Today the US Patent & Trademark Office published a patent application from Apple that relates to various methods and apparatus for eye tracking in virtual and mixed or augmented reality (VR/AR) applications using head motion sensors referred to as 'head odometers.'  

A VR/AR system may include a device such as a headset, helmet, goggles, or glasses (referred to herein as a head-mounted device (HMD)) that includes a display (e.g., left and right displays) for displaying frames including left and right images in front of a user's eyes in order to provide three-dimensional (3D) virtual views to the user.

The VR/AR system may include an eye tracking system (which may also be referred to as a gaze tracking system).

A key to providing accurate eye tracking is knowing the location of the user's eyes with respect to the eye tracking cameras. In some embodiments of an eye tracking system, to accurately determine the location of the user's eyes with respect to the eye tracking cameras, the controller may execute an algorithm that performs a three-dimensional (3D) reconstruction using images captured by the eye tracking cameras to generate 3D models of the user's eyes.

The 3D models of the eyes indicate the 3D position of the eyes with respect to the eye tracking cameras, which allows the eye tracking algorithms executed by the controller to accurately track eye movement.

Methods and apparatus for tracking relative movement of a device with respect to a user's head are described in which sensors (referred to herein as head motion sensors or head odometers) are placed at one or more positions in or on the device, for example at or near the user's ears to primarily track pitch and at or near the bridge of the nose to primarily track y movement. Signals from the head odometers may be used to detect movement of the device with respect to the user's eyes. This may allow 3D reconstruction to be performed only when movement of the device with respect to the user's eyes has been detected, thus significantly reducing power consumption by the eye tracking system.

Apple's patent FIG. 2 below illustrates an example VR/AR HMD that implements an eye tracking system that includes sensors to detect movement of the HMD with respect to the user's eyes; FIG. 3 is a flowchart of an eye tracking method in which sensors are used to detect movement of the HMD with respect to the user's eyes and in which 3D reconstruction is performed only when movement of the HMD is detected.

Apple's patent FIG. 12 below is a block diagram illustrating an example VR/AR system that includes components of an eye tracking system as illustrated in FIGS. 2 through 11; FIG. 11 is a flowchart of an eye tracking method in which head odometers are used detect movement of the HMD with respect to the user's eyes and eye odometers are used to track movement of the eyes in intervals between the processing of frames captured by the eye tracking cameras.

For finer details, review Apple's patent application number 20210081039.

Various Apple engineering teams are working on various aspects of Eye Tracking systems. Today Apple also had other patents published covering this technology. Below are links to the other in-depth patent applications published today by the U.S. Patent and Trademark Office.

02: Low-Power Eye Tracking System (Patent #20210081038)

03: Eye Tracking Using Low Resolution Images (Patent #20210081040)

Considering that these are patent applications, the timing of such device features to market is unknown at this time.