US 12,146,773 B2
Position encoder with fusion of different sensor types
Daniel J. Holmes, Boylston, MA (US); Paul A. Remillard, Littleton, MA (US); and Deepak Surendran, Wilmington, MA (US)
Assigned to Novanta Corporation, Bedford, MA (US)
Filed by Novanta Corporation, Bedford, MA (US)
Filed on May 19, 2022, as Appl. No. 17/748,203.
Claims priority of provisional application 63/190,298, filed on May 19, 2021.
Prior Publication US 2022/0373360 A1, Nov. 24, 2022
Int. Cl. G01D 5/56 (2006.01); G01D 5/14 (2006.01); G01D 5/20 (2006.01); G01D 5/244 (2006.01); G01D 5/34 (2006.01); G01D 5/58 (2006.01)
CPC G01D 5/56 (2013.01) [G01D 5/145 (2013.01); G01D 5/2053 (2013.01); G01D 5/24476 (2013.01); G01D 5/344 (2013.01); G01D 5/58 (2013.01)] 19 Claims
OG exemplary drawing
 
1. An opto-magnetic rotary position encoder for sensing rotational position of a rotating component, comprising:
a polarization-based optical encoder configured for on-axis placement and operation with respect to a rotational axis of the rotating component, including (1) a polarizer configured for mounting for rotation with the rotating component, and (2) polarization source/sensing components configured for mounting in proximity to the polarizer to provide a source light beam to the polarizer and to detect a polarized return light beam therefrom;
a magnetic encoder configured for on-axis placement and operation with respect to the rotational axis of the rotating component, including (1) a magnet configured for mounting for rotation with the rotating component, and (2) magnetic sensing components configured for mounting in proximity to the magnet to detect a magnetic field from the magnet; and
control circuitry configured and operative to generate polarizer channel position data from the detected polarized return light beam and magnetic channel position data from the detected magnetic field,
and further including a magnetic sensor channel compensation unit having a comparison block for determining magnetic channel error, and a memory structure used as a lookup table, and wherein the control circuitry is configured and operative, during a system calibration mode of operation, to store polarization angle data into the lookup table at locations addressed by uncorrected magnetic angle data, and during normal operation to use the uncorrected magnetic angle data as an address to the lookup table which produces reference angle data that was stored during calibration mode.