A surface clinging robotic device. The device includes a supporting
structure or base, on which is mounted (a) a lead pivoting support
surface, such as a pivoting wheel, and (b) two or more traction drives,
such as drive wheels. Each of the traction drives are independently
driven by a separate drive motor. A plurality of vacuum cups are mounted
on the bottom of the base. The vacuum cups each have a low friction foot
designed for movement over a surface with minimal friction while vacuum
is maintained. The low friction foot portion is provided by a generally
surface direction oriented C-shaped Teflon skin. The robotic device can
move over gaps or obstructions in the surface without losing vacuum in
all of the vacuum cups, using a fluid limiting valve at each vacuum cup
to interrupt flow in the event of loss of vacuum in that vacuum cup.