Rolled Orthogonal Sensor Assembly for 6-DOF Probe Tracking
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Solution Overview
Problem
Existing medical device tracking systems are limited in their ability to accurately track the roll angle of medical probes due to the reliance on single magnetic field sensors, which restricts them to tracking in only five degrees of freedom.
Innovation Solution
A sensor assembly with at least two magnetic field sensors, including inductive sensing coils and various magneto-resistive sensing elements, is designed to be rolled such that their primary sensing directions are orthogonal to each other, allowing for tracking in six degrees of freedom by sensing magnetic fields in multiple directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single magnetic field sensor is used for tracking, then the device complexity is reduced, but the measurement precision of roll angle is insufficient
Solution Approach 1:
The sensor assembly is segmented into multiple magnetic field sensors (first, second, and third sensors) with different sensing directions. Each sensor measures magnetic fields along specific orthogonal axes, and their combined data enables precise six-degree-of-freedom tracking including roll angle, resolving the limitation of single-sensor systems.
Solution Approach 2:
The patent transitions from single-dimension sensing to multi-dimensional sensing by arranging three magnetic field sensors along orthogonal axes (x, y, z directions). This dimensional expansion allows the system to capture magnetic field variations in all three spatial dimensions, enabling accurate roll angle measurement that was impossible with single-sensor configurations.
2Measurement precision
If five degrees of freedom tracking is used, then the device complexity is minimized, but the measurement precision of orientation including roll angle is restricted
Solution Approach 1:
Each magnetic field sensor is assigned a specific local quality with a unique sensing direction along orthogonal axes. The first sensor measures along the longitudinal axis, the second along one transverse axis, and the third along the other transverse axis. This localized specialization of sensing directions enables comprehensive six-degree-of-freedom orientation tracking.
Solution Approach 2:
The tracking system uses a composite sensing approach combining multiple magnetic field sensors with different sensing characteristics. By integrating sensors with orthogonal sensing directions, the system creates a composite measurement capability that captures all six degrees of freedom, achieving complete orientation tracking including roll angle.
3Measurement precision
If magnetic field sensors are arranged in orthogonal directions, then the measurement precision of six degrees of freedom is achieved, but the device complexity increases
Solution Approach 1:
The sensor assembly utilizes a rolled or curved substrate configuration that naturally positions the three magnetic field sensors in orthogonal directions. This curved geometry provides a compact three-dimensional arrangement of sensors, enabling six-degree-of-freedom tracking capability while maintaining a space-efficient structure suitable for catheter integration.
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
The sensor assembly enables precise tracking of medical probes in six degrees of freedom, including roll angles, by utilizing a flexible substrate with orthogonal magnetic field sensors to determine location and orientation within a patient.
Implementation Method 1
a first magnetic field sensor coupled to the first portion. The first magnetic field sensor has a primary sensing direction aligned with a longitudinal axis of the sensor assembly
Implementation Method 2
a second magnetic field sensor coupled to the second portion. The rolled section is shaped such that the second magnetic field sensor is oriented with respect to the first magnetic field sensor so that the second magnetic field sensor has a primary sensing direction aligned with an axis orthogonal to the longitudinal axis
Implementation Method 3
The first, second, and third magnetic field sensors include one of inductive sensing coils, magneto-resistive sensing elements, giant magneto-impedance sensing elements, and flux-gate sensing elements
Data Source
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AI summary
A sensor assembly (200) includes a substrate (204) including a first portion (206A), a second portion (206B), and a rolled section (208 shown in an "unrolled" form) positioned between the first portion and the second portion. The sensor assembly further includes a first magnetic field sensor (202A) coupled to the first portion. The first magnetic field sensor has a primary sensing direction aligned with a longitudinal axis of the sensor assembly. The sensor assembly further includes a second magnetic field sensor (202B) coupled to the second portion. The rolled section is shaped such that the second magnetic field sensor is oriented with respect to the first magnetic field sensor so that the second magnetic field sensor has a primary sensing direction aligned with an axis orthogonal to the longitudinal axis.