Self-Aligning Fluid Transfer Couplings for Blind-Mate Refueling
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Solution Overview
Problem
Current fluid transfer systems in space environments face challenges with misalignment during mating, lack of dedicated alignment features, and complexity in robotic access, leading to operational inefficiencies and potential delays in fluid replenishment and transfer.
Innovation Solution
A fluid transfer coupling system with an Active Side and a Passive Side, featuring a poppet valve mechanism, alignment cone, and locking mechanism, designed for bi-directional fluid flow and capable of operating under misaligned conditions, with rotational degrees of freedom and redundant safety features for reliable operation in space environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard Fill and Drain Valve interfaces are used for robotic propellant transfer, then human operator safety features are maintained, but device complexity and operational time increase due to multiple redundant closeout caps and safety lock wire cutting requirements
Solution Approach 1:
The valve interface is segmented into modular components including a valve body, multiple closeout caps (first, second, and third closeout caps), and integrated pressure relief features. This segmentation allows robotic systems to access specific components independently while maintaining safety functions, reducing the complexity of manual operations.
Solution Approach 2:
The system incorporates automatic pressure relief mechanisms that activate when pressure exceeds safe levels, eliminating the need for manual pressure monitoring and intervention. The pressure relief valve automatically vents excess pressure, and the system includes self-diagnostic capabilities that detect cap removal and valve status without human input.
2Reliability
If multiple redundant closeout caps and safety lock wire features are included in FDV interfaces, then human operator safety is ensured, but operational time and productivity decrease due to sequential removal and cutting operations
Solution Approach 1:
The system pre-positions multiple closeout caps and pressure relief valves in specific configurations before robotic access. The first closeout cap protects the valve inlet, the second closeout cap protects the outlet, and the third closeout cap provides redundant sealing. This preliminary arrangement allows robotic systems to systematically remove caps in a predetermined sequence, reducing decision time and operational complexity.
Solution Approach 2:
Manual operations involving lock wire cutting and cap removal are replaced with robotic end-effectors equipped with specialized tools. The robotic system uses automated cutting mechanisms and magnetic or mechanical gripping systems to manipulate caps and valves, eliminating the need for human manual dexterity and significantly reducing operational time.
3Reliability
If FDV interfaces are designed for ground-based human operation with PPE, then safety features are optimized, but ease of robotic access and operation deteriorates due to small threaded features without anti-cross-threading characteristics
Solution Approach 1:
The valve interface incorporates asymmetric threading patterns and non-circular engagement features that prevent cross-threading. The closeout caps feature keyed interfaces that only engage in the correct orientation, and the valve body includes asymmetric port configurations that guide robotic end-effectors into proper alignment. This asymmetric design eliminates the need for precise manual alignment while maintaining safety functions.
Solution Approach 2:
Adaptive compliance mechanisms and alignment features act as intermediaries between the robotic system and the valve interface. These features include self-aligning mounting brackets, compliant mounting structures that accommodate positional tolerances, and guide features that automatically correct minor misalignments during robotic approach and engagement.
4Ease of operation
If alignment features are added to enable blind-mate and telerobotic operations, then ease of robotic operation improves, but device complexity increases due to additional alignment and positioning mechanisms
Solution Approach 1:
The alignment mechanism utilizes a spherical ball joint with inherent self-centering geometry. The ball joint allows rotational movement in multiple axes while maintaining a fixed center point, enabling the valve to automatically align with mating interfaces during approach. This curved, spherical geometry provides alignment capability without requiring complex mechanical guidance structures.
Solution Approach 2:
The system incorporates adaptive compliance features that change their mechanical parameters (stiffness, damping) based on operational conditions. The compliant mounting structure adjusts its rigidity to accommodate alignment tolerances during approach, then locks into a rigid fixed position once mated. This dynamic parameter change enables blind-mate operation without permanent complex alignment mechanisms.
Data Source
AI summary
The present invention relates to couplers for transferring fluid between space assets, particularly in a vacuum microgravity environment with radiation exposure. In particular, the couplers provide for transfer of fluids, such as propellants, coolants, pressurant gases, or life-support fluids, preferably between assets in the space environment or in terrestrial environments such as Earth, the Moon, or Mars. The couplers provide self-alignment features which enable their use in blind-mate, telerobotic, fully autonomous robotic systems. The invention provides a common design architecture for different fluids accommodating a variety of flow rates and pressure drops depending upon the particular fluid. The basic wetted component design of the invention involves a rigid, centrally-disposed nozzle on the Passive Side which contacts and opens a poppet valve on the Active Side as the two sides are coupled; and a rigid annular nozzle on the Active Side, coaxially located with but occupying a different radius than the Passive Side nozzle, which contacts and opens a corresponding contamination cover on the Passive Side.