Capacitive Gyroscope Linearization and Variable Rate Range Control
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Solution Overview
Problem
Capacitive gyroscopes suffer from non-linearities in pick off transducer signals, leading to errors in determining the angular rate of rotation.
Innovation Solution
A capacitive gyroscope with a primary and secondary pick off transducer system, a secondary drive transducer, a divider, and a linearizer that uses higher order harmonics to correct non-linearities, and a variable rate range loop to adjust the amplitude of the primary drive signal based on the angular rate of rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitive gyroscope uses a primary pick off transducer to detect oscillation in the primary mode of motion, then the angular rate of rotation can be determined, but non-linearities in the pick off transducer signals cause errors in the determined angular rate of rotation
Solution Approach 1:
The patent introduces a linearizer circuit as an intermediary component between the primary pick off transducer and the divider. This linearizer processes the non-linear output signal from the primary pick off transducer and produces a linearized signal that accurately represents the angular rate of rotation, thereby eliminating measurement errors caused by transducer non-linearities
Solution Approach 2:
The patent replaces the direct mechanical/electrical relationship where the primary pick off transducer output is fed directly to the divider with an electronic signal processing system. The linearizer uses electronic circuits to detect and correct non-linearities in the signal, substituting the simple mechanical coupling with an intelligent electronic intermediary that actively compensates for non-linear behavior
2Use of energy by moving object
If the amplitude of the primary drive signal is increased to improve signal strength, then the measurable rate range is limited due to non-linearities becoming more significant
Solution Approach 1:
The patent implements a variable rate range loop that dynamically adjusts the amplitude of the primary drive signal based on the current operating conditions and measured angular rate. This dynamic adaptation allows the system to optimize signal strength at low rates while preventing non-linearities from dominating at high rates, thereby extending the measurable rate range across multiple decades
Solution Approach 2:
The patent changes the operating parameter of primary drive signal amplitude from a fixed value to a variable parameter controlled by the variable rate range loop. By continuously adjusting this parameter based on feedback from the measurement system, the gyroscope maintains optimal performance across a wide range of angular rates, effectively extending the measurable rate range
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
Significantly reduces errors in angular rate measurement by linearizing the output from the primary pick off transducer, improving accuracy and extending the measurable rate range.
Implementation Method 1
a primary drive transducer configured to oscillate the structure in a primary mode of motion
Implementation Method 2
a primary pick off transducer configured to detect oscillation of the structure in the primary mode of motion
Implementation Method 3
a secondary pick off transducer configured to detect oscillation of the structure in a secondary mode of motion
Implementation Method 4
a secondary drive transducer configured to null oscillation of the structure in the secondary mode of motion
Implementation Method 5
Capacitive gyroscopes determine angular rate of rotation by driving a structure to vibrate at its resonant frequency and then nulling oscillations caused by the Coriolis effect
Data Source
Figure 1
Figure 2a~3
Figure 4a~4b
AI summary
A capacitive gyroscope comprising: a structure configured to vibrate; a primary drive transducer configured to oscillate the structure in a primary mode of motion; a primary pick off transducer configured to detect oscillation of the structure in the primary mode of motion; a secondary pick off transducer configured to detect oscillation of the structure in a secondary mode of motion; a secondary drive transducer configured to null oscillation of the structure in the secondary mode of motion; a divider configured to determine an angular rate of rotation of the capacitive gyroscope based on an output from the primary pick off transducer and an output indicative of a secondary drive signal for the secondary drive transducer; and a linearizer configured to linearize the output from the primary pick off transducer based on at least one higher order harmonic of the output from the primary pick off transducer.