Treadmills are generally discussed herein with specific discussion to Omni-directional treadmills that incorporate powered offset casters to move a belt in the X, Y, and theta directions. The belt is positioned over a frame and the frame includes a plurality of rollers for allowing the belt to turn about the frame. The powered offset casters can be mounted under the belt or on top of the belt and are controlled by a control system, which controls the translational motion and rotational motion of the belt.