Gyroscope Frequency Locking via Quartz Resonator Clock
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Solution Overview
Problem
Existing gyroscopes face bias instability due to temperature fluctuations, with prior art solutions being costly and voluminous, and low-cost MEMS gyroscopes lacking sufficient bias stability for navigational applications.
Innovation Solution
A precision gyroscope integrated with a quartz resonator clock and a control loop on a semiconductor or quartz substrate, utilizing heaters and a phase-locked loop to stabilize the gyroscope's frequency and temperature, achieving sub-ppb frequency control and improved bias stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature compensation and/or ovenization are utilized to control temperature, then bias stability is improved, but volume and power consumption increase significantly
Solution Approach 1:
The patent combines the gyroscope and quartz resonator clock onto a single substrate, integrating temperature sensing and frequency reference functions directly with the gyroscope. This merging eliminates the need for separate temperature control modules and external reference clocks, achieving compact volume while maintaining bias stability through on-chip temperature monitoring and frequency locking.
Solution Approach 2:
The quartz resonator clock serves as an intermediary reference that mediates between temperature fluctuations and gyroscope frequency stability. By using the resonator's highly stable frequency as a reference and implementing frequency locking through a phase-locked loop, the system achieves temperature compensation without requiring physical temperature control hardware, thus reducing volume.
2Reliability
If temperature compensation and/or ovenization are utilized to control temperature, then bias stability is improved, but power consumption increases to several watts
Solution Approach 1:
The system uses the quartz resonator clock's inherent frequency stability as a self-contained reference that requires no external power-intensive temperature control. The resonator naturally maintains its frequency across temperature ranges, and the phase-locked loop uses this reference to self-correct gyroscope frequency drift, eliminating the need for high-power ovenization while maintaining bias stability.
Solution Approach 2:
The patent replaces the mechanical/thermal temperature control system (ovens and heaters consuming several watts) with an electronic frequency locking system. By substituting thermal management with electronic frequency reference and phase-locked loop control, the system achieves the same bias stability outcome with minimal power consumption.
3Measurement precision
If Si thermistors are used to detect temperature fluctuations, then temperature detection is achieved, but accuracy is insufficient (10-100 mK range) resulting in inadequate bias stability
Solution Approach 1:
The patent changes the fundamental parameter being controlled from temperature to frequency. Instead of attempting to measure and control temperature with high-precision thermistors, the system monitors and locks the gyroscope's operating frequency to the quartz resonator reference. This frequency-based approach achieves superior stability because frequency can be measured and controlled with much higher precision than temperature, directly addressing the bias stability requirement.
4Ease of manufacture
If low cost MEMS gyroscopes are used without temperature control, then cost is reduced, but bias stability becomes insufficient for navigational applications
Solution Approach 1:
The patent integrates the quartz resonator clock and temperature sensing capabilities directly onto the MEMS gyroscope substrate, creating a single low-cost integrated unit. This merging eliminates the need for separate expensive temperature control modules while providing sufficient bias stability through on-chip frequency locking, making navigational-grade gyroscopes economically viable.
Solution Approach 2:
The system shifts from temperature-based control (which requires expensive precision thermistors and ovens) to frequency-based control using a quartz resonator reference. This parameter change enables low-cost implementation because quartz resonators are inexpensive and can be integrated directly on the MEMS substrate, providing navigational-grade bias stability without the high costs of traditional temperature control approaches.
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
The solution provides a low-cost, low-volume gyroscope with significantly improved bias stability, enabling its use in various applications such as micro UAVs and handheld GPS systems, with a bias stability three orders of magnitude better than prior art.
Implementation Method 1
a quartz resonator clock integrated on the substrate
Implementation Method 2
utilizing heaters and a phase-locked loop to stabilize the gyroscope's frequency and temperature
Data Source
AI summary
A precision gyroscope includes a semiconductor substrate, a gyroscope integrated on the substrate, and a quartz resonator clock integrated on the substrate. In another embodiment the substrate is a quartz substrate.