# US 11,029,385 B2 · Tracking system for head-mounted display apparatus and method of tracking

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- Number: US 11,029,385 B2
- Document ID: US11029385B2
- Status: Granted
- Kind: B2
- Application number: 16/376,085
- Filed: 2019-04-05
- Published: 2020-10-08
- Granted: 2021-06-08
- Earliest claimed: 2019-04-05
- Assignees: Varjo Technologies Oy
- Applicants: Varjo Technologies Oy
- Inventors: Urho Konttori; Klaus Melakari
- Web page: https://patentgrep.com/patent/US11029385B2

## CPC

- G01S 5/02: using radio waves (using satellite radio beacon systems for determining position G01S19/00)
- G01S 5/0294: {Trajectory determination or predictive filtering, e.g. target tracking or Kalman filtering}
- G01S 5/0221: {Receivers}
- G01S 5/0247: {Determining attitude}
- G01S 5/0284: {Relative positioning}
- G01S 5/16: using electromagnetic waves other than radio waves
- G01S 5/18: using ultrasonic, sonic or infrasonic waves
- G06F 3/011: {Arrangements for interaction with the human body, e.g. for user immersion in virtual reality (blind teaching G09B21/00)}
- G06F 3/017: {Gesture based interaction, e.g. based on a set of recognized hand gestures (interaction based on gestures traced on a digitiser G06F3/04883)}
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

A tracking system for use in head-mounted display apparatus includes at least one emitter that emits signals; a first receiver and a second receiver that sense the emitted signals and generate sensor data, the first receiver and the second receiver being arranged on a first portion and a second portion, respectively, wherein the first portion faces a user when the head-mounted display apparatus is worn by the user, and the second portion is a part of a user-interaction controller of a head-mounted display; and a processor configured to process the generated sensor data to determine relative positions and orientations of first receiver and second receiver with respect to the emitter, and to determine a relative position and orientation of the second receiver with respect to the first receiver.

## Claims

### Claim 1

A tracking system for use in a head-mounted display apparatus, the tracking system comprising:
at least one emitter that, in operation, emits signals;
a first receiver and a second receiver that, in operation, sense the emitted signals and generate sensor data, the first receiver and the second receiver being arranged on a first portion and a second portion of the head-mounted display apparatus, respectively, wherein the first portion faces a user when the head-mounted display apparatus is worn by the user, and the second portion is a part of a user-interaction controller of the head-mounted display apparatus; and
a processor configured to process the generated sensor data to determine relative positions and orientations of the first receiver and the second receiver with respect to the at least one emitter, and to determine, based on the determined relative positions and orientations, a relative position and orientation of the second receiver with respect to the first receiver.

### Claim 2 (depends on 1)

The tracking system of claim 1, wherein the first portion is in a proximity of an image renderer of the head-mounted display apparatus, a relative position and orientation of the first receiver with respect to the image renderer being known, wherein the processor is configured to determine a relative position and orientation of the user-interaction controller with respect to a field of view that is visible to the user via the image renderer, based on the relative position and orientation of the first receiver with respect to the image renderer and the relative position and orientation of the second receiver with respect to the first receiver.

### Claim 3 (depends on 1)

The tracking system of claim 1, wherein the at least one emitter is arranged on a third portion of the head-mounted display apparatus that is different from the first portion and the second portion.

### Claim 4 (depends on 3)

The tracking system of claim 3, wherein the third portion is a part of a head strap of the head-mounted display apparatus.

### Claim 5 (depends on 1)

The tracking system of claim 1, wherein the at least one emitter is arranged on an external device.

### Claim 6 (depends on 1)

The tracking system of claim 1, wherein the at least one emitter is arranged at a reference location.

### Claim 7 (depends on 1)

The tracking system of claim 1, wherein the at least one emitter comprises a plurality of emitters, and wherein a given receiver, in operation, senses signals emitted by the plurality of emitters.

### Claim 8 (depends on 1)

The tracking system of claim 1, further comprising a third receiver arranged at a reference location, wherein the processor configured to determine a relative position and orientation of the third receiver with respect to the at least one emitter, and to determine, based on said relative position and orientation, relative positions and orientations of the first receiver and the second receiver with respect to the third receiver.

### Claim 9 (depends on 1)

The tracking system of claim 1, wherein the emitted signals are electromagnetic signals.

### Claim 10 (depends on 1)

The tracking system of claim 1, wherein the emitted signals are acoustic signals.

### Claim 11 (depends on 1)

The tracking system of claim 1, wherein the generated sensor data comprises measurements of at least one signal characteristic of the signals.

### Claim 12 (depends on 11)

The tracking system of claim 11, wherein the at least one signal characteristic comprises at least one of: a strength, a phase, a wavelength, a frequency, a time-of-flight, an angle of arrival, a polarization, a Doppler spread, a delay spread, a delay signature.

### Claim 13

A method of tracking, the method comprising:
emitting signals, via at least one emitter;
sensing, via a first receiver and a second receiver, the emitted signals and generating sensor data, the first receiver and the second receiver being arranged on a first portion and a second portion of a head-mounted display apparatus, respectively, wherein the first portion faces a user when the head-mounted display apparatus is worn by the user, and the second portion is a part of a user-interaction controller of the head-mounted display apparatus;
processing the generated sensor data to determine relative positions and orientations of the first receiver and the second receiver with respect to the at least one emitter; and
determining, based on the determined relative positions and orientations, a relative position and orientation of the second receiver with respect to the first receiver.

### Claim 14 (depends on 13)

The method of claim 13, wherein the first portion is in a proximity of an image renderer of the head-mounted display apparatus, a relative position and orientation of the first receiver with respect to the image renderer being known, wherein the method further comprises determining a relative position and orientation of the user-interaction controller with respect to a field of view that is visible to the user via the image renderer, based on the relative position and orientation of the first receiver with respect to the image renderer and the relative position and orientation of the second receiver with respect to the first receiver.

### Claim 15 (depends on 13)

The method of claim 13, wherein the at least one emitter is arranged on a third portion of the head-mounted display apparatus that is different from the first portion and the second portion.

### Claim 16 (depends on 15)

The method of claim 15, wherein the third portion is a part of a head strap of the head-mounted display apparatus.

### Claim 17 (depends on 13)

The method of claim 13, wherein the at least one emitter is arranged on an external device.

### Claim 18 (depends on 13)

The method of claim 13, wherein the at least one emitter is arranged at a reference location.

### Claim 19 (depends on 13)

The method of claim 13, wherein the at least one emitter comprises a plurality of emitters, and wherein the step of sensing the emitted signals comprises sensing, via a given receiver, signals emitted by the plurality of emitters.

### Claim 20 (depends on 13)

The method of claim 13, wherein a third receiver is arranged at a reference location, and wherein the method further comprises
determining a relative position and orientation of the third receiver with respect to the at least one emitter; and
determining, based on said relative position and orientation, relative positions and orientations of the first receiver and the second receiver with respect to the third receiver.

### Claim 21 (depends on 13)

The method of claim 13, wherein the emitted signals are electromagnetic signals.

### Claim 22 (depends on 13)

The method of claim 13, wherein the emitted signals are acoustic signals.

### Claim 23 (depends on 13)

The method of claim 13, wherein the generated sensor data comprises measurements of at least one signal characteristic of the signals.

### Claim 24 (depends on 23)

The method of claim 23, wherein the at least one signal characteristic comprises at least one of: a strength, a phase, a wavelength, a frequency, a time-of-flight, an angle of arrival, a polarization, a Doppler spread, a delay spread, a delay signature.