Disclosed is a delivery system including a position detecting unit, comprising a housing (1), a reservoir (2), a piston (3), a lead screw (4) and at least two or more position sensors (5a,5b,5c,5d,5e), wherein the piston (3) includes a detectable feature. The position sensors (5a,5b,5c,5d,5e) are arranged on or adjacent to the outer wall of the reservoir (2) composing a sensor array, configured to sense a change of the magnetic field or the electric field caused by the displacement of the detectable feature to generate a signal based on which the position of the piston (3) can be determined using algorithms, and to detect the infusion abnormality by sensing the displacement abnormality of the piston (3), endowing an infusion device with performances as compact structure, low cost, high precision, fast reaction and a minimum volume under the premise of safety guarantee.
