Ultrasonic Sensor Snow Accretion Detection via Periodic Transmission Stop
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Solution Overview
Problem
Ultrasonic object detection devices in vehicles face difficulties in accurately detecting snow accretion due to its high absorbency of ultrasonic waves, leading to reduced detection accuracy.
Innovation Solution
The device employs a control unit and multiple ultrasonic sensors that operate in a reception mode to count wave frequencies, determining snow accretion by comparing intensity counts between sensors, with the control unit stopping wave transmission and using a difference in counts to determine if snow has adhered to the sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ultrasonic waves are transmitted continuously for object detection, then object detection capability is maintained, but snow accretion detection accuracy deteriorates due to high absorbency of snow
Solution Approach 1:
The control unit alternates between a detection mode (transmitting ultrasonic waves for object detection) and an adhesion determination mode (stopping transmission to detect snow accretion). This periodic switching allows the system to perform both functions at different time intervals, resolving the contradiction between maintaining object detection capability and achieving accurate snow accretion detection.
2Measurement precision
If ultrasonic wave transmission is stopped to detect snow accretion, then snow detection accuracy improves, but object detection capability deteriorates
Solution Approach 1:
The system implements periodic switching between detection mode and adhesion determination mode. During adhesion determination mode, transmission is stopped temporarily to accurately detect snow accretion by counting received waves, while object detection capability is restored in the subsequent detection mode, thus resolving the contradiction between snow detection accuracy and object detection capability.
3Measurement precision
If multiple ultrasonic sensors are used to compare wave frequency counts, then snow accretion detection accuracy improves, but device complexity increases
Solution Approach 1:
The system divides the detection task among multiple ultrasonic sensors, with each sensor independently counting received waves. The control unit then compares the counts from different sensors to determine snow accretion. This segmentation approach improves detection accuracy by utilizing multiple measurement points while keeping each individual sensor simple.
Solution Approach 2:
The control unit merges the detection results from multiple ultrasonic sensors by comparing their wave frequency counts. By combining the data from multiple sensors and analyzing the differences, the system achieves more accurate snow accretion detection while utilizing the collective information from all sensors.
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 method improves the accuracy of snow accretion detection by utilizing the difference in noise levels between sensors, allowing for better differentiation and notification of snow accretion, thus enhancing the reliability of object detection.
Implementation Method 1
The plurality of ultrasonic sensors are disposed so as to be exposed from the outer surface of a vehicle to transmit ultrasonic waves, or search waves, toward the outside of the vehicle, and receive waves including reflected waves of the search waves
Implementation Method 2
snow has high absorbency to ultrasonic waves
Data Source
AI summary
An ECU of an object detection device stops transmission of search waves from a plurality of ultrasonic sensors when a vehicle travels at a predetermined speed or more, and counts the frequency of receiving waves with an intensity of not less than a threshold intensity for each of the plurality of ultrasonic sensors. The ECU acquires a first count that is a count of the frequency in a first sensor that is one of the plurality of ultrasonic sensors, and a second count that is a count of the frequency in a second sensor different from the first sensor. The ECU determines that snow accretion has occurred on the first sensor if the first count is smaller than the second count, and a difference between the first count and a representative value that is set based on the second count is not less than a predetermined value.