.org/rosserial_arduino/Tutorials/Blink, this code runs on the arduino, subscribes to /toggle_led - when someone publishes to /toggle_led, either from command line, or from a python script, the /toggle_led subscriber takes that messages, and turns on/off the led.
Instead of /toogle_led make a subsriber /cmd_vel with Twist message type. There should be code available if you search for it.
This could be useful: https://answers.ros.org/question/29706/twist-message-example-and-cmd_vel/
Best regards, C.A.
Asked by wintermute on 2019-11-08 02:09:46 UTC
Yes you can use an arduino to subscribe to cmd_vel topic, or any topic for that matter. Just include the necessary header file. In your case, that would be:
#include <geometry_msgs/Twist.h>
and then initialise the subscriber as below:
ros::Subscriber<geometry_msgs/Twist> sub("cmd_vel", &callback_func)
Asked by parzival on 2019-11-09 05:20:53 UTC
Comments
Can you give me the detailed code ?
I dont really understand about this
thank you for your help!
Asked by Crowdeal on 2019-11-10 01:10:24 UTC
thank you i did it
Asked by Crowdeal on 2019-11-10 02:11:04 UTC
but i have another problem
can i println the linear.x on my arduino serial
it seems to appear error
Asked by Crowdeal on 2019-11-10 02:12:08 UTC
See this, http://wiki.ros.org/rosserial_arduino/Tutorials/Logging
use e.g
nh.loginfo("Hello world");
I believe this should appear as outputs in your rosserial node.
Asked by bob-ROS on 2019-11-11 03:51:40 UTC
Comments