MEMS Rotation Sensor Free Fall Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Micromechanical rotation rate sensors with continuous drive excitation tend to generate particles in the MEMS core during free fall, leading to electrical short circuits and increased noise due to delayed detection and natural decay of drive oscillations.
Innovation Solution
A rotation rate sensor with a micromechanical structure and mass oscillator that actively reduces the amplitude of drive oscillations upon detection of a free fall signal, using a drive controller with an amplifier device or phase inversion device to minimize particle generation during impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the mass oscillator is continuously driven to maintain operational readiness, then the sensor can quickly detect rotation rates, but particles are generated in the MEMS core during free fall collisions
Solution Approach 1:
The system performs preliminary detection of free fall conditions using an acceleration sensor before the harmful impact occurs. When free fall is detected, the drive oscillation is proactively reduced or interrupted in advance, preventing particle generation during the subsequent collision while maintaining quick response capability through the pre-positioned detection mechanism
Solution Approach 2:
The system uses feedback from the acceleration sensor to continuously monitor the operational state and dynamically adjust the drive oscillation. When free fall is detected, the feedback loop triggers immediate reduction or interruption of the drive signal, creating a closed-loop control system that prevents particle generation while maintaining operational readiness
2Reliability
If the drive oscillation amplitude is reduced during free fall to prevent particle generation, then sensor safety is improved, but the detection capability is temporarily compromised
Solution Approach 1:
The system implements periodic monitoring of free fall conditions through the acceleration sensor and applies periodic modulation to the drive oscillation. During normal operation, the drive continues uninterrupted; when free fall is periodically detected, the drive is temporarily reduced or interrupted. This periodic on/off control pattern maintains sensor safety while minimizing impact on overall detection capability
Solution Approach 2:
The system dynamically adjusts the drive oscillation amplitude based on real-time detection of free fall conditions. The drive controller modifies the drive signal characteristics (amplitude, frequency, or phase) in response to acceleration sensor input, creating a dynamic control system that adapts to changing operational conditions to balance safety and detection performance
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 active reduction of drive oscillation amplitude significantly reduces particle generation during free fall, enhancing sensor safety by minimizing damage and noise, and restoring normal operation once the free fall is over.
Implementation Method 1
the mass oscillator is drivable to a drive oscillation by means of a drive device
Implementation Method 2
the detection of a rotation rate via the action of the Coriolis force associated therewith
Implementation Method 3
the mass oscillator is coupled to the substrate of the micromechanical sensor by spring elements
Data Source
AI summary
A rotation rate sensor with a micromechanical structure and with a mass oscillator. The mass oscillator is drivable to a drive oscillation using a drive device. The rotation rate sensor is configured to protect the micromechanical structure and, during a time interval of a detected free fall situation, in such a way that a reduction of the amplitude of the drive oscillation is achieved. The free fall situation is signaled using a free fall signal supplied to the rotation rate sensor. The rotation rate sensor is configured in such a way that, after the reception of a further free fall signal signaling the end of the free fall situation, the drive device again drives the mass oscillator to its operative drive oscillation. The reduction of the amplitude of the drive oscillation is realized faster than in a mere dying-away process of the drive oscillation of the mass oscillator.