Moving robot and method of calculating moving distance of the same

A mobile robot, comprising:

• a body configured to move on a surface in a travel direction;
• a left spin mop and a right spin mop, wherein the left and right spin mops support the body and are rotatably coupled to the body;
• a left mop motor configured to rotate the left spin mop and a right mop motor configured to rotate the right spin mop;
• a sensing module including a lower image sensor, the sensing module being disposed on a surface of the body, wherein the sensing module is configured to obtain data corresponding to at least one of (i) a moving distance or (ii) a moving speed of the body for a predetermined period of time when the body moves;
• and
• a sweep module configured to collect foreign matter from the surface and coupled to the body,
• wherein the sweep module comprises an agitator, a left caster and a right caster,
• wherein the left and right casters are configured to contact the surface,
• wherein the lower image sensor is disposed behind the left and right casters,
• wherein the lower image sensor is disposed between a virtual front horizontal line and a virtual rear horizontal line, the virtual front horizontal line being a virtual line that connects a front end of the left spin mop and a front end of the right spin mop, and the virtual rear horizontal line being a virtual line that connects a rear end of the left spin mop and a rear end of the right spin mop,
• wherein the sweep module is spaced apart from, and positioned in front of, the left and right spin mops,
• wherein a center of the sweep module is disposed on a virtual central vertical line which vertically intersects a virtual central horizontal line at a center of the virtual central horizontal line,
• wherein the virtual central horizontal line is a virtual line that connects a spin shaft of the left spin mop and a spin shaft of the right spin mop,
• wherein a center of mass of the left mop motor and a center of mass of the right mop motor vertically overlap with the virtual central horizontal line,
• wherein the left mop motor is disposed on the left spin mop,
• wherein the right mop motor is disposed on the right spin mop,
• wherein the left mop motor is biased leftward from the spin shaft of the left spin mop,
• wherein the right mop motor is biased rightward from the spin shaft of the right spin mop,
• wherein the center of mass of the left mop motor is disposed between the spin shaft of the left spin mop and a left end of the left spin mop, and the center of mass of the right mop motor is disposed between the spin shaft of the right spin mop and a right end of the right spin mop,
• wherein the agitator is parallel to the virtual central horizontal line,
• wherein the left caster and the right caster are positioned in front of the agitator,
• wherein the body further includes a water tank configured to store water,
• wherein the water tank is disposed behind the sensing module,
• wherein the sweep module is disposed in front of the lower image sensor,
• wherein the agitator is disposed between the left and right casters and the left and right spin mops,
• wherein the lower image sensor is disposed between the agitator and the virtual central horizontal line on a bottom surface of the body on the virtual central vertical line,
• wherein the sweep module is disposed entirely in between the center of mass of the left mop motor and the center of mass of the right mop motor, and
• wherein a distance between end portions of the agitator is larger than a distance between the left and right casters.