Equivalent Weight: Connecting Exoskeleton Effectiveness with Ergonomic Risk during Manual Material Handling

Area of Science:

• Biomechanics
• Ergonomics
• Occupational Health

Background:

• Work-related musculoskeletal disorders are prevalent in manual material handling.
• Occupational exoskeletons offer a potential solution to mitigate these risks.
• Integrating exoskeletons requires dialogue between evaluators and Health & Safety professionals.

Purpose of the Study:

• To propose an innovative interpretation of lower-back assistive exoskeleton effects on erector spinae muscle activation.
• To introduce the concept of "equivalent weight" for quantifying perceived effort.
• To support exoskeleton adoption by assessing ergonomic risk.

Main Methods:

• Experimental testing involving 12 subjects.
• Analysis of erector spinae muscle activation.
• Introduction of the "equivalent weight" concept to measure perceived load reduction.

Main Results:

• A significant reduction in erector spinae muscle activation was observed.
• The perceived weight of handled objects was reduced by 37.5% (over one-third).
• The "equivalent weight" concept effectively quantifies the ergonomic benefit.

Conclusions:

• Lower-back assistive exoskeletons provide a measurable ergonomic benefit by reducing perceived load.
• The "equivalent weight" metric offers a novel approach to quantify exoskeleton assistance.
• This method supports the adoption of exoskeletons in workplaces to reduce ergonomic risk.