Patent ID: 7568434

Claim:
A system comprising: a housing having a center of mass; a first wheel configured to rotate about a first axis of rotation, the first wheel being displaced a first distance from the center of mass; a second wheel connected to the housing and configured to rotate about a second axis that is displaced from the center of mass by a second distance and generally parallel to the first axis; a guide tangentially engaging a perimeter of each of the first and second wheels and positioned such that said guide is at least partially located between said first and second wheels; wherein, positioning of each of the first and second axes with respect to the center of mass creates a rotating moment that biases the first wheel and second wheel into frictional engagement with the guide; a rotator for rotating the first wheel; a first set of controls in communication with the rotator and positioned at a location remote from the housing; an attachment including a cage connected to the housing; wherein, the rotation of the first wheel causes the system to move relative the guide.