Angular position sensor for assembly on a rotating shaft

Angular position sensor for mounting on a rotary shaft, said rotary shaft being rotatably guided on a support structure, said angular position sensor comprising an annular element (10) with an inner surface (11) adapted for plug-fitting onto said shaft rotary with no possibility of relative rotation between the two, and a housing (12) where a permanent magnet (40) is inserted, characterized in that it further comprises a support (60) provided with: a through opening (21, 31) through which said rotary shaft and said annular element (10) extend, said through opening (21, 31) having an inner surface (22, 32) facing and proximate to the annular element (10) with sufficient radial clearance to allow relative rotation and movement in radial directions within a range of tolerances; a cavity (24), adjacent to the through opening (21, 31), which houses a detector device (50) capable of detecting variations in the magnetic field produced by said permanent magnet (40) when rotating with respect to said support together with the annular element (10); and at least one anchoring configuration (25) by means of which said support (60) is fastened to a fixed structure with respect to the rotary axis.