An Unobtrusive Measurement Method for Assessing Physiological Response in Physical Human–Robot Interaction

The objective of this work was to develop and validate a novel unobtrusive method for measuring person's physiological response with a low-cost integrated sensory system for use in a physical control task. Two different sensory handles were designed (cylindrical and hemispherical shape) and used in a physical human-robot control task. Twenty-three participants underwent a measurement session with both handles, performing four different tasks for each handle. Two basic task conditions were permuted: physical load (high/low) and task dynamics (high/low). Electrocardiogram, photoplethysmogram, electrodermal activity, and peripheral skin temperature signals were recorded by sensory handles and a reference high-accuracy biosignal amplifier to determine the raw signal correlation between the measurement systems. Additionally, several standardized physiological parameters were calculated and discussed for both systems. Results of raw signal correlation showed a high correlation between the reference measurement system and the sensory handles. Pearson's correlation coefficients were above 0.8 for most of the physiological signals in all task conditions. Some effect of physical load and high task dynamics was registered. In terms of signal quality, the hemispherical design outperformed the cylindrical design. Correlation results show that the proposed system correlates well with the reference system for all tasks. In terms of optimal design for signal quality and comfort, hemispherical handle shape is more appropriate. Unobtrusive nature and short setup time of such a method deems it appropriate for home use, monitoring, and research.