The kobuki base alone would not drift, so it makes sense the tilted inertia causes the drift. Naturally I'm able to hack my URDF having a weightless superstructure, but I planned to resolve this in a more reasonable way. I attempted all I am able to contemplate, and all failed: https://www.uk-exhibitionstands.co.uk/product-category/light-box-displays/pro-light-box-displays/