Ultrasonic Obstacle Sensing with Alternating-Frequency Echo Separation
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Solution Overview
Problem
Ultrasonic sensors in vehicles face challenges in providing reliable minimum distance detection and consistent measurements due to temperature variations and aging effects, which cause residual reverberation and structural noise, making it difficult to detect nearby obstacles accurately.
Innovation Solution
The use of a controller that generates a series of acoustic bursts with alternating frequencies to determine the offset frequency difference between responses, allowing for enhanced detection of nearby obstacles by distinguishing between echo sensitivity and structural noise insensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasonic sensors 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 parameter changes by transmitting acoustic bursts at multiple different frequencies and comparing the responses. By varying the frequency parameter and analyzing the differences between responses at different frequencies, the system can distinguish between structural noise (which remains relatively constant across frequencies) and actual echo reflections (which vary with frequency), thereby resolving the contradiction between detection capability and noise interference
Solution Approach 2:
The patent converts the harmful effect of residual reverberation and structural noise into a beneficial differentiation method. By intentionally transmitting at multiple frequencies and analyzing response differences, the system uses the presence of noise as a reference point to identify and eliminate it from the measurement, turning the noise problem into a solution for noise rejection
2Reliability
If sensors provide tens of measurements each second to ensure reliable detection, then obstacle detection reliability is improved, but temperature variations and aging significantly change sensor response characteristics
Solution Approach 1:
The patent implements feedback by continuously transmitting acoustic bursts at multiple frequencies and comparing the responses in real-time. The system uses the response differences as feedback to identify and compensate for drift in sensor characteristics caused by temperature variations and aging, maintaining reliable detection despite environmental changes
Solution Approach 2:
The patent applies periodic action by transmitting sequences of acoustic bursts at alternating frequencies in a continuous cycle. This periodic multi-frequency transmission allows the system to continuously monitor and adapt to changing sensor characteristics, maintaining measurement reliability over time despite environmental stressors
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 improves the reliability and accuracy of obstacle detection by filtering out structural noise and enhancing echo sensitivity, enabling precise distance measurement even in changing environments.
Implementation Method 1
Ultrasonic sensors as well as other forms of acoustic sensors are often configured to both transmit acoustic bursts and to receive the resulting reflections or 'echoes'.
Implementation Method 2
The acoustic transducers employed by such sensors are subject to residual reverberation of the transducer as well as structural noise
Implementation Method 3
The acoustic transducers employed by such sensors are subject to residual reverberation of the transducer as well as structural noise (i.e., vibration of any housing or overlying surface)
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.