Vibration Sensor Self-Test via Frequency Sweep
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Solution Overview
Problem
Existing ultrasonic obstacle detection systems lack a reliable self-test routine to provide detailed information about the state of the vibration component or sensor, beyond basic pulse emission, and fail to differentiate between mass changes and property alterations due to contamination or aging.
Innovation Solution
A self-test method that analyzes the post-vibration process by varying the excitation frequency, allowing for the evaluation of the resonant frequency and amplitude characteristics of the vibration component, enabling detection of changes in mass or properties through Fourier analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the excitation frequency is fixed at the resonant frequency for maximum signal strength, then the sensor provides direct feedback on pulse emission function, but no information about quality changes or contamination is obtained
Solution Approach 1:
The patent applies dynamics by making the excitation frequency variable rather than fixed. The control unit varies the excitation frequency around the resonant frequency to dynamically probe the system's response characteristics. This dynamic approach allows detection of changes in resonant frequency and damping that indicate contamination or aging, while still maintaining the ability to excite maximum amplitude at resonance for functional feedback.
Solution Approach 2:
The patent changes the parameter of excitation frequency to resolve the contradiction. By sweeping or modulating the excitation frequency around the resonant peak and analyzing the resulting amplitude and phase responses, the system extracts information about mass changes (contamination) and damping changes (aging) without sacrificing the ability to operate at maximum signal strength when needed.
2Reliability
If reference obstacles are used for generating self-test signals, then the self-test routine can be implemented, but the reference obstacles may change continuously making reproducible reference signals unavailable
Solution Approach 1:
The patent extracts the self-test function from dependence on external reference obstacles. Instead of using ground surface or other environmental references that change continuously, the system uses the intrinsic post-oscillation behavior of its own vibrating component as the reference. This internal reference is stable and reproducible, allowing reliable self-testing without being affected by external environmental changes.
Solution Approach 2:
The system performs self-testing using its own inherent characteristics. The vibrating component's natural post-oscillation decay provides a self-contained reference signal that requires no external references. This self-service approach ensures reproducible test signals while eliminating dependence on unstable external obstacles.
3Power
If the vibrating component is excited at resonant frequency for maximum amplitude, then high signal strength is achieved, but detailed information about mass changes versus property changes cannot be differentiated
Solution Approach 1:
The patent uses periodic action by applying excitation signals at multiple frequencies periodically around the resonant frequency. By measuring the amplitude and phase response at each frequency point in the sweep and analyzing the pattern of responses, the system can differentiate between mass changes (which shift resonant frequency) and property changes (which affect damping). This periodic multi-frequency excitation maintains high signal strength at resonance while providing detailed diagnostic information.
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 method provides detailed feedback on the vibration sensor's state, differentiating between mass increases and property changes, ensuring accurate obstacle detection and system performance monitoring.
Implementation Method 1
the excitation of a diaphragm is used on which a piezo element is mounted
Implementation Method 2
a harmonic oscillator has a resonant frequency at which, when being used as excitation frequency, the maximum amplitude is reached in relation to the excitation amplitude
Implementation Method 3
If the periodic excitation signal of a harmonic oscillator is switched off, then the vibrational energy stored in the oscillator is compensated by the damping, such that the oscillator vibration decreases across a decay process
Implementation Method 4
In the decay process, the harmonic oscillator is vibrating freely, i.e., without being excited into a forced vibrations by an excitation signal
Implementation Method 5
the sensor generates a sound pulse which travels away from the sensor at the propagation rate of the particular medium (usually air), is reflected by an obstacle
Implementation Method 6
the reflected pulse is then detected using the same sensor or a different sensor, so that the propagation time is able to be determined from the time interval between the emission of the pulse and the detection of the reflected pulse
Data Source
AI summary
In a method for functional testing of a mechanical vibration sensor, a vibration signal is generated on the vibration component of the vibration sensor with the aid of a periodic excitation signal, the frequency of which excitation signal is varied, and a post-vibration process of the vibration component of the vibration sensor is analyzed once the excitation signal has been switched off.