Pybullet: pendulum swing independent of moment of inertia

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ryan72
Posts: 3
Joined: Mon May 15, 2017 2:26 am

Pybullet: pendulum swing independent of moment of inertia

Post by ryan72 »

Attached in a minimum working example of two bars swinging. Each bar is 1 m long and weighs 1 kg. The center of mass of each bar is at the end. The diagonal terms of the moment of Inertia tensor are 9999 for one and 0 for the other. One should behave like a simple pendulum, while the other should fall very slowly.

In pybullet they both behave identically. As expected, the simple pendulum's period is slightly longer than the small angle period of 2*pi*sqrt(1/9.8 ) or 2.01 s probably due to the reasons discussed here http://www.bulletphysics.org/Bullet/php ... =9&t=11694. Is there any reason why the pendulum with large moment of inertia does not fall slowly?
Attachments
links9999.urdf.txt
urdf file for I = 9999
(1.04 KiB) Downloaded 362 times
links0000.urdf.txt
urdf file for I = 0
(1.04 KiB) Downloaded 373 times
I_MWE.py.txt
main python script
(1.39 KiB) Downloaded 298 times
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