A method for automatically loading reels onto an unwinding assembly comprising a first and a second unwinding and handling unit (34', 34") comprising respective robots (35', 35") having respective wrists (38', 38") movable under the control of at least one electronic control unit, wherein each of said unwinding and handling units (34', 34") comprises a respective unwinding device (40', 40") mounted on the wrist (38', 38") of the respective robot (35', 35") comprising a support (42', 42") fixed to the respective wrist (38', 38") and carrying a respective unwinding shaft (44', 44") rotating about a respective axis, wherein each of said unwinding shafts (44', 44") comprises a plurality of mobile expansion elements (51', 51") projecting from an outer surface (55', 55") of the unwinding shaft (44', 44"), wherein the method comprises: - arranging a plurality of reels (10', 10") in a storage area (33', 33") having respective central cores provided with respective openings, - detecting images of a reel (10', 10") by means of a vision device (50', 50") carried by a respective unwinding device (40', 40"), - moving the wrist (38', 38") of one of said robots (35', 35") under the control of said at least one electronic control unit and inserting the respective unwinding shaft (44', 44") inside an opening of a central core of a reel (10', 10") located in said storage area (33', 33"), and - pushing said mobile expansion elements (51', 51") outwards to block the reel (10', 10") on the respective unwinding shaft (44', 44"), wherein the method further comprises: - moving one of said unwinding devices (40', 40") about a reel (10', 10") located in said storage area (33', 33"), - acquiring images of an outer surface of said reel (10', 10") by means of said vision device (50', 50"), - processing the images of the outer surface of said reel (10', 10") by means of said at least one electronic control unit and determining the angular position of a strip of adhesive tape that joins a head end (12'e, 12"e) of a web (12', 12") wound onto said reel (10', 10") to the outer surface of the reel (10', 10"). - arranging a plurality of reels (10', 10") in a storage area (33', 33") having respective central cores provided with respective openings, - detecting images of a reel (10', 10") by means of a vision device (50', 50") carried by a respective unwinding device (40', 40"), - moving the wrist (38', 38") of one of said robots (35', 35") under the control of said at least one electronic control unit and inserting the respective unwinding shaft (44', 44") inside an opening of a central core of a reel (10', 10") located in said storage area (33', 33"), and - pushing said mobile expansion elements (51', 51") outwards to block the reel (10', 10") on the respective unwinding shaft (44', 44"), - moving one of said unwinding devices (40', 40") about a reel (10', 10") located in said storage area (33', 33"), - acquiring images of an outer surface of said reel (10', 10") by means of said vision device (50', 50"), - processing the images of the outer surface of said reel (10', 10") by means of said at least one electronic control unit and determining the angular position of a strip of adhesive tape that joins a head end (12'e, 12"e) of a web (12', 12") wound onto said reel (10', 10") to the outer surface of the reel (10', 10").