5.2 Range-of-motion limits

Ergoniza Intelligent lets you define the posture adopted by the biomechanical model by directly manipulating the different segments of the graphical model in the user interface.

Human joints cannot rotate without limit. Ergoniza Intelligent therefore establishes a range between a minimum and a maximum angle for each available degree of freedom.

By default, Apply biological constraints to the movement of the model's joints, located under Model settings on the right side of the interface, prevents direct manipulation from exceeding these limits. For certain joints, it also applies geometric constraints intended to prevent incompatible configurations between segments. If this option is disabled, the available degrees of freedom may exceed the configured angular limits; axes that the model does not include as degrees of freedom remain locked.

Disabling the constraints may produce anatomically implausible or impossible postures. Results obtained from such postures may fall outside the model's validity range and must be interpreted with particular caution.

Joint ranges of motion can vary substantially among individuals because of factors such as age, sex, body build, injury history, and physical activity. For this reason, the limits implemented in Ergoniza Intelligent are broad. They should be interpreted as operational software limits, not as normative population values or as a guarantee that every posture within those limits is suitable for a particular person.

The range-of-motion limits for each segment are provided in Table 1. For the upper-arm and thigh segments, flexion/extension describes movement in a plane approximately parallel to the sagittal plane, whereas abduction/adduction describes movement in a plane approximately parallel to the frontal plane.