Motion control system for the Large Optic Diamond Turning Machine (LODTM)
LODTM, built by LLNL for DOD, is a precision vertical lathe used to diamond turn large optical parts (to 64'' diameter) to 1 ..mu..inch rms figure error. The LODTM motion controls require precision sensors, precision servos, and a wideband (330 Hz) real time computer. Position is sensed to 1/40 ..mu..inch resolution by laser interferometers and differential capacitance gauges. Presision servos operating at 1/10 ..mu..inch resolution and at low velocities with zero backlash are required. A unique Fast Tool Servo (FTS), located close to the diamond tool, adjusts the final tool position. The LODTM controls coordinate the X, Z and FTS servos to cause the tool to move on a specified contour and at a specified feedrate in the X-Z plane. The part floppy diskette commands this motion with a linear CNC and real time (32-bit) computer. During each 1.5 ms sample time, the computer must DMA 14 sensor readings into memory, calculate the X and Z Tool Coordinates, calculate the FTS input, output the following errors, output the FTS input, store ''flight recorder'' information, and check for anomalies.
- Research Organization:
- Lawrence Livermore National Lab., CA (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5756145
- Report Number(s):
- UCRL-89362; CONF-830874-33; ON: DE85005515
- Country of Publication:
- United States
- Language:
- English
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