Patent ID: 8196309

Claim:
An apparatus for measuring distance on a loose surface, the apparatus comprising: a frame; a wheel operatively coupled to the frame, wherein the wheel rotates relative to the frame, the wheel comprising: a hub for operatively coupling the wheel to the frame, wherein the hub rotates relative to the frame in response to one of pushing and pulling of the frame; and a plurality of spikes projecting outwardly from a peripheral surface of the wheel in a direction away from the hub; and a counter operatively coupled to the wheel, wherein the counter tracks a number of rotations of the wheel as the peripheral surface of the wheel rolls on the loose surface thereby measuring distance traversed by the wheel on the loose surface and calculates the distance on the loose surface based on a predefined correction factor corresponding to the loose surface, the predefined correction factor being proportional to a portion of a spike of the plurality of spikes that sinks into the loose surface.