A mobile robot, comprising: a body and a drive system for driving a movement of the mobile robot, a light emitter for emitting light toward a surface to be detected, a photoelectric sensor responsive to light from an environment and/or emitted by the light emitter, a variable impedance unit connected to the photoelectric sensor and having a reduced impedance when the photoelectric sensor is responsive to light of a preset intensity, and a control unit, where the light emitter is controlled by the control unit to form at least two operating states in which light is emitted at different intensities, and in the operating state other than the last operating state, if a sampling difference value determined when the light emitter is in the OFF state and ON state does not satisfy a preset condition, an operating state of the light emitter is changed to prevent misjudgment.