Ultrasonic Object Detection Device With Frequency Modulation
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Solution Overview
Problem
Existing object detection devices using ultrasonic waves face interference issues, particularly when the frequency of transmission is increased or when vehicles are in close proximity, leading to inaccurate determination of object height.
Innovation Solution
The device employs a transmitter that sends ultrasonic waves with frequency modulation, and a receiver that processes the signals using correlation filters to identify the received wave and determine if an object is within the detection region with a single transmission/reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the frequency of ultrasonic wave transmission is increased to improve detection precision, then measurement precision improves, but inter-sensor interference increases
Solution Approach 1:
The patent applies frequency modulation to the ultrasonic transmission signal, changing the frequency parameter over time according to a predetermined pattern. This allows the receiving sensor to distinguish signals from different transmitting sensors through correlation detection, resolving the interference problem while maintaining high frequency transmission for accurate height measurement
Solution Approach 2:
The system uses correlation detection where the receiving sensor compares the received signal with a reference signal that matches the transmitted frequency-modulated pattern. This feedback mechanism enables precise identification of the transmitted signal characteristics, allowing accurate object height determination while filtering out interference from other sensors
2Measurement precision
If multiple transmission/reception operations are performed to improve detection accuracy, then measurement precision improves, but loss of time increases
Solution Approach 1:
The patent combines multiple functions into a single transmission/reception operation: frequency-modulated ultrasonic transmission for distance measurement, object detection, and object height determination all occur simultaneously. The frequency modulation pattern embedded in the signal allows the receiving sensor to extract multiple pieces of information in one measurement cycle, eliminating the need for multiple separate operations
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 effectively reduces inter-sensor interference, allowing for accurate object detection and height determination without the need for multiple transmissions, thereby enhancing the performance and efficiency of the object detection process.
Implementation Method 1
an object detection device for detecting an object by transmitting and receiving ultrasonic waves
Implementation Method 2
a first correlation filter that performs correlation detection between the reception signal and a first reference signal corresponding to the drive signal
Data Source
AI summary
An object detection device includes a drive signal generator that generates a drive signal including frequency modulation, a first correlation filter that performs correlation detection between the reception signal and a first reference signal corresponding to the drive signal, a first determiner that determines, based on the correlation signal from the first correlation filter, whether the reception signal is a reflected wave of the probe wave transmitted from the transmitter, a second correlation filter that performs correlation detection between the reception signal and a second reference signal corresponding to a portion of the drive signal, a third correlation filter that performs correlation detection between the reception signal and a third reference signal corresponding to another portion of the drive signal having higher frequencies than the second reference signal, and a second determiner that determines whether there is an object within a detection region based on correlation signals from the second and third correlation filters.