Variable Force Limiter Control for Vehicle Collision Safety
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Solution Overview
Problem
Existing collision safety systems fail to adjust the force limiter load effectively when a preceding vehicle cannot be detected due to close proximity, leading to unnecessary restraint or inadequate protection during collisions.
Innovation Solution
A force limiter control system that includes a variable force limiter unit, relative speed detection, and a low load invalidation mechanism to adjust the force limiter load based on relative speed, inter-vehicular distance, and predicted collisions, ensuring appropriate restraint levels and preventing unnecessary seatbelt tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the force limiter load is reduced based on relative speed detection, then unnecessary restraint is avoided in low-speed collisions, but inadequate protection occurs when collision with other objects is possible
Solution Approach 1:
The force limiter load is made dynamically adjustable based on real-time detection of relative speed and prediction of collision risk. The system transitions between different load states (reduced load for low-speed collisions, normal load for high-risk scenarios) to optimize both comfort and safety under varying conditions.
Solution Approach 2:
The system performs preliminary assessment of collision risk by detecting relative speed and predicting potential collisions with objects other than the preceding vehicle before the actual collision occurs. This allows proactive adjustment of the force limiter load to prevent unnecessary restraint while maintaining protection when needed.
2Device complexity
If the preceding vehicle detection range is limited, then the system remains simple, but collision safety is compromised when lateral movement occurs
Solution Approach 1:
The system extends detection capability from the longitudinal dimension (distance to preceding vehicle) to include lateral dimension considerations. By calculating estimated lateral movement amount and comparing it with the detection region boundary, the system indirectly monitors lateral collision risks without requiring additional lateral detection sensors.
Solution Approach 2:
The system uses the relative speed detection unit and collision prediction algorithm as intermediaries to infer lateral collision risks. Instead of directly detecting objects in the lateral direction, the system processes longitudinal detection data through computational logic to predict potential lateral collisions, maintaining simplicity while improving safety.
3Reliability
If the force limiter load is always maintained at high level, then occupant protection is ensured in all scenarios, but unnecessary restraint occurs in low-speed rear collisions
Solution Approach 1:
The force limiter load parameter is changed based on detected relative speed values. When relative speed is below a threshold indicating low-severity collision, the load parameter is reduced to minimize unnecessary restraint. This dynamic parameter adjustment allows the system to adapt to different collision scenarios without requiring complex structural changes.
Data Source
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AI summary
A force limiter control system includes: a variable force limiter unit (24) configured to change a force limiter load; a relative speed detection unit (40) that detects a relative speed between a host vehicle and a preceding vehicle; a force limiter load changing unit (48) that sets a lower load as the force limiter load in a case in which the relative speed is lower than a predetermined threshold value, than in a case in which the relative speed is equal to or greater than the predetermined threshold value; and a low load invalidation unit (54) that invalidates a change to the force limiter load by the force limiter load changing unit in a case in which a collision with a collision object other than the preceding vehicle has been predicted in an undetectable region in which an inter-vehicular distance to the preceding vehicle is smaller than a predetermined distance.