DRIVING-POINT MECHANICAL IMPEDANCE OF THE HUMAN HAND-ARM SYSTEM - SYNTHESIS AND MODEL DEVELOPMENT

A synthesis of the measured values of human male hand-arm impedance ch aracteristics reported in the literature has been performed. The drivi ng-point mechanical impedance data of the human hand-arm grasping a vi brating handle has been compared to highlight the various similarities and differences among the data. Unexplained differences among the res ults of various studies, conducted independently under nominally equiv alent measurement conditions, led to the exclusion of outliers from th e analysis. The most probable values of impedance phase and magnitude are defined by lower and upper envelopes of the mean values of the acc epted data sets. The mean of the data sets, together with the smoothen ed envelopes, are used to define the target and range of idealized val ues of the X(h), Y-h and Z(h) components of impedance in the 10-1000 H z frequency range. A pooling of results from different studies suggest s that there is a small dependence of the X(h) component of impedance magnitude on the hand grip forces. The dependence of the phase of the corresponding impedance component on the hand grip force, however, is insignificant. There is insufficient data from independent sources to establish a dependence of other components of impedance on the hand gr ip and thrust forces. A four-degrees-of-freedom, lumped parameter mode l is derived to fit the target impedance magnitude and phase values us ing a constrained optimization algorithm. The predicted values correla te well with the target values in the selected frequency range.