Autonomous coverage robot

A mobile surface cleaning robot comprising:

• a robot body having a forward drive direction;
• a drive system supporting the robot body above a floor surface for maneuvering the robot across the floor surface;
• a wet cleaning system supported by the robot body and arranged to clean the floor surface;
• and
• a robot controller in communication with at least one of the drive system or the cleaning system;
• wherein the cleaning system comprises:
• a liquid collection volume defining at least one fluid orifice and a shaft aperture;
• and
• an anti-spill device in communication with the robot controller, the robot controller causing the anti-spill device to open and close the at least one orifice based on a robot state, the anti-spill device comprising:
• at least one orifice sealer supported inside the liquid collection volume to move between an open position that allows fluid through the least one fluid orifice and a closed position that seals the at least one fluid orifice closed;
• an actuator shaft coupled to the at least one orifice sealer and supported to move through the shaft aperture defined by the liquid collection volume;
• and
• an orifice opener actuator coupled to the actuator shaft and in communication with the robot controller, the orifice opener actuator configured to move the actuator shaft to cause movement of the at least one orifice sealer between the open and closed positions.