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Category: Publications: Information Technology Laboratory (ITL)
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  • Integrating MOVEit Motion Constraints on a Novel Robotic Manipulator

    Abstract: MOVEit, a widely used Robot Operating System framework, plans composite tasks, where the high-level sequence of actions is fixed and known in advance. However, these tasks need to be tailored and adapted to the environmental context. This framework uses custom trajectory planners, known as controllers, to solve goals that are fully defined within the configuration space. Libraries, such as the Open Motion Planning Library, provide a collection of motion planners that can solve task-space goals. An exact spatial and joint replication of the robotic manipulator’s mechanics, typically Universal Robot Description Format and Semantic Robot Description Format files, is required. Common arms such as the Panda-Manipulator and OpenMANIPULATOR-X provide these files in their respective public repositories, but custom arms require significant modification or even a complete rewrite of these files.
  • Low Size, Weight, Power, and Cost (SWaP-C) Payload for Autonomous Navigation and Mapping on an Unmanned Ground Vehicle

    Abstract: Autonomous navigation and unknown environment exploration with an unmanned ground vehicle (UGV) is extremely challenging. This report investigates a mapping and exploration solution utilizing low size, weight, power, and cost payloads. The platform presented here leverages simultaneous localization and mapping to efficiently explore unknown areas by finding navigable routes. The solution utilizes a diverse sensor payload that includes wheel encoders, 3D lidar, and red-green-blue and depth cameras. The main goal of this effort is to leverage path planning and navigation for mapping and exploration with a UGV to produce an accurate 3D map. The solution provided also leverages the Robot Operating System
  • Mapping and Localization Within a Mock Sewer System

    Abstract: Herein, we explored a robot’s ability to localize and map, both in simulation and on a physical robot, within a mock sewer system. Mapping and localization techniques were first developed and tested in simulation and were then transitioned to the actual robot for additional physical testing. Several odometry and simultaneous localization and mapping (SLAM) techniques, including gmapping, SLAM toolbox, elevation mapping, and RTABMap, were evaluated for this particular environment. The results of the odometry and the various SLAM approaches are discussed in detail.
  • Accelerated Corrosion of Infrastructural Seven-Strand Cables via Additively Manufactured Corrosion Flow Cells

    Purpose: The purpose of this project was to generate an accelerated corrosion methodology capable of producing seven-strand cables with simulated corrosive defects for calibration of nondestructive analysis (NDA) techniques. An additively manufactured accelerated corrosion cell was motivated and designed. Previous attempts at accelerated electrochemical corrosion used a large cable area with a current density that was too low (i.e., 1 A/m²)* to effectuate efficient corrosion. The accelerated corrosion cell presented here takes advantage of the restricted area within the corrosion flow cell to maximize the corrosion rate in a consistent and calibrated manner (i.e., 2,000 A/m²).
  • Scaling and Sensitivity Analysis of Machine Learning Regression on Periodic Functions

    Abstract: In this report we document the scalability and sensitivity of machine learning (ML) regression on a periodic, highly oscillating, and 𝐶∞ function. This work is motivated by the need to use ML regression on periodic problems such as tidal propagation. In this work, TensorFlow is used to investigate the machine scalability of a periodic function from one to three dimensions. Wall clock times for each dimension were calculated for a range of layers, neurons, and learning rates to further investigate the sensitivity of the ML regression to these parameters. Lastly, the stochastic gradient descent and Adam optimizers wall clock timings and sensitivities were compared.
  • Unmanned Ground Vehicle (UGV) Path Planning in 2.5D and 3D

    Abstract: Herein, we explored path planning in 2.5D and 3D for unmanned ground vehicle (UGV) applications. For real-time 2.5D navigation, we investigated generating 2.5D occupancy grids using either elevation or traversability to determine path costs. Compared to elevation, traversability, which used a layered approach generated from surface normals, was more robust for the tested environments. A layered approached was also used for 3D path planning. While it was possible to use the 3D approach in real time, the time required to generate 3D meshes meant that the only way to effectively path plan was to use a preexisting point cloud environment. As a result, we explored generating 3D meshes from a variety of sources, including handheld sensors, UGVs, UAVs, and aerial lidar.
  • A/E/C Graphics Standard: Release 2.2

    Abstract: The A/E/C Graphics Standard Release 2.2 has been developed by the Computer-Aided Design/Building Information Modeling Technology Center to document how proper hand-drafting practices can be achieved in advanced modeling. It is through the collection and documentation of these practices that consistent models and drawings shall be achieved throughout the US Army Corps of Engineers (USACE), as well as other federal agencies. In the collection of these practices, various historical USACE District drafting manuals were consulted and compared against practices contained in industry and national standards, with consideration toward whether software can achieve those practices. The documentation of these practices will help to achieve both clear and aesthetically pleasing construction documents.
  • Repair of Corroded Steel Girders of Hydraulic Steel Structures (HSS) Using Fiber-Reinforced Polymers (FRP)

    Abstract: Although steel hydraulic structures have a protective system to prevent corrosion, this type of deterioration will eventually occur due to the constant exposure to harsh environmental conditions. There are several techniques that can be implemented to repair corroded steel structural elements. This report presents a numerical study to evaluate the mechanical behavior of corroded steel girders used in hydraulic steel structures and to evaluate several carbon fiber–reinforced polymers (CFRP) layups to repair them. The girders were modeled as simply supported with four-point loading boundary conditions. The corrosion deterioration was modeled as loss in section as 10%, 25%, and 40%. The effectiveness of the deterioration was established based on the level of stresses at the steel compared with the undamaged condition after it is strengthened with CFRP. It was found that CFRP repair is more practical for reducing the stresses at the steel in the shear dominated zone if deterioration is below 25%. At the tensile dominated zone, CFRP is effective for reducing the stresses for deterioration below 40%.
  • Adverse Outcome Pathways for Engineered Systems

    Abstract: Companies and organizations around the world spend massive amounts of money each year to discover, predict, and remediate failures within engineered systems. These tasks require individuals with specialized knowledge in a variety of topics related to failure. This knowledge is often acquired through years of academic and on-the-job training centered around the review of scientific documentation such as books, reports, manuals, and peer-reviewed publications. The loss of this knowledge through employee attrition can be detrimental to a group as knowledge is often difficult to reacquire. The aggregation and representation of known failure mechanisms for engineered materials could aid in the sharing of knowledge, the acquisition of knowledge, and the discovery of failure causes, reducing the risk of failure. Thus, the current work proposes the Adverse Outcome Pathway for Engineered Systems (AOP-ES) framework, an extension of the Adverse Outcome Pathway used in toxicology. The AOP-ES is designed to document failure knowledge, enabling knowledge transfer and the prediction of failures of novel engineered materials based on the performance of similar materials. This paper introduces the AOP-ES framework and its key elements alongside the principles that govern the framework. An application of the framework is presented, and additional benefits are explored.
  • A General-Purpose Multiplatform GPU-Accelerated Ray Tracing API

    Abstract: Real-time ray tracing is an important tool in computational research. Among other things, it is used to model sensors for autonomous vehicle simulation, efficiently simulate radiative energy propagation, and create effective data visualizations. However, raytracing libraries currently offered for GPU platforms have a high level of complexity to facilitate the detailed configuration needed by gaming engines and high-fidelity renderers. A researcher wishing to take advantage of the performance gains offered by the GPU for simple ray casting routines would need to learn how to use these ray tracing libraries. Additionally, they would have to adapt this code to each GPU platform they run on. Therefore, a C++ API has been developed that exposes simple ray casting endpoints that are implemented in GPU-specific code for several contemporary device platforms. This API currently supports the NVIDIA OptiX ray tracing library, Vulkan, AMD Radeon Rays, and even Intel Embree. Benchmarking tests using this API provide insight to help users determine the optimal backend library to select for their ray tracing needs. HPC research will be well-served by the ability to perform general purpose raytracing on the increasing amount of graphics and machine learning nodes offered by the DoD High Performance Computing Modernization Program.