Robotic Handling
Spheremapper
Embedded Files
Automated Spheremapper
General Atomics Energy Group (2013)
Spheremapper
An instrument created by the General Atomics Energy Group that combines Atomic Force Microscopy (AFM) with a 6DOF robotic arm to measure the sphericity and surface roughness of a small capsule used for Inertial Confinement Fusion (ICF). While the purpose of the AFM is to trace along the capsule for its mapping, the robotic arm re-orients the capsule to enable traces along multiple equatorial lines.
Background
Inertial Confinement Fusion (ICF) is a process in which atoms are fused together to form new elements and as a byproduct, produce massive amounts of energy. The goal is to mimic the nuclear fusion that powers the sun, which has the potential to power human society without contributing to pollution or global energy. During ICF, an array of laser beams are focused on a small cylindrical casing that encloses a spherical capsule typically containing deuterium and tritium isotopes of hydrogen. These capsules that range in diameter from 2-4 mm can heavily influence the final reaction of the fusion process since their sphericity and surface roughness affect the balance of forces during its compression stage.
As such, the quality control and characterization of each capsule is important, thereby creating the need to accurately measure them and reassure that they are mostly free of imperfections. The General Atomics Energy Group accomplishes this task through their Spheremapper, but an estimated 3° random orientation error has been noticed each time the robotic arm repositions the capsule. Because of this, parts of the capsule are being missed and an accurate measuring cannot be guaranteed.
Inertial Confinement Fusion Process
National Ignition Facility (Lawrence Livermore National Laboratory)
Project Objective
The spheremapping process currently utilizes 3 orthogonal traces to measure the capsule, but if more traces are desired, the error would become much more pronounced. In order to facilitate a possible future increase of trace density, this project was established with the goal of quantifying the aforementioned reorientation error. This required that the primary sources of error be identified, a reasonably accurate visual tracking system or suite be developed and tested, and recommendations to reduce the error be proposed.
-Team Workspace-
In order to provide less restricted access to a workspace, the team was given an older model of the robotic arm to test and conduct work. Because of outdated hardware and software, the team's work included updating and programming the setup.
On-site Workspace
Robot Arm Test
(Video is played at an increased speed)
Final Design
To address the need for a method to measure the capsule reorientation as well as to facilitate further investigation and experimental data collection, the primary focus of the project shifted to creating the foundations of a comprehensive testing suite and workflow. The development of an experimental workflow in combination with the design's hardware and software led to the framework for regression estimation approach using OpenCV in Python. Depicted below is the testing implementation of an automated orientation tracking system.
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