Eye tracking system for VR/AR HMD units including pancake lens modules
A virtual reality (VR) wearable assembly is described herein. The VR wearable assembly includes a wearable frame adapted to be worn over a patient's eyes and 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 patient. Each PSOG assembly includes a display housing 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, 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.
1. A virtual reality (VR) wearable assembly comprising:
a wearable frame adapted to be worn over a patient's eyes; and
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 patient, 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:
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 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; 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.
2. The VR wearable assembly of claim 1 , wherein
the pancake lens is substantially disk shaped and the ring support frame extends around a perimeter of the pancake lens such that the first and second group of photosensors and light emitters are arranged around a perimeter of the pancake lens.
3. The VR wearable assembly of claim 2 , further comprising a processor coupled to the first and second group of photosensors and light emitters, the processor configured to execute an algorithm including the steps of:
operating the light emitters to emit light towards the patient's eye;
detecting reflected light from the patient's eye via the photosensors; and
determining a gaze position of the patient's eye based on intensities of the reflected light detected by the photosensors.
4. The VR wearable assembly of claim 2 , wherein the pancake lens is positioned adjacent to eye tracking assembly such that a first distance defined between the pancake lens and the eye tracking assembly along a longitudinal axis is less than a second distance defined between the pancake lens and the micro-OLED display along the longitudinal axis.
5. The VR wearable assembly of claim 3 , wherein the processor is configured to execute the algorithm including the steps of:
receiving the sensed ambient temperature adjacent the ring support frame from the thermistor;
determining an estimated temperature of the photosensors based on the sensed ambient temperature adjacent the ring support frame and a coefficient based on the VR wearable assembly;
compensating photosensor measurement error based on the estimated temperature of the photosensors; and
determining the gaze position of the patient's eye based on the intensities of the reflected light detected by the photosensors and the compensated photosensor measurement error.
6. The VR wearable assembly of claim 1 , wherein the first and second group of photosensors and light emitters are arranged around a perimeter of the pancake lens.
7. The VR wearable assembly of claim 3 ,
wherein the processor is configured to execute the algorithm including the steps of:
alternatingly operate the first and second groups of photosensors and light emitters.
8. The VR wearable assembly of claim 7 , wherein the first group of photosensors and light emitters includes a plurality of photosensors positioned between a pair of light emitters.
9. A PSOG assembly for use with a VR wearable assembly, comprising:
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;
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 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; 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.
10. The PSOG assembly of claim 9 , wherein the eye tracking assembly includes:
the pancake lens is substantially disk shaped and the ring support frame extends around a perimeter of the pancake lens such that the first and second group of photosensors and light emitters are arranged around a perimeter of the pancake lens.
11. The PSOG assembly of claim 10 , further comprising a processor coupled to the first and second group of photosensors and light emitters, the processor configured to execute an algorithm including the steps of:
operating the light emitters to emit light towards a patient's eye;
detecting reflected light from the patient's eye via the photosensors; and
determining a gaze position of the patient's eye based on intensities of the reflected light detected by the photosensors.
12. The PSOG assembly of claim 10 , wherein the pancake lens is positioned adjacent to eye tracking assembly such that a first distance defined between the pancake lens and the eye tracking assembly along a longitudinal axis is less than a second distance defined between the pancake lens and the micro-OLED display along the longitudinal axis.
13. The PSOG assembly of claim 10 , wherein the processor is configured to execute the algorithm including the steps of:
receiving the sensed ambient temperature adjacent the ring support frame from the thermistor;
determining an estimated temperature of the photosensors based on the sensed ambient temperature adjacent the ring support frame and a coefficient based on the VR wearable assembly;
compensating photosensor measurement error based on the estimated temperature of the photosensors; and
determining the gaze position of the patient's eye based on the intensities of the reflected light detected by the photosensors and the compensated photosensor measurement error.
14. The PSOG assembly of claim 9 , wherein the first and second group of photosensors and light emitters are arranged around a perimeter of the pancake lens.
15. The PSOG assembly of claim 11 ,
wherein the processor is configured to execute the algorithm including the steps of:
alternatingly operate the first and second groups of photosensors and light emitters.
16. The PSOG assembly of claim 15 , wherein the first group of photosensors and light emitters includes a plurality of photosensors positioned between a pair of light emitters.
17. A method of assembling a VR wearable assembly, comprising:
assembling a PSOG assembly including:
providing a display housing including a substantially cylindrical shape having an inner surface defining an interior cavity extending between a first end and second end;
coupling an eye tracking assembly to the display housing 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:
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 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;
coupling a pancake lens to the display housing positioned within the interior cavity adjacent the eye tracking assembly; and
coupling a micro-OLED display to the display housing positioned within the interior cavity adjacent the second end of the display housing such that the pancake lens is orientated between the eye tracking assembly and the micro-OLED display; and
coupling the assembled PSOG assembly to a rim of a wearable frame adapted to be worn over a patient's eyes.
18. The method of claim 17 , further comprising assembling the eye tracking assembly by:
coupling the pancake lens to the ring support frame such that the first and second group of photosensors and light emitters are arranged around a perimeter of the pancake lens.
19. The method of claim 18 , wherein pancake lens is positioned adjacent to eye tracking assembly such that a first distance defined between the pancake lens and the eye tracking assembly along a longitudinal axis is less than a second distance defined between the pancake lens and the micro-OLED display along the longitudinal axis.
20. The method of claim 17 , further comprising:
operatively coupling a processor to the photosensors, the light emitters, and the thermistor, the processor configured to execute an algorithm including the steps of:
operating the light emitters to emit light towards the patient's eye;
detecting reflected light from the patient's eye via the photosensors;
receiving the sensed ambient temperature adjacent the ring support frame from the thermistor;
determining an estimated temperature of the photosensors based on the sensed ambient temperature adjacent the ring support frame and a coefficient based on the VR wearable assembly;
compensating photosensor measurement error based on the estimated temperature of the photosensors; and
determining the gaze position of the patient's eye based on the intensities of the reflected light detected by the photosensors and the compensated photosensor measurement error.