The kobuki base by itself doesn't drift, so it is sensible which the tilted inertia causes the drift. Obviously I can hack my URDF by using a weightless superstructure, but I wished to deal with this in a more realistic way. I tried all I can give thought to, and https://www.uk-exhibitionstands.co.uk/product-category/light-box-displays/casonara-light-box-walls/