A damper tuned to the tremor frequency reduces the bow's vibration while aiming

The summary today

There is a single piece of work, from Japan, dating from 2017. The authors use accelerometers on the sight to measure the tremor that reaches the bow while aiming, with the subjects seated to remove body sway, and find two dominant peaks around 8 and 14 hertz. With a model of the arms and shoulders they work out the frequency to target for each person, starting from the stiffness of muscles and tendons estimated from maximal force in the shooting position, and build two beam dampers tuned to 9.30 and 8.70 hertz. Fitted to the bow they reduce the amplitude of the tremor by 35 per cent in the band between 8 and 10 hertz in the first case and by 80 per cent between 9 and 10 hertz in the second, about half on average. The result comes with three cautions: only two people were tested, they are not described as archers, and the tremor was measured with the subjects seated; for the individual the prediction does not hold, because where the model predicted 70 per cent the measurement gave 35 and where it predicted 43 it gave 80; and nobody looked at what happens to the group on the target.

Also phrased as: "dynamic vibration absorber on the bow"; "reducing tremor while aiming"; "bow vibration while aiming"; "vibration damper"; "bow arm tremor"

Evidence

• 2017
  For Equipment tests Published later

  Two custom-built beam dampers tuned to 9.30 and 8.70 hertz, fitted to the bow of two subjects: the amplitude of the tremor falls by 35 per cent in the first, in the band between 8 and 10 hertz, and by 80 in the second, between 9 and 10 hertz, about 50 per cent on average.

  Suppression of tremor on bow by using dynamic vibration absorber · Yusuke Mizuno, Ikuma Ikeda, Nobuyuki Iwatuki

• 2017
  Context Equipment tests Published later

  The reduction cannot be predicted for the individual: the model predicted 70 per cent for the first subject and 43 for the second, and the measurement gave 35 and 80. Only the average of the two matches, about 50 per cent both in theory and in the experiment.

  Suppression of tremor on bow by using dynamic vibration absorber · Yusuke Mizuno, Ikuma Ikeda, Nobuyuki Iwatuki

• 2017
  Context General population Published later

  The stiffness of the muscles and tendons that move the shoulder, derived from tremor measurements on three people, was approximated as a linear function of the maximal force each could produce in the aiming position: this is the step that allows the damper to be tuned without measuring the tremor every time. In the same measurements, sampled at 500 hertz for 5 seconds, the tremor on the bow shows two dominant peaks around 8 and 14 hertz.

  Suppression of tremor on bow by using dynamic vibration absorber · Yusuke Mizuno, Ikuma Ikeda, Nobuyuki Iwatuki

Status history

1. 2017 Reported The only test arrives: two beam dampers, custom-built and tuned to each person's frequency, 9.30 and 8.70 hertz, reduce the amplitude of the tremor on the bow by 35 and 80 per cent, in the bands between 8 and 10 and between 9 and 10 hertz, about half on average. The tuning starts from the stiffness of the shoulder's muscles and tendons, estimated from maximal force in the shooting position, but for the individual the prediction does not work: where the model predicted 70 per cent the measurement gave 35, and where it predicted 43 it gave 80. Two people not described as archers, tremor measured seated and no measurement on the target: reported.

Related

Related articles

• Bow arm tremor in archery: why it happens and how to reduce itBow arm shake at full draw is two movements, a slow sway and a fast tremor. What the studies measure, where the tremor comes from and how to reduce it.

Research lines

• 27 studiesTremor and sway while aiming: telling two phenomena apart since 1990
• 10 studiesVibration and stabilisers: what research has measured since 1987

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