A hand speed and duty cycle equation for estimating the ACGIH hand activity level rating
Published Date:Oct 24 2014
Pubmed Central ID:PMC4664886
Funding:R01 OH007914/OH/NIOSH CDC HHS/United States
R01OH007914/OH/NIOSH CDC HHS/United States
R21 EB014583/EB/NIBIB NIH HHS/United States
R21 OH010221/OH/NIOSH CDC HHS/United States
R21OH010221/OH/NIOSH CDC HHS/United States
An equation was developed for estimating hand activity level (HAL) directly from tracked RMS hand speed (S) and duty cycle (D).
Table lookup, equation, or marker-less video tracking can estimate HAL from motion/exertion frequency (F) and D. Since automatically estimating F is sometimes complex, HAL may be more readily assessed using S.
Hands from 33 videos originally used for the HAL rating were tracked to estimate S, scaled relative to hand breadth (HB), and single-frame analysis was used to measure D. Since HBs were unknown, a Monte Carlo method was employed for iteratively estimating the regression coefficients from US Army anthropometry survey data.
The equation: =10[e−15.87+0.02D+2.25lnS1+e−15.87+0.02D+2.25lnS], R2 = 0.97, had a residual range ±0.5 HAL.
The S equation superiorly fit the Latko (1997) data and predicted independently observed HAL values (Harris, 2011) better (MSE=0.16) than the F equation (MSE=1.28).
An equation was developed for estimating the HAL rating for the ACGIH Threshold Limit Value® based on hand RMS speed and duty cycle. Speed is more readily evaluated from videos using semi-automatic markerless tracking, than frequency. The speed equation predicted observed HAL values much better than the F equation.
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