Aerotech: Direct-coupled motor boosts bandwidth of tiny linear stage

ATS125, the smallest hardcover, side-sealed linear stage from Aerotech, attributes several benefits to the design that directly couples its brushless motor to the ball-screw drive.

By Control Engineering Staff July 22, 2004
A holding brake can be added to the motor modular assembly for vertical application of ATS125 stages. Aerotech can also specially prepare the stage for vacuum operation.

ATS125, the smallest hardcover, side-sealed linear stage from Aerotech , attributes several benefits to the design that directly couples its brushless motor to the ball-screw drive. A stiffer system with higher servo bandwidth is one of the results. The compact stage can travel up to 600 mm (23.62 in.) and offers speeds up to 600 mm/s (nearly 2 ft/s).

Eliminating the typical flexible coupling between motor and drive in screw-driven stages also:

  • Reduces device footprint for use in space-constrained applications; and

  • Improves system reliability by removing a component susceptible to failure.

The integral brushless rotary motor is enclosed in a modular subassembly, easing a field replacement, if needed. The motor has a “slotless” design that produces ultra-smooth velocity without torque ripple, according to Aerotech.

Other features of ATS125 Series linear ball-screw stage include an aluminum cover, hard-coated for scratch resistance, to protect against debris created in manufacturing processes. In addition, side seals keep dirt and debris out of the unit and protect the bearing surfaces. Vertical orientation of the seals helps deflect debris away from the stage—in contrast to top seal designs that can collect debris. The latter design can result “in the eventual failure and replacement of the sealing mechanism,” says Aerotech.

ATS125 Series stages come with standard- and precision-grade ball-screw options to match the price/performance point of numerous positioning applications. With the integral motor design, a square-wave encoder output with a net resolution of 1 micron for 10-mm ball screw is standard (0.5 micron resolution for 5-mm ball screw is likewise standard). An optional analog output encoder, coupled with external interpolation electronics, can supply even higher resolution, as needed.

—Frank J. Bartos, executive editor, Control Engineering, fbartos@reedbusiness.com