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Sawyer Simulation Vibrating

I am currently running ubuntu 16.04, gazebo 7 and ros kinetic.

I'm trying to run the new sawyer simulation on gazebo that was recently released. Has anyone noticed small vibrations in the model? I am running a force/torque sensor on the end effector but the output has a weird amount of noise. the noise isn't being caused by the model of the sensor. I know this because i've also tested the force/torque sensor on a baxter simulation and it works fine.

If anyone has experienced this and has been able to resolve it, please let me know.

Asked by lr101095 on 2018-03-28 00:04:03 UTC

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Answers

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

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/sawyer_simulator/compare/master...kinematics_gravity_torques#diff-3d709d3c805e7153135d0d32960a5b21L449

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*

Asked by lr101095 on 2018-04-23 01:09:21 UTC

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@lr101095 This page show as "Please email Rethink Robotics to gain permission" whats there on that page may you share with us ?

Asked by lagankapoor on 2018-04-23 02:53:25 UTC

my apologies @lagankapoor. please see edited answer

Asked by lr101095 on 2018-04-23 18:24:38 UTC

This has been fixed and released. Assuming you already have your workspace configured for sawyer_simulator, simply run:

$ cd ~/ros_ws/src
$ wstool update
$ catkin build

to pull in the latest changes for Sawyer Simulator.

Asked by imcmahon on 2018-04-24 09:03:09 UTC

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