The next-generation spacesuit, compared to that of historical designs, requires additional capabilities for controlling and adjusting internal pressure. Next-generation suit pressures will range from slightly above ambient, for astronaut prebreathe comfort during intrave-hicular activities, to hyperbaric pressure levels for emergency medical treatment, reduced prebreathe operation, and variable vehicle pressure schedule integration. With more than two setpoints identified, we challenged historical linkage-based mechanical regulator designs to enable the five-setpoint minimum and continuously variable goal for the new regulator design. Although the base regulator architecture is very similar to the existing secondary oxygen pack (SOP) regulator used in the current shuttle extravehicular mobility unit (EMU), the major difference is electrical selectivity of multiple setpoints rather than the mechanical On/Off feature found on the SOP regulator. The concept regulator employs a linear actuator stepper motor combination that provides variable compression to a custom-designed main regulator spring. This concept allows for adjustable outlet pressures from 8.2 psid down to full shutoff in as many steps as the selected stepper motor/actuator requires (-4,000). This paper details the prototype regulator design and presents test results on regulation bandwidth, command setpoint accuracy, slue rate, and regulation stability. Projections for a flight configuration version are also offered for performance, architectural layout, and weight.
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