For obtaining a diameter of a main roller included in a multi-roller module system

A method for obtaining a diameter of a rotatable main roller included in a multi-roller module system, the multi-roller module system further including a fixed-diameter rotating component, and a wire wound on the rotatable main roller and the fixed-diameter rotating component and to be driven to move by rotation of the rotatable main roller and the fixed-diameter rotating component, the method comprising steps of:

• a) designating a target linear velocity (VT) associated with the wire moving in the multi-roller module system, and a value of a presumed diameter parameter (Rs) associated with a diameter of the main roller;
• c) activating the multi-roller module system to rotate the main roller and to drive the wire to move;
• d) measuring a current rotational speed of the fixed-diameter rotating component when the multi-roller module system is running in a stable state in which the wire is moving at a constant linear speed;
• e) calculating an actual linear velocity (VR) of the wire based on the current rotational speed;
• and
• f) comparing the target linear velocity (VT) and the actual linear velocity (VR) of the wire, increasing the value of the presumed diameter parameter (Rs) when it is determined that a ratio of the target linear velocity to the actual linear velocity is smaller than one, decreasing the value of the presumed diameter parameter (Rs) when it is determined that the ratio of the target linear velocity to the actual linear velocity is greater than one, and determining that the value of the presumed diameter parameter (Rs) equals an actual diameter (Rr) of the main roller when it is determined that the ratio of the target linear velocity to the actual linear velocity is equal to one.