Impact Motion Tracking Sensor Calibration
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Solution Overview
Problem
Current impact motion tracking systems, such as the MTi 100-series products, are not robust enough for crash tests and fail to meet the requirements of high spatial and time resolution due to limitations in measuring linear and angular acceleration, and are affected by ferromagnetic metals which distort magnetic fields, leading to positional inaccuracies.
Innovation Solution
An improved impact motion tracking system with a motion tracking sensor comprising a housing, magnetic, and inertial measurement modules, where a transmitter module generates magnetic fields, and an electronic processor calibrates impact motion information using a reference magnetic measurement module to correct for field distortions, ensuring a fixed positional relationship and high resolution tracking of up to 60g linear acceleration and 1500°/sec angular acceleration with spatial and time resolutions of less than 2mm and 0.02msec respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic measurement modules are used for tracking, then positional information can be obtained, but ferromagnetic metals distort magnetic fields leading to positional inaccuracies
Solution Approach 1:
The system uses a reference magnetic measurement module to continuously monitor magnetic field distortions caused by ferromagnetic metals. The electronic processor compares measurements from the reference module with those from other modules, detecting deviations caused by metal interference. This feedback mechanism enables real-time correction of positional data to compensate for magnetic field distortions.
Solution Approach 2:
The reference magnetic measurement module acts as an intermediary that measures the ambient magnetic field distortions separately. By placing this reference module in a known fixed position, the system can characterize the distortion pattern and use it to correct measurements from other modules, effectively mediating between the interfering magnetic environment and the tracking accuracy requirement.
2Reliability
If standard motion tracking sensors are used, then the system is easy to implement, but they lack structural robustness for crash tests and cannot measure high accelerations
Solution Approach 1:
The motion tracking system is divided into independent modular components: inertial measurement modules for acceleration tracking, magnetic measurement modules for positional tracking, and a reference module for distortion compensation. Each module is optimized for its specific function and can be independently calibrated and replaced, enhancing overall system robustness while maintaining manageable complexity.
Solution Approach 2:
The system changes the operational parameters of the sensors to match crash test requirements. The inertial measurement modules are configured with high acceleration ranges (±60g linear, ±1500°/sec angular) and high sampling rates (≥60kS/sec). The magnetic measurement system operates at high spatial resolution (≤2mm) and time resolution (≤0.02msec), with periodic calibration at regular intervals to maintain accuracy under extreme conditions.
3Measurement precision
If high sampling rates are used for impact motion tracking, then time resolution improves, but data processing requirements and system complexity increase
Solution Approach 1:
The system performs preliminary calibration of the inertial measurement modules using magnetic field data from the magnetic measurement modules before impact events occur. This pre-calibration establishes baseline relationships between the sensor modules, reducing the computational burden during high-speed impact tracking. The reference magnetic measurement module continuously monitors field conditions to maintain accurate calibration references.
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 system provides accurate and robust tracking of crash test dummies and vehicles with improved spatial and time resolution, maintaining a fixed connection during impact and correcting for magnetic field distortions, thereby enhancing the reliability of crash test data.
Implementation Method 1
a transmitter module (30) generates magnetic fields
Implementation Method 2
The magnetic measurement module measures magnetic fields generated by a transmitter module
Implementation Method 3
The inertial measurement module measures a linear acceleration and an angular acceleration
Data Source
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AI summary
An impact motion tracking system for tracking an object in a three-dimensional space, whereby a motion tracking sensor comprises a housing, a magnetic measurement module and an inertial measurement module; a transmitter module generates magnetic fields; said magnetic measurement module measures magnetic fields generated by said transmitter module, said magnetic measurement modules has a fixed positional relationship with at least one object portion of said object; said inertial measurement module measures at least one of a linear acceleration and an angular acceleration, said inertial measurement module has a fixed positional relationship with said at least one object portion; an electronic processor receives measured signals from said motion tracking sensor; said electronic processor derives an impact motion information for said object portion based on received measured signals from said inertial measurement module; said electronic processor derives a magnetic motion information for said object portion based on received measured signals from said magnetic measurement module; said electronic processor periodically calibrates impact motion information with magnetic motion information; and said object is at least one of a crash test dummy and a vehicle to be crashed.