Project critical mission requirements often drive design decisions and processes. This was the case for National Aeronautics and Space Administration (NASA) funded DEep Phreatic THermal eXplorer (DepthX), an underwater robot designed to autonomously map, navigate, and acquire biological samples. Mission requirements led the authors to develop a novel core sampling mechanism for variable density materials. Preliminary testing was conducted on variable density materials simulating real world specimens to identify the series of motions to acquire an acceptable core and optimize the geometry of the coring tube. A geometric modeling approach with configuration functions was employed to design the overall mechanism and establish the cam profile. The design was tested and evaluated during multiple field expeditions to cenotes (sinkholes) in Mexico. The culmination of the preliminary testing and the selected design methodology resulted in a core sampling mechanism that is compact, has minimal operational torque requirements, and utilizes a single motor to complete a series of complex functions. Future applications are envisioned for space expeditions, underwater exploration, and medical sampling.

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