Inertial Sensor Continuous Self-Test Electrode Segmentation
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Solution Overview
Problem
Current self-test techniques for inertial sensors are limited to startup and do not allow continuous monitoring, leading to potential distortion and catastrophic failures due to electrostatic forces during normal operation, and fail to detect errors in transducers under varying mechanical forces and frequencies.
Innovation Solution
A continuous self-test (CST) method is introduced, which includes multiple phases to detect errors in inertial sensors during operation, using electrostatic actuation and specialized electrodes to maintain normal operation while identifying offset and sense errors across a range of forces and frequencies, including 0 Hz, through a processing device and associated circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-test is performed during normal operation using electrostatic forces, then transducer errors can be detected in real-time, but distortion and catastrophic failures occur due to interfering electrostatic forces
Solution Approach 1:
The patent divides the electrode structure into separate functional groups: proof mass electrodes for sensing and self-test electrodes for testing. This segmentation allows independent operation of sensing and testing functions, enabling self-test without interfering with normal sensor operation and avoiding the harmful electrostatic forces that caused distortion in previous designs.
Solution Approach 2:
The patent extracts the self-test function from the sensing function by providing dedicated self-test electrodes that are separate from the proof mass sensing electrodes. This extraction allows self-test to be performed independently without the electrostatic interference that occurred when testing and sensing shared the same electrode structure.
2Measurement precision
If startup self-test is performed, then manufacturing variations can be detected, but continuous monitoring is not possible leading to undetected drift during operation
Solution Approach 1:
The patent enables continuous self-testing during normal sensor operation through dedicated self-test electrodes and circuitry. The self-test function can be performed continuously or periodically without interrupting the sensing operation, allowing ongoing detection of drift and errors throughout the sensor's operational lifetime, not just at startup.
3Reliability
If electrostatic forces are applied for self-test during operation, then transducer response can be verified, but false triggers may be initiated due to resulting distortion
Solution Approach 1:
By segmenting the electrode functions into separate proof mass electrodes and self-test electrodes, the patent eliminates the electrostatic interference that caused distortion during self-test. The separate self-test electrodes apply forces only to the proof mass for testing purposes without affecting the sensing output, thereby preventing false triggers while still verifying transducer response.
Solution Approach 2:
The patent introduces self-test electrodes as intermediary elements that mediate between the test signal and the proof mass. These intermediary electrodes allow self-test forces to be applied without directly interfering with the sensing electrodes or the sensing output, thus preventing false triggers while enabling response verification.
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 CST method enables reliable and accurate detection of transducer errors in real-time, ensuring the integrity and performance of inertial sensors across various applications, including automotive safety systems, by allowing self-testing during operation without interfering with input signals, thus enhancing reliability and preventing false triggers.
Implementation Method 1
Self-test electrodes are provided in addition to the proof mass electrodes. The self-test electrodes are used to apply forces to the proof mass during self-test modes of operation.
Data Source
AI summary
A sensor with continuous self test is provided. An exemplary inertial sensor may include one or more self test electrodes so that one or more test signals may be applied to the electrodes during normal operation of the sensor. Normal sensor output may be read and stored during normal operation, when self test signals are typically not applied to the sensor. The normal sensor output provides a baseline for comparison to a sensor offset error detection signal produced when a test signal may be applied to one self test electrode, and also to a sense error detection signal when a test signal may be applied to both self test electrodes.