Abstract: A more accurate tension of a belt or a more accurate target natural frequency of the belt when the belt tension is adjusted is determined. A method for calculating a belt tension includes receiving a natural frequency of a belt and a span; performing calculation for determining a tension of the belt using a predetermined expression, based on the natural frequency, the span, and a unit mass of the belt read from a memory; and displaying the tension on a display, wherein in a case where the span is within a predetermined range corresponding to the belt, the predetermined expression is corrected so that an error caused by a bending stiffness of the belt is reduced.

Abstract: A natural-frequency measurement device for measuring the natural frequency of a belt includes: an acceleration sensor attached to a portion of the belt between an adjacent pair of pulleys to sense acceleration resulting from the vibration of the belt; and a measuring instrument configured to measure the natural frequency of the belt based on the acceleration sensed by the acceleration sensor.

Abstract: The tension of a belt is determined accurately at a low cost. A natural-frequency measurement device is configured to measure, in a belt transmission system including at least two pulleys between which a belt is stretched, the natural frequency of the belt based on a vibration generated by hitting a portion of the belt stretched between two adjacent ones of the at least two pulleys, and includes: an acceleration sensor attached to the portion of the belt to sense acceleration resulting from the vibration of the belt; and a measuring instrument configured to measure the natural frequency of the belt based on the acceleration sensed by the acceleration sensor. The measuring instrument transmits the natural frequency to a belt tension calculator which determines the tension of the belt based on the natural frequency.

Abstract: A natural-frequency measurement device for measuring the natural frequency of a belt includes: an acceleration sensor attached to a portion of the belt between an adjacent pair of pulleys to sense acceleration resulting from the vibration of the belt; and a measuring instrument configured to measure the natural frequency of the belt based on the acceleration sensed by the acceleration sensor.

Abstract: A more accurate tension of a belt or a more accurate target natural frequency of the belt when the belt tension is adjusted is determined. A method for calculating a belt tension includes receiving a natural frequency of a belt and a span; performing calculation for determining a tension of the belt using a predetermined expression, based on the natural frequency, the span, and a unit mass of the belt read from a memory; and displaying the tension on a display, wherein in a case where the span is within a predetermined range corresponding to the belt, the predetermined expression is corrected so that an error caused by a bending stiffness of the belt is reduced.

Abstract: A swing analysis method of the present invention includes steps of: preparing a radio type acceleration measuring device 4 capable of measuring respective accelerations in three axis directions; mounting the acceleration measuring device 4 to a golf player's body t1; receiving measured data from the acceleration measuring device 4 during a swing through radio communication; and analyzing a golf swing based on the acceleration data. Preferably, the acceleration measuring device is attached to each of two or more portions of the tester t1. Preferably, an attached position of the acceleration measuring device is any part selected from the group consisting of a head, a neck, a shoulder, a back, a waist and a wrist. Preferably, a weight of the acceleration measuring device is equal to or more than 10 g.

Abstract: A swing analysis method of the present invention includes steps of: preparing a radio type acceleration measuring device 4 capable of measuring respective accelerations in three axis directions; mounting the acceleration measuring device 4 to a golf player's body t1; receiving measured data from the acceleration measuring device 4 during a swing through radio communication; and analyzing a golf swing based on the acceleration data. Preferably, the acceleration measuring device is attached to each of two or more portions of the tester t1. Preferably, an attached position of the acceleration measuring device is any part selected from the group consisting of a head, a neck, a shoulder, a back, a waist and a wrist. Preferably, a weight of the acceleration measuring device is equal to or more than 10 g.