Rationale, Implementation and Evaluation of Assistive Strategies for an Active Back-Support Exoskeleton

Area of Science:

• Robotics
• Biomechanics
• Human-Computer Interaction

Background:

• Active exoskeletons offer greater versatility than passive designs but face challenges in assistive strategy development.
• Modulating actuation forces to meet user needs during physical activity is a key challenge for active exoskeletons.
• Reducing compressive low-back loads during manual material handling is crucial for preventing musculoskeletal injuries.

Purpose of the Study:

• To address the challenge of assistive strategy design for active exoskeletons.
• To develop and evaluate control strategies for an active exoskeleton prototype aimed at reducing low-back loads during lifting.
• To enhance exoskeleton versatility and user acceptance through adaptive control.

Main Methods:

• Analysis of lifting biomechanics to identify key factors influencing low-back loads.
• Implementation of three control strategies: posture-based, electromyographic (EMG) control adapting to object mass, and a combined strategy.
• Experimental testing of the exoskeleton prototype with 11 participants performing a lifting task.

Main Results:

• The implemented strategies successfully modulated exoskeleton assistance based on user posture and lifted object mass.
• Experimental data confirmed effective adjustment of assistive torque during operation.
• A significant reduction in lumbar spine muscular activity (approximately 30%) was observed, comparable to existing literature.

Conclusions:

• The developed control strategies enable active exoskeletons to adapt to diverse task conditions and individual user preferences.
• The adaptive strategies enhance exoskeleton versatility and user acceptance, promoting wider adoption.
• The findings suggest potential for reduced musculoskeletal injury risk in manual material handling and applicability to more powerful exoskeleton systems.