Optical Accelerometer Array for Beacon-Free Position Tracking
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Solution Overview
Problem
Conventional accelerometers suffer from significant noise, limiting their accuracy and usefulness, especially as they scale down in size, and existing 3D camera-based tracking systems rely on fixed beacons, which is impractical for portable applications.
Innovation Solution
An array of optical accelerometers with a common axis sensitivity is used, exploiting their low self-noise characteristics to enhance accuracy and enable beacon-free tracking by combining optical accelerometer outputs with camera data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional accelerometers are used, then device size can be reduced, but measurement precision deteriorates due to significant noise
Solution Approach 1:
The patent divides a single accelerometer function into multiple optical accelerometer elements arranged in an array. By segmenting the measurement function across multiple low-noise optical sensors, the system achieves high precision acceleration measurements while maintaining a compact form factor, resolving the contradiction between small size and measurement accuracy.
Solution Approach 2:
The patent replaces conventional mechanical accelerometers with optical accelerometers that use light reflection and interference patterns to measure acceleration. This substitution eliminates the mechanical noise inherent in traditional accelerometers, enabling high-precision measurements in a compact device.
2Measurement precision
If optical accelerometers are used, then measurement precision improves due to low self-noise, but device complexity increases due to array configuration
Solution Approach 1:
The patent combines multiple optical accelerometer elements into a unified array structure with shared optical components and integrated signal processing. This merging approach maintains the low noise benefits of individual optical accelerometers while reducing overall system complexity through shared resources and coordinated operation.
Solution Approach 2:
The optical accelerometer array is designed to perform multiple functions including acceleration measurement, rotation detection, and position tracking. This multi-functionality reduces the need for separate sensors, thereby decreasing overall device complexity while maintaining high measurement precision.
3Measurement precision
If 3D camera-based tracking is used, then position determination is achieved, but power consumption increases and fixed beacons are required
Solution Approach 1:
The patent uses optical accelerometers to pre-calculate and predict device position and orientation between camera updates. This preliminary action using low-power inertial measurements reduces the frequency and duration of high-power camera operations, thereby reducing overall power consumption while maintaining accurate position determination.
Solution Approach 2:
The optical accelerometer array serves as an intermediary between the camera and the final position solution. It provides continuous low-power motion data that bridges camera updates, enabling accurate position tracking without requiring continuous high-power camera operation or fixed beacon infrastructure.
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 array of optical accelerometers provides more accurate movement and rotation data, reducing noise and power consumption, enabling effective tracking in various mobile applications without fixed beacons.
Implementation Method 1
a light source arranged to provide a light beam which is reflected by a reflective surface moved by the measurement mass to detect the displacement thereof
Implementation Method 2
each of the accelerometers comprises a diffraction grating through which part of said light beam passes before being reflected from the reflective surface
Implementation Method 3
The reflected light interferes with light reflected from the diffraction grating to produces an interference pattern, changes in which can give a more accurate indication of movement of the reflective surface and thus the measurement mass
Data Source
Figure 1
Figure 2~3b
Figure 4
AI summary
An optical accelerometer arrangement (20) comprises an array of optical accelerometers (26)attached to a common structure (22). Each oftheoptical accelerometers (26) providesa signal indicative of displacement of a measurement mass (6) as a result of an acceleration along a given axis applied to the common structure (22). The arrangement (20) also comprises a processor (31a) configured to determine an estimate of the acceleration using the signals provided by the accelerometers (26). The arrangement (20) may be attached to an object (40; 46; 0; 52) which also comprises a gyroscope (44) and/or a camera (48).