11.3.1 Assessing postural risk using the REBA method

Ergoniza Intelligent assesses postural load using the REBA method65F¹. This whole-body observational method analyzes the positions of the trunk, neck, legs, upper arms, forearms, and wrists and combines them with factors related to the applied load or force, coupling, and type of activity. The result is a score associated with a risk and action level that indicates how urgently corrective measures should be considered.

Ergoniza Intelligent automatically calculates the score for each body segment from the model posture, as well as the partial scores for Groups A and B defined by the method. It then obtains a final score for each side of the body and displays the risk and action level for the less favorable side as the overall result in the REBA section of the Postural Load panel (Figure 60).

The result obtained through REBA analysis depends on parameters such as body segments that remain static, repetitive movements, and coupling quality. These parameters can be defined in the REBA Analysis Settings dialog, which is opened with the gear button in the REBA section.

When assessing the upper arm, REBA reduces the score if the arm is supported or if its posture is assisted by gravity. This condition allows different scores to be assigned to situations in which the upper arm adopts the same angular position but is either supported or assisted by gravity.

Ergoniza Intelligent can automatically detect whether an upper arm is favorably oriented relative to gravity. This avoids requiring the user to mark the condition manually when the arm's orientation allows it to be inferred geometrically. The system analyzes the spatial direction of the upper arm, defined by the segment between the shoulder and elbow, and compares it with the downward vertical. If the upper arm is sufficiently aligned with the direction of gravity, the system interprets the posture as gravity-assisted and automatically applies the REBA score reduction for the upper arm. To use this automatic detection, enable Automatically Detect Gravity-Assisted Upper Arms in the REBA Analysis Settings dialog (Figure 60).

When automatic detection is enabled, the manual upper-arm checkboxes indicate only that support exists. Whether the posture is gravity-assisted is determined automatically from the upper arm's orientation. When automatic detection is disabled, the manual checkboxes regain their general REBA meaning and can indicate either that support exists or that the upper-arm posture is assisted by gravity.

The user can also define the angular threshold used for automatic detection. This threshold specifies how close the upper arm must be to the downward vertical for Ergoniza Intelligent to consider the posture gravity-assisted. A low value makes detection stricter and applies it only when the upper arm hangs almost vertically. A higher value makes detection more permissive and allows it to apply to positions somewhat farther from vertical.

This automation does not modify the REBA method or its general scoring rules. Its purpose is to assist the assessor in identifying one of the conditions considered by the method. As with any ergonomic assessment, the result must be reviewed in light of the actual task, the presence of supports, the handled loads, and the analyst's professional judgment.