Determining position and orientation from a Helmholtz device
Inventors
Assignees
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Publication Number
US-11340311-B2
Publication Date
2022-05-24
Expiration Date
Abstract
A method includes receiving, at a magnetic sensor, a series of transmitter signals that are detected as a series of signals corresponding to different locations and/or orientations of a magnetic transmitter emitting a magnetic field, calculating, receiving, at the magnetic sensor, a measurement transmitter signal that is detected as a signal corresponding to a magnetic field provided by the magnetic transmitter, and calculating, based at least on the received measurement sensor signal and the calibration matrix, one or both of an orientation matrix indicative of an orientation of the magnetic sensor relative to the magnetic transmitter and a positional matrix indicative of a position of the magnetic sensor relative to the magnetic transmitter, wherein the series of transmitter signals are transmitted from the same physical location relative to the magnetic sensor.
Core Innovation
Orthogonal three-axis Helmholtz coil sets are driven to generate a magnetic field so that a magnetic sensor is steered virtually without moving. Transmitter signals are generated for different locations and/or orientations of a virtually-moving transmitter, and the series of transmitter signals are transmitted from the same physical location, so different poses correspond to fields originating from that fixed transmitter location relative to the sensor.
The magnetic sensor detects the series of transmitter signals as measurement sensor signals, including induced voltage signals. A Helmholtz calibration matrix is applied to the measurement sensor signals to compute an orientation matrix and/or a positional matrix, where the positional matrix includes x/y/z position components and the orientation matrix is indicative of the orientation of the magnetic sensor relative to the virtually-moving transmitter.
A coupling matrix and a signal matrix are used in the calibration framework, including deriving or using a sensor characterization matrix, scaling constants, and a formulation that maps transmitted virtual transmitter signals to the measurement sensor signals. Helmholtz parameters are calibrated and validated, including validation against tolerances and detecting calibration failure when results are outside tolerance.
Claims Coverage
The independent claims are directed to a method, a non-transitory computer-readable medium, and a system, each centered on receiving transmitter signals representing different virtual locations/orientations from the same physical transmitter location and calculating orientation and/or positional matrices using a calibration matrix. The inventive features across the independent claims include using transmitter signals from the same physical location, computing orientation and positional matrices via a calibration matrix, and dependent refinements specifying reliability checking, voltage-signal generation, and particular three-axis sensor and three-axis Helmholtz coil set structures.
Virtually-moving transmitter from a same physical location
A series of transmitter signals corresponding to different locations and/or orientations of a virtually-moving transmitter is transmitted from the same physical location.
Orientation matrix and positional matrix from calibration matrix
Calculating, based at least on the received transmitter signals and a calibration matrix, one or both of an orientation matrix indicative of an orientation of the magnetic sensor relative to the virtually-moving transmitter and a positional matrix indicative of a position of the magnetic sensor relative to the virtually-moving transmitter.
Computing device receiving transmitter signals and calculating matrices
A computing device receives transmitter signals detected by the magnetic sensor that correspond to different locations and/or orientations of the virtually-moving transmitter and calculates, based at least on the received transmitter signals and a calibration matrix, one or both of an orientation matrix and a positional matrix.
Across the independent claims, the core claim coverage is the virtual steering concept where the transmitter signals represent different virtual locations/orientations while being transmitted from the same physical location, combined with calculating an orientation matrix and/or positional matrix using a calibration matrix. The independent claim set further supports dependent refinements on reliability checking, voltage-signal interaction, and specific three-axis sensor and three-axis Helmholtz coil set structures.
Stated Advantages
No gantry/translation system needed.
Faster calibration/testing.
Calibration failure can be detected when results are outside tolerance.
Documented Applications
EMT systems, including medical, gaming, and AR/VR.
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