Measurement of a relative position of movable elements

An assembly for measuring a relative position of two elements that are movable with respect to one another, said assembly comprising:

• a ribbon, which has a longitudinal extension and which comprises, parallel to this longitudinal extension, a magnetic strip with magnetic poles in which the individual orientations of the poles are fixed and alternated periodically along the strip, from one end of said strip;
• a first magnetic sensor, which is capable of measuring a position of magnetic poles whose respective orientations are different between two successive poles, in front of a sensitive surface of the first magnetic sensor when the ribbon is secured to a first of the two elements and the first magnetic sensor is secured to the other of said two elements, the position being measured within a period of alternation of the orientations of the magnetic poles along the strip of the ribbon;
• and
• a second magnetic sensor, which is capable of detecting a passage of at least one magnetic pole of the end of the magnetic strip of the ribbon, or of at least two successive magnetic poles of said end of the magnetic strip of the ribbon and whose respective orientations are different, in front of a sensitive surface of the second magnetic sensor, when said second magnetic sensor is secured to said other of the two elements with said first magnetic sensor.