Control of a liquid cooling garment for extravehicular astronauts by cutaneous and external auditory meatus temperatures

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1970

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Abstract

An improved, temperature control concept is developed, for liquid cooling garments used during astronaut extravehicular activity. Several modifications and extensions to previously known physiological parameter measurement techniques and control approaches are implemented to provide an automatic controller which responds directly to man's thermoregulatory requirements for cooling during work. The temperature of the wall of the external auditory meatus and four averaged, unweighted skin temperatures are used as input signals to a controller of liquid cooling garment inlet water temperature. The absolute change in derived mean body temperature from a setpoint and its time rate of change are sensed and used to control the temperature of water to an Apollo liquid cooling garment. A crewman metabolic transient thermal computer simulation is conducted to demonstrate feasibility and to supply design parameters for a prototype system. The prototype controller is described and unmanned and manned test data are provided. It is concluded that minimizing variations in test subject mean body temperature from a thermally neutral setpoint during work provides subjective comfort and low thermal strain. Standard deviations in mean body temperature using the controller developed range from 0.07 - 0.32°F for one hour treadmill tests at high and moderate working levels and selected controller gains.

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