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Rpeatable results in gazebo

asked 2015-09-10 06:18:11 -0500

AbdealiJK gravatar image

updated 2015-09-10 06:19:12 -0500

I am trying to get repeatable results in gazebo, along with a ros_control in hector_quadrotor.

It seems as though the controller is giving me different results every time. If I disable the controller, the model falls freely - and the positions after every 10 steps can be reproduced consistently. But when I switch on the controller and set a constant velocity of z as 100 (the controller uses /cmd_vel) - I get different positions every 10 steps.

I dont understand why this would happen

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answered 2015-09-15 04:09:36 -0500

niall gravatar image

When you say different positions, I expect you mean different velocities or position changes as if you set the velocity constant, the position will never be constant...

So how different are your velocities? If they are slightly different I wouldn't be worried. If you're running hector_quadrotor with all it's plugins there is a lot (!) going on. For one there are aerodynamics and propulsion plugins that could cause the results to be different every time. The drag and propeller forces are calculated each step and these could vary considerably each simulation. Also are you using ground_truth for pose estimation or the imu? Here again the imu is of course more realistic but less accurate and can cause differences. You can even add wind to the simulation which changes the results. I don't know how much of this you have changed but I think it's good to know a lot of things can influence your results.

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Asked: 2015-09-10 06:18:11 -0500

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Last updated: Sep 15 '15