Improving Harness–based Partial Gravity Simulators by Implementing Engineering Systems Modeling

The unique gravitational environments of the Moon and Mars present challenges for many aspects of human spaceflight. Harness-based Partial Gravity Simulators (H-PGS) that rely on mechanical systems to offload subjects from Earth gravity are an accessible, ground-based technology that can train astronauts and inform researchers of the physiological, psychological, and operational effects of reduced gravity on human subjects. The fidelity of H-PGS impacts the validity of astronaut training and research, necessitating constant improvement to such systems to meet the needs of upcoming crewed missions. Currently, there is no formal design and diagnostic model for H-PGS or standardization in subsystem identification and nomenclature, and there is limited literature on the study of subject-harness interactions. The lack of an organized approach to understanding H-PGS as a collection of dynamic subsystems limits the ease of the design cycle for greater simulation usability and fidelity for future space mission operations. To initiate structured understanding, a systems-based model of H-PGS was developed using literature on notable H-PGS and their designs. The model distinguishes and organizes subsystems to be generalizable to most H-PGS and other harness-based systems. Several aspects of usability and fidelity often disrupted by H-PGS are described. Possible impacts on usability and fidelity by each H-PGS subsystem are preliminarily identified. The model was validated following the design iterations of the Moonwalker Partial Gravity Simulator as a case study. Structured descriptions and examinations of possible interferences of each H-PGS subsystem reveal the significance of the harness subsystem, which encourages its centrality in future development. The model’s applicability to the Moonwalker demonstrates its potential usefulness in understanding current and future H-PGS designs and contributes a benchmark for future studies characterizing subsystem influences on usability and fidelity. Overall, this proposed model can act as a customizable design and diagnostic tool for researchers developing and using H-PGS.