A Novel Elastic Model for Exoskeleton-User Coupling Interfaces

Current research on physical human-robot interactions (pHRI) in wearable assistive robots, such as lower-limb exoskeletons, primarily focuses on improving net force estimates at each interface to improve robot controller performance. Consequently, estimating force distribution along physical interfaces of wearable robots, crucial for user safety and comfort, has been largely overlooked. We propose a novel computational model that uses interface geometry and strapping tension as inputs, and predicts the static pressure field generated during the user donning process by treating the supporting surface as an elastic foundation. Accuracy of the proposed computational method was validated by comparing the estimated static pressure field of a commercially available interface to experimental data. While measured pressure magnitudes were significantly lower than model prediction, likely due to a combination of assumptions and limitations associated with model design, similar loading patterns were observed. Identifying regions of high pressure from simulation and similar patterns allow for reliable scaling to reduce inaccuracies, and may be used to inform design. Further refinements of the proposed model will provide a valuable tool for developing more comfortable and safer interfaces for wearable robots.