A device and a method for determining rotational position of a rotating shaft

A method for determining rotational position of a rotating shaft (12) of a remotely operated vehicle of a system (1) for storing and retrieving goods holders, wherein a reflector (14) is attached to the rotating shaft (12), the reflector (14) rotating simultaneously with said shaft (12) and said rotating shaft (12) being a wheel axle of the remotely operated vehicle, said method comprising:

• providing a distance measuring unit (16) for measuring a distance to said reflector (14) by emitting a beam (18) of radiation towards a portion of the reflector (14) as the shaft (12) and reflector (14) are rotated with respect to the distance measuring unit (16), the emitted beam being parallel to the rotating shaft, wherein said portion of the reflector (14) has an irregular surface, and wherein the reflector (14) is integrally formed with the rotating shaft (12) and arranged at an end of the rotating shaft (12) and said reflector (14) is substantially cylindrically-shaped and doesn't radially extend beyond outer surface of the rotating shaft (12) and by receiving a return beam (20) generated when the emitted beam (18) is reflected by the portion of the reflector (14), the distance measuring unit (16) being configured to output a signal based on a distance of said beam to said portion of the reflector (14), and
• determining a rotational position of the rotating shaft (12) based on the output signal of measured distance of said distance measuring unit (16).