  Analysis of sediments from rivers, lakes, reservoirs, wetlands and other
constructed surface water impoundments is an important tool to characterize the
function and health of these systems, but is generally carried out manually.
This is costly and can be hazardous and difficult for humans due to
inaccessibility, contamination, or availability of required equipment. Robotic
sampling systems can ease these burdens, but little work has examined the
efficiency of such sampling means and no prior work has investigated the
quality of the resulting samples. This paper presents an experimental study
that evaluates and optimizes sediment sampling patterns applied to a robot
sediment sampling system that allows collection of minimally-disturbed sediment
cores from natural and man-made water bodies for various sediment types. To
meet this need, we developed and tested a robotic sampling platform in the
laboratory to test functionality under a range of sediment types and operating
conditions. Specifically, we focused on three patterns by which a cylindrical
coring device was driven into the sediment (linear, helical, and zig-zag) for
three sediment types (coarse sand, medium sand, and silt). The results show
that the optimal sampling pattern varies depending on the type of sediment and
can be optimized based on the sampling objective. We examined two sampling
objectives: maximizing the mass of minimally disturbed sediment and minimizing
the power per mass of sample. This study provides valuable data to aid in the
selection of optimal sediment coring methods for various applications and
builds a solid foundation for future field testing under a range of
environmental conditions.
