Rotation Rate Sensor Free Fall Protection
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Solution Overview
Problem
Microelectromechanical inertial sensors, particularly rotation rate sensors, are prone to damage and mechanical blockages during mechanical shocks, such as falls, due to the deflection and potential jamming of the seismic mass and drive comb structures.
Innovation Solution
The sensor system includes a control unit that detects free falls using acceleration sensors and temporarily deactivates the driving force to the seismic mass, preventing damage and mechanical blockages by halting the seismic mass's movement during impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the seismic mass is actively driven to oscillate for measurement, then the rotation rate measurement capability is improved, but the susceptibility to impact damage and mechanical blockage increases
Solution Approach 1:
The control unit continuously monitors acceleration signals to detect free fall conditions before impact occurs. Upon detecting a free fall event, the control unit preemptively deactivates the drive electrodes, stopping the seismic mass oscillation before impact can cause damage. This preliminary action prevents the contradiction by eliminating the vulnerable oscillating state before the harmful impact event.
Solution Approach 2:
The system applies a counter-action by deactivating the driving force during detected free fall events. This anti-action directly opposes the harmful effect by ensuring the seismic mass is stationary during impact, thereby preventing the combination of oscillation and impact that causes damage and mechanical blockage.
2Power
If the drive comb is engaged with the opposing comb for actuation, then the seismic mass can be driven effectively, but the risk of interlocking or jamming during mechanical shock increases
Solution Approach 1:
Upon detecting a free fall event, the control unit immediately deactivates the drive electrodes, stopping the drive comb oscillation before impact can cause interlocking or jamming. This preliminary deactivation prevents the drive comb from being in a vulnerable engaged state during the harmful impact event.
3Force
If the seismic mass is deflected during mechanical shock, then impact energy is absorbed, but damage to the sensor structure and impairment of functional capability occur
Solution Approach 1:
The control unit detects free fall events and deactivates the drive electrodes before impact occurs, ensuring the seismic mass is stationary during the impact event. This eliminates the harmful superposition of oscillation and impact that causes excessive deflection and structural damage.
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 solution effectively reduces the risk of damage and mechanical blockages in rotation rate sensors during impacts, enhancing the robustness and reliability of the sensor system, and expanding its potential applications.
Implementation Method 1
The control unit is configured to detect a free fall of the sensor system, in particular, as a function of a measuring signal of an acceleration sensor
Implementation Method 2
The electrode array is configured to generate an alternating electrostatic field, which acts as a driving force on the seismic mass and causes it to oscillate
Implementation Method 3
During a rotation of the sensor, a Coriolis acceleration acts on the oscillating mass, which causes a detection oscillation extending perpendicularly to the drive oscillation
Data Source
AI summary
A sensor system. The sensor system includes a rotation rate sensor and a control unit, the rotation rate sensor including a seismic mass and being configured to drive a movement of the seismic mass with the aid of a driving force, the control unit being configured to detect a free fall of the sensor system and to deactivate the driving force in the event of a detection of the free fall. A method for securing a sensor system, in a detection step a free fall of the sensor system being detected by the control unit, and in a securing step the driving force being deactivated by the control unit, is also described.