# Revision history [back]

vibrating due to error in calculating for gravity compensation.

See more details here: http://rethinkrobotics.interaforum.com/topic/490-vibrating-model/

vibrating vibrations are possibly due to an error in calculating for the calculations of gravity compensation.compensation within gazebo.

See more details here: http://rethinkrobotics.interaforum.com/topic/490-vibrating-model/Courtesy of Ian McMahon from RethinkRobotics:

*The caveat when working with the simulator is that it will never perform exactly the same as the real robot. That said, you have indeed encountered a bug with how gravity_compensation_torques are being calculated: one of the KDL::JntArray vectors being used to calculate the gravity torques is being used uninitialized. The uninitialized values cause the calculated simulated gravity torque to vary a fair amount, which causes jitter. I have a fix for this that has not been yet merged into master, but I will hotfix the simulator shortly:

https://github.com/RethinkRobotics/sa...

I will update this topic with details once merged into master. In the mean time, if you like living life on the bleeding edge, free to checkout the kinematics_gravity_torques branch on github:

$roscd sawyer_gazebo && git fetch origin && git checkout kinematics_gravity_torques$ roscd sawyer_robot && git fetch origin && git checkout gravity_inertia \$ catkin build*