Analysis of handle dynamics-induced errors in hand biodynamic measurements

Abstract Reliable experimental data of the driving-point biodynamic response (DPBR) of the hand–arm system are required to develop better biodynamic models for several important applications. The objectives of this study are to enhance the understanding of mechanisms of errors induced via the dynamics of instrumented handles and to identify a relatively more reliable method for DPBR measurement. A model of the handle–hand–arm system was developed and applied to examine various measurement methods. Both analytical and finite element methods were used to perform the examinations. This study found that the handle dynamic response could cause an uneven vibration distribution on its structures, especially at high frequencies (⩾500 Hz), and hand coupling on the handle could influence the distribution characteristics. Whereas the uneven distribution itself could directly result in measurement error, the hand coupling-induced vibration changes could cause errors in tare mass cancellation. The essential reason for both types of error is that the acceleration measured at one point on the handle may not be the same as that distributed at other locations. Because the cap measurement method that separately measures the DPBRs distributed at the fingers and palm can minimize both types of error, it is the best one among the methods examined in this study. The theory developed in this study can be used to help select, develop, and improve the measurement method for a specific application.

[1]  Subhash Rakheja,et al.  A method for analyzing absorbed power distribution in the hand and arm substructures when operating vibrating tools , 2008 .

[2]  Antonio Besa,et al.  Characterisation of the mechanical impedance of the human hand–arm system: The influence of vibration direction, hand–arm posture and muscle tension , 2007 .

[3]  Ren G. Dong,et al.  Instrumented handles for studying hand-transmitted vibration exposure , 2006 .

[4]  S. Rakheja,et al.  Driving-point mechanical impedance of the human hand-arm system: synthesis and model development , 1995 .

[5]  Ronnie Lundström,et al.  Mechanical impedance of the human hand-arm system , 1989 .

[6]  Pierre Marcotte,et al.  Effect of handle size and hand–handle contact force on the biodynamic response of the hand–arm system under zh-axis vibration , 2005 .

[7]  Toshisuke Miwa.  STUDIES ON HAND PROTECTORS FOR PORTABLE VIBRATING TOOLS , 1964 .

[8]  Subhash Rakheja,et al.  Modeling of biodynamic responses distributed at the fingers and the palm of the human hand-arm system. , 2007, Journal of biomechanics.

[9]  Ren G Dong,et al.  Recent advances in biodynamics of human hand-arm system. , 2005, Industrial health.

[10]  Thomas W. McDowell,et al.  Development of hand-arm system models for vibrating tool analysis and test rig construction , 2008 .

[11]  L Burström,et al.  Measurements of the impedance of the hand and arm , 1990, International archives of occupational and environmental health.

[12]  M J Griffin,et al.  Foundations of hand-transmitted vibration standards. , 1994, Nagoya journal of medical science.

[13]  D. D. Reynolds,et al.  A study of hand vibration on chipping and grinding operators, part II: Four-degree-of-freedom lumped parameter model of the vibration response of the human hand , 1984 .

[14]  H. H. Ryffel.  Machinery's Handbook , 1984 .

[15]  R. G. Dong,et al.  Measurement of biodynamic response of human hand–arm system , 2006 .

[16]  R G Dong,et al.  Distribution of mechanical impedance at the fingers and the palm of the human hand. , 2005, Journal of biomechanics.