An official website of the United States government
Soil strength testing and collecting soil cores from wetlands is currently a slow, manual process that runs the risk of disturbing and contaminating soil samples. This paper describes a method using an instrumented dart deployed and retrieved by a drone for performing core sample tests in soft soils. The instrumented dart can simultaneously conduct free- fall penetrometer tests. A drone-mounted mechanism enables deploying and reeling in the dart for sample return or for multiple soil strength tests. Tests examine the effect of dart tip diameter and drop height on soil retrieval, and the requisite pull force to retrieve the samples. Further tests examine the dart’s ability to measure soil strength and penetration depth. Hardware trials demonstrate that the drone can repeatedly drop and retrieve a dart, and that the soil can be discretely sampled.
more »
« less
Assessment of Soil Strength using a Robotically Deployed and Retrieved Penetrometer
This paper presents a method for performing free-fall penetrometer tests for soft soils using an instrumented dart deployed by a quadcopter. Tests were performed with three soil types and used to examine the effect of drop height on the penetration depth and the deceleration profile. Further tests analyzed the force required to remove a dart from the soil and the effect of pulling at different speeds and angles. The pull force of a consumer drone was measured, and tests were performed where a drone delivered and removed darts in soil representative of a wetland environment.
more »
« less
- PAR ID:
- 10219786
- Date Published:
- Journal Name:
- 2020 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)
- Page Range / eLocation ID:
- 7324 to 7329
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
This paper presents the results of soil characterization and element tests of Ottawa F65 sand. The data presented is intended to be used as calibration material for the prediction exercise conducted as part of the Liquefaction Experiments and Analysis Project (LEAP 2017). The databank generated includes soil specific gravity tests, particle size analysis, hydraulic conductivity tests, maximum and minimum void ratio tests, and cyclic triaxial stress-controlled tests. An effort was made to ensure the consistency and repeatability of the test results by reducing the sources of variability in the sample preparations and increasing the number of tests. The uniformity of the soil was evaluated by conducting tests on samples from five different batches. The results showed that the sand is uniform among the five batches. Due to significant variability in previously reported maximum and minimum void ratio results, the effects of the test operator were studied by comparing test results obtained from three different operators. For the triaxial tests, a constant height dry pluviation method was used for sample preparation. To eliminate the effect of the human error in maintaining a constant drop height and to ensure consistency of the sand fabric between different samples, a device was developed to facilitate the sample preparation. The cyclic triaxial experiments were performed using three different soil densities, and a liquefaction strength curve was obtained for each density based on a 2.5% single amplitude axial strain criteria. The developed databank in this study was made publicly available for the community through DesignSafe.more » « less
-
In this study, direct analysis in real time mass spectrometry (DART-MS) was coupled to the solid phase microextraction (SPME) to extract and analyze the ignitable liquid residues (ILR) present in the sample matrices. The SPME extraction parameters, such as extraction temperature and extraction time, were optimized using a two factor central composite design. The SPME-DART-MS setup was utilized to analyze the substrates and fire debris matrices spiked with gasoline. The results indicate that the less volatile marker compounds from gasoline were recovered from the substrates and fire debris, and their profiles matched well with the gasoline liquid samples analyzed directly by DART-MS. As expected, the effective extraction of marker compounds in gasoline required a relatively high temperature, i.e., 150 ℃. In the presence of a matrix, a higher extraction temperature and longer extraction time could benefit the extraction efficiency. The desorption of ILR on SPME fiber was performed by inserting the fiber into the DART-MS helium gas stream at 300 ℃ for 1 min with no carry-over residues being observed between successive samples. The chemical information attained with this method is typically not observed in the current GC/MS-based practice. The SPME-DART-MS was also extended to reanalyze less volatile components of ILR on substrates after the ASTM E1412 activated charcoal method, which indicates its possible application subsequent to the traditional GC/MS ILR analysis. The SPME-DART-MS has shown promise in ILR detection as an important complementary tool.more » « less
-
Abstract The purpose of this study is to develop an unmanned aerial vehicle (UAV)‐based remote sensing method that can estimate vegetation indicators in arid and semiarid rangelands. This method was used to quantify six rangeland indicators (canopy size, bare soil gap size, plant height, scaled height, vegetation cover, and bare soil cover) in a semiarid grass–shrub ecosystem. The drone‐based estimates were validated with field measurements by using the standard transect methods (gap intercept, drop disk, and line‐point intercept methods) in the spring and summer of 2017. The drone‐based estimates showed strong agreements with in situ measurements in cases where deciduous vegetation (mesquite) had leaves withR2for bare soil gap size and vegetation height of 0.97 and 0.89 in the summer, respectively. The RMSE of bare soil gap size and vegetation height are 0.2 m and 6.72 cm in the summer, respectively. Based on these results, we found that drone‐based remote sensing proved to be an efficient and highly accurate method that serves as a complement to field measurements for rangeland indicator estimation. We discussed the possible applications of drone‐based products on arid and semiarid rangelands: the spatially explicit input of an ecological model, to detect and characterize non‐stationarity, and to detect landscape anisotropy.more » « less
-
In automated layup manufacturing processes of fiber-reinforced polymer composites, the quality of the manufactured part is strongly dependent on frictional behavior. Improper control of frictional forces can lead to defect formation. Frictional sliding rheometry tests provide an innovative methodology to accurately characterize the tool-ply friction of unidirectional (UD) prepreg employing unique annular plate geometries. The effect of processing parameters (temperature, velocity, and normal force) on the frictional response of a carbon fiber prepreg was studied. Moreover, utilizing custom designed plate geometries coupled with optically transparent fixtures allowed for in-situ quantification of the prepreg-rigid surface contact area along with simultaneous characterization of the process parameter-dependent frictional mechanisms. Our findings highlight the reduction in frictional forces with increasing temperature, attributed to the increased resin flowability, while increases in sliding rates resulted in a pronounced increase in the frictional forces. The effect of applied load on the frictional characteristics was more complicated due to contributions from both the adhesive and normal forces. Finally, the results were interpreted in light of the contact area measurements performed at different temperatures, normal force, and sliding rate.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/IROS45743.2020.9341424
