Novel Self-Calibration for Air-Bearing Rotary Encoders

A method for self-calibrating air-bearing rotary encoders that eliminates the need for additional calibration instruments

Advantages

  • Self calibration without external equipment
  • No hardware modifications required

Technology Details

The University of British Columbia (UBC) has developed a self-calibration method for air-bearing rotary encoders that eliminates the need for additional calibration instruments.

High accuracy rotary encoders are widely used for rotational axis position measurement in ultra-precision manufacturing equipment and measurement machines. The angular measurement accuracy of a rotary encoder is highly dependent on the grating disk manufacturing error, glass disk installation on the measured axis, the scanning head installation alignment, and signal processing circuits. Because all these elements unavoidably contribute to rotary encoder errors, encoders must be calibrated, which can require the use of additional instruments such as an auto-collimator and a high precision polygon mirror. However, using the UBC invention, the encoder can self-calibrate with the encoder output signal of the spindle free response. This method can be applied to the existing widely used rotary encoders and no hardware modification on the encoder is required.

The UBC invention may be used in many industries where accurate and repeatable measurements of a rotating component’s position are required. For instance, applications may be found in the manufacture of CD-ROM’s or DVD’s, hard drives, servo track writers, and precision spindles.