MEMS Gyroscope Start-Up Circuit for Stable Resonant Oscillation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing MEMS gyroscope start-up processes struggle to ensure that the driving mass oscillates at the desired resonant frequency and amplitude, particularly avoiding unstable operation regions and hysteresis, while efficiently minimizing start-up time.
Innovation Solution
A method involving sensing residual mechanical oscillation phase, frequency, and amplitude to determine appropriate drive signals, including anti-phase, phase lock loop, and automatic gain control, to actively dampen or induce oscillations, ensuring oscillation at the desired resonant mode and controlled amplitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a drive signal is applied to start the MEMS gyroscope, then oscillation is initiated, but the oscillation may occur at spurious modes or unstable frequencies due to the duffing effect
Solution Approach 1:
The system performs preliminary sensing of residual mechanical oscillation characteristics (phase, frequency, amplitude) before applying the drive signal. This preliminary action allows the system to detect the current state of the driving mass and determine the appropriate start-up strategy, preventing entry into unstable operation regions while initiating oscillation efficiently.
Solution Approach 2:
The system uses feedback from the sensed residual oscillation characteristics to dynamically adjust the drive signal parameters. By continuously monitoring phase, frequency, and amplitude, and comparing against desired resonant mode parameters, the system can adaptively control the drive signal to maintain stable oscillation and avoid spurious modes during start-up.
2Loss of time
If the drive signal amplitude is increased to reduce start-up time, then oscillation amplitude increases, but the system enters unstable operation regions with frequency hysteresis
Solution Approach 1:
The system dynamically adjusts the drive signal amplitude based on the sensed oscillation state rather than applying a fixed amplitude. The amplitude is modulated in real-time according to the detected frequency and phase, allowing the system to navigate through the start-up process efficiently while avoiding unstable operation regions characterized by frequency hysteresis.
Solution Approach 2:
The system changes the drive signal parameters (amplitude, phase, frequency) based on the sensed residual oscillation characteristics. By adjusting these parameters dynamically during start-up, the system can achieve rapid oscillation initiation while maintaining frequency stability and avoiding the duffing effect's unstable regions.
3Device complexity
If residual oscillation is not sensed before applying drive signal, then start-up process is simpler, but the system cannot avoid spurious modes or optimize start-up timing
Solution Approach 1:
The system uses the MEMS gyroscope's own residual mechanical oscillation as the basis for determining start-up timing and drive signal characteristics. By sensing its own state and using this information to control the drive signal, the system achieves reliable resonant mode initiation without requiring external complex control mechanisms.
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 method efficiently and quickly initiates MEMS gyroscope operation by avoiding unwanted modes, reducing start-up time, and maintaining stable oscillations within desired resonant frequencies and amplitudes, thus enhancing operational reliability.
Implementation Method 1
a drive actuation electrode configured to respond to a applied drive signal by applying an electrostatic force to induce oscillation of the driving mass
Implementation Method 2
the sensing mass is subjected to a Coriolis force proportional to the angular velocity itself
Implementation Method 3
The two mobile masses are both capacitively coupled to the stator body
Implementation Method 4
Because the MEMS gyroscope is a coupled spring-mass-damper system, it intrinsically possesses a plurality of resonant modes
Data Source
AI summary
At start-up of a microelectromechanical system (MEMS) gyroscope, the drive signal is inhibited, and the phase, frequency and amplitude of any residual mechanical oscillation is sensed and processed to determine a process path for start-up. In the event that the sensed frequency of the residual mechanical oscillation is a spurious mode frequency and a quality factor of the residual mechanical oscillation is sufficient, an anti-phase signal is applied as the MEMS gyroscope drive signal in order to implement an active dampening of the residual mechanical oscillation. A kicking phase can then be performed to initiate oscillation. Also, in the event that the sensed frequency of the residual mechanical oscillation is a resonant mode frequency with sufficient drive energy, a quadrature phase signal with phase lock loop frequency control and amplitude controlled by the drive energy is applied as the MEMS gyroscope drive signal in order to induce controlled oscillation.