Acoustic Sensor Phase Analysis Near-Field Detection
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Solution Overview
Problem
Existing acoustic transducers in pulse-echo methods, such as those used in parking-assistance systems, face a dead time after pulse emission due to post-pulse oscillation, limiting the minimal measurable distance to around 20 cm, as shorter echo signals merge with the oscillation and cannot be detected, thereby restricting the sensing capability in close proximity.
Innovation Solution
The method involves analyzing the received signal during the post-pulse oscillation time by considering phase information to separate the influence of the reflected transmit pulse from the transducer's post-pulse oscillatory motion, using a predefined setpoint phase response based on the transducer's construction, allowing for the detection of objects even during this dead time by comparing the actual phase response to the setpoint phase response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If additional mechanical damping is used to reduce post-pulse oscillation, then the dead time is reduced, but the overall sensitivity of the transducer is decreased
Solution Approach 1:
The received signal is segmented into two components: the post-pulse oscillation signal and the reflected transmit pulse signal. By separating these components through phase analysis, the system can process the reflected pulse independently without being overwhelmed by the oscillation, thus reducing dead time without requiring additional damping that would reduce sensitivity.
Solution Approach 2:
Phase information serves as an intermediary parameter to distinguish between the post-pulse oscillation and the reflected transmit pulse. By analyzing phase characteristics rather than directly processing the composite signal amplitude, the system can identify reflected pulses during the oscillation period without needing to reduce the oscillation itself, thereby maintaining transducer sensitivity while reducing dead time.
2Measurement precision
If the receiving cycle is delayed until post-pulse oscillation ends, then the transducer can accurately receive signals, but objects at short distances cannot be detected
Solution Approach 1:
The system replaces the conventional time-based gating approach (mechanical waiting for oscillation to end) with phase-based signal analysis. By using phase information to identify reflected pulses, the system can detect objects at minimal distances without the need to wait for post-pulse oscillation to subside, thus reducing the minimal measuring distance while maintaining detection accuracy.
Solution Approach 2:
The system performs preliminary phase analysis on the received signal during the post-pulse oscillation period to identify reflected transmit pulses. This preliminary detection allows the system to register objects at short distances before the conventional receiving cycle would begin, effectively extending the detection capability into the previously blind near-field zone.
3Length of stationary object
If echo signals from short distances are received during post-pulse oscillation, then objects at minimal distances become detectable, but the reflected pulse merges with oscillation and cannot be detected using conventional methods
Solution Approach 1:
The system transforms the detection criterion from amplitude-based (conventional) to phase-based (invention). By analyzing the phase characteristic of the received signal, the system can distinguish the reflected pulse from the post-pulse oscillation even when they merge in the time domain, analogous to how color changes can distinguish objects that are otherwise visually similar.
Solution Approach 2:
Phase information acts as an intermediary parameter that simplifies the detection task. Instead of directly attempting to separate the merged reflected pulse from the oscillation in the time domain (difficult task), the system uses phase analysis as an intermediate step to identify the reflected pulse characteristics, making detection feasible during the post-pulse oscillation period.
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 enables the detection of objects at shorter distances, covering a previously blind area close to the transducer, enhancing collision warning systems by reducing the danger of collision without increasing the risk, and allowing safer maneuvering in close proximity without extending the dead time.
Implementation Method 1
an acoustic transducer (120) which is set up to emit an acoustic transmit pulse into the area and receive the transmit pulse reflected from the area
Implementation Method 2
The mass and the springiness of an acoustic transducer first of all define a self-resonant frequency of the transducer, and secondly, form mechanical energy stores. An oscillatory system results which oscillates post-pulse even after the excitation has ended.
Implementation Method 3
a received signal of an acoustic transducer (120) is acquired with the aid of the transducer in order to receive the transmit pulse reflected from the area
Data Source
AI summary
A method for acoustically sensing an area is described. An acoustic transmit pulse is transmitted into the area by an acoustic transducer and a received signal is acquired with the aid of the transducer, in order to receive the transmit pulse reflected back from the area. Within a post-pulse oscillation time of the transducer, which directly follows the emission of the transmit pulse, the actual phase response of the received signal is determined. In the event the actual phase response deviates from a predefined setpoint phase response, an object is detected within the area. Also described is a device for acoustically sensing an area, which is designed to carry out the method.