Patent ID: 8292007

Claim:
A wheeled structure comprising: a body; right and left sets of forward and rearward wheels rotatably coupled to corresponding sides of the body, at least one wheel of each set of wheels driven to propel the wheeled structure; a non-articulated tail element extending from a first end pivotally coupled to the body by an articulation element and terminating at an element-free second end; and a drive module coupled to the tail element to control the movement of the tail element between a first, stowed position, wherein the tail element and element-free second end of the tail element are pivoted to lay along the body, and a second, non-stowed position where the tail element can make selective contact with a plurality of steps of a stairway; wherein the tail element is configured to contact a first step of the stairway and lift the first end wheel to attain the first step.