Ultrasonic Obstacle Sensing Using Alternating Frequency Bursts
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Solution Overview
Problem
Ultrasonic sensors in automobiles face challenges in providing reliable minimum distance detection due to residual reverberation and structural noise, which are temperature-dependent and affected by sensor aging, making it difficult to consistently measure distances to nearby obstacles.
Innovation Solution
The use of acoustic transducers that generate alternating frequency bursts and process the resulting responses to determine offset frequency differences, which are insensitive to structural noise, allowing for enhanced detection of nearby obstacles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic transducers transmit acoustic bursts to detect nearby obstacles, then obstacle detection capability is improved, but residual reverberation and structural noise blind the sensor to reflections from nearby obstacles
Solution Approach 1:
The patent applies periodic action by transmitting acoustic bursts at regular intervals and using alternating frequency offsets between successive bursts. This periodic transmission allows the system to accumulate measurements over time while the frequency alternation enables differentiation between structural noise (which remains constant in frequency) and actual obstacle reflections (which exhibit frequency shifts), thereby resolving the contradiction between detection capability and noise interference
Solution Approach 2:
The patent changes the frequency parameter of the acoustic bursts by alternating the frequency offset between successive transmissions. This parameter change allows the system to distinguish between structural noise (constant frequency) and obstacle reflections (frequency-varying), improving measurement precision while maintaining obstacle detection capability despite the presence of reverberation and noise
2Reliability
If sensors provide tens of measurements each second to ensure reliable detection, then detection reliability is improved, but temperature variation and sensor aging significantly change response characteristics
Solution Approach 1:
The patent implements feedback by continuously monitoring the acoustic transducer's response characteristics across multiple measurements and using this information to adjust subsequent measurements. The system analyzes the frequency offset differences between successive bursts and uses this feedback to maintain accurate obstacle detection despite temperature variations and aging effects, thereby preserving detection reliability while compensating for changing sensor characteristics
Solution Approach 2:
The patent applies preliminary action by performing frequency offset calibration and characterization measurements before actual obstacle detection. The system预先 determines the frequency offset between transmitted bursts and uses this pre-established reference to compensate for temperature and aging effects during operation, ensuring reliable detection without requiring continuous recalibration
3Device complexity
If the acoustic transducer operates at a fixed frequency to simplify design, then device complexity is reduced, but the sensor cannot distinguish between structural noise and obstacle reflections
Solution Approach 1:
The patent uses periodic alternation of frequency offsets between successive acoustic bursts to enable obstacle detection without requiring a complex multi-frequency transmitter design. The simple two-frequency alternation scheme allows the system to distinguish obstacle reflections from structural noise through frequency offset analysis, maintaining low device complexity while achieving precise measurement
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 reliability and accuracy of obstacle detection by minimizing the impact of structural noise and temperature variations, enabling precise measurement of distances as close as 0 cm from the transducer.
Implementation Method 1
a transmitter to drive an acoustic transducer to generate a first acoustic burst and a second acoustic burst
Implementation Method 2
a receiver coupled to the acoustic transducer to sense a first response to the first acoustic burst and a second response to the second acoustic burst
Data Source
AI summary
An illustrative controller includes: a transmitter to drive an acoustic transducer to generate a first acoustic burst and a second acoustic burst; a receiver coupled to the acoustic transducer to sense a first response to the first acoustic burst and a second response to the second acoustic burst; and a processing circuit to derive output data from the first and second responses in part by determining an offset frequency difference between the first and second responses, wherein the first acoustic burst has a first characteristic frequency and the second acoustic burst has a second characteristic frequency different from the first characteristic frequency.