Rotating MEMS Gyroscope Bias Modulation for Aircraft Navigation
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Solution Overview
Problem
Current inertial measurement systems, particularly those using MEMS technology, face challenges in achieving the necessary precision and stability for aircraft navigation, especially in instrument flight rules (IFR) conditions, due to significant biases in gyroscope measurements, which are not adequately addressed by existing solutions.
Innovation Solution
An inertial measurement device with a rotating assembly driven by an electric motor, where the motor controls the rotational speed to offset bias frequencies, using orthogonal measurement axes and complementary sensors to project measurements without bias, and a control method that maintains constant inertial rotation speed to minimize temperature compensation and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If MEMS gyroscopes are used to reduce cost, then manufacturing cost is reduced, but measurement precision and bias stability deteriorate
Solution Approach 1:
The patent changes the operational parameters of the MEMS gyroscope by rotating the sensing assembly at a controlled speed to modulate the bias instability. This frequency modulation transforms the low-frequency bias drift into a higher-frequency signal that can be filtered and corrected, thereby improving measurement precision while maintaining the use of low-cost MEMS gyroscopes
Solution Approach 2:
The patent introduces an intermediary processing system that includes a rotating assembly mechanism and signal processing electronics. This intermediary system modulates the raw gyroscope signals through rotational movement and applies correction algorithms, effectively bridging the gap between low-cost MEMS sensors and the precision requirements for IFR navigation
2Measurement precision
If high rotation speed is used to attenuate measurement biases, then measurement precision is improved, but device complexity and energy consumption increase
Solution Approach 1:
The patent employs dynamic rotation of the sensing assembly at a controlled, variable speed rather than maintaining constant high-speed rotation. The rotation speed can be adjusted based on operational requirements, and the system dynamically compensates for bias through signal processing, thereby achieving precision improvement without requiring continuously complex high-speed mechanical systems
Solution Approach 2:
The patent replaces complex mechanical bias compensation mechanisms with an electronic signal processing system. Instead of using additional mechanical gyroscopes or complex gimbal systems to physically counteract bias, the invention uses electronic algorithms to detect and correct bias errors in the signal domain, significantly reducing mechanical complexity
3Measurement precision
If temperature stabilization is implemented to reduce bias instability, then measurement precision is improved, but energy consumption and startup time increase
Solution Approach 1:
The patent introduces an intermediary signal processing system that acts as a mediator between the gyroscope sensor and the navigation system. This intermediary includes electronic correction algorithms that compensate for temperature-induced bias variations without requiring active thermal management, thereby achieving precision improvement without the energy penalty of temperature stabilization systems
4Measurement precision
If periodic recalibrations are performed to correct bias drift, then measurement precision is maintained, but loss of time and operational availability decrease
Solution Approach 1:
The patent implements continuous bias correction through the rotational modulation mechanism and ongoing signal processing, rather than relying on periodic recalibration events. The system continuously monitors and corrects bias drift as it occurs, maintaining measurement precision without interrupting operations for recalibration, thereby eliminating time loss while sustaining bias accuracy
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 significantly reduces measurement biases, enhances precision, and allows for lower-quality gyroscopes to achieve performance equivalent to FOG technology with lower power consumption and higher reliability, eliminating the need for temperature stabilization and periodic recalibrations.
Implementation Method 1
controlling at least one inertial speed of rotation of the moving assembly so that the sine and cosine functions of the angle of the moving assembly with respect to an inertial frame are substantially zero on average over an integer number of revolutions, the speed of rotation being greater than a reference value imposing a frequency offset of the bias of the measuring means
Implementation Method 2
calculation means for determining from of the angular position of the movable assembly, the projection of the measurements taken along the rotating axes X' and Z' by the said at least two measuring means onto the fixed axes X and Z of the structure
Data Source
Figure 1~2a
Figure 2b~11
Figure 3~7
AI summary
The device has an electric motor (6) comprising units for controlling inertial rotation speed of a moving element, so that sine and cosine functions of an angle of the moving element with respect to reference inertia are zero on average on integer number of revolutions. The inertial rotation speed is greater than a reference value of imposing bias frequency shifting of measurement units, where the shifting is greater than bandwidth of bias instability of the measurement units. Independent claims are also included for the following: (1) a method for measuring inertia of a vehicle or aircraft (2) a method for controlling and regulating enslaving inertial rotation speed of an electric motor of an inertia measuring device.