# US 12,182,343 B2 · Virtual reality tracker and tracker correction position method

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- Number: US 12,182,343 B2
- Document ID: US12182343B2
- Status: Granted
- Kind: B2
- Application number: 17/898,687
- Filed: 2022-08-30
- Published: 2024-02-29
- Granted: 2024-12-31
- Earliest claimed: 2022-08-30
- Assignees: HTC Corporation
- Applicants: HTC Corporation
- Inventors: Chun-Kai Huang; Chih-Chien Chen; Yan-Ru Chen
- Web page: https://patentgrep.com/patent/US12182343B2

## CPC

- A63F 13/211: using inertial sensors, e.g. accelerometers or gyroscopes
- G06F 3/0346: with detection of the device orientation or free movement in a three-dimensional [3D] space, e.g. 3D mice, 6-DOF [six degrees of freedom] pointers using gyroscopes, accelerometers or tilt-sensors
- A63F 13/213: comprising photodetecting means, e.g. cameras, photodiodes or infrared cells (A63F13/219 takes precedence)
- A63F 13/24: Constructional details thereof, e.g. game controllers with detachable joystick handles
- A63F 13/428: involving motion or position input signals, e.g. signals representing the rotation of an input controller or a player's arm motions sensed by accelerometers or gyroscopes
- G01C 21/1656: {with passive imaging devices, e.g. cameras}
- G06F 3/011: {Arrangements for interaction with the human body, e.g. for user immersion in virtual reality (blind teaching G09B21/00)}
- G06F 3/0308: {comprising a plurality of distinctive and separately oriented light emitters or reflectors associated to the pointing device, e.g. remote cursor controller with distinct and separately oriented LEDs at the tip whose radiations are captured by a photo-detector associated to the screen}
- G06T 7/74: {involving reference images or patches}
- A63F 2300/8082: Virtual reality
- G06T 2207/30196: Human being; Person
- A63F: CARD, BOARD, OR ROULETTE GAMES; INDOOR GAMES USING SMALL MOVING PLAYING BODIES; VIDEO GAMES; GAMES NOT OTHERWISE PROVIDED FOR
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S)
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL

## Abstract

A virtual reality tracker includes a first part and a second part. The first part includes a plurality of first light-emitting diodes (LEDs) and an inner measurement unit (IMU). The inertial measurement unit is used for measuring the acceleration and the triaxial angular velocity of the first part. The second part includes a plurality of second light-emitting diodes. Moreover, the first part and the second part are connected by a flexible component.

## Claims

### Claim 1

A virtual reality tracker, comprising:
a first part, comprising:
a plurality of first light-emitting diodes; and
an inertial measurement unit (IMU), configured to measure an acceleration and a triaxial angular velocity of the first part; and
a second part, comprising:
a plurality of second light-emitting diodes;
wherein the first part and the second part are connected by a flexible component,
wherein the inertial measurement unit transmits the acceleration and the triaxial angular velocity to a head-mounted display (HMD) device,
wherein the head-mounted display device captures the first light-emitting diodes on the first part to generate a plurality of first images,
wherein the head-mounted display device calculates a first pose of the first light-emitting diodes in three-dimensional space through the first images, the acceleration, and the triaxial angular velocity, and
wherein when the first part and the second part are bound to an object, the first pose of the first part at an initial time is multiplied by a displacement amount, which is regarded as being equal to the first pose of the first part at a first time; and after multiplying a second pose of the second part at the initial time by the displacement amount to obtain an initial result, and then multiplying the initial result by a transform function, a calculation result obtained is regarded as being equal to the first pose of the first part at the first time.

### Claim 2 (depends on 1)

The virtual reality tracker of claim 1, wherein the inertial measurement unit comprises:
an accelerometer, configured to measure acceleration; and
a gyroscope, configured to measure triaxial angular velocity;
wherein the inertial measurement unit transmits the acceleration and the triaxial angular velocity to an inertial calculation program through a transmission interface; according to the acceleration and the triaxial angular velocity, the inertia calculation program calculates a detailed pose using an image-pose back-measurement method; and the head-mounted display device generates a real-time image in the detailed pose.

### Claim 3 (depends on 1)

The virtual reality tracker of claim 1, wherein the inertial measurement unit transmits the acceleration and the triaxial angular velocity to the head-mounted display device through a transmission interface; and
a first camera on the head-mounted display device captures the first light-emitting diodes on the first part to generate the plurality of first images.

### Claim 4 (depends on 3)

The virtual reality tracker of claim 3, wherein the head-mounted display device transmits the first pose to the inertial calculation program, the inertial measurement unit transmits the acceleration and the triaxial angular velocity to the inertial calculation program through the transmission interface; the inertia calculation program calculates a detailed pose using an image-pose back-measurement integration method according to the first pose, the acceleration and the triaxial angular velocity; and
the head-mounted display device generates a real-time image in the detailed pose.

### Claim 5 (depends on 3)

The virtual reality tracker of claim 3, wherein the first camera or a second camera on the head-mounted display device captures the second light-emitting diodes on the second part to generate a plurality of second images; and
the head-mounted display device calculates the second pose of the second light-emitting diodes in three-dimensional space using the second images.

### Claim 6 (depends on 5)

The virtual reality tracker of claim 5, wherein a first coordinate system of the first pose corresponds to the first camera;
wherein a second coordinate system of the second pose corresponds to the second camera;
the first coordinate system is different from the second coordinate system.

### Claim 7 (depends on 5)

The virtual reality tracker of claim 5, wherein the first camera and the second camera are located in the same head-mounted display device; a distance conversion between the first camera and the second camera is defined when the head-mounted display device is deployed; the first coordinate system and the second coordinate system are converted to a general coordinate system, and the calculation of pose is mainly based on the general coordinate system.

### Claim 8 (depends on 3)

The virtual reality tracker of claim 3, wherein the flexible component is a strap.

### Claim 9

A tracker correction position method, suitable for use in a virtual reality system, wherein the tracker correction position method comprises:
capturing a plurality of first light-emitting diodes (LEDs) on a first part to obtain a plurality of first images;
measuring the acceleration and the triaxial angular velocity of the first part using an inertial measurement unit (IMU);
capturing a plurality of second light-emitting diodes (LEDs) on a second part to obtain a plurality of second images; and
correcting a position of a tracker according to the first images, the acceleration, the triaxial angular velocity and the second images;
wherein the first part and the second part are connected by a flexible component,
wherein the tracker correction position method further comprising:
the inertial measurement unit transmitting the acceleration and the triaxial angular velocity to a head-mounted display (HMD) device;
the head-mounted display device capturing the first light-emitting diodes on the first part polar bodies to generate the first images; and
the head-mounted display device calculates a first pose of the first light-emitting diodes in three-dimensional space using the first images, the acceleration and the triaxial angular velocity,
wherein after the first part and the second part are bound to an object, the tracker correction position method further comprises:
multiplying the first pose of the first part at the initial time by an amount of rotational displacement is regarded as being equal to the first pose of the first part at the first time; and
after multiplying a second pose of the second part at the initial time by the amount of rotational displacement, it is regarded as being equal to the second pose of the second part at the first time; wherein the second pose is multiplied by a transform function to obtain the calculation result, and the calculation result is equal to the first pose of the first part at the first time.

### Claim 10 (depends on 9)

The tracker correction position method of claim 9, further comprising:
measuring acceleration with an accelerometer of the inertial measurement unit; and
measuring triaxial angular velocity with a gyroscope of the inertial measurement unit;
wherein the inertial measurement unit calculates a detailed pose using an image interpolation method according to the first images, the acceleration, and the triaxial angular velocity, and transmits the detailed pose to the head-mounted display device through a transmission interface, wherein the head-mounted display device generates a real-time image in the detailed pose.

### Claim 11 (depends on 9)

The tracker correction position method of claim 9, wherein the step of the inertial measurement unit transmitting the acceleration and the triaxial angular velocity to a head-mounted display device comprises:
the inertial measurement unit transmits the acceleration and the triaxial angular velocity to the head-mounted display device through a transmission interface; and
wherein the step of the head-mounted display device capturing the first light-emitting diodes on the first part polar bodies to generate the first images comprises:
a first camera on the head-mounted display device captures the first light-emitting diodes on the first part polar bodies to generate the first images.

### Claim 12 (depends on 11)

The tracker correction position method of claim 11, further comprising:
returning the first pose to an inertial calculation program through the head-mounted display device;
wherein the calculation program calculates a detailed pose using the image interpolation method according to the first pose, the acceleration and the triaxial angular velocity, and transmits the detailed pose to the head-mounted display device through a transmission interface;
wherein the head-mounted display device generates a real-time image in the detailed pose.

### Claim 13 (depends on 11)

The tracker correction position method of claim 11, further comprising:
capturing the second light-emitting diodes on the second part using the first camera or the second camera on the head-mounted display device to generate the second images;
wherein the head-mounted display device calculates the second pose of the second light-emitting diodes in three-dimensional space using the second images.

### Claim 14 (depends on 13)

The tracker correction position method of claim 13, wherein the first coordinate system of the first pose corresponds to the first camera; wherein the second coordinate system of the second pose corresponds to the second camera; and the first coordinate system is different from the second coordinate system.

### Claim 15 (depends on 13)

The tracker correction position method of claim 13, wherein the first camera and the second camera are located in the same head-mounted display device; the distance conversion between the first camera and the second camera is defined when the head-mounted display device is deployed; the first coordinate system and the second coordinate system are converted to a general coordinate system, and the calculation of pose is mainly based on the general coordinate system.

### Claim 16 (depends on 13)

The tracker correction position method of claim 13, wherein the flexible component is a strap.

### Claim 17 (depends on 16)

The tracker correction position method of claim 16, wherein the transform function is used to transfer the second pose of the second part to the first pose of the first part, and the first pose of the first part at the first time is equal to the second pose of the second part multiplying by the transform function at the first time.

### Claim 18 (depends on 17)

The tracker correction position method of claim 17, further comprising:
solving the transform function through the head-mounted display device through the first pose, the second pose and a displacement amount at each of multiple time points.