15.2 APPENDIX 2: Details of the calculation of postural discomfort in instantaneous or non-sustained postures

This appendix presents the mathematical procedure used by Ergoniza Intelligent to calculate postural discomfort in instantaneous or non-sustained postures, summarized in Section 11.2.3.3. Unlike the procedures applied to sustained or repetitive postures, this calculation does not estimate how discomfort evolves over time. Instead, it assesses the instantaneous proximity of each joint to the extreme regions of its effective range of motion.

This appendix provides the indicator's detailed formulation, including the smooth transition function used to prevent abrupt changes in the assessment, the method for determining the threshold at which instantaneous discomfort begins, the use of LUBA as a relative reference for the upper limbs, neck, and trunk, and the alternative procedure based on isocomfort equations for the hip, knee, and ankle. It also describes the operational age adjustment of effective ROM, used solely as a reference for calculating relative proximity to the joint limit.

The procedure presented here should be interpreted as a preventive ergonomic parameterization.