Osamu Kanbara

Using facial skin temperature to objectively evaluate sensations

Abstract Facial skin temperature enables automatic non-contact measurement, and is valid for objectively evaluating sensations like stress and fatigue because it varies with autonomic nerve activity triggered by the onset of sensations. The present report therefore proposes a method that uses facial skin temperature to infer stress, and outlines the results of evaluations conducted to confirm the validity of the inference formula. At the same time, this report also proposes a formula that infers fatigue through facial skin temperature based on the assumption that fatigue is the result of accumulated stress, and experimental results here suggest that the fatigue inference formula is also valid. Furthermore, color image evaluations using the stress inference formula suggest that the stress inference formula is valid for objectively evaluating color images as well. Relevance to industry The present method can be used to create a system of evaluating sensations through facial skin temperature. The system is useful not only to estimate stress and fatigue of operators in nuclear power plant, but also to evaluate color images.

Attempt to control an artificial heart system using sympathetic nervous signals

Changes in skin sympathetic nerve activity (SSNA), which accelerates the constriction of peripheral blood vessels, were measured microneurographically from the median nerve of a subject, and were used for controlling the driving parameters of a pneumatically-driven artificial heart (AH) system. The number of SSNA pulses per second was calculated using a pulse counter, and the driving parameters (pulse rate, positive pressure, and vacuum pressure) of the artificial heart system were altered in accordance with the algorithm for changes in the number of SSNA pulses by means of batch processing. After that, the driving parameters and the pump output of the AH system and the arterial pressure of the mock circulatory system which was connected with the AH pump were compared with the SSNA, digital arterial pressure, and skin blood flow of the subject. The increase/decrease in the number of SSNA pulses essentially matched the changes in digital blood pressure and skin blood flow; in such cases, it was possible to alter the AH pump output and the arterial pressure of the mock circulatory system similar to the change in the actual hemodynamic data of the subject. The authors are currently planning to utilize cardiac nerve activity instead of SSNA.

Use of skin sympathetic nerve activity for the automatic control of an air-conditioning system

As the first stage of a long-term project aimed at developing an automatic control system for external devices which utilizes signals from the nervous system, the current study utilized changes in the skin sympathetic nervous activity (SSNA) measured microneurographically in order to accomplish the switching control of an external device between the cooling and heating modes. The number of SSNA (vasomotor) bursts decreased in proportion to the increase in the thermal sensation of the subject, demonstrating the possibility of operating an air-conditioner by using feedback from the number of SSNA bursts.

Analysis of sympathetic activity induced by stimulation

Brain waves, sympathetic nerve activity, blood flow, perspiration and skin temperature induced by sensation stimulation were simultaneously measured in order to analyze mechanisms that cause skin temperature changes associated with sensations. The results suggested that stimulation of the sympathetic nerve system, including skin temperature, is induced when intense stressful stimulation is recognized, and also indicated that the reaction gradually declines even though it may at times recover to the level of an initial reaction. The results also suggested that skin sympathetic nerve activity (in the case of vasomotor) may decline as ambient temperature rises.