LOSA Tracker Using Multi-Slit Aperture for 3D Motion Tracking
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Solution Overview
Problem
Existing indoor motion tracking systems are expensive, bulky, and limited in versatility due to their reliance on multiple video cameras and magnetic measurements, which are prone to interference, making them unsuitable for widespread applications beyond research.
Innovation Solution
The LOSA Tracker, an active marker-based 3D tracking system combining inertial sensing with optical sensing using a Linear Optical Sensor Array (LOSA) and an omnidirectional active marker, estimates position, velocity, and attitude without magnetometers, extending the field of view and reducing costs by eliminating lenses and bulky setups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple video cameras are used for motion tracking, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The system divides the tracking function into two segments: the LOSA tracker module handles optical position tracking using linear sensor arrays, while the active marker with IMU handles attitude estimation using inertial sensors and geometric relationships. This segmentation eliminates the need for multiple video cameras while maintaining tracking precision.
Solution Approach 2:
The patent replaces the optical-mechanical system of multiple video cameras with a hybrid system combining linear optical sensor arrays and inertial measurement units. The IMU-based attitude estimation substitutes for the computationally intensive optical flow analysis required by multiple cameras, reducing device complexity.
2Measurement precision
If magnetic measurements are used for attitude estimation, then measurement precision is improved, but reliability deteriorates due to electromagnetic interference
Solution Approach 1:
The patent introduces an intermediary approach by using the active marker's geometric structure as a reference frame. The marker's known geometry allows the system to calculate attitude through geometric relationships and LOS vector transformations, serving as an intermediary between direct magnetic measurement and final attitude estimation, thereby avoiding magnetic interference.
Solution Approach 2:
The system replaces magnetic field-based attitude estimation with a geometric-optical-inertial approach. The active marker uses its physical geometry combined with LOSA optical tracking and IMU data to determine attitude, substituting the vulnerable magnetic sensing mechanism with a more reliable multi-sensor geometric method.
3Measurement precision
If lenses are used in the tracking system, then measurement precision is improved, but cost and device complexity increase
Solution Approach 1:
The patent extracts and removes the lens component from the optical tracking system. Instead of using lenses to focus light onto 2D camera sensors, the system employs linear optical sensor arrays that directly detect light intensity distributions. This extraction eliminates the need for expensive and complex lens assemblies while maintaining position tracking capability through alternative optical principles.
Solution Approach 2:
The system replaces expensive lens-based optical systems with more economical linear sensor arrays. The LOSA modules use simpler optical components that are less costly to manufacture, making the overall tracking system more affordable and easier to produce without sacrificing essential tracking functionality.
4Reliability
If active marker geometry is used for attitude estimation, then reliability is improved by eliminating magnetometers, but device complexity increases
Solution Approach 1:
The patent merges multiple sensing modalities into the active marker: optical tracking from LOSA, inertial measurement from IMU, and geometric reference from the marker's known structure. By combining these elements, the system achieves reliable attitude estimation through data fusion in the EKF, where the geometric information from the active marker complements rather than complicates the overall system.
Solution Approach 2:
The active marker serves multiple functions simultaneously: it acts as an optical target for LOSA tracking, carries IMU sensors for inertial measurement, and provides a geometric reference frame for attitude calculation. This multi-functionality consolidates what would otherwise require separate components, actually reducing overall system complexity while improving reliability.
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 LOSA Tracker provides accurate, cost-effective motion tracking for robotics and virtual reality applications, enabling wireless human interface devices and gesture-based control with improved power efficiency and reduced computational intensity.
Implementation Method 1
The various embodiments locate the Light Emitting Diode (LED) illuminated active marker by using triangulation on a pinhole camera image of the active marker on a photosensitive area of the LOSA
Implementation Method 2
The various embodiments locate the Light Emitting Diode (LED) illuminated active marker
Implementation Method 3
A computer fuses the position estimates from stereovision and IMU data from the active marker using Extended Kalman Filter (EKF) to extract more accurate position and attitude estimates
Data Source
AI summary
The present invention is a standalone motion tracking device using Linear Optical Sensor Arrays (LOSA). The invention constitutes a tracker module and an active marker, which communicate with each other wirelessly. The motion tracking device uses optical tracking along with inertial sensing to estimate the position and attitude of the active marker relative to the tracker module. The system determines the position of the active marker using stereovision triangulation through multiple views emanating from different LOSA modules. The present invention also features novel use of a multi-slit aperture for LOSA sensors in order to increase the field of view and resolution of the position estimates. The system uniquely leverages the structural geometry of the active marker, along with inertial sensing, to estimate the attitude of the active marker relative to the tracker module without relying on magnetic sensing that may often be unreliable.