Pedestrian Impact Sensor Assembly for Vehicle Front Fascia
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing pedestrian impact detection systems struggle to effectively sense low-energy impacts, particularly at the outer corners of vehicle front ends, due to the lack of supporting structures necessary for compression-based sensors, leading to inadequate reaction forces and sensor outputs during glancing impacts.
Innovation Solution
A unitary package integrating acceleration and pressure sensors, with acceleration sensors oriented to detect impacts without requiring compression, and a flexible tube system generating pressure pulses, is mounted behind the vehicle fascia and energy-absorbing materials to cover the entire front end, including outer corners, ensuring comprehensive impact detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If compression-based sensors are used for pedestrian impact detection, then impact detection capability is improved in areas with supporting structures, but detection reliability deteriorates in outer corner areas lacking supporting structures
Solution Approach 1:
The patent combines two different sensing technologies (compression-based pressure sensors and acceleration-based sensors) into a hybrid detection system. The acceleration sensor is mounted on the energy absorbing cross beam in outer corner areas where compression-based sensors cannot be effectively used, while pressure sensors are used in areas with adequate supporting structures. This merging of sensing approaches ensures reliable impact detection across the entire front end surface.
Solution Approach 2:
The energy absorbing cross beam serves as an intermediary structure that enables acceleration-based sensing in outer corner areas. The beam is specifically designed to extend to these areas and provide a mounting platform for acceleration sensors, acting as a mediator that bridges the gap between the fascia surface and the sensing elements in regions where traditional compression sensors fail.
2Area of stationary object
If the sensitive area is extended to outer corners, then coverage area is improved, but device complexity increases due to additional sensor types and mounting requirements
Solution Approach 1:
The energy absorbing cross beam is designed to serve multiple functions: it provides structural support for meeting low speed impact requirements, extends the mounting platform to outer corner areas, and serves as the mounting base for acceleration sensors. This multi-functionality reduces the need for separate dedicated sensor mounting structures, thereby limiting the increase in device complexity while expanding coverage area.
3Measurement precision
If acceleration sensors are used instead of compression sensors, then detection capability is improved in areas without supporting structures, but manufacturing cost increases
Solution Approach 1:
The patent applies different sensing technologies to different locations based on local structural characteristics. Acceleration sensors are deployed specifically in outer corner areas where the fascia lacks supporting structures, while compression-based pressure sensors are used in central areas with adequate structural support. This localized approach ensures optimal detection capability in each region while controlling overall manufacturing costs by not universally deploying more expensive acceleration 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 solution enhances the sensitivity of impact detection systems to include outer corners, providing reliable sensor outputs for impact mitigation countermeasures, while maintaining cost-effectiveness and efficient manufacturing for automotive applications.
Implementation Method 1
an acceleration sensor, which produces an acceleration signal in response to changes in acceleration forces experienced during an impact event
Implementation Method 2
the sensor tube is compressed, generating a gas pressure in the tube which is transmitted to a pressure sensor
Implementation Method 3
generating a gas pressure in the tube which is transmitted to a pressure sensor
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A sensor assembly for a motor vehicle adapted for sensing impacts including pedestrian impacts. The sensor assembly integrates functions of pressure based sensors used in one embodiment with a compressible tube extending laterally across the front surface of the vehicle and the outboard front boundary areas of the front end of the vehicle. Both acceleration and pressure based sensors are mounted into an integrated sensor housing which is mounted in a desired position at the vehicle front fascia front boundary areas. The system optimizes pressure based sensing while providing acceleration based sensing at the lateral boundary areas where supporting structure does not enable pressure based sensing. The invention further including sensor arrangements including discrete pressure and acceleration sensors deployed for detecting pedestrian impacts at the center and front boundary areas of the vehicle front end.