Ultrasonic Sensor Dead Time Reduction via Post-Oscillation Measurement
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Solution Overview
Problem
Ultrasonic sensors have a minimum detection range due to dead time caused by transient excitation and decay processes, making it difficult to detect objects closer than a certain distance, and existing methods struggle to accurately determine object distance in close proximity.
Innovation Solution
A method that measures the post-oscillation period of the electro-acoustic converter and adjusts the sensitivity of the reception path using camera images to enhance the detection of single-echo and multiple-echo signals, allowing for indirect and precise measurement of object distance by evaluating the difference in post-oscillation durations and multiple echo pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the ultrasonic sensor uses a resonant electro-acoustic converter to transmit ultrasonic pulses, then the transmission efficiency and signal strength are improved, but the transient excitation and decay processes cause a dead time that prevents detection of objects within a minimum distance
Solution Approach 1:
The system measures the post-oscillation duration of the electro-acoustic converter before attempting to detect echo signals. This preliminary measurement allows the system to determine when the converter has settled and is ready to accurately detect weak echo signals from close objects, eliminating the dead time problem caused by transient decay processes
Solution Approach 2:
The system dynamically adjusts the sensitivity of the reception path based on the measured post-oscillation duration. By adapting the reception sensitivity in real-time according to the converter's oscillation state, the system can detect echo signals from objects at distances below the traditional minimum range while maintaining accurate detection
2Measurement precision
If the sensitivity of the reception path is increased to detect weak echo signals from close objects, then the detection probability of single-echo and multiple-echo signals is improved, but the detection stability decreases due to noise and false detections
Solution Approach 1:
The system dynamically adapts the reception path sensitivity based on the measured post-oscillation duration. When the post-oscillation is short (indicating close objects), the sensitivity is increased to detect weak echo signals. When the post-oscillation is long, the sensitivity is reduced to maintain detection stability and avoid false detections from noise
Solution Approach 2:
The system uses feedback from the measured post-oscillation duration to control the reception path sensitivity. This closed-loop control allows the system to automatically adjust its detection parameters based on the actual acoustic environment, optimizing both detection probability and stability
3Measurement precision
If the post-oscillation duration is used to estimate object distance for close objects, then the minimum detection range is reduced, but additional processing complexity is required to differentiate between single-echo and multiple-echo signals
Solution Approach 1:
The system uses the post-oscillation duration of the electro-acoustic converter as an intermediary parameter to indirectly determine object distance for close objects. Instead of directly measuring echo signals that are obscured by the converter's own oscillations, the system measures the oscillation duration itself, which serves as a proxy for distance calculation
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 reduces the minimum detection range of ultrasonic sensors, enabling more precise detection of obstacles in close proximity, improving short-range capability and parking functions by accurately determining object distances even at distances less than 20 cm.
Implementation Method 1
an electro-acoustic converter for transmitting an acoustic signal and for receiving an echo signal which is reflected by the object
Implementation Method 2
at least one acoustic signal which is reflected by the object and received by means of the electro-acoustic converter
Implementation Method 3
the received acoustic signal being generated from an echo signal
Implementation Method 4
The transmission frequency of the electro-acoustic converter is tuned to the resonant frequency of the converter
Implementation Method 5
Due to the resonant character of the electro-acoustic converter, transient excitation and decay processes occur
Data Source
Figure 1a~1c
Figure 2
Figure 3a~3b
AI summary
A means is provided for determining the position and/or the movement of at least one object, in particular of a vehicle, in the environment of a movement aid by means of at least one acoustic signal identified as an echo signal reflecting off the object and received, said signal being transmitted by the receiving electro-acoustic converter, wherein a reverberation time (ND) after the transmission of the acoustic signal is measured and in the case of a match between the measured reverberation time (ND) and the known reverberation time of the electro-acoustic converter, the first detected echo signal (USE1) is recognised as the first echo signal originating from an individual reflection of the transmitted acoustic signal from the object, and the object distance (d) is determined from the transit time of the first detected echo signal, and/or if a measured reverberation time (ND) is longer than the known reverberation time, the transit time of the received first echo signal and therefore also the object distance (d) is estimated from the difference between the measured and the known reverberation time of the first echo signal.