In this paper. we present motion analysis and prototype design of a new omni-directional wheel mechanism "ACROBAT-S". The authors group has proposed a special kind of transmission with a dual-ball configuration for transmit drive powers to wheel shaft and steering shaft of an active-caster mechanism (ACROBAT). In the transmission design. https://www.alarecre.com/NFL-Atlanta-Falcons-Double-Vision-iPhone-13-Pro-MagSafe-Case-p92343/