Differential Soft Sensor-Based Measurement of Interactive Force and Assistive Torque for a Robotic Hip Exoskeleton.

Area of Science:

• Robotics and Human-Machine Interaction
• Wearable Technology
• Biomedical Engineering

Background:

• Human-robot physical interaction safety is crucial for emerging wearable robots.
• Online measurement of interaction forces is essential for wearable exoskeleton performance.
• Current indirect methods (e.g., motor current) for force/torque sensing in exoskeletons have limitations.

Purpose of the Study:

• To present a compact, low-cost soft sensor system for direct force measurement in wearable gait assistance exoskeletons.
• To address the open problem of direct force/torque sensing in compact wearable sensors.
• To evaluate the sensor system's performance on a robotic hip exoskeleton.

Main Methods:

• Developed a soft pneumatic sensor system where contact force is converted to voltage via air pressure measurement.
• Integrated the soft force sensor system onto a robotic hip exoskeleton.
• Measured real-time interaction forces using differential soft chambers and calculated delivered torque via a characterization model.

Main Results:

• Achieved direct force measurement with a mean error of 10.3 ± 6.58%.
• Enabled real-time torque monitoring for the hip exoskeleton.
• Demonstrated the system's compactness, low cost, and adaptability compared to traditional rigid sensors.

Conclusions:

• The developed soft sensor system provides a viable solution for direct force and torque measurement in wearable exoskeletons.
• Direct force measurement enhances understanding and potentially improves the assistive performance of exoskeletons.
• The sensor's soft, compact, and low-cost nature makes it suitable for wearable gait assistance applications.