An omni-directional drive device, comprising: a base; a first moveable member and a second moveable member rotatably supported by the base; a first drive unit and a second drive unit (24, 25) configured to selectively drive the first and second moveable members along first and second directions of rotation, respectively; a plurality of first free rollers rotatably supported by the first moveable member and arranged along the direction of rotation of the first moveable member, each first free roller having a rotation axis extending at a nonzero first angle relative to a direction perpendicular to the direction of rotation of the first moveable member at a part where the first free roller is supported; and a plurality of second free rollers rotatably supported by the second moveable member and arranged along the direction of rotation of the second moveable member, each second free roller having a rotation axis extending at a nonzero second angle relative to a direction perpendicular to the direction of rotation of the second moveable member at a part where the second free roller is supported, wherein the first free rollers come into a rolling contact with the corresponding second free rollers as at least one of the moveable members rotates along the direction of rotation thereof such that the rotation axes of the first and second free rollers in the rolling contact are not parallel to each other; wherein the rotation axis of each first free roller is in a skew relationship with the center line of the corresponding second free roller when in the rolling contact therewith; wherein the first free roller is configured to contact a road surface or a floor surface, or wherein the first free roller engages a ball which in turn is configured to engage a road surface or a floor surface; and wherein the first and second moveable members comprise a pair of annular members (22, 23) having a coaxial center of rotation, each annular member having a peripheral wall rotatably supporting the corresponding free rollers. a base; a first moveable member and a second moveable member rotatably supported by the base; a first drive unit and a second drive unit (24, 25) configured to selectively drive the first and second moveable members along first and second directions of rotation, respectively; a plurality of first free rollers rotatably supported by the first moveable member and arranged along the direction of rotation of the first moveable member, each first free roller having a rotation axis extending at a nonzero first angle relative to a direction perpendicular to the direction of rotation of the first moveable member at a part where the first free roller is supported; and a plurality of second free rollers rotatably supported by the second moveable member and arranged along the direction of rotation of the second moveable member, each second free roller having a rotation axis extending at a nonzero second angle relative to a direction perpendicular to the direction of rotation of the second moveable member at a part where the second free roller is supported, wherein the first free rollers come into a rolling contact with the corresponding second free rollers as at least one of the moveable members rotates along the direction of rotation thereof such that the rotation axes of the first and second free rollers in the rolling contact are not parallel to each other; wherein the rotation axis of each first free roller is in a skew relationship with the center line of the corresponding second free roller when in the rolling contact therewith; wherein the first free roller is configured to contact a road surface or a floor surface, or wherein the first free roller engages a ball which in turn is configured to engage a road surface or a floor surface; and wherein the first and second moveable members comprise a pair of annular members (22, 23) having a coaxial center of rotation, each annular member having a peripheral wall rotatably supporting the corresponding free rollers.