Helmholtz Coil Virtual Calibration for Electromagnetic Tracking
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Solution Overview
Problem
Existing Electromagnetic Tracking (EMT) systems face inaccuracies due to improper calibration of sensors and transmitters, requiring physical movement and complex gantry systems for calibration and testing, which is time-consuming and inefficient.
Innovation Solution
The use of Helmholtz coils to generate a uniform magnetic field, allowing for virtual calibration and testing by simulating sensor movements relative to a virtual transmitter, eliminating the need for physical translation systems and simplifying the calibration process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical gantry systems are used to move sensors to known positions for calibration, then measurement precision can be verified, but device complexity and time consumption increase significantly
Solution Approach 1:
The patent creates a virtual copy of the physical transmitter within the simulation environment. This virtual transmitter replicates the electromagnetic field characteristics of the physical device, allowing sensors to be calibrated and tested against known virtual positions without requiring physical movement mechanisms. The virtual model preserves all necessary measurement properties while eliminating the need for complex physical gantry systems.
Solution Approach 2:
The patent replaces the mechanical gantry system with a computational simulation approach. Instead of physically moving the sensor or transmitter through space using mechanical components, the system uses software to simulate various positions and orientations. This substitution eliminates mechanical complexity while maintaining the ability to verify measurement precision through comparison of expected versus actual sensor readings across multiple virtual positions.
2Measurement precision
If physical translation systems are used to move sensors during calibration, then accurate position measurements can be obtained, but productivity and calibration speed decrease
Solution Approach 1:
The patent pre-calculates and stores the expected electromagnetic field characteristics and sensor readings for numerous known positions and orientations of the virtual transmitter. During calibration, the system simply compares actual sensor measurements against these pre-computed reference values, eliminating the time-consuming process of physically moving components through each calibration position. This preliminary computation of reference data significantly accelerates the calibration process while maintaining precision.
Solution Approach 2:
The patent replaces the physical translation system with a computational approach that instantly generates virtual position data. Instead of mechanically moving sensors or transmitters through space to obtain different measurement positions, the simulation software computationally generates the equivalent of physical movement by calculating electromagnetic field characteristics for any desired position. This eliminates mechanical constraints and speeds up calibration while preserving measurement accuracy.
3Measurement precision
If complex gantry systems are implemented for sensor calibration, then calibration accuracy can be ensured, but ease of operation and system simplicity are reduced
Solution Approach 1:
The patent uses a virtual copy of the transmitter that can be positioned and oriented through software control rather than physical manipulation. This virtual model allows calibration operations to be performed by simply changing numerical parameters in the simulation, making the process much easier to operate compared to physically adjusting and positioning components using complex gantry systems. The virtual copy maintains all necessary electromagnetic field properties for accurate calibration.
4Measurement precision
If physical movement of sensors is performed during testing, then position and orientation can be verified, but time consumption and operational complexity increase
Solution Approach 1:
The patent replaces physical movement during testing with computational simulation of movement. The system virtually positions the transmitter at various known locations and orientations, then compares sensor readings against expected values for those positions. This computational approach verifies position and orientation accuracy without the time loss associated with physically moving components through each test position, while still providing comprehensive verification of measurement precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate and efficient calibration and testing of sensors without physical motion, reducing the need for complex gantry systems and speeding up the calibration process, while ensuring precise position and orientation measurements.
Implementation Method 1
Helmholtz coils are used to generate a uniform magnetic field over a certain volume in space between them
Implementation Method 2
a magnetic sensor configured to detect the generated magnetic field
Data Source
AI summary
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.