System and method for calibrating a rotary absolute position sensor

A calibration module configured to calibrate a pair of rotary absolute position (RAP) sensors for a system having a rotary device, wherein the pair of RAP sensors are configured to measure a rotary position of the rotary device and output encoded pairs of voltage signals describing the rotary position, the calibration module comprising:

• a host machine in communication with the RAP sensors, wherein the host machine receives the encoded pairs of voltage signals from the RAP sensors and records the received encoded pairs of voltage signals as data points forming an ellipse and is operable for deriving calibration parameters for determining an absolute position of the rotary device using the encoded pairs of voltage signals;
• wherein the host machine is configured to:
• use an ellipse-of-best fit to map the ellipse of the recorded encoded pairs of voltage signals to corresponding sine/cosine pairs;
• derive the calibration parameters from the ellipse-of-best-fit, wherein the calibration parameters relate the sine/cosine pairs to the encoded voltage signals;
• and
• determine the absolute position of the rotary device using the derived calibration parameters.

A method of calibrating a pair of rotary absolute position (RAP) sensors used for measuring a rotary position of a rotary device, the method comprising:

• measuring the rotary position over time as encoded pairs of voltage signals using the pair of RAP sensors;
• recording a plurality of the encoded pairs of voltage signals as an ellipse, wherein each of the data points forming the ellipse describes a respective one of the encoded pairs of voltage signals;
• using the ellipse defined by the encoded pairs of voltage signals to calculate calibration parameters suitable for calibrating the RAP sensor using a host machine, including:
• using an ellipse-of-best fit to map the ellipse of the recorded encoded pairs of voltage signals, via a host machine, to corresponding sine/cosine pairs;
• deriving the calibration parameters from the ellipse-of-best-fit via the host machine, wherein the calibration parameters relate the sine/cosine pairs to the encoded voltage signals;
• and
• determining the absolute position of the rotary device using the derived calibration parameters.