A robotic cleaner may include a body, one or more driven wheels configured to urge the body across a surface to be cleaned, one or more distance sensors disposed at least partially within the body such that the one or more distance sensors face the surface to be cleaned and a processor. The one or more distance sensors may be configured to output a measure of a detection distance that extends in a direction of the surface to be cleaned. The processor may be configured to determine whether an abnormality has been detected based, at least in part, on the measure of the detection distance and may be configured to determine a first velocity estimate based, at least in part, on the detection of the abnormality.