The kobuki base by yourself does not drift, so it is sensible the tilted inertia will cause the drift. Obviously I can hack my URDF that has a weightless superstructure, but I wanted to repair this in a more practical way. I tried all I can consider, and all unsuccessful: https://www.uk-exhibitionstands.co.uk/product/casonara-blimp-cube-360o-hanging-light-box-display-100l/