Hybrid Tracker Fusing Inertial and Electromagnetic Data
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Solution Overview
Problem
Inertial and electromagnetic tracking systems face challenges such as drift errors, noise, and latency, which affect the accuracy and stability of position and orientation determination, especially in dynamic environments like moving reference frames.
Innovation Solution
A hybrid electromagnetic-inertial tracking system that combines inertial measurement units (IMUs) and inertial navigation systems (INS) with electromagnetic tracking, using magnetic fields to communicate and optimize position and orientation calculations, thereby reducing noise and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If inertial tracking is used to continuously measure position and orientation, then tracking coverage and responsiveness are improved, but drift error increases over time
Solution Approach 1:
The patent combines inertial tracking (IMU) with electromagnetic tracking systems to create a hybrid tracker. The inertial system provides continuous high-speed tracking data while the electromagnetic system provides periodic absolute position references. The fusion algorithm merges these two data sources, using the inertial data for continuous motion tracking and electromagnetic data to correct drift accumulation, thereby maintaining both responsiveness and long-term accuracy.
Solution Approach 2:
The electromagnetic tracking system serves as a feedback mechanism that periodically corrects the drift in the inertial tracking system. By comparing the inertial position estimates with electromagnetic position measurements, the system generates correction signals that are fed back to the inertial navigation algorithm, enabling drift compensation and maintaining measurement precision over extended periods.
2Measurement precision
If electromagnetic tracking is used to determine position relative to a moving reference frame, then absolute position accuracy is improved, but latency increases due to signal processing time
Solution Approach 1:
The system performs preliminary action by using the inertial measurement unit to continuously predict and track position and orientation in advance. This allows the system to maintain up-to-date position estimates without waiting for electromagnetic signal processing, thereby reducing latency while preserving accuracy through subsequent electromagnetic corrections.
Solution Approach 2:
By merging inertial tracking (which provides low-latency continuous estimates) with electromagnetic tracking (which provides high-accuracy periodic corrections), the hybrid system achieves both low latency and high precision. The inertial component fills the time gaps between electromagnetic measurements, ensuring continuous responsive tracking.
3Measurement precision
If high-cost gyroscopes or accelerometers are used to correct drift in inertial tracking, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The electromagnetic tracking system acts as an intermediary that provides external reference measurements for drift correction. Instead of relying on more expensive inertial sensors, the system uses the electromagnetic field measurements as a mediator to verify and correct inertial tracking drift, achieving high precision through a different technical approach that avoids increasing inertial sensor complexity.
Solution Approach 2:
The patent replaces the mechanical approach of using higher-precision inertial sensors (gyroscopes and accelerometers) with an electromagnetic field-based correction system. This substitution achieves drift correction through electromagnetic measurements and computational fusion algorithms, thereby avoiding the need for expensive mechanical inertial sensors while maintaining measurement precision.
4Adaptability or versatility
If inertial sensors are used to measure acceleration and angular velocity, then tracking coverage is improved, but noise in measurements increases
Solution Approach 1:
The hybrid system merges inertial tracking (which provides broad tracking coverage and continuous motion data) with electromagnetic tracking (which provides high signal quality periodic references). The fusion algorithm combines these complementary strengths, using electromagnetic measurements to filter and reduce noise in the inertial sensor signals, thereby maintaining versatile tracking coverage while improving overall signal quality.
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 hybrid system improves the accuracy and stability of tracking by optimizing electromagnetic measurements with inertial data, reducing drift and latency, and enhancing the overall precision of position and orientation determination in dynamic environments.
Implementation Method 1
The object transceiver assembly communicates with the reference frame transceiver assembly using magnetic fields
Implementation Method 2
The linear acceleration a may be measured using an accelerometer
Implementation Method 3
the angular velocity w may be measured using a gyroscope
Implementation Method 4
An electromagnetic source generates an electromagnetic field within a platform
Data Source
AI summary
Apparatus for determining the position of a selected object relative to a moving reference frame, the apparatus including at least one reference frame transceiver assembly firmly attached to the moving reference frame, at least one object transceiver assembly firmly attached to the selected object, an inertial measurement unit firmly attached to the selected object, an inertial navigation system firmly attached to the moving reference frame, and a tracking processor coupled with the object transceiver assembly, with the inertial measurement unit and with the inertial navigation system, the object transceiver assembly communicating with the reference frame transceiver assembly using magnetic fields, the inertial measurement unit producing IMU inertial measurements of motion of the selected object with respect to an inertially fixed reference frame, the inertial navigation system producing INS inertial measurements of motion of the moving reference frame with respect to the inertially fixed reference frame, the tracking processor receiving electromagnetic measurements resulting from the magnetic communication between the reference frame transceiver assembly and the object transceiver assembly, the tracking processor determining the position of the selected object relative to the moving reference frame by using the IMU inertial measurements and the INS inertial measurements to optimize the electromagnetic measurements.