Adaptive Filtering for Low-Latency Electromagnetic Tracking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electromagnetic tracking systems face challenges with increased latency due to the exponential drop in magnetic field strength and interference, which are exacerbated by noise, leading to jitter in sensor measurements, especially at greater distances from the magnetic field source.
Innovation Solution
Integrate a non-magnetic tracking device, such as an inertial sensor, to provide accurate motion measurements that control an adaptive filter, allowing for low jitter and low latency by adjusting filtering based on sensor motion, independent of magnetic field strength fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a low-pass filter is applied to reduce jitter in sensor measurements, then measurement precision is improved, but system latency increases
Solution Approach 1:
The patent implements an adaptive filter that dynamically adjusts its filtering strength based on detected sensor motion. When motion is detected, the filter reduces its aggressive filtering to minimize latency; when stationary, it increases filtering to reduce jitter. This dynamic adaptation resolves the contradiction by making the filter behavior context-dependent rather than fixed.
Solution Approach 2:
The system changes the filter parameters (filtering strength) based on the motion state of the sensor. By monitoring velocity or acceleration thresholds, the system adjusts the filter's aggressiveness, transitioning between high-filtering mode (for jitter reduction) and low-filtering mode (for latency reduction), thus optimizing both measurement precision and response time.
2Measurement precision
If an adaptive filter is used to transition between filter settings based on sensor motion, then the tradeoff between jitter and latency is improved, but additional delay is introduced in filter transitions
Solution Approach 1:
The system performs preliminary action by pre-detecting motion states and preparing filter settings in advance. When motion thresholds are detected, the system proactively adjusts filter parameters before jitter or latency issues manifest, reducing the perceived transition delay and enabling smoother adaptations.
3Reliability
If a pre-filter is applied to improve velocity estimation for adaptive filter control, then measurement reliability is improved, but additional delay is introduced in adaptive filter transitions
Solution Approach 1:
The patent introduces an intermediary mechanism (motion detection based on velocity/acceleration thresholds) that mediates between the raw sensor data and the adaptive filter control. This intermediary layer processes motion information to trigger filter adjustments, ensuring reliable control signals are generated without excessive delay from the underlying sensor measurements.
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 achieves low latency and fast filter setting transitions without introducing additional delay, maintaining accurate tracking even at greater distances from the magnetic source by using non-magnetic tracking data to control the adaptive filter.
Implementation Method 1
a receiver circuit including a plurality of receiver elements aligned at different receiver axes, each receiver element configured to detect a magnetic field along its respective axis
Data Source
AI summary
An apparatus and method for determining position and orientation (PnO) of an object within an environment using an electromagnetic tracking system. An adaptive filter is used to strike a tradeoff between low jitter and low latency. When the object is slow moving or stationary, the adaptive filter is set to filter out jitter from the electromagnetic tracking system. When the object is in motion, the adaptive filter is set to reduce latency of the electromagnetic tracking system. An amount of motion of the object is monitored using a non-magnetic tracking device, whereby the setting of the adaptive filter is controlled based on the monitored motion using signals from the non-magnetic tracking device.