Lessons from Building Laser-Driven Fusion Ignition Targets with the Precision Robotic Assembly Machine

The Precision Robotic Assembly Machine was developed to manufacture the small and intricate laser-driven fusion ignition targets that are being used in the National Ignition Facility. The machine enables one person to assemble a high-quality precision target in 1 day with repeatable quality. The target assembly technician provides top-level control of the machine, initiating and controlling the movement of the motorized precision instruments. Hand movements are scaled to precision at the 100-nm level. Sensors embedded in the manipulator system provide 100-mg resolution force and gram-millimeter resolution torque feedback of the contact loads between delicate components being assembled with micrometer-level or no clearance. Combining precision motion control with force and torque feedback provides active compliance for assembling tightly fitting or snap-together components. The machine provides simultaneous manipulation of five objects in a 1-cm³ operating arena and can stitch together multiple millimeter-scale operating arenas over distances spanning tens of centimeters with micrometer-level accuracy. Technology developed with the machine has been migrated to other machines used to assemble fusion targets.