Different Phases in Manual Materials Handling Have Different Performance Criteria: Evidence From Multi-Objective...

Area of Science:

• Biomechanics
• Occupational Health
• Ergonomics

Background:

• Manual material handling (MMH) tasks involve distinct phases: reaching, lifting, unloading, and standing up (RLUS).
• Understanding MMH mechanisms is crucial for occupational health and developing assistive devices.
• Predictive models for MMH exist but primarily focus on the lifting phase, leaving other phases under-researched.

Purpose of the Study:

• To develop an optimization model for predicting the reaching, lifting, unloading, and standing up (RLUS) phases of manual material handling.
• To investigate the importance of minimum dynamic effort and maximum balance as performance criteria in different MMH phases.

Main Methods:

• Utilized a multi-objective optimization method to create a predictive model for RLUS tasks.
• Evaluated two distinct performance criteria: minimum dynamic effort and maximum balance.
• Analyzed the impact of each criterion on joint angle errors across the RLUS phases.

Main Results:

• Maximum balance criterion resulted in significantly smaller joint angle errors during reaching and unloading phases (27.6% and 40.9% less, respectively).
• Conversely, minimum dynamic effort was superior in lifting and standing up phases, yielding 40.4% and 65.9% smaller errors.
• Combining both criteria improved predictive accuracy across reaching, lifting, and unloading phases.

Conclusions:

• Human motion strategies in manual material handling (MMH) differ depending on the specific task phase.
• Maximum balance and minimum dynamic effort are not universally optimal; their importance varies.
• The developed model and findings contribute to a better understanding of MMH motion strategies, enabling more accurate predictive models for occupational safety and device development.