Autonomous surface cleaning robot for wet and dry cleaning

A robot comprising:

• a differential drive system along a lateral axis of the robot;
• a supply volume that stores cleaning liquid;
• at least one spray nozzle that applies the cleaning liquid to a surface;
• a pump assembly that moves the cleaning liquid from the supply volume to the at least one spray nozzle;
• a bumper comprising:
• a first sensor on a first portion of the bumper, the first sensor being configured to generate a first signal;
• and
• a second sensor on a second portion of the bumper, the second sensor being configured to generate a second signal;
• and a controller configured to:
• operate the differential drive system to maintain contact between the bumper and a wall surface, in response to receiving the first signal, the second signal, or both the first signal and the second signal, while advancing the robot over the surface in a forward direction.