Vestibular Prosthesis Multi-Axis Tilt Estimation
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Solution Overview
Problem
Current vestibular prostheses are limited in providing accurate tilt and sway information in multiple axes and lack effective remedial actions, such as fall detection and prevention, due to gyroscopic bias errors and lateral accelerations, which affect postural stability in individuals with balance impairments.
Innovation Solution
A wearable vestibular prosthesis system that combines accelerometers and gyroscopes to generate accurate tilt estimates using quaternions and Euler angles, and employs a Kalman filter to reduce errors, with the capability to deploy an airbag for fall prevention, providing tactile stimulation to aid balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-axis tilt estimation is used in vestibular prostheses, then device complexity is reduced, but measurement precision and reliability of postural stability control deteriorate
Solution Approach 1:
The patent transitions from single-axis tilt estimation to multi-axis tilt estimation by incorporating gyroscopes and accelerometers that measure motion in multiple dimensions. The system uses quaternions to represent orientation in 3D space, allowing accurate estimation of tilt angles (roll and pitch) while accounting for complex multi-axis movements. This dimensional expansion resolves the contradiction by providing comprehensive spatial awareness without excessive complexity increase.
Solution Approach 2:
The patent combines data from multiple sensor types (gyroscopes and accelerometers) into a unified tilt estimation system. By merging the high-frequency response of gyroscopes with the gravity-reference accuracy of accelerometers through quaternion-based fusion algorithms, the system achieves superior measurement precision that neither sensor could provide alone, while maintaining manageable device complexity through integrated processing.
2Device complexity
If gyroscopic bias errors are not corrected, then device complexity is reduced, but reliability of tilt estimates deteriorates over time
Solution Approach 1:
The patent implements feedback mechanisms where the system continuously monitors gyroscopic bias errors and applies corrective adjustments to the tilt estimation. The quaternion-based processing framework incorporates bias compensation that uses feedback from accelerometer measurements (which provide a stable gravity reference) to correct drift in gyroscopic integration, ensuring long-term reliability without requiring overly complex correction systems.
Solution Approach 2:
The patent uses accelerometers as an intermediary reference to correct gyroscopic bias errors. The accelerometer provides a stable gravity vector measurement that serves as a mediator to detect and correct drift in the gyroscopic integration over time. This intermediary approach allows reliable long-term tilt estimation by using the accelerometer's gravity reference to periodically recalibrate the gyroscopic data without requiring complex active correction systems.
3Device complexity
If lateral accelerations are not compensated, then device complexity is reduced, but measurement precision of tilt estimates deteriorates
Solution Approach 1:
The patent segments the acceleration measurements into distinct components: gravity-related acceleration (useful for tilt estimation) and lateral motion acceleration (disturbance to be rejected). By separately identifying and processing these components through quaternion-based algorithms, the system can selectively use the gravity component for tilt calculation while filtering out lateral acceleration effects, achieving high precision without excessive complexity.
Solution Approach 2:
The patent applies local quality by treating different components of the acceleration vector differently in the processing algorithm. The system identifies the vertical gravity component and preserves it for tilt estimation, while applying different processing (filtering or rejection) to the horizontal lateral acceleration components. This selective processing of local vector components allows precise tilt measurement during movement without requiring complex full-vector compensation systems.
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 effectively improves postural stability by providing accurate multi-axis tilt information and remedial actions, reducing sway and preventing falls, with enhanced accuracy and reliability over long periods.
Implementation Method 1
a wearable motion sensing system, the motion sensing system generating a motion signal indicative of a motion thereof, the motion thereof including rotation about two distinct axes
Implementation Method 2
The estimates reduce the impact of gyroscopic bias errors and lateral accelerations
Data Source
AI summary
Among other things, a vestibular prosthesis includes a wearable motion sensing system, the motion sensing system generating a motion signal indicative of a motion thereof, wherein the motion includes rotation about two distinct axes; a signal processor in communication with the motion sensing system, the signal processor being configured to generate an estimate of a tilt of the motion sensing system; and an actuator responsive to the estimate of the tilt made by the signal processor.