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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.

A transient thermal model of the portable life support system (PLSS) is being developed for use in thermal control studies. The transient thermal PLSS (TTPLSS) model has been developed and implemented using SIMULINK in conjunction with MATLAB. The TTPLSS has been developed with modularity and flexibility in mind so that alternative PLSS designs and configurations can easily be implemented and evaluated. The basic structure and functionality of the TTPLSS SIMULINK model is described and demonstrated. The various thermal dynamics issues associated with the PLSS such as time delays and the dynamics of individual components are discussed and considered.

The NASA JSC Shuttle EMU computer model (SINDA EMU) is presently used to analyze the thermal behavior of the Space Shuttle EMU. This paper uses the SINDA EMU model along with EMU experimental and flight data to investigate and define several performance characteristics of the Space Shuttle EMU related to thermal comfort control.

A transient model of the Minimum Consumables Portable Life Support System (MPLSS) Advanced Space Suit design has been developed and implemented using MAT-LAB/Simulink. The purpose of the model is to help with sizing and evaluation of the MPLSS design and aid development of an automatic thermal comfort control strategy. The MPLSS model is described, a basic thermal comfort control strategy implemented, and the thermal characteristics of the MPLSS Advanced Space Suit are investigated.

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.