High-Level Job Planning for Automated Earthmoving

High-level job planning strategies were developed which enable pile transfer and area clearing jobs to be performed autonomously by a robotic wheel loader. A job is first planned on a 3D surface model of a worksite by positioning graphical tools representing areas and approach directions for scooping, dumping and clearing material. The ground model can be from a recently-acquired surface scan, allowing the job to be configured ad-hoc without the prior need of a global map. Algorithms interpret the high-level plan and, based on an updated ground model, generate commands which ideally guide the job to completion with no further human input. Lower-level plans such as driving points are also represented graphically, allowing a remote supervisor to stay in-the-loop by monitoring the intentions of the machine and modifying the plans if necessary. Fully automated jobs were demonstrated in an earthmoving simulation environment developed using Matlab. The algorithms and search parameters for finding clearing paths and filling locations which worked in the simulator were also found to correctly generate commands using ground models obtained from manually-performed area clearing and filling tests using snow and gravel. As proofs-of-concept, a snow clearing test and two pile transfer tests with gravel demonstrated semi-automated work cycles with a robotic loader, whereby driving and joint actuation were computer-controlled, with transitions between separate actions commanded manually. The snow clearing test demonstrated updated paths being generated based on the changing state of the worksite. The planning tools and algorithms were also extended to jobs including dump trucks and multiple loaders, and applied to a large-scale simulated hillside excavation. Additional simulations evaluated the proposed alternative High Point (HP) method for generating scooping commands, which orients the loader towards the highest point in the pile or slope section from an adjacent stage point. This was compared with a Zero Contour (ZC) method which selects perpendicular scooping approaches along the bottom contour of the slope. Various excavation jobs with truck loading showed that assuming the same bucket filling efficiency, the HP method offers the advantage of a higher excavation rate due to its more limited driving pattern. For the larger plateau excavation jobs, the workspace was subdivided by scanning with the smaller rectangular Scoop Area (SA). It was found that compared with the ZC method, the HP method tends to achieve its maximum excavation rate with SAs which are narrower and longer. Factors which increased the amount of material to excavate per area, including a higher plateau and more surrounding slope collapse, were found to generally result in smaller SAs achieving higher excavation rates

Towards Semi-Autonomous Control of Heavy-Duty Tracked Earth-Moving Mobile Manipulators : Use Case: The Bulldozer

A mobile manipulator (MM) comprises a manipulator attached to a mobile base, making it capable of manipulation tasks in large workspaces. In the field of construction, heavy-duty MMs are extensively used for soil excavation at construction sites. One such machine is the bulldozer, which is widely used because of its robustness and maneuverability. With its onboard blade, the bulldozer shapes terrain and transports soil material by pushing it. However, operating the blade with joysticks to accurately shape the terrain surface and moving material productively are difficult tasks that require extensive training and experience. Automating the motion of the blade, therefore, has the potential to reduce skill requirements, improve productivity, and reduce operators’ workloads. This thesis studies and develops methods for the semi-autonomous control of a bulldozer to increase surface quality and earthmoving productivity. These goals were reflected in the main research problems (RPs). Furthermore, as bulldozers drive over the terrain shape generated by the blade, the RPs are coupled because earthmoving productivity is partially dependent on surface quality. The RPs and their coupling were addressed in four publications by coordinating the mobile base and manipulator control and by using the surrounding terrain shape in automatic blade motion reference computations. Challenges to automatic control emerge from the tracked mobile platform driving on rough terrain while the manipulator tool interacts with the soil. It is shown in the first two publications that coordinating the control of the MM mobile base and blade manipulator subsystems can improve surface quality and productivity by temporarily slowing down the machine when the required manipulator joint rates increase or when the tractive performance reduces. The third publication showed that feedforward–feedback control of the blade manipulator can be used on a real-world bulldozer for accurate terrain shaping. The thesis work culminates in the final publication with an experimental implementation of a semi-autonomous blade control system that continuously maps the worksite terrain and uses it to compute the required blade motion

Dust control handbook for industrial minerals mining and processing

"This handbook was written by a task force of safety and health specialists, industrial hygienists, and engineers to provide information on proven and effective control technologies that lower workers' dust exposures during all stages of mineral processing. The handbook describes both dust-generating processes and the control strategies necessary to enable mine operators to reduce worker dust exposure. Implementation of the engineering controls discussed can assist operators, health specialists, and workers in reaching the ultimate goal of eliminating pneumoconiosis and other occupational diseases caused by dust exposure in the mining industry. Designed primarily for use by industrial minerals producers, this handbook contains detailed information on control technologies to address all stages of the minerals handling process, including drilling, crushing, screening, conveyance, bagging, loadout, and transport. The handbook's aim is to empower minerals industry personnel to apply state-of-the-art dust control technology to help reduce or eliminate mine and mill worker exposure to hazardous dust concentrations - a critical component in ensuring the health of our nation's mine workers." - NIOSHTIC-2NIOSHTIC no. 20055113Suggested citation: NIOSH [2019]. Dust control handbook for industrial minerals mining and processing. Second edition. By Cecala AB, O\u2019Brien AD, Schall J, Colinet JF, Franta RJ, Schultz MJ, Haas EJ, Robinson J, Patts J, Holen BM, Stein R, Weber J, Strebel M, Wilson L, and Ellis M. Pittsburgh PA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2019\u2013124, RI 9701. https://doi.org/10.26616/NIOSHPUB2019124201910.26616/NIOSHPUB2019124606

Lifelines

Harris Solomon takes readers into the trauma ward of one of Mumbai’s busiest public hospitals, narrating the stories of the patients, providers, families, and frontline workers who experience and treat traumatic injury from traffic

Lifelines

Harris Solomon takes readers into the trauma ward of one of Mumbai’s busiest public hospitals, narrating the stories of the patients, providers, families, and frontline workers who experience and treat traumatic injury from traffic