Vehicle Soft Impact Detection Using Piezo Film and Terfenol-D Sensors
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Solution Overview
Problem
Current vehicle crash sensors fail to differentiate between collisions with pedestrians/animals and collisions with massive or rigid objects, which hinders the optimal deployment of active safety systems.
Innovation Solution
The system employs a piezo fluoropolymer film sensor mounted on the vehicle bumper, sensitive to low-frequency shock waves, in conjunction with a Terfenol-D sensor, to differentiate between soft tissue impacts and rigid object impacts by analyzing the frequency and amplitude of shock waves, and combines these signals with acceleration sensors for precise impact classification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single type of crash sensor is used to detect all collisions, then the device complexity is reduced, but the measurement precision for differentiating between soft tissue impacts and rigid object impacts deteriorates
Solution Approach 1:
The patent divides the sensor system into multiple specialized sensors: piezoelectric film sensors for detecting low-frequency shocks from soft tissue impacts, and accelerometers for detecting high-frequency shocks from rigid object impacts. Each sensor type is optimized for specific impact characteristics, enabling accurate differentiation between collision types while maintaining manageable system complexity through functional segmentation.
Solution Approach 2:
The patent utilizes different physical parameters detected by different sensors - piezoelectric sensors respond to low-frequency shock waves characteristic of soft tissue impacts, while accelerometers detect high-frequency vibrations from rigid object impacts. By monitoring multiple parameters (frequency, amplitude, shock waveform) simultaneously, the system achieves precise impact classification.
2Measurement precision
If piezoelectric film sensors are used to detect low-frequency shock waves from soft tissue impacts, then the measurement precision for pedestrian/animal collision detection is improved, but the device complexity increases due to multiple sensor types
Solution Approach 1:
The patent integrates multiple sensor types (piezoelectric film sensors and accelerometers) into a unified crash detection system that handles both soft tissue impacts (pedestrian/animal collisions) and rigid object impacts. The control unit processes signals from both sensor types to determine appropriate safety responses, making the system universally applicable to various collision scenarios.
Solution Approach 2:
The patent introduces a control unit as an intermediary that receives and processes signals from both piezoelectric film sensors and accelerometers. This intermediary component analyzes the combined data to differentiate between impact types and triggers appropriate safety responses, managing the complexity of multiple sensor types through centralized signal processing and decision logic.
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
Enables timely and precise activation of safety systems to protect vehicle occupants by accurately distinguishing between pedestrian/animal impacts and impacts with rigid objects, optimizing the deployment of safety devices such as elevated hoods to prevent injuries.
Implementation Method 1
uses a piezo or piezoelectric film mounted to a front vehicle bumper. Piezo fluoropolymer film (PVDF) is a piezoelectric material
Implementation Method 2
The second sensor could be, for example, a Terfenol-D based sensor
Data Source
AI summary
A vehicle soft impact detection system uses a piezo film mounted to a front vehicle bumper. The piezo film is selected and mounted to have a greater sensitivity to low-frequency shock waves as compared to high-frequency shock waves, the frequency and amplitude is then compared to a selected range of frequencies and amplitudes that are indicative of a crash with a soft tissue body. In a further embodiment the output of the piezo film is compared with the output of a second sensor which is more sensitive to high-frequency shock waves than to low-frequency shock waves such as a Terfenol-D based sensor.