ABRS Air-Bearing Direct-Drive Rotary Stage


Design Features

  • Direct-drive, slotless, brushless servomotor
  • Zero cogging motor for outstanding velocity stability
  • Outstanding error motion and wobble performance
  • Direct coupled, high-accuracy rotary encoder
  • Low-profile planar design
  • No mechanical contact

Aerotech's ABRS series rotary air-bearing stages provide superior angular positioning, velocity stability and error motion performance in an exceptionally low-profile package. The ABRS is designed to meet the exacting requirements of wafer inspection, high precision metrology, x-ray diffraction systems, optical inspection and fabrication, and MEMS/nanotechnology device fabrication.

Compact Package

The design of the ABRS series direct-drive rotary stage has been optimized to minimize stage height. The low profile of the stage reduces the effective working height of the system, minimizing "stack-up" related errors. In addition to the low overall height, the ABRS series provides a clear aperture that can be used for product feed-through, laser beam delivery, cable clearance or application-specific requirements.

Superior Mechanical Design

The ABRS design features large air-bearing surfaces for high stiffness and load capacity, producing not only excellent axial and radial error motions but outstanding tilt error motion, as well. The resultant face error motion is significantly better than other rotary air-bearing tables and spindles, greatly benefiting applications requiring exceptional planar performance.

Brushless Direct-Drive

To maximize positioning performance, the ABRS series utilizes 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 ABRS stages ideal for applications requiring smooth scan velocities at low or high speeds.

Accurate Positioning

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

Custom Designs

Custom versions of the ABRS are available for rate table and inertial guidance test-stand applications.


ABRS Series Specifications

Width 150 mm 200 mm 250 mm 300 mm
Tabletop Diameter 128.1 mm 178.1 mm 228.1 mm 278.1 mm
Height 80 mm 90 mm 100 mm 110 mm
Aperture 8 mm 20 mm 35 mm 75 mm
Travel 360° Continuous
Motor S-50-39-A S-76-35-A S-130-39-A S-180-44-A
Stall Torque, Continuous 0.20 N-m 0.48 N-m 2.36 N-m 5.99 N-m
Peak Torque 0.82 N-m 1.92 N-m 9.42 N-m 23.98 N-m
BEMF, Line-Line, Max 10.3 Vpk/Krpm 29.1 Vpk /Krpm 75.1 Vpk /Krpm 268.7 Vpk /Krpm
Continuous Current, Stall 2.4 Apk 2.0 Apk 3.8 Apk 2.7 Apk
1.7 Arms 1.4 Arms 2.7 Arms 1.9 Arms
Torque Constant 0.09 N-m/Apk 0.24 N-m/Apk 0.62 N-m/Apk 2.22 N-m/Apk
0.12 N-m/Arms 0.34 N-m/Arms 0.88 N-m/Arms 3.14 N-m/Arms
Bus Voltage 80 VDC
Resolution(1) 0.873 µrad
(0.18 arc sec)
0.383 µrad
(0.079 arc sec)
0.267 µrad
(0.055 arc sec)
0.174 µrad
(0.036 arc sec)
Fundamental Encoder Resolution 3600 lines/rev 8192 lines/rev 11,840 lines/rev 18,000 lines/rev
Max Speed(2) 300 rpm 300 rpm 500 rpm 500 rpm
Accuracy(3) ±3 arc sec ±2 arc sec
Bidirectional Repeatability <2 arc sec <1 arc sec
Max Load(4) Axial 8 kg 31 kg 66 kg 97 kg
Radial 4 kg 15 kg 36 kg 51 kg
Tilt 3 N-m 10 N-m 28 N-m 45 N-m
Axial Error Motion (Synchronous) <175 nm <100 nm
Radial Error Motion (Synchronous) <450 nm <250 nm
Tilt Error Motion (Synchronous) <9.7 µrad
(<2.0 arc sec)
<3.4 µrad
(<0.7 arc sec)
<2.4 µrad
(<0.5 arc sec)
<2.4 µrad
(<0.5 arc sec)
Axial Error Motion (Asynchronous) <20 nm
Radial Error Motion (Asynchronous) <20 nm
Tilt Error Motion (Asynchronous) <0.4 µrad
(<0.08 arc sec)
<0.3 µrad
(<0.06 arcsec)
<0.2 µrad
(<0.04 arc sec)
<0.2 µrad
(<0.04 arc sec)
Operating Pressure(6) 80 psig (5.5 bar) + 0 psig (0.0 bar)/-10 psig (0.7 bar)
Air Consumption(7) <56.6 SLPM (<2 SCFM)
Inertia Unloaded 3850 kg-mm2 13,800 kg-mm2 39,100 kg-mm2 102,000 kg-mm2
Total Mass 4.8 kg 9.1 kg 15.6 kg 24.5 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.


  • ABRS-150MP
  • ABRS-200MP
  • ABRS-250MP
  • ABRS-300MP

Ordering Information

Ordering Example

ABRS -200MP -M -AS

Ordering Options

Series Width (mm)Mounting PatternPosition Transducer
-M -AS

ABRS Series Direct-Drive, Air-Bearing Rotary Stage

Option Description
ABRS-150MP 150 mm wide air-bearing rotary stage with 0.82 N-m peak torque output
ABRS-200MP 200 mm wide air-bearing rotary stage with 2.12 N-m peak torque output
ABRS-250MP 250 mm wide air-bearing rotary stage with 9.42 N-m peak torque output
ABRS-300MP 300 mm wide air-bearing rotary stage with 23.98 N-m peak torque output

Mounting Pattern

Option Description
-M Metric dimension mounting pattern and holes

Position Transducer

Option Description
-AS Standard feedback device, sine wave output; 3600 cycles per rev on ABRS-150MP; 8192 cycles per rev on ABRS-200MP; 11,840 cycles per rev on ABRS-250MP; 18,000 cycles per rev on ABRS-300MP
-X50 Square-wave digital output; 180,000 cycles per rev on ABRS-150MP; 409,600 cycles per rev on ABRS-200MP; 592,000 cycles per rev on ABRS-250MP; 900,000 cycles per rev on ABRS-300MP
    Note: Digital output encoder signals are synthesized with a 16 MHz clock. Care must be taken to ensure that the encoder sample rate on the controller is 16 MHz or higher. Slower clock rates are available upon request.