on the base of the robot 1 when the valve 16 is open operating fluid such as air or water flows through a flexible supply hose 20 to the nozzle 14 the vacuum generated within the throat of the nozzle 14 is ported to the suction cup 12 which is in contact with the walking or inspection surface 50 once a vacuum is established the pressure sensor 18 confirms the presence of a vacuum within the suction cup 12 in known manner the vacuum is maintained as long as fluid flows through the nozzle 14 and the vacuum is released by shutting off the flow to the nozzle 14 the pressure sensor 18 preferably may be a switch that is closed in the presence of a vacuum from its default open position in a preferred embodiment the vacuum generator 14 is based on a venturi nozzle 14 a venturi nozzle or tube includes an inlet a convergent cone a throat and an optional divergent cone as fluid flows through the convergent portion of the nozzle 14 the fluid velocity increases and at the same time its pressure decreases in use a vacuum is created within the suction cup 12 by porting the throat of the nozzle 14 thereto a divergent zone can optionally be included downstream of the throat to reduce the overall pressure loss preferably the vacuum generator 14 provides a suction force of at least 25 pounds as measured in air this should ensure the robot 1 remains connected to the surface 50 during operation if additional suction force is required the flow through the nozzle 14 can be increased alternatively or additionally the surface area of the foot assemblies can be increased either by including additional feet or increasing the size of the existing feet while oval.