Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Publication Number
US-10948278-B2
Publication Date
2021-03-16
Expiration Date
Abstract
A calibration system comprising: a Helmholtz device comprising thee pairs of coils defining an inner volume, wherein each of the three pairs of coils is configured to generate a magnetic field that is uniform throughout the inner volume; a mount configured to accept a device that includes a magnetic sensor, wherein at least a portion of the mount is positioned within the inner volume such that the magnetic sensor is positioned at or near a center of the inner volume when the device is positioned on the mount; and a computer system configured to communicate with the Helmholtz device and the magnetic sensor, wherein the computer system is configured to: provide instructions to cause each of the three pairs of coils to generate a magnetic field; receive signals from the magnetic sensor that are based on characteristics of the magnetic fields received at the magnetic sensor; measure, based on the signals received from the magnetic sensor, one or more characteristics of the magnetic sensor; and determine, using a calibration algorithm, one or more calibration correction factors for the magnetic sensor based on the one or more characteristics of the magnetic sensor and the provided instructions.
Core Innovation
The invention calibrates a magnetic sensor using a Helmholtz device that includes three pairs of coils defining an inner volume, where each of the three pairs of coils generates a magnetic field that is uniform throughout the inner volume. A mount positions a device containing the first magnetic sensor at or near a center of the inner volume so that the first magnetic sensor is exposed to the uniform magnetic fields. A computer system provides instructions to cause each of the three pairs of coils to generate a first magnetic field and receives signals from the first magnetic sensor based on characteristics of the first magnetic fields received at the first magnetic sensor.
Based on the received signals, the system measures one or more characteristics of the first magnetic sensor and determines, using a calibration algorithm, one or more calibration correction factors for the first magnetic sensor based on the measured characteristics and the provided coil-field instructions. The described approach includes sensor characterization data, calibration correction factors, and use of calibration files that can be generated and/or consumed as part of the calibration process. Calibration can be performed with the magnetic sensor embedded in a head-mounted display.
The invention also uses Helmholtz self-calibration with a reference device that includes a second magnetic sensor positioned at or near the same center of the inner volume. With instructions causing each of the three pairs of coils to generate a second uniform magnetic field, the system receives signals from the second magnetic sensor, measures one or more characteristics of the second magnetic sensor, and determines calibration correction factors for one or more of the three pairs of coils based on the measured characteristics of the second magnetic sensor.
Claims Coverage
The document provides two independent claims, a calibration system claim and a calibration method claim. Each independent claim shares the core concept of three coil pairs in a Helmholtz device generating uniform magnetic fields in an inner volume and computing calibration correction factors using a calibration algorithm based on measured sensor characteristics, including a reference sensor centered in the inner volume for self-calibration.
Helmholtz three-pair uniform field calibration at inner-volume center
A calibration system with a Helmholtz device comprising three pairs of coils defining an inner volume, wherein each of the three pairs of coils generates a magnetic field uniform throughout the inner volume and a device with a first magnetic sensor is positioned at or near a center of the inner volume.
Calibration algorithm determines sensor correction factors from measured sensor characteristics
A computer system that provides instructions to cause each of the three pairs of coils to generate a first magnetic field, receives signals from the first magnetic sensor based on characteristics of the first magnetic fields received at the first magnetic sensor, measures one or more characteristics of the first magnetic sensor, and determines using a calibration algorithm one or more calibration correction factors for the first magnetic sensor based on the measured characteristics and the provided instructions.
Reference device self-calibrates coil-pair correction factors using centered reference sensor
A reference device including a second magnetic sensor positioned at or near a center of the inner volume, where the computer system provides instructions to cause each of the three pairs of coils to generate a second magnetic field uniform throughout the inner volume, receives signals from the second magnetic sensor based on characteristics of the second magnetic fields received at the second magnetic sensor, measures one or more characteristics of the second magnetic sensor, and determines using a calibration algorithm one or more calibration correction factors for one or more of the three pairs of coils based on the measured characteristics of the second magnetic sensor.
Three-pair Helmholtz uniform field calibration method with centered reference sensor
A method providing instructions by a computer system to cause current to flow through each of three pairs of coils that define an inner volume, generating a first magnetic field uniform throughout the inner volume, receiving signals from a first magnetic sensor incorporated into a device positioned within the inner volume, measuring one or more characteristics of the first magnetic sensor, and determining using a calibration algorithm one or more calibration correction factors for the first magnetic sensor based on the one or more characteristics and the provided instructions, including positioning a reference device with a second magnetic sensor at or near a center of the inner volume.
Reference-sensor calibration algorithm determines coil-pair correction factors
The method further providing instructions to cause second current to flow through each of the three pairs of coils to generate a second magnetic field uniform throughout the inner volume, receiving signals from the second magnetic sensor based on characteristics of the second magnetic fields received at the second magnetic sensor, measuring one or more characteristics of the second magnetic sensor, and determining using a calibration algorithm one or more calibration correction factors for one or more of the three pairs of coils based on the one or more characteristics of the second magnetic sensor.
Across the independent claims, the main coverage is a Helmholtz device with three coil pairs generating uniform magnetic fields in an inner volume, positioning sensors at or near the center of the inner volume, and using a calibration algorithm to compute calibration correction factors from measured sensor characteristics, including self-calibration using a centered reference sensor to determine correction factors for one or more coil pairs.
Stated Advantages
Calibration can be performed with the magnetic sensor embedded in a head-mounted display.
Documented Applications
Head-mounted display calibration.
Interested in licensing this patent?