Nanoseries AIME-2 encoder

BEI Precision Systems and Space Company is now offering an Absolute Intuitive Modular Encoder (AIME-II) configuration in the nanoSeries® Encoder family.

This is a high-resolution, single read station, absolute optical encoder available in our standard array of 3.6in disk diameters. The 4in disk model achieves a resolution of 24 bits with an accuracy of one arc-second RMS (excluding user bearing and spindle errors).

Standard disk sizes are 3in, 4in and 6in with special diameters, configurations, and resolutions available on request at additional cost.

The encoder comes equipped with in situ auto-calibration capability and wide angle error correction. The encoder may be calibrated in full revolution, as well as partial angle designs with as few as ten degrees swept arc, making it an excellent choice for gimbal applications. Mounting and alignment on a pilot shaft simplifies the installation on a user bearing / shaft assembly by removing the need for optical alignment.

The optical system uses a large air gap (-0.015in) and is tolerant to shock and vibration induced gap variations. The absolute encoder data is derived from several tiers of multispeed sinusoidal data tracks, which are digitised and merged into a continuous data word.

The resultant absolute position word is not sensitive to power interruptions. This technique minimises the number of data tracks (minimises size and parts count). All data is derived from ratiometric tracks on the code disk, resulting in excellent tolerance to aging and temperature.

There are a number of BEI PSSC proprietary techniques used in these encoders that allow most repeatable errors to be removed from the output data. These encoders incorporate algorithms that can cancel disk centering and bearing eccentricities, even with a single readhead. The ultimate limitation of how accurate and repeatable the nanoSeries® AIME-II can be is determined by the thermal and mechanical stability of the axis of rotation of the spindle.

The encoder accuracy is only limited by the mechanical and thermal stability of the spindle, whereas most other errors are cancelled or minimised. Axial and radial alignment error reporting feature makes precise mounting of the code disk and readhead easy and fast. For detailed information on this feature see MM-247 ARA / AIME-II nanoSeries® Encoder Alignment Mode Technical Bulletin.

Key features include:

  • All electronics contained in read station
  • High resolution (up to 28 bits)
  • Accuracy of less than one arcsecond RMS
  • Sample rate to 8KHz
  • Wide temperature range
  • In-situ auto calibration
  • Cancellation of repeatable errors
  • Large air gap and depth of focus
  • Absolute serial output
  • High reliability
  • Monolithic photodiode array
  • Long life LED light source
  • Low profile, lightweight and low power
  • 6VDC to 36VDC input power
  • Built-in-test and diagnostics
  • Piloted hub to ease installation