Eye tracking system for VR/AR HMD units including pancake lens modules

1. A virtual reality (VR) wearable assembly comprising:

a wearable frame adapted to be worn over a user's eyes;

a pair of photosensor oculography (PSOG) assemblies mounted to the wearable frame such that each PSOG assembly is positioned adjacent a corresponding eye of the user, each PSOG assembly including:

a display housing including a substantially cylindrical shape having an inner surface defining an interior cavity extending between a first end and second end;

a micro-OLED display coupled to the display housing and positioned within the interior cavity adjacent the second end of the display housing;

an eye tracking assembly coupled to the display housing and positioned adjacent the first end of the display housing, the eye tracking assembly including:

a ring support frame coupled to the first end of the display housing;

a first group of photosensors and light emitters mounted along a first side of the ring support frame; and

a second group of photosensors and light emitters mounted along a second side of the ring support frame opposite the first group of photosensors and light emitters; and

a pancake lens mounted to the display housing and positioned within the interior cavity between the eye tracking assembly and the micro-OLED display, with the first and second group of photosensors and light emitters arranged around a perimeter of the pancake lens; and

a controller including one or more processors coupled to each PSOG assembly and programmed to execute an algorithm for displaying computer-generated images using the micro-OLED displays including the steps of:

operating each PSOG assembly to emit light towards the user's eyes;

detecting reflected light from the user's eyes via the photosensors;

determining a gaze position of the user's eyes based on intensities of the reflected light detected by the photosensors; and

rendering images of a virtual environment on the micro-OLED displays using foveated rendering in accordance with the determined gaze direction.

2. The VR wearable assembly of claim 1 , wherein the one or more processors is programmed to execute the algorithm including the steps of:

operating each PSOG assembly to alternatingly operate the first and second groups of photosensors and light emitters.

3. The VR wearable assembly of claim 1 , wherein the one or more processors is programmed to execute the algorithm including the steps of:

compensating for a photosensor measurement error due to an operating temperature of the photosensors.

4. The VR wearable assembly of claim 3 , wherein each PSOG assembly includes a thermistor mounted to the ring support frame between the first and second group of photosensors and light emitters for sensing an ambient temperature adjacent the ring support frame, the one or more processors is programmed to execute the algorithm including the steps of:

compensating for the photosensor measurement error based on the sensed ambient temperature adjacent the ring support frame received from the thermistors.

5. The VR wearable assembly of claim 4 , wherein the one or more processors is programmed to execute the algorithm including the steps of:

compensating for the photosensor measurement error by calculating a heat transfer formula between the sensed ambient temperature and the photosensors to estimate a temperature of photosensors.

6. The VR wearable assembly of claim 1 , wherein the one or more processors is programmed to execute the algorithm including the steps of:

performing inter-pupilar distance (IPD) measurements based on the determined gaze position of the user's eyes; and

rendering images of the virtual environment based on the IPD measurements.

7. The VR wearable assembly of claim 1 , wherein the one or more processors is programmed to execute the algorithm including the steps of:

performing a calibration procedure by:

operating each PSOG assembly to present fixation targets on the micro-OLED displays sequentially at multiple known locations; and

detecting and storing light intensities gathered by the photosensors during presentation of the fixation targets.

8. A method of operating a virtual reality (VR) wearable assembly a wearable frame adapted to be worn over a user's eyes, a pair of photosensor oculography (PSOG) assemblies mounted to the wearable frame such that each PSOG assembly is positioned adjacent a corresponding eye of the user, and a controller including one or more processors coupled to each PSOG assembly, each PSOG assembly including a display housing including a substantially cylindrical shape having an inner surface defining an interior cavity, a micro-OLED display positioned within the interior cavity, an eye tracking assembly including a ring support frame coupled to the display housing, a first group of photosensors and light emitters mounted along a first side of the ring support frame, and a second group of photosensors and light emitters mounted along a second side of the ring support frame opposite the first group of photosensors and light emitters, and a pancake lens mounted to the display housing and positioned within the interior cavity between the eye tracking assembly and the micro-OLED display with the first and second group of photosensors and light emitters are arranged around a perimeter of the pancake lens, the method including the one or more processors performing an algorithm for displaying computer-generated images using the micro-OLED displays including the steps of:

operating each PSOG assembly to emit light towards the user's eyes;

detecting reflected light from the user's eyes via the photosensors;

determining a gaze position of the user's eyes based on intensities of the reflected light detected by the photosensors; and

rendering images of a virtual environment on the micro-OLED displays using foveated rendering in accordance with the determined gaze direction.

9. The method of claim 8 , including the one or more processors executing the algorithm including the steps of:

operating each PSOG assembly to alternatingly operate the first and second groups of photosensors and light emitters.

10. The method of claim 8 , including the one or more processors executing the algorithm including the steps of:

compensating for a photosensor measurement error due to an operating temperature of the photosensors.

11. The method of claim 10 , wherein each PSOG includes a thermistor mounted to the ring support frame between the first and second group of photosensors and light emitters for sensing an ambient temperature adjacent the ring support frame, the method including the one or more processors is programmed to execute the algorithm including the steps of:

compensating for the photosensor measurement error based on the sensed ambient temperature adjacent the ring support frame received from the thermistors.

12. The method of claim 11 , including the one or more processors executing the algorithm including the steps of:

compensating for the photosensor measurement error by calculating a heat transfer formula between the sensed ambient temperature and the photosensors to estimate a temperature of photosensors.

13. The method of claim 8 , including the one or more processors executing the algorithm including the steps of:

performing inter-pupilar distance (IPD) measurements based on the determined gaze position of the user's eyes; and

rendering images of the virtual environment based on the IPD measurements.

14. The method of claim 8 , including the one or more processors executing the algorithm including the steps of:

performing a calibration procedure by:

operating each PSOG assembly to present fixation targets on the micro-OLED displays sequentially at multiple known locations; and

detecting and storing light intensities gathered by the photosensors during presentation of the fixation targets.

15. A non-transitory computer-readable storage media having computer-executable instructions embodied thereon for operating a virtual reality (VR) wearable assembly a wearable frame adapted to be worn over a user's eyes, a pair of photosensor oculography (PSOG) assemblies mounted to the wearable frame such that each PSOG assembly is positioned adjacent a corresponding eye of the user, and a controller including one or more processors coupled to each PSOG assembly, each PSOG assembly including a display housing including a substantially cylindrical shape having an inner surface defining an interior cavity, a micro-OLED display positioned within the interior cavity, an eye tracking assembly including a ring support frame coupled to the display housing, a first group of photosensors and light emitters mounted along a first side of the ring support frame, and a second group of photosensors and light emitters mounted along a second side of the ring support frame opposite the first group of photosensors and light emitters, and a pancake lens mounted to the display housing and positioned within the interior cavity between the eye tracking assembly and the micro-OLED display with the first and second group of photosensors and light emitters are arranged around a perimeter of the pancake lens, when executed by the one or more processors the computer-executable instructions cause the one or more processors to perform an algorithm for displaying computer-generated images using the micro-OLED displays including the steps of:

operating each PSOG assembly to emit light towards the user's eyes;

detecting reflected light from the user's eyes via the photosensors;

determining a gaze position of the user's eyes based on intensities of the reflected light detected by the photosensors; and

rendering images of a virtual environment on the micro-OLED displays using foveated rendering in accordance with the determined gaze direction.

16. The non-transitory computer-readable storage media of claim 15 , wherein the computer-executable instructions cause the one or more processors to execute the algorithm including the steps of:

operating each PSOG assembly to alternatingly operate the first and second groups of photosensors and light emitters.

17. The non-transitory computer-readable storage media of claim 15 , wherein the computer-executable instructions cause the one or more processors to execute the algorithm including the steps of:

compensating for a photosensor measurement error due to an operating temperature of the photosensors.

18. The non-transitory computer-readable storage media of claim 17 , wherein each PSOG includes a thermistor mounted to the ring support frame between the first and second group of photosensors and light emitters for sensing an ambient temperature adjacent the ring support frame, the computer-executable instructions cause the one or more processors to execute the algorithm including the steps of:

compensating for the photosensor measurement error based on the sensed ambient temperature adjacent the ring support frame received from the thermistors.

19. The non-transitory computer-readable storage media of claim 15 , wherein the computer-executable instructions cause the one or more processors to execute the algorithm including the steps of:

performing inter-pupilar distance (IPD) measurements based on the determined gaze position of the user's eyes; and

rendering images of the virtual environment based on the IPD measurements.

20. The non-transitory computer-readable storage media of claim 15 , wherein the computer-executable instructions cause the one or more processors to execute the algorithm including the steps of:

performing a calibration procedure by:

operating each PSOG assembly to present fixation targets on the micro-OLED displays sequentially at multiple known locations; and

detecting and storing light intensities gathered by the photosensors during presentation of the fixation targets.