GNSS-IMU Synchronization via Magnetic Loop Antenna Timing
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Solution Overview
Problem
The synchronization between Global Navigation Satellite System (GNSS) measurements and inertial measurements is challenging due to potential time synchronization errors, especially in scenarios where GNSS conditions are poor or when high dynamics applications require precise timing alignment.
Innovation Solution
A method involving a mobile device that processes an output-timing signal from a GNSS receiver, detects pulses using a magnetometer, and determines a time delay between the GNSS and Inertial Measurement Unit (IMU) clocks to adjust the time-base of inertial measurements to match GNSS measurements, using a magnetic loop antenna to generate electromagnetic pulses aligned with the GNSS Epoch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GNSS measurements and inertial measurements are used together for location determination, then location accuracy is improved, but time synchronization errors occur between the two measurement systems
Solution Approach 1:
The patent introduces an intermediary electromagnetic signal transmission mechanism where the GNSS receiver outputs timing signals that are transmitted through a magnetic loop antenna. The IMU's magnetometer detects these transmitted signals, creating a shared time reference between the two systems. This intermediary approach allows synchronization without direct clock coupling, resolving the time synchronization error while maintaining improved location accuracy through fused GNSS and inertial measurements
2Device complexity
If separate clocks are used for GNSS receiver and IMU, then device complexity is reduced, but time synchronization between measurements deteriorates
Solution Approach 1:
Instead of using a complex shared clock mechanism, the patent employs a simple electromagnetic signal transmission through a magnetic loop antenna as an intermediary. The GNSS receiver's timing signals are transmitted and detected by the IMU's magnetometer, providing time synchronization without requiring complex clock coupling mechanisms. This approach maintains device simplicity while achieving accurate time alignment between separate measurement systems
Solution Approach 2:
The patent replaces the traditional mechanical/electrical clock synchronization mechanism with an electromagnetic field-based approach. Rather than coupling clocks through physical connections or shared crystal oscillators, the system uses electromagnetic signal transmission detected by the magnetometer to synchronize timing. This substitution reduces mechanical complexity while maintaining synchronization accuracy
3Loss of time
If electromagnetic signal transmission through magnetic loop antenna is used for synchronization, then time synchronization accuracy is improved, but device complexity increases due to additional components
Solution Approach 1:
The patent makes the magnetic loop antenna and magnetometer serve multiple functions: the magnetometer not only performs its primary inertial measurement function but also detects the electromagnetic timing signals for synchronization. The magnetic loop antenna similarly serves both as part of the device's electromagnetic structure and as a signal transmission medium. This multi-functionality reduces the need for dedicated synchronization components, minimizing additional complexity while improving time synchronization accuracy
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 effectively compensates for time synchronization errors, enhancing the accuracy of location determination in both good and poor GNSS conditions, particularly in high dynamics applications where precise timing is critical.
Implementation Method 1
an antenna to emit an electromagnetic signal based on the output-timing signal, the electromagnetic signal configured to be measured by the magnetometer
Data Source
AI summary
Some demonstrative embodiments include apparatuses, devices, systems and methods of synchronizing time. For example, an apparatus may include a GNSS receiver to output GNSS measurements, and an output-timing signal including a plurality of pulses based on a clock of the GNSS receiver; an IMU to output inertial measurements, the IMU including a magnetometer to output magnetometer measurements; an antenna to emit an electromagnetic signal based on the output-timing signal, the electromagnetic signal to be measured by the magnetometer; and a processor to process the GNSS measurements and the inertial measurements, to detect in the magnetometer measurements one or more detected pulses of the output-timing signal, to determine a time delay between a clock of the IMU and the clock of the GNSS receiver based the detected pulses, and to adjust a time-base of the inertial measurements to a time-base of the GNSS measurements based on the time delay.