Electromagnetic tracking with augmented reality systems

Patent metadata

Field	Value
Publication number	US-10948721-B2
Application number	US-201916670172-A
Country	US
Kind code	B2
Filing date	Oct 31, 2019
Priority date	Apr 26, 2016
Publication date	Mar 16, 2021
Grant date	Mar 16, 2021

Abstract

Head-mounted augmented reality (AR) devices can track pose of a wearer's head to provide a three-dimensional virtual representation of objects in the wearer's environment. An electromagnetic (EM) tracking system can track head or body pose. A handheld user input device can include an EM emitter that generates an EM field, and the head-mounted AR device can include an EM sensor that senses the EM field. EM information from the sensor can be analyzed to determine location and/or orientation of the sensor and thereby the wearer's pose. The EM emitter and sensor may utilize time division multiplexing (TDM) or dynamic frequency tuning to operate at multiple frequencies. Voltage gain control may be implemented in the transmitter, rather than the sensor, allowing smaller and lighter weight sensor designs. The EM sensor can implement noise cancellation to reduce the level of EM interference generated by nearby audio speakers.

First claim

What is claimed is:

1. An augmented reality (AR) display system comprising:
a display configured to project virtual images to eyes of a wearer;
a frame configured to mount the display in front of the eyes of the wearer;
one or more cameras mechanically coupled to the frame and configured to capture images of an environment in front of the wearer;
an electromagnetic (EM) field emitter configured to generate a magnetic field;
an EM sensor configured to sense the magnetic field, wherein one of the EM field emitter or the EM sensor is mechanically coupled to the frame and the other of the EM field emitter or the EM sensor is mechanically coupled to a component of the AR display system that is independently movable relative to the frame; and
a hardware processor programmed to:
receive images of the environment in front of the wearer from the one or more cameras;
receive signals from the EM sensor indicative of a sensed magnetic field;
analyze the received images to determine whether the component of the AR display system is outside of a field of view (FOV) of the one or more cameras; and
determine a position of the component of the AR display system based on the received signals and whether the component of the AR display system is determined to be outside of the FOV of the one or more cameras.

2. The AR display system of claim 1 , wherein in response to a determination that the component of the AR display system is outside of the FOV of the one or more cameras, the hardware processor is programmed to:
determine the component of the AR display system is in a 180-degree zone in back of the wearer.

3. The AR display system of claim 1 , wherein in response to a determination that the component of the AR display system is outside of the FOV of the one or more cameras, the hardware processor is programmed to:
receive user input that the component of the AR display system is in a 180-degree zone in back of the wearer.

4. The AR display system of claim 1 , further comprising an inertial measurement unit (IMU), and wherein the hardware processor is further programmed to determine the position of the component of the AR display system based on a signal from the IMU.

5. The AR display system of claim 1 , wherein the one or more cameras comprise a depth camera.

6. The AR display system of claim 1 , wherein to determine the position of the component of the AR display system based on the received signals, the hardware processor is programmed to detect whether the component of the AR display system is on a positive side or a negative side of a reference axis.

7. The AR display system of claim 1 , wherein the component of the AR display system comprises a handheld user-input device.

8. The AR display system of claim 1 , wherein the EM sensor is mechanically coupled to the frame and the EM field emitter is mechanically coupled to the component of the AR display system.

9. The AR display system of claim 1 , wherein the component of the AR display system comprises a user-input totem or a belt pack, the EM sensor is mechanically coupled to the frame, and the EM field emitter is mechanically coupled to the user-input totem or the belt pack.

10. The AR display system of claim 1 , wherein the display comprises a light field display.

Assignees

• Magic Leap Inc

Inventors

• Bucknor Brian
• Lopez Christopher
• Woods Michael Janusz
• Aly Aly H M
• Palmer James William
• Rynk Evan Francis

Classifications

• G01S2201/01

  adapted for specific applications or environments · CPC title

• G01S2205/01

  specially adapted for specific applications · CPC title

• H01H9/0235

  specially adapted for remote control, e.g. of audio or video apparatus · CPC title

• H01H9/0228

  Line cord switches · CPC title

• G06F3/014

  Hand-worn input/output arrangements, e.g. data gloves · CPC title