In one aspect and one example, a method for calibrating robotic picker mechanisms in automated storage library systems includes detecting a calibration mark with at least one sensor from a first position and a second position, where the first position and the second position are separated by an offset distance. Further, the method includes determining a shift in the calibration mark between the first position and the second position, and determining a distance between a reference position and the calibration mark based on the shift in the calibration mark, the offset distance, and the focal length of the sensor.