Ultrasonic Sensor Signal Evaluation for Vehicle Speed Detection
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Solution Overview
Problem
Current ultrasonic sensor systems for vehicle surroundings detection primarily focus on distance measurement and obstacle recognition, but they lack the capability to accurately determine vehicle speed, especially in varying operational modes and conditions.
Innovation Solution
The method involves adapting the threshold value curve of the ultrasonic sensor to differentiate between useful and interfering signal components, allowing for distance measurement in one mode and vehicle speed determination using the Doppler effect in another, by sensitively programming the threshold curve to filter out interference and analyze ground reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the threshold value curve is adapted to evaluate useful signal components for distance measurement, then distance measurement functionality is improved, but the ability to detect ground reflections for speed measurement deteriorates
Solution Approach 1:
The threshold value curve is made dynamically adaptable through multiple operating modes. The evaluation unit can switch between a first operating mode for distance measurement (using a first threshold value curve) and a second operating mode for speed measurement (using a second threshold value curve with different characteristics). This dynamic adaptation allows the same ultrasonic sensor to serve multiple functions by changing its evaluation parameters based on the required measurement type.
Solution Approach 2:
The ultrasonic sensor system is designed to perform multiple functions: distance measurement of objects and vehicle speed measurement. By storing different threshold value curves (first threshold value curve for distance, second threshold value curve for speed) and selectively applying them based on the operating mode, the system achieves multi-functionality without requiring separate sensors for each function.
2Reliability
If the threshold value curve is sensitively programmed to filter out interference for distance measurement, then distance measurement reliability is improved, but ground reflection detection for speed measurement deteriorates
Solution Approach 1:
The system dynamically switches between different threshold value curves based on the operating mode. When in the first operating mode for distance measurement, a first threshold value curve is applied that filters out ground reflections. When in the second operating mode for speed measurement, a second threshold value curve is applied that enables detection of ground reflections. This dynamic switching resolves the contradiction by making the filtering behavior context-dependent rather than fixed.
Solution Approach 2:
The threshold value curve parameters are changed depending on the operating mode. The evaluation unit adapts the threshold value curve by adjusting parameters such as amplitude thresholds and time-gain compensation characteristics. This parameter adaptation allows the same hardware to achieve different measurement objectives: reliable distance measurement when ground reflections should be rejected, and accurate speed measurement when ground reflections should be detected.
3Device complexity
If a fixed threshold value curve is used for distance measurement, then the system complexity is reduced, but the versatility to determine vehicle speed deteriorates
Solution Approach 1:
The system achieves multi-functionality by storing multiple threshold value curves in the evaluation unit and selectively applying them based on the operating mode. Instead of using completely different hardware for distance and speed measurement, the system reuses the same ultrasonic sensor and evaluation circuitry, merely changing the software parameters (threshold value curves). This approach provides versatility while keeping the hardware complexity relatively low.
Solution Approach 2:
The system implements operating mode flexibility by changing the evaluation parameters (threshold value curve characteristics) rather than changing the hardware architecture. The evaluation unit can adapt the threshold value curve parameters based on whether distance measurement or speed measurement is required, allowing a single fixed hardware design to support multiple functions through parameter adaptation.
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 ultrasonic system to provide a redundant and cost-effective speed measurement, enhancing safety during vehicle operation by integrating vehicle speed data into other vehicle systems, particularly during parking maneuvers and high-speed driving.
Implementation Method 1
This excitation is transmitted to a piezo element, which converts this mechanical vibration into an electrical signal and outputs it to an evaluation and control unit for evaluation
Implementation Method 2
in a second operating mode by evaluating ground reflections detected interfering signal components the current speed of the vehicle can be determined
Data Source
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AI summary
The method involves transmitting a predetermined transmitting time of a measurement signal (24) and receiving and evaluating echo signals (26,28) in response to the measurement signal. A course of a threshold curve is adapted such that the received echo signals are identified and masked in a mode. The course of the threshold curve is adapted such that the identified disturbing signal share is detected as a base reflection in another mode. An independent claim is also included for a device for surround recording in a vehicle.