Self-Diagnosing Pedestrian Protection Sensor Using Tension Cable
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Solution Overview
Problem
Conventional pedestrian protection sensor systems lack the ability to self-diagnose failures in the field, which is crucial for ensuring pedestrian safety and expanding safety-related countermeasures in crash responses.
Innovation Solution
A self-diagnosing sensor system with an elongated, deflectable cable integrated into the vehicle bumper, featuring tensioning and sensing units at each end, which include a cable drive member, biasing member, and tension sensors connected to an ECU to detect cable tension and indicate potential damage or impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pressure sensor system with a silicone tube is used, then the system can detect pressure changes during impact, but the system lacks the ability to self-diagnose sensor damage or failures in the field
Solution Approach 1:
The sensor system is divided into multiple independent tension sensors positioned at different locations along the cable. Each tension sensor independently monitors tension in its local segment, allowing the system to detect both impact events and sensor-specific failures. This segmentation enables self-diagnosis without requiring a single complex centralized diagnostic system.
Solution Approach 2:
The biasing member (spring) pre-tensions the cable before any impact occurs, establishing a known baseline tension state. This preliminary action allows the system to detect both impact events (changes from baseline) and sensor failures (loss of baseline tension). The pre-established tension state serves as a reference for self-diagnosis, enabling the system to identify abnormalities without requiring external calibration or complex diagnostic algorithms.
2Reliability
If tension sensors and biasing members are added to enable self-diagnosis, then the system can detect in-field failures, but the device complexity increases
Solution Approach 1:
The tension sensors serve multiple functions simultaneously: they detect impact forces, monitor cable integrity, identify sensor failures, and provide baseline tension verification. This multi-functionality eliminates the need for separate diagnostic sensors or systems, achieving self-diagnosis capability without proportionally increasing system complexity. The same hardware components perform both operational sensing and diagnostic functions.
Solution Approach 2:
The system uses its own operational components (tension sensors and cable) to perform self-diagnosis. The tension sensors monitor their own operational status by detecting changes in cable tension, and the system can identify which specific sensor has failed based on the pattern of tension readings. This self-service capability allows the system to diagnose its own failures without requiring external diagnostic equipment or complex additional hardware.
3Difficulty of detecting and measuring
If the cable is made deflectable to sense impact, then the system can detect pedestrian contact, but the system cannot distinguish between normal deflection and sensor damage
Solution Approach 1:
The biasing member establishes a known pre-tension state in the cable before impact occurs. This preliminary action creates a reference baseline that allows the system to distinguish between normal impact-induced deflection (temporary change from baseline) and sensor damage (permanent loss of baseline tension). The pre-established tension state provides the information needed to differentiate between operational deflection and failure conditions.
Solution Approach 2:
The multiple tension sensors provide continuous feedback on cable tension at different locations. By comparing the pattern of tension readings across multiple sensors, the system can distinguish between uniform tension changes (indicating impact) and asymmetric or localized tension losses (indicating sensor damage or cable failure). This feedback mechanism enables the system to interpret cable behavior and identify the nature of the event.
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 the detection of in-field failures, disables crash response functions if damage is detected, and activates user warnings, ensuring the integrity of the sensor system and enabling more effective crash response measures.
Implementation Method 1
a biasing member acting on the cable drive member so as to bias the cable to a non-deflected, sensing position
Implementation Method 2
a tension sensor constructed and arranged to detect tension of the cable
Data Source
AI summary
A self-diagnosing sensor system for a vehicle is provided. The vehicle has a bumper with fascia material. The sensor system includes an elongated, deflectable cable disposed in the bumper generally adjacent to the fascia material. A tensioning and sensing unit is coupled to each end of the cable and fixed to the vehicle. Each unit includes a tension sensor electrically connected with an ECU of the vehicle such that the ECU receives signals from the tension sensors regarding tension in the cable, indicative of 1) whether the bumper has been impacted based on deflection of the cable from a sensing position, or 2) whether damage to the cable or a tensioning and sensing unit has occurred.