Dual Axis Rate Sensor with Coupled Proof Masses
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Solution Overview
Problem
Current angular rate sensors for automotive applications require two separate gyroscopes and ASICs, leading to increased size, cost, and complexity due to the need for dual sensing and drive control circuits.
Innovation Solution
A dual-axis angular rate sensor design featuring coupled masses for torsional drive mode oscillation and Coriolis force-induced rotation detection, utilizing a single ASIC and package to measure rotation about two orthogonal axes, with independent suspension members to minimize dynamic coupling and parasitic resonant modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two separate rate sensors are used to measure rotation about two orthogonal axes, then measurement capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines two separate rate sensing functions into a single integrated device. Two proof masses are coupled together through torsion beams to form a unified mechanical structure that senses rotation about two orthogonal axes simultaneously. The drive control circuit and sensing circuit are integrated to control both masses with a single ASIC, merging previously separate functions into one cohesive system.
Solution Approach 2:
The single rate sensor device performs multiple functions by measuring angular rate about two different orthogonal axes. The coupled proof masses are designed to respond to rotation about both axes, with each mass detecting Coriolis forces from rotation about the other axis, enabling one device to replace two separate sensors.
2Reliability
If two separate rate sensors with separate packages are used, then measurement redundancy is improved, but packaging size and cost increase
Solution Approach 1:
The patent integrates two previously separate packaged sensors into a single package. The coupled proof masses share common suspension elements and are housed together in one package, eliminating the need for two separate packages while maintaining the redundancy needed for measuring two orthogonal axes.
3Measurement precision
If two separate ASICs are used for drive control and sensing, then control precision is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent integrates the drive control and sensing functions for both proof masses into a single ASIC. This consolidated approach reduces manufacturing complexity and cost compared to using two separate ASICs, while the ASIC maintains the precision needed to control and sense from both coupled masses.
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 reduces the number of required ASICs and packages, lowering costs and complexity while enhancing mechanical response and reducing failure modes, allowing for efficient detection of angular rates with improved packaging and reduced cross-axis sensitivity.
Implementation Method 1
The first mass is mounted for oscillation about the second axis in response to Coriolis forces produced by rotation about the first axis
Implementation Method 2
the second mass is mounted for oscillation about the first axis in response to Coriolis forces produced by rotation about the second axis
Implementation Method 3
first and second masses coupled together for torsional drive mode oscillation of equal amplitude and opposite phase about third axes which are perpendicular to the first and second axes
Data Source
AI summary
Angular rate sensor for detecting rotation about first and second mutually perpendicular axes which has first and second masses coupled together for torsional drive mode oscillation of equal amplitude and opposite phase about third axes which are perpendicular to the first and second axes. The first mass is mounted for oscillation about the second axis in response to Coriolis forces produced by rotation about the first axis, and the second mass is mounted for oscillation about the first axis in response to Coriolis forces produced by rotation about the second axis. In some disclosed embodiments, the rate sensor also includes a pair of accelerometer masses which are connected together for torsional movement of equal amplitude and opposite phase about axes parallel to the third axes in response to acceleration along the second axis and for torsional movement of equal amplitude and opposite phase about axes parallel to the second axis in response to acceleration along the third axes.