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This paper presents a definition of human thermal comfort that can be used for control purposes. A control strategy and architecture based on a Proportional Integral Derivative (PID) controller format is developed. Problems and limitations are discussed and the results from both simulations and experiments are used to demonstrate the practicality of the comfort definition.

Experimental apparatus simulating a space suit Portable Life Support System (PLSS) was developed for testing human thermal comfort in a suited environment. Various uncertainties of the experimental apparatus were studied from which the accuracy of the entire setup was determined. Experimental and Simulated data from existing human thermal models were collected for similar cases. Differences/similarities between experimental and simulated data were then discussed. Based on this comparison, the human thermal model can be validated or changes can be made to either the experimental setup or simulation to more accurately reflect the thermal state of a human in a suited environment.

As the National Aeronautics & Space Administration (NASA) continues to plan for extended missions in space, the need increases for an automatic thermal comfort controller within NASA spacesuits. The temperature control in the current model of the spacesuit is operated manually. For this reason, the University of Missouri-Columbia (MU) Thermal Control Group has been working with NASA for the past nine years on several related topics such as human thermal dynamics, spacesuit thermal dynamics, and the design of an automatic thermal comfort controller for advanced spacesuits. The objectives of this paper are to i) present and ii) discuss the thermal physiological differences between men and women. This information will then be included in the MU Human Thermal Model, which will improve its accuracy and account for gender variation and individuality.

This study investigates the complexities associated with quantifying human thermal comfort using indices. A detailed review of the literature is first performed. The uncertainties associated with comfort modeling are then highlighted. Possible indices are developed and evaluated using integrated human-suit-PLSS (Portable Life Support System) simulations developed at the University of Missouri. The study forms part of a larger project aimed at developing automatic thermal controllers for NASA space suits.

This paper proposes an optimal control strategy for thermal comfort control of an advanced space suit. During an extravehicular activity (EVA), the astronaut's metabolic rate is time-varying depending on the working load, which would prescribe different reference skin temperatures. The purpose of thermal comfort control is to control the skin temperature to the reference value at a certain metabolic rate via a liquid cooling garment (LCG) for astronaut comfort. MPC is expected to achieve the control with the minimum consumable energy. After developing an operational definition of comfort, the structure of the controller and preliminary results are reported.