  This paper introduces the Passive Transformable Omni-Ball (PTOB), an advanced
omnidirectional wheel engineered to enhance step-climbing performance,
incorporate built-in actuators, diminish vibrations, and fortify structural
integrity. By modifying the omni-ball's structure from two to three segments,
we have achieved improved in-wheel actuation and a reduction in vibrational
feedback. Additionally, we have implemented a sliding mechanism in the follower
wheels to boost the wheel's step-climbing abilities. A prototype with a 127 mm
diameter PTOB was constructed, which confirmed its functionality for
omnidirectional movement and internal actuation. Compared to a traditional
omni-wheel, the PTOB demonstrated a comparable level of vibration while
offering superior capabilities. Extensive testing in varied settings showed
that the PTOB can adeptly handle step obstacles up to 45 mm, equivalent to 35
$\%$ of the wheel's diameter, in both the forward and lateral directions. The
PTOB showcased robust construction and proved to be versatile in navigating
through environments with diverse obstacles.
