Optimal Allocation of Lifting Workload Using MILP Model under Time and Ergonomic Constraints
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Abstract
This study aims to develop an optimal workload allocation model for manual lifting tasks by applying a Mixed Integer Linear Programming (MILP) framework under the Deterministic Allocation concept. The objective is to enhance operational efficiency while minimizing ergonomic risks in repetitive lifting activities. Experimental data were collected from ten volunteers in a controlled laboratory environment. Each participant performed repetitive lifting tasks of 10 kg objects, while video recordings were used to analyze time duration and postural behavior in each lifting phase. The ergonomic risk level was assessed using the Rapid Upper Limb Assessment (RULA) method. The results showed that the average lifting cycle time was 7.17 seconds, and the overall RULA scores indicated a moderate risk level. The MILP model was then applied to determine optimal workload allocation under three scenarios: (A) minimum total ergonomic load, (B) fair distribution, and (C) equal distribution. The findings revealed that scenario A achieved the lowest total risk but lacked fairness, while scenario B provided a balanced allocation between efficiency and equity. Scenario C demonstrated practicality for real applications requiring ease of management. Sensitivity analysis ±10% confirmed the model’s robustness and low sensitivity to parameter variations. Overall, the study highlights that MILP can serve as a quantitative decision-making framework for designing safe, ergonomic, and efficient lifting workload allocation policies.
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ลิขสิทธ์ ของมหาวิทยาลัยเทคโนโลยีราชมงคลพระนครReferences
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