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Gazebo provides different world pose between two simulation instances

asked 2020-12-16 09:51:05 -0600

GB gravatar image

updated 2020-12-16 22:58:33 -0600

I am running Gazebo Simulation with applying constant force for 6 sec multiple times ( two different instances ). I found that, the robot poses are different in two instances. such that, x = 8.515776 in first instance and x = 8.514708 in second instance, and similar for y,z, roll, pitch and yaw. image description image description Here, force and simulation time is constant ( green color), while poses are different. Though, the difference looks very small, I want to ask, 1] Is Gazebo non-deterministic ? 2] Can we control this non-deterministic behavior ?

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answered 2020-12-18 13:21:23 -0600

Carlos Agüero gravatar image

In general Gazebo is non-deterministic, as there are multiple threads running concurrently and some components (e.g.: physics engines) with a non-deterministic nature. In your particular example, it's probably the physics engine (ODE by default) the one that potentially has some non-determinism. My two suggestions are:

  1. Launch Gazebo with the --seed <value> argument using the same VALUE in both instances.

http://gazebosim.org/tutorials?tut=ra...

  1. If that doesn't work try using a different physics engine (Gazebo supports multiple ones). Maybe for your example that physics engine is deterministic.
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Asked: 2020-12-16 09:51:05 -0600

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Last updated: Dec 18 '20