ABRT Air-Bearing Direct-Drive Rotary Stage


Design Features

  • High torque output, direct-drive, slotless, brushless servomotor
  • Zero-cogging motor for outstanding velocity stability
  • Outstanding error motion and wobble performance
  • Direct coupled, high-accuracy rotary encoder
  • Large diameter clear aperture
  • No mechanical contact

Aerotech's ABRT series rotary air-bearing stages provide superior angular positioning, velocity stability and error motion performance along with impressive payload capacity and outstanding radial and axial stiffness. The ABRT is designed to meet the exacting requirements of DVD mastering, wafer inspection, high precision metrology applications, X-ray diffraction systems, optical inspection and fabrication, and MEMS/nanotechnology device fabrication.

Superior Mechanical Design

The ABRT design features large air-bearing surfaces and innovative preloading for high stiffness and load capacity, producing not only excellent axial and radial error motions, but outstanding tilt error motion, as well. The resultant performance is significantly better than other rotary air-bearing tables and spindles, greatly benefiting applications requiring exceptional planar performance. Furthermore, this stage family provides a clear aperture that can be used for product feed-through, laser beam delivery, cable clearance or application-specific requirements.

Brushless Direct-Drive

To maximize positioning performance, the ABRT series utilizes optimized versions of Aerotech's S-series slotless, brushless motor. The motor uses an advanced magnetic circuit design to produce high torque output with minimal heat generation. The slotless design is inherently zero-cogging and torque-ripple-free. This makes ABRT stages ideal for applications requiring smooth scan velocities at low or high speeds.

Accurate Positioning

An optical encoder is standard with the ABRT. When coupled with Aerotech's feedback multipliers and controls, resolutions of <0.03 arc second are achievable.

Custom Designs

Custom versions of the ABRT are available to satisfy rate table and high precision inertial guidance test-stand applications. Other features, such as slip rings and rotary unions, are available.

Flexible Configurations

Aerotech manufactures a wide range of servo amplifiers and advanced controllers to provide a complete, integrated package.


ABRT Specifications

Width 146 mm 196 mm 260 mm
Tabletop Diameter 100 mm 145 mm 200 mm
Height 135 mm 165 mm 185 mm
Aperture 20 mm 30 mm 50 mm
Travel 360° Continuous
Motor Direct-Drive Brushless Servomotor
Stall Torque, Continuous 0.36 N-m 3.7 N-m 6.7 N-m
Peak Torque 1.4 N-m 14.6 N-m 26.6 N-m
BEMF, Line-Line, Max 10.9 Vpk/krpm 163.6 Vpk/krpm 129.8 Vpk/krpm
Continuous Current, Stall 3.8 Apk 2.7 Apk 6.2 Apk
2.7 Arms 1.9 Arms 4.4 Arms
Torque Constant 0.09 N-m/Apk 1.35 N-m/Apk 1.07 N-m/Apk
0.13 N-m/Arms 1.91 N-m/Arms 1.52 N-m/Arms
Bus Voltage Up to 320 VDC
Resolution(1) 0.267 µrad (0.055 arc sec) 0.174 µrad (0.036 arc sec) 0.133 µrad (0.027 arc sec)
Fundamental Encoder Resolution 11,840 lines/rev 18,000 lines/rev 23,600 lines/rev
Max Speed(2) 1200 rpm 800 rpm 600 rpm
Accuracy(3) ±2 arc sec
Repeatability <1 arc sec
Max Load(4) Axial 20 kg 41 kg 69 kg
Radial 3 kg 6 kg 10 kg
Tilt 3.5 Nm 8 Nm 18 Nm
Axial Error Motion (Synchronous) <100 nm
Radial Error Motion (Synchronous) <150 nm
Tilt Error Motion (Synchronous) <2.4 µrad (<0.5 arc sec)
Axial Error Motion (Asynchronous) <20 nm
Radial Error Motion (Asynchronous) <20 nm
Tilt Error Motion (Asynchronous) <0.2 µrad (<0.04 arc sec)
Operating Pressure(6) 80 psig (5.5 bar) ±5 psig (0.3 bar)
Air Consumption(7) <56.6 SLPM (<2 SCFM)
Inertia Unloaded 2300 kg·mm2 13,500 kg·mm2 46,400 kg·mm2
Total Mass 6.7 kg 14.7 kg 27.1 kg
Material Aluminum
Finish Hardcoat (62 Rockwell Hardness)
  1. Maximum resolution presumes A3200 controller using MXH500 multiplication, and accounts for controller quadrature.
  2. Maximum speed based on stage capability. Maximum application velocity may be limited by system data rate and system resolution.
  3. Certified with each stage. Requires the use of an Aerotech controller.
  4. Maximum loads are mutually exclusive.
  5. All error motion specifications measured at 60 rpm.
  6. To protect air bearing against under-pressure, an in-line pressure switch tied to the motion controller is recommended.
  7. Air supply must be clean, dry to 0°F dew point and filtered to 0.25 µm or better. Recommend nitrogen at 99.9% purity.


  • ABRT-150
  • ABRT-200
  • ABRT-260

Ordering Information

Ordering Example

ABRT -200 -AS

Ordering Options

Series Width (mm)Position Transducer
ABRT -150

ABRT Series Direct-Drive, Air-Bearing Rotary Stage

Option Description
ABRT-150 150 mm wide air-bearing rotary stage with 0.36 N-m continuous torque output
ABRT-200 200 mm wide air-bearing rotary stage with 3.7 N-m continuous torque output
ABRT-260 260 mm wide air-bearing rotary stage with 6.7 N-m continuous torque output

Position Transducer

Option Description
-AS Standard feedback device, sine wave output; 11,840 cycles per rev on ABRT-150; 18,000 cycles per rev on ABRT-200; and 23,600 cycles per rev on ABRT-260
-X50 Square-wave digital output; 592,000 cycles per rev on ABRT-150; 900,000 cycles per rev on ABRT-200; and 1,180,000 cycles per rev on ABRT-260
    Note: Digital output encoder signals are synthesized with a 40 MHz clock. Care must be taken to ensure that the encoder sample rate on the controller is 40 MHz or higher. Slower clock rates are available upon request.