Personal Inertial Navigation Using Tri-Sensor Fusion
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Solution Overview
Problem
Existing inertial navigation systems (INS) face challenges in accurately deriving angular acceleration, leading to error accumulation, making them unsuitable for low-cost, portable applications like consumer devices due to noise, sampling rate limitations, and environmental interference.
Innovation Solution
The use of three independent sensors: a compass for angle measurement, a gyroscope for angular velocity, and an angular accelerometer for angular acceleration, combined to minimize errors and improve precision, with noise suppression techniques to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If angular acceleration is derived from gyroscope data through mathematical operations, then system cost is reduced, but measurement precision and reliability deteriorate due to error accumulation and noise
Solution Approach 1:
The patent segments the angular acceleration measurement function into two independent parts: a low-cost gyroscope for capturing angular velocity trends and a specialized angular accelerometer for providing precise acceleration corrections. This segmentation allows each component to operate in its optimal performance range while compensating for the other's weaknesses, resolving the contradiction between cost reduction and precision maintenance.
Solution Approach 2:
The angular accelerometer acts as an intermediary component that mediates between the gyroscope's noisy integrated output and the final angular acceleration measurement. By introducing this intermediate sensor, the system can filter out gyroscope errors and noise while maintaining low overall cost, as the accelerometer only needs to provide correction signals rather than operate independently at full specification.
2Measurement precision
If high-precision sensors are used for angular velocity and acceleration measurements, then measurement precision improves, but device size and weight increase
Solution Approach 1:
The patent employs low-cost, lightweight MEMS-based gyroscopes and angular accelerometers that sacrifice some individual sensor precision compared to military-grade alternatives. However, through sophisticated signal processing and fusion algorithms, the system achieves navigation-grade precision output, effectively using cheap components to deliver high-performance results.
Solution Approach 2:
The system creates a composite sensing solution by combining multiple low-cost MEMS sensors (gyroscope and angular accelerometer) to achieve performance equivalent to or exceeding single high-precision sensors. This composite approach leverages the complementary strengths of each sensor type while minimizing weight and cost.
3Device complexity
If mathematical operations are performed on sensor data to derive navigation parameters, then system complexity is reduced, but reliability deteriorates due to error accumulation and noise
Solution Approach 1:
The patent implements feedback mechanisms where the angular accelerometer continuously monitors and corrects drift errors in the gyroscope's angular velocity measurements. This feedback loop prevents error accumulation by actively compensating for gyroscopic drift, thereby maintaining reliable navigation solutions without requiring overly complex error correction algorithms.
Solution Approach 2:
The system replaces complex mechanical error correction mechanisms with electronic signal processing and sensor fusion algorithms. By using digital signal processing to fuse data from the gyroscope and angular accelerometer, the system achieves high reliability without the mechanical complexity of traditional inertial navigation 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
This approach achieves high accuracy comparable to expensive military-grade systems, enabling low-cost, lightweight, and portable inertial navigation devices with reduced error drift, suitable for consumer products.
Implementation Method 1
Angular velocity and acceleration sensors use inertial properties to detect and measure the angular displacement due to acceleration or velocity
Implementation Method 2
The angle measurement can be measured using a compass or magnetic field
Implementation Method 3
the angular velocity can be measured using a gyroscope (such as a MEMS gyroscope)
Data Source
AI summary
A system (400, 500) and method (800) of personal inertial navigation measurements can include measuring (802) an angle, measuring (804) an angular velocity independent of an angle measurement, measuring (806) an angular acceleration independent of the angle measurement and independent of an angular velocity measurement, and combining (808) the angle measurement, the angular velocity measurement, and an angular acceleration to provide an angled output. The angle measurement can be measured using a compass or magnetic field, the angular velocity can be measured using a gyroscope (such as a MEMS gyroscope), and the angular acceleration measurement can be measured using an angular accelerometer (such as a molecular electronic transfer device having a magneto hydrodynamic effect device). The method can further include suppressing (810) noise caused by the angle measurement by using a sample and hold circuit (504) controlled by a higher ordered component to suppress noise from a lower ordered component.