"The reported driving-point mechanical impedance (DPMI) characteristics of the hand–arm system exposed to vibration show extreme variabilities among them at higher frequencies. The sources of these discrepancies under zh-axis vibration, particularly above 500 Hz, are investigated using experimental and analytical techniques. Four different handle designs with varying geometric and dynamic properties are considered for characterizing DPMI responses of the handles and hand–arm system using two different measurement methods involving acceleration measurements at the fixture base and in the vicinity of the hand. A split handle design is analytically modeled and integrated with the 3-DOF model defined in ISO-10068 [International Standards Organization, ISO-10068, 1998. Mechanical vibration and shock-free mechanical impedance of the human hand–arm system at the driving point.]. Both the measured and simulation results show that the measurement location and handle natural frequency significantly influence the hand–arm impedance response at higher frequencies. The experiments involving measurements at the fixture base resulted in a sharp increase in magnitude near the resonance, while those near the hand caused the magnitudes at high frequencies to decrease or remain relatively constant. From the model and measured results, it is concluded that reliable impedance responses could be attained up to a limiting frequency that depends upon the measurement location and handle natural frequency. Handle design guidelines are also proposed on the basis of the results. The results also show that the contributions due to handle inertia at higher frequencies cannot be entirely eliminated through mass cancellation."

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