Differential Seesaw Accelerometer for Angular Acceleration Noise
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Solution Overview
Problem
Existing multi-axis accelerometers suffer from low resistance to external angular acceleration and bias errors due to tilting of the base, particularly affecting Y-axis and Z-axis detection, and are susceptible to noise from angular rotations and thermal stress.
Innovation Solution
The accelerometer employs nested seesaw structures with asymmetric mass distributions and differential detection capacitors, driven by normal and reversed phase carrier signals, to cancel out common mode changes and suppress the impact of angular acceleration noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single seesaw structure is used for acceleration detection, then the device complexity is reduced, but the ability to resist external angular acceleration impact deteriorates
Solution Approach 1:
The accelerometer is divided into multiple independent detection systems: a first seesaw structure for Y-axis detection and a second seesaw structure for Z-axis detection. Each seesaw structure operates independently with its own test mass and detection capacitors, allowing simultaneous multi-axis detection while maintaining resistance to angular acceleration through differential measurement techniques
Solution Approach 2:
The first seesaw structure and second seesaw structure are nested within the same housing and share common components such as the base, detection capacitors, and signal processing circuits. This nested arrangement reduces overall device complexity and footprint while maintaining the independent operational capability of each detection axis
2Measurement precision
If the center of mass of the structure is not aligned with the center of mass of the test mass, then the detection sensitivity is improved, but the impact of external angular acceleration increases
Solution Approach 1:
The test mass is designed with an asymmetric mass distribution where the center of mass is deliberately offset from the pivot point of the seesaw structure. This asymmetric configuration creates a larger torque for the same acceleration force, improving detection sensitivity while the differential measurement approach compensates for angular acceleration effects
Solution Approach 2:
The differential detection system uses two detection capacitors positioned on opposite sides of the seesaw structure. When angular acceleration occurs, both capacitors experience similar parasitic effects that cancel out in the differential measurement, effectively counteracting the harmful impact of angular acceleration on measurement accuracy
3Adaptability or versatility
If the base tilts due to thermal stress, then the structural adaptability is improved, but bias error in output increases
Solution Approach 1:
The detection capacitors are arranged symmetrically with respect to the base, creating an equipotential configuration where thermal expansion or tilting of the base affects both capacitors equally. This symmetric arrangement ensures that thermal-induced base tilting produces common-mode signals that are rejected by the differential detection system, maintaining measurement accuracy despite thermal stress
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 design effectively reduces the impact of angular acceleration noise and enhances detection sensitivity by canceling out common mode changes, improving the accelerometer's robustness and accuracy in detecting Z-axis, Y-axis, and X-axis accelerations.
Implementation Method 1
under the action of an acceleration in a Z-axis direction, the first seesaw structure rotates and tilts anticlockwise around the Y-axis direction, and the second seesaw structure rotates and tilts clockwise around the Y-axis direction
Implementation Method 2
under the action of an acceleration in the Y-axis direction, the first seesaw structure rotates and tilts clockwise around the Z axis direction, and the second seesaw structure rotates and tilts anticlockwise around the Z axis direction
Implementation Method 3
under an acceleration in the X-axis direction, the first seesaw structure and the second seesaw structure both translate along the X axis direction
Implementation Method 4
the first seesaw structure comprises first elastic members connected to the first anchor points, and a first mass block connected to the first elastic members
Data Source
AI summary
The present invention provides an accelerometer, including base, anchor points, seesaw structures elastically, and a differential detection assembly; the seesaw structures includes a first seesaw structure and a second seesaw structure which are parallel to each other and placed in reverse; the anchor points includes first anchor points and second anchor points; the first seesaw structure includes first elastic members and a first mass block connected to the first elastic members; the first mass block is driven by a normal phase carrier drive signal from the first anchor points; the second seesaw structure includes second elastic members and a second mass block connected to the second elastic members; and the second mass block is driven by a reversed phase carrier drive signal from the second anchor points. The accelerometer can effectively suppress the impact of noise of an angular acceleration of rotation.