Computation Team Delivers Full-Service Support for New TANDM Positioner
Among the National Ignition Facility’s (NIF’s) 2016 priorities was the installation of a dual-purpose positioner called TANDM (Target and Diagnostic Manipulator), which holds either the target capsule or diagnostic equipment inside NIF’s 10 meter-diameter target chamber. The new positioner helps the NIF team increase productivity by reducing the time needed to switch between diagnostic instruments and targets. Like any equipment associated with the world’s largest high-energy laser system, TANDM depends on flexible yet precise software and hardware components. Computation software engineers Mikhail Fedorov, Lyle Beaulac, and Rick Wilson, along with summer intern Sara Woods, worked closely with the TANDM mechanical design team to ensure reliable configuration.
NIF uses positioners for various purposes during shot and maintenance operations, from alignment of targets and diagnostic instruments to damage inspection of all final optics. A range of data (e.g., nuclear, optical, x-ray, and alignment measurements) must be captured for every shot of the 192-beam system. As a dual-purpose positioner, TANDM supports both targets and diagnostic instruments via a transparent, automated control system that complements physical payload exchanges. NIF shot planners can now design experiments with a richer set of capabilities. TANDM’s flexibility also frees up other positioners for the preparation of cryogenically cooled targets, a process that takes several days to coat the capsule’s interior in layers of ice. As a result of the TANDM installation, the rate of cryogenic experiments is expected to increase.
In the spring of 2015, the team began designing the software control system for TANDM using established software frameworks, coding patterns, and development methodologies while considering customization needs. TANDM boasts new features in addition to its dual target/diagnostic capability, such as a laser-tracking system for precise positioning and encoder feedback for motion control. “This is the tenth NIF positioner supported by our team,” states Fedorov. “During the design phase, our attention was focused on identifying which systems and behaviors to maintain, which to change, and which to improve.”
TANDM design and assembly draw from commercially procured parts, which are then tailored to NIF’s specific environment and objectives. Similarly, the software design integrates third-party drivers and firmware into NIF’s control system, which relies on multiple platforms as well as proprietary embedded systems. Fedorov explains, “Various platforms are needed to accommodate third-party components and instruments. For instance, we use VxWorks for motion control, Windows for video cameras, and Linux for everything else.” Like data from other NIF target and diagnostic positioners, TANDM data are captured in an archiving system for post-processing and transfer to users.
Figure 1. Weighing in at 20,000 pounds and measuring more than 25 feet long, the TANDM (Target and Diagnostic Manipulator) mechanical assembly is shown prior to installation at the National Ignition Facility.
Carefully coordinated technology enables smooth TANDM operation from the NIF control room. For movements not performed automatically, joysticks allow independent control of the main boom and the target adapter at the end of the positioner, while cameras provide visual feedback. Notes Fedorov, “Our software couples the cameras with the joysticks to assure the appropriate scale when operators perform coarse or fine movements.”
One significant challenge in bringing TANDM online was integrating newly configured hardware and software into the existing system. Fedorov states, “We spent a great deal of time with electrical engineers to understand and address unexpected signal distortions and electrical noise. We also worked with mechanical engineers to understand vibrations and optimize motion controls.”
Configuring computerized controls was only one facet of the team’s involvement in TANDM’s setup. They advised on controls selection and reuse of existing hardware and software, helping to accelerate the delivery schedule and minimize risks. They also reduced operational impact by fine-tuning the assembled configuration in an offline facility prior to qualification and deployment.
Once TANDM was installed, Fedorov and colleagues provided 24/7 support during commissioning activities—many of which were performed off-hours to avoid interference with shot operations—and continue to support NIF operations in rotating shifts. Each team member is responsible for the core control system, analyzing logs, troubleshooting, and escalating issues when necessary. They also provide hands-on training to NIF operators. The first target shot using TANDM occurred on September 20, 2016.
Figure 2. The TANDM (Target and Diagnostic Manipulator) positioner is controlled with software customized by Computation personnel. Through this interface, operators can monitor multiple video feeds, joystick movements, and other metrics to ensure correct positioning.
TANDM’s successful deployment depended in part on tight coordination with multidisciplinary teams. Software engineers from Computation worked closely with mechanical, electrical, and optical engineers, physicists responsible for targets and diagnostics, and shot planners and coordinators. “We appreciate Computation’s willingness to integrate their personnel into our design team at the concept phase,” says NIF engineer Terry Malsbury. “This has proven critical to delivering quality designs that can be effectively tested and efficiently deployed. The project’s success also relied heavily upon their ability to support offline testing and integrate TANDM’s dual functionality into existing NIF control systems.”
Looking ahead to 2017, the team is planning for a second TANDM positioner with similar software controls. “User feedback and machine history data from early TANDM operations have helped us identify and correct minor issues related to configuration and calibration parameters,” Fedorov says. “The next installation will benefit from what we’ve learned.”