Defining space models of arm reach envelopes for static forced postures

Forced postures are regarded as related to the location of a technical structure's touch points. The aim of this research study was to interpret the basic biomechanical criteria of the EN 1005-4 standard (also ISO/DIS 11226), defining standing posture categories as parameters of the corresponding arm reach envelopes. This form of data presentation makes direct application of these criteria possible in the design and evaluation of a technical structure. Forced static postures were simulated according to angle ranges of the standard for trunk bending and upper arm elevation. Arm reach of representatives of the Polish population was measured with a model consisting of modular elements movable perpendicularly to the frontal plane. The results formulated in the Cartesian system of co-ordinates were developed with Mechanical Desktop software and presented as spatial arm reach envelope models, and graphically, too. In practice it was possible to compare the location of touch points with reach envelopes to assess just the technical structure according to the assumed working posture categories as acceptable, conditionally acceptable or unacceptable.