A mobile cleaner includes a body, a mop module, and a sweep module. The mop module includes a pair of spin mops configured to rotate and mop a surface. The sweep module is configured to sweep up foreign material on the surface using a rotating agitator. The sweep module includes a dust housing, the agitator, and a wheel assembly. The wheel assembly is configured to support the dust housing on the surface and includes a wheel body that is movable in a vertical direction. A cliff sensor is configured to detect movement of the wheel body.