The Kobuki base by itself does not drift, so it is sensible that the tilted inertia will cause the drift. Of course I am able to hack my URDF having a weightless superstructure, but I needed to correct this in a more reasonable way. I tried all I'm able to https://www.uk-exhibitionstands.co.uk/product-category/fabric-display-stands/fabric-pop-up-stands/