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On the OCRA Measurement: Automatic Computation of the Dynamic Technical Action Frequency Factor
Juri Taborri1, Marco Bordignon2, Francesco Marcolin2
1Department of Economics, Engineering, Society and Business Organization (DEIM), University of Tuscia, 01100 Viterbo, VT, Italy.
Sensors (Basel, Switzerland)
|March 20, 2020
Summary
This study introduces an automated method using inertial data to count repetitive actions, improving the OCRA (OCcupational Repetitive Action) risk assessment. This approach significantly reduces time and variability compared to traditional video analysis.
Area of Science:
- Occupational health and safety
- Biomechanics
- Ergonomics
Background:
- The OCRA (OCcupational Repetitive Action) method is a standard for assessing upper limb repetitive movement risks.
- Current OCRA frequency factor calculation relies on time-intensive video analysis, prone to significant operator variability (up to 30%).
Purpose of the Study:
- To develop and validate an innovative, automated procedure for counting dynamic technical actions using inertial data.
- To overcome the limitations of manual video analysis in OCRA assessments.
Main Methods:
- A threshold-based algorithm was developed for automatic counting of dynamic technical actions.
- The algorithm was tested across four industrial case studies with 20 workers.
- Nine algorithm variations were evaluated by adjusting time and amplitude thresholds.
Main Results:
- The automated method achieved an average relative error of less than 5.7% for frequency factor computation across all case studies.
- Accurate threshold selection was crucial for achieving high precision.
Conclusions:
- The proposed threshold-based algorithm offers a viable and efficient alternative for automatic OCRA frequency factor computation.
- This method can substantially reduce the time and effort associated with video-based analysis in occupational biomechanics.
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