Apparatus and method for determining a circumference

A method of determining the circumference (2) of a body (3), which has at least the following steps:

• a) Laying a wire (5) with a known length section of length LD around the body (3) in the circumferential direction, the wire (5) being in operative contact with a position sensor (4) such that the position sensor (4) outputs a signal S as soon as the wire (5) exerts at least a predetermined tensile force Z on the position sensor (4),
• b) Introducing the wire (5) into a drive device (6, 7) which is in operative contact with a distance meter (10),
• c) Tensioning the wire (5) along the circumference (2) of the body (3) by starting the drive device (6, 7), until the position sensor (4) in operative contact with the wire (5) provides a signal,
• d) Reading the distance WD, determined by the distance meter (10), traced by the wire (5) as it is tensioned along the circumference (2) of the body (3) by the drive device (6, 7),
• e) Determining the circumference (2) of the body (3) from the length LD, the distance WD and an apparatus-dependent geometry factor G.

A device (1) for determining the circumference (2) of a body (3), comprising:

• a wire (5) comprising a loose end and at least one section having a known length;
• a position sensor (4) coupled to the wire (5), wherein the position sensor (4) is configured to generate an output signal when the wire (5) exerts at least a predetermined tensile force on the position sensor (4);
• a drive device (6,7) configured to pull in the loose end of the wire (5) and further configured to tension at least a section of the wire (5), wherein the drive device (6,7) is coupled to the position sensor (4) such that when an output signal is generated by the position sensor (4) the drive device (6,7) is inhibited from further tensioning the wire (5);
• and
• a distance meter (10) coupled to the drive device (6,7), wherein the distance meter (10) is configured to determine the distance traced by the wire (5) as the wire (5) is tensioned by the drive device (6,7) to determine the circumference (2) of the body (3).

A method of determining the circumference (2) of a body (3), comprising:

• positioning a wire (5) around a body (3), wherein the wire (5) comprises at least a section of known length;
• pulling the wire (5) using a drive device (6,7), until a predetermined tension is achieved;
• determining the distance traced by the wire (5) as the wire (5) is pulled by the drive device (6,7);
• and
• determining the circumference (2) of the body (3) based at least in part on the known length of at least one section of the wire (5), the distance traced by the wire (5) as the wire (5) is pulled by the drive device (6,7) and an apparatus-dependent geometry factor.