The accumulation of falling snow is a complex physical process that involves a variety of environmental factors. While much past work has been done on the rendering of accumulated snow for gaming applications, scientific simulation of snow accumulation has been limited to large-scale mountain ranges and watersheds. These largescale simulations are not relevant for simulations of autonomous ground vehicle (AGV) performance, for which the relevant length scales are a few meters to a few hundred meters. In this work, we present a physics-based simulation of the accumulation of falling snow that is implemented using smoothed-particle hydrodynamics (SPH) to represent snow mass elements. SPH has been used in past work to simulate not only fluids but also deformable and continuous media ranging from concrete to fabric to soil. In this work we show that SPH can be parametrized to have material properties that reasonably approximate the bulk properties of accumulated snow. We present several example simulations in which SPH has been used to calculate the accumulation of fallen snow in an off-road scene. Finally, we show how the SPH simulation output can be combined with a rendering simulation to create realistic synthetic images.
Off-road autonomous navigation remains an ongoing challenge for autonomous ground vehicles (AGV). The challenges of navigating in an unstructured environment include identifying and detecting both positive and negative obstacles, distinguishing navigable from non-navigable vegetation, identifying soft soil, and negotiating rough or sloping terrain. While many recent works have dealt with various aspects of the off-road navigation problem, up to now there has not been a free and open-source autonomy stack for off-road that included integrated modules for perception, planning, and control. Therefore, we have recently developed the NATURE (Navigating All Terrains Using Robotic Exploration) autonomy stack as a publicly available resource to facilitate the advancement of off-road navigation research. The NATURE stack is implemented using the Robotic Operating System (ROS) and can be built to work with both ROS-1 and ROS-2. The modular nature of the NATURE stack makes it an ideal resource for researchers who want to evaluate a particular algorithm for perception, planning, or control without developing an entire navigation stack from scratch. NATURE features several options for both global and local path planning including A*, artificial potential field, and spline-based planning, as well as multiple options for perception including a simple geometrically based obstacle finder and more advanced custom traversability algorithm derived from 3D lidar. In this presentation we give an overview of the NATURE stack and show some past uses of the stack in both simulated and field experiments.
Failures by autonomous ground vehicles (AGV) may be caused by many different factors in hardware, software, or integration. Effective safety and reliability testing for AGV is complicated by the fact that failures are not only infrequent but also difficult to diagnose. In this work, we will discuss the results of a three-phase project to develop a simulation-based approach to AGV architecture design, test implementation, and simulation integration. This approach features a modular AGV architecture, reliability testing with a physics-based simulator (the MSU Autonomous Vehicle Simulator, or MAVS), and validation with a limited number of field trials.
High voltage electrical failures are dangerous and costly events in any type of power system. The troubleshooting and diagnostic time required to identify and locate these failures can be significant. Partial discharge is one of the early warning signs for electrical degradation. In insulation systems, partial discharge typically occurs in voids located within the dielectric, at material interfaces, or along energized electrode surfaces. Effective methods for finding this failure precursor enabling circumvention of future catastrophic events are highly valuable as successful detection can improve safety, reduce service interruptions, and result in significant financial savings. Challenges arise when these events are obstructed from a direct line of sight (which is common in compact electrical systems). Conventional electrical partial discharge measurements capable of diagnosing concealed defects based on phased resolved partial discharge (PRPD) patterns require coupling devices physically connected to the circuit. This paper presents a non-invasive, real-time, method to detect and locate partial discharge and faulty insulation with potential for automated quality control of in-factory manufactured products and in-service operational devices, in contrast to post-failure assessment. This paper will cover both Alternating Current (AC), previous research, and Direct Current (DC), new research, detection methods and results.
The target of this research is to develop a machine-learning classification system for object detection based on three-dimensional (3D) Light Detection and Ranging (LiDAR) sensing. The proposed real-time system operates a LiDAR sensor on an industrial vehicle as part of upgrading the vehicle to provide autonomous capabilities. We have developed 3D features which allow a linear Support Vector Machine (SVM), Kernel (non-linear) SVM, as well as Multiple Kernel Learning (MKL), to determine if objects in the LiDARs field of view are beacons (an object designed to delineate a no-entry zone) or other objects (e.g. people, buildings, equipment, etc.). Results from multiple data collections are analyzed and presented. Moreover, the feature effectiveness and the pros and cons of each approach are examined.
The Sensor Analysis and Intelligence Laboratory (SAIL) at Mississippi State University's (MSU's) Center for Advanced Vehicular Systems (CAVS) and the Social, Therapeutic and Robotic Systems Lab (STaRS) at MSU's Computer Science and Engineering department have designed and implemented a modular platform for automated sensor data collection and processing, named the Hydra. The Hydra is an open-source system (all artifacts and code are published to the research community), and it consists of a modular rigid mounting platform (sensors, processors, power supply and conditioning) that utilize the Picatinny rail (a standardized mounting system originally developed for firearms) as a rigid mounting system, a software platform utilizing the Robotic Operating System (ROS) for data collection, and design packages (schematics, CAD drawings, etc.). The Hydra system streamlines the assembly of a configurable multi-sensor system. This system is motivated to enable researchers to quickly select sensors, assemble them as an integrated system, and collect data (without having to recreate the Hydras hardware and software). Prototype results are presented from a recent data collection on a small robot during a SWAT-robot training.
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