MEMS Resonator Frequency Sweep Start-Up for Faster Gyroscopes
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Solution Overview
Problem
MEMS gyroscopes face significant start-up time delays due to the need for the proof-mass motion to reach its natural resonance frequency, which is not consistently known and is affected by manufacturing tolerances and interactions between electrical and mechanical components, leading to inefficient power consumption and slow gain increase.
Innovation Solution
A digital actuator is introduced to initiate the motion of the MEMS proof mass in an open loop mode with a frequency sweep kick, followed by fine-tuning in a closed loop mode, reducing start-up time by generating and providing a frequency sweep of pulses around the targeted natural frequency of the proof mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the proof-mass motion is allowed to naturally reach its resonance frequency without external assistance, then the system operates with simple control circuitry, but the start-up time is significantly delayed and power consumption increases
Solution Approach 1:
The patent applies preliminary action by providing a kick-start signal to the proof mass before it begins its natural oscillation. This initial impulse helps the system reach its resonant frequency faster, reducing start-up time without requiring continuous complex control during the entire operation
Solution Approach 2:
The patent uses periodic action through oscillating the proof mass at its natural resonant frequency. By detecting when the proof mass passes through its neutral position and applying periodic kick-start signals synchronized with this natural oscillation, the system efficiently builds up amplitude without requiring complex continuous control circuitry
2Speed
If the drive actuation signal is continuously maintained at high level to ensure quick response, then the response speed is improved, but the power consumption increases
Solution Approach 1:
The patent employs periodic action by applying drive actuation signals only when needed - specifically when the proof mass passes through its neutral position during oscillation. This periodic stimulation maintains the oscillation amplitude without requiring continuous high-level signaling, thus reducing power consumption while maintaining fast response capability
Solution Approach 2:
The system applies self-service by utilizing the natural resonant oscillation of the proof mass to generate its own drive signal timing. The detection circuit monitors the proof mass position and automatically triggers the drive signal at the optimal moment, eliminating the need for continuous external control and reducing power consumption
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 approach significantly reduces the start-up time for MEMS devices by quickly reaching the drive activation signal, allowing for faster oscillation and meaningful measurements while conserving power by maintaining the oscillation in an idle state.
Implementation Method 1
the proof-mass motion to reach its natural resonance frequency
Implementation Method 2
A vibrating micro-electro-mechanical-system (MEMS) gyroscope
Implementation Method 3
The drive actuation unit typically comprises a capacitive coupling along the driving axis between a capacitor plate on the substrate and an opposite capacitor plate on the movable gyroscope mass
Implementation Method 4
A Coriolis force acting on the gyroscope mass may be induced as a capacitive force by applying a voltage to the capacitor plates of the drive actuation unit, whereby the gyroscope mass is moved
Data Source
AI summary
A system comprises a mechanical resonator; an analog circuit operably coupled to the mechanical resonator; the analog circuit arranged to receive a mechanical resonator measurement signal and to output a mechanical resonator actuation signal to the mechanical resonator; and a digital actuator operably coupled to the analog circuit and configured to provide a frequency sweep of signals to the analog circuit that induces movement of the mechanical resonator.