EMT Sensor Orientation via Transmitter Frequency Rotation
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Solution Overview
Problem
Existing Electromagnetic Tracking (EMT) systems require the sensor to be initialized in a known orientation to lock the demodulating signal, which is time-consuming and requires effort, and re-initialization is necessary if the sensor loses connection, making it inefficient for real-time tracking in medical procedures.
Innovation Solution
The system uses a frequency rotation technique where the transmitter coils operate at three different frequencies, and the sensor signals are compared before and after frequency rotation to determine if any frequencies are locked out-of-phase, allowing for mathematical correction of the sensor signals to ascertain the orientation without initial known orientation, using a computing device to manage the magnetic fields and sensor signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor is initialized in a known orientation to lock the demodulating signal, then the measurement precision is improved, but the loss of time increases due to manual initialization and re-initialization requirements
Solution Approach 1:
The system automatically determines sensor orientation by analyzing sign changes in sensor signal components after frequency rotation, eliminating the need for manual initialization. The computing device performs automated phase correction by comparing sensor signals before and after frequency rotation, allowing the system to self-calibrate without user intervention.
Solution Approach 2:
The transmitter rotates the operating frequencies of its coils (changing frequency parameters) to induce predictable sign changes in sensor signal components. By observing which components change sign after frequency rotation, the system determines the sensor's orientation and applies appropriate phase corrections, enabling automated orientation detection without manual intervention.
2Reliability
If the sensor loses connection and re-initialization is required, then the reliability is improved by re-establishing known orientation, but the productivity decreases due to interruption of real-time tracking
Solution Approach 1:
After connection loss, the system automatically performs orientation determination and phase correction using the frequency rotation technique, restoring tracking functionality without requiring manual re-initialization. This self-service capability maintains continuous real-time tracking and prevents productivity interruptions.
Solution Approach 2:
The system continuously monitors sensor signal components and detects orientation changes or connection losses in real-time. By maintaining readiness to perform automated phase correction at any moment, the system ensures rapid recovery from connection interruptions without disrupting the overall tracking workflow.
3Ease of operation
If the demodulating signal is locked to the sensor signal at a time when the sensor orientation is reversed, then the ease of operation is improved by allowing arbitrary initial orientation, but the measurement precision deteriorates due to opposite sign indication
Solution Approach 1:
The system uses feedback from sensor signal component signs to detect orientation reversals. By monitoring which components change sign after frequency rotation, the system identifies when the sensor orientation is reversed and applies appropriate phase corrections to restore accurate orientation indication, maintaining measurement precision while allowing operational flexibility.
Solution Approach 2:
The system changes the phase parameter of the demodulating signal based on detected orientation reversals. By applying phase corrections (changing the phase from 0 to 180 degrees or vice versa) when orientation reversal is detected, the system maintains accurate orientation measurement while allowing the sensor to operate in any initial orientation.
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 method enables efficient and accurate determination of the sensor's orientation without initial orientation alignment, reducing the need for manual initialization and re-initialization, thus improving the reliability and efficiency of EMT systems in medical tracking applications.
Implementation Method 1
A transmitter includes at least three coils and is configured to generate magnetic fields
Data Source
AI summary
A system comprising: a transmitter that includes at least three coils, the transmitter configured to generate magnetic fields; a sensor that includes at least three coils, the sensor configured to provide sensor signals that correspond to the magnetic fields generated by the transmitter; and a computing device in communication with the transmitter and the sensor, the computing device configured to compare a first sensor signal and a second sensor signal, and based on the comparison, determine whether any of the sensor coils are locked to a corresponding frequency out-of-phase.