Vehicle Stress Wave Sensor for Multi-Axis Collision Detection
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Solution Overview
Problem
Existing vehicle collision detection systems, such as acceleration and pressure sensors, are limited by their sensitivity to single-axis collisions and response time, which can be impacted by mechanical impedance and are not omnidirectional, making them less effective for detecting collisions along multiple axes with fast response times.
Innovation Solution
A stress wave sensor configured with a sensor body rigidly coupled to a vehicle frame member, featuring strain sensing devices at distinct locations to detect stress waves propagating through the frame, utilizing trapezoidal prism-shaped end portions and an arcuate-shaped elastic beam to enhance sensitivity and response time, capable of detecting transverse and torsional stress waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acceleration based sensors are used to detect vehicle collision, then collision detection capability is provided, but response time is slowed due to mechanical impedance caused by sensor mass and single-axis sensitivity requires multiple sensors
Solution Approach 1:
The patent replaces acceleration-based mechanical sensors with a stress wave detection system that uses piezoelectric or piezoresistive sensing elements. These elements detect stress waves propagating through the vehicle frame member, eliminating the mechanical impedance issue inherent in acceleration sensors with mass. The stress wave sensor has no moving parts and responds directly to collision-induced stress waves, achieving faster response time while maintaining reliable multi-axis collision detection capability through the propagation characteristics of stress waves through the frame structure.
2Loss of time
If pressure based sensors are used for vehicle collision detection, then faster response time and omnidirectional sensitivity are achieved, but still not as fast as stress wave detection through frame members
Solution Approach 1:
The patent uses the vehicle frame member itself as an intermediary medium to transmit collision information to the sensing elements. Instead of placing sensors directly at the collision point or using fluid-filled bladders, the stress wave propagates through the rigid frame member to the piezoelectric/piezoresistive sensing elements mounted on the frame. This intermediary approach leverages the frame's structural integrity to rapidly transmit collision information while maintaining high detection accuracy through the direct mechanical coupling between the frame and sensing elements.
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
The stress wave sensor provides faster response times than traditional sensors, enabling reliable detection of vehicle collisions along multiple axes, with a response time of 3 to 4 milliseconds, and can trigger airbag deployment by accurately sensing stress wave components, improving occupant safety.
Implementation Method 1
a stress wave sensor configured to detect a stress wave propagating through a vehicle frame member
Implementation Method 2
a first strain sensing device attached to the sensor body at a first location on the sensor body in a manner effective to detect stress in the sensor body at the first location
Data Source
AI summary
A sensor configured to detect a stress wave propagating through a vehicle frame member caused by a vehicle collision is provided. The sensor includes a sensor body configured to be rigidly coupled to the vehicle frame member, a first strain sensing device and a second strain sensing device attached to the sensor body. The sensor body is configured to exhibit stress in response to transverse and torsional stress wave propagating along the vehicle frame member. The first strain sensing device generates a first signal indicative of stress in the sensor body and the second strain sensing device generates a second signal indicative of stress in the sensor body. A first end portion of the sensor body is characterized as trapezoidal prism shaped and a second end portion of the sensor body is characterized as trapezoidal prism shaped.