Angular Velocity Estimation via Sensor Fusion
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Solution Overview
Problem
MEMS rate gyroscopes are power-intensive circuits that drain energy from electronic devices, particularly those powered by batteries, and increase costs, necessitating more efficient methods for estimating angular velocity.
Innovation Solution
A system and method using an accelerometer and magnetometer for 9-axis sensor fusion to estimate angular velocity, with adaptive filter lengths to balance measurement noise and responsiveness, and incorporating a processor to combine partial estimates from both sensors, thereby reducing the reliance on gyroscopes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a MEMS rate gyroscope is used to measure angular velocity, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent combines accelerometer and magnetometer sensors to estimate angular velocity, merging their measurements through sensor fusion algorithms. This approach replaces the dedicated gyroscope while achieving comparable angular velocity estimation accuracy, thereby reducing power consumption by eliminating the power-intensive gyroscope circuit.
Solution Approach 2:
The accelerometer and magnetometer, originally designed for other measurement purposes (acceleration and magnetic field detection respectively), are utilized to perform angular velocity measurement as well. This multi-functionality allows the system to achieve gyroscope-like functionality using existing sensors, avoiding the need for additional power-intensive dedicated gyroscope hardware.
2Reliability
If a MEMS rate gyroscope is used to detect changes in electronic device orientation, then reliability is improved, but device cost increases
Solution Approach 1:
The patent merges data from accelerometer and magnetometer sensors through sensor fusion to produce reliable angular orientation estimates. By combining the complementary information from these two sensors (accelerometer for gravity reference, magnetometer for magnetic north reference), the system achieves reliable orientation detection without requiring expensive gyroscope hardware.
Solution Approach 2:
Instead of using a physical gyroscope, the patent creates a virtual gyroscope by computationally estimating angular velocity from accelerometer and magnetometer measurements. This software-based approach copies the functional behavior of a gyroscope without requiring the expensive physical hardware, thereby reducing device cost while maintaining reliability.
3Measurement precision
If adaptive filter lengths are used to process sensor data, then measurement precision is improved, but computational complexity increases
Solution Approach 1:
The patent implements adaptive filter lengths that dynamically adjust based on current motion conditions. During periods of high motion or rapid orientation changes, shorter filter lengths are used to maintain responsiveness and capture fast changes. During stable periods, longer filter lengths are applied to reduce noise and improve precision. This dynamic adaptation optimizes the balance between precision and computational complexity.
Solution Approach 2:
The filter length parameter is changed adaptively based on motion characteristics detected by the sensors. By monitoring motion intensity and adjusting the filter length parameter accordingly, the system achieves high measurement precision when needed while reducing computational complexity during less demanding periods. This parameter adaptation allows the system to optimize performance based on actual operating conditions.
Data Source
AI summary
A system and method for estimating angular velocity are provided. The system and method use an accelerometer and magnetometer to estimate an angular velocity in place of a gyroscope in 9-axis sensor fusion to estimate angular orientation. The final angular velocity estimate is constructed from two partially independent angular velocity estimates, one using only magnetometer measurements and the other using only accelerometer measurements. The unobservable portion of each partial angular velocity estimate is provided by a projection from a third complete estimate that uses both accelerometer and magnetometer data.