Moving Lego NXT's motor

Question

I've been playing with ROS+Lego NXT and after successfully playing with the sensors I got stuck trying to move one motor.

The only parameter I found on nxt_msgs related to that is JointCommand, but JointCommand only has "effort".

So I tried:

rostopic pub /joint_command nxt_msgs/JointCommand '{name: 'motor', effort: 10}'

And confirmed that this value changed with:

rostopic echo joint_command

name: motor effort: 10.0

But no movement. I also tried the nxt_teleop demo, but no matter the arrow key I press, none of the motor move.

I also tried the steps described in this post, but had no success (http://answers.ros.org /question/486/trouble-following-lego-nxt-tutorials)

Any ideas? thanks

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Originally posted by Rafael Aroca on ROS Answers with karma: 1 on 2011-08-10

Post score: 0

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Original comments

Comment by mmwise on 2011-08-10:
were you able to run the test on the installation page (http://www.ros.org/wiki/nxt/Installation)? or run the first tutorial (http://www.ros.org/wiki/nxt_ros/Tutorials/Getting%20started)

Answer 1

Try using the command rxgraph when your system is running to see what is subscribing and publishing in order to better diagnose the problem.

nxt_teleop should publish to cmd_vel which publishes to base_controller which publishes to joint_command

There are 2 tutorials online for Teleoperation, I found the nxt_teleop (http://www.ros.org/wiki/nxt_teleop) works, and I have not had success with nxt_assisted_teleop.

So I run roscore, a robot.launch file (which reads robot.yaml for parameters), and then I launch teleop_keyboard.launch from the directory .../stacks/nxt_apps/nxt_teleop and then use the arrow keys to drive the nxt.

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Originally posted by Jhatch with karma: 16 on 2011-08-11

This answer was ACCEPTED on the original site

Post score: 0