Robot wabbles in gazebo
I have been working on a robot, and have got it to move in gazebo. Unfortunately, the robot does not go straight when given the command:
rostopic pub /cmd_vel geometry_msgs/Twist "linear:
x: 1.0
y: 0.0
z: 0.0
angular:
x: 0.0
y: 0.0
z: 0.0"
it makes the robot move forward in a wabble or teetering way that seems like one wheel is moving at a time.
The files are located here: https://github.com/matrhint/src
A video is posted here with just joints being shown: https://youtu.be/Z8d7ynoP_RQ
A video is posted here with joints, collisions, and contacts being shown: https://youtu.be/Ye9SlvWYKrw
It appears that there may be some Issues with the wheels being off center of the joint (one higher on one side and one lower on the other), thus leading to the one stopping while the other is free to turn. I am uncertain on how to make this perfectly center. I believe this is my issue but I think I might have to resize the wheel, re-measure it, or just change the xacro file to have a more precise radius for the joint (I may have rounded it too much-- and shouldn't have rounded at all).
Thanks in advance for any help.
Update 6/29/17: I found that the wheels were (slightly) oval in shape an not perfect circle. I remade the wheels and still have the same symptom. I have also tried to change the location of the wheel joints.
It would be helpful to see a video of what is happening. Even better if collision and contacs visualization is on.
I am out of idea to try on this issue
One thing I would try is to make the robot's collision objects into actual geometries, rather than using CAD files. Also try to add a small amount of friction in the joints and see what happens, especially the joint above the casters.
Thanks a lot for responding! I will give that a try and let you know what happens soon.
@matrhint: this seems to be really a Gazebo question, which we typically close and have people repost over at
answers.gazebosim.org. Not because we don't want to help you, but because you have a higher chance of getting good answers there.Do please link back if you open a new question.
@ufr3c_tjc: It worked! Thanks