The invention concerns a device forming a mechanism, in particular for use in the space industry, characterised in that it comprises in combination: two structural elements (100, 200) capable of relative displacement, locking means (300) adapted to prevent initially the relative displacement between the two structural elements (100, 200), and means (400) for controlled locking of the locking means (300) designed to prevent initially the release thereof, then when activated, successively, in a first phase, a sliding action in controlled amplitude of the locking means (300), for limited release between the two structural elements (100, 200), then in a second phase, complete release of the locking means (300) and hence of the structural elements (100, 200).