Ultrasonic Sensor Sensitivity Tuning From Membrane Frequency Response
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Solution Overview
Problem
Existing ultrasonic sensors in vehicles face sensitivity issues due to temperature variations, affecting the accuracy of distance measurements, which current temperature compensation methods do not adequately address.
Innovation Solution
A method for ultrasonic sensors that involves obtaining calibration data at different temperatures, determining the current membrane temperature, and adjusting the electric current and gain to match a target sensitivity, thereby compensating for temperature-dependent frequency responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If temperature compensation is applied using existing methods (temperature sensor with threshold values or resonance frequency observation), then the sensor can operate across different temperatures, but the sensitivity accuracy deteriorates because these methods do not adequately address temperature-dependent frequency response variations
Solution Approach 1:
The patent applies preliminary action by pre-measuring and storing frequency response data at multiple temperatures before actual operation. During operation, the system retrieves pre-calculated sensitivity values corresponding to the current temperature, eliminating the need for real-time complex calculations and enabling accurate temperature compensation without adding computational burden during measurement
Solution Approach 2:
The patent changes the parameter approach by transitioning from simple threshold-based compensation to frequency-response-based compensation. Instead of using fixed threshold values or resonance frequency observations, the system utilizes comprehensive frequency response measurements at different temperatures to calculate and adjust sensitivity values, directly addressing the temperature-dependent frequency response variations that cause measurement inaccuracies
2Measurement precision
If the electric current to the exciter element and gain are adjusted to compensate for temperature effects, then the sensitivity accuracy improves, but the device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent implements feedback by continuously monitoring the membrane temperature and using this information to adjust the electric current to the exciter element and the gain of the ultrasonic sensor. The control unit receives temperature data, determines the appropriate sensitivity correction based on pre-stored frequency response data, and applies compensatory adjustments to maintain accurate sensitivity across varying temperatures
Solution Approach 2:
The system applies self-service by automatically compensating for temperature effects without requiring external intervention. The control unit autonomously monitors temperature changes, retrieves appropriate correction factors from stored frequency response data, and adjusts the exciter current and sensor gain accordingly, enabling the sensor to self-correct for temperature-induced sensitivity variations
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 enhances the accuracy of ultrasonic sensors by effectively adjusting sensitivity across varying temperatures, ensuring consistent performance and improved distance measurement precision.
Implementation Method 1
an exciter element for exciting the membrane and/or for detecting a vibration of the membrane
Implementation Method 2
The exciter element then detects vibrations of the ultrasonic membrane, which result from an echo signal returning from the vehicle environment
Implementation Method 3
The ultrasonic membrane, excited by an exciter element attached to it, emits energy in the form of an ultrasonic signal
Implementation Method 4
DE 10 2012 002979 A1 shows an ultrasonic sensor according to the above. A temperature dependent oscillator is used as the exciter element to compensate for the signal propagation time depending on the surrounding temperature of the ultrasonic sensor
Data Source
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AI summary
A method for operating an ultrasonic sensor (2) comprising a membrane (3) and an exciter element (4); the method comprising: obtaining (S1) calibration data from a storage unit (9) storing the calibration data, the calibration data comprising a first frequency response (FR1) of the ultrasonic sensor in a sending direction (SD) depending on of a membrane excitation frequency at different membrane temperatures and a second frequency response (FR2) of the ultrasonic sensor in a receiving direction (RD) depending on a membrane vibration frequency at different membrane temperatures; determining (S2) a current membrane temperature; determining (S3) a sensitivity of the ultrasonic sensor using the first and second frequency responses at the current membrane temperature; and controlling (S4) an electric current provided to the exciter element and/or a gain of the ultrasonic sensor based on a difference between the determined sensitivity and a prestored sensitivity.