Steering Torque Sensor Fatigue Detection
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Solution Overview
Problem
Existing methods for detecting driver fatigue without a steering angle sensor on the steering wheel are unreliable due to the elasticity of the steering system acting as a low-pass filter, making it difficult to measure steering activity with the required resolution for fatigue detection.
Innovation Solution
The method involves using the signal from the steering torque sensor, which correlates with the steering angle speed, to infer driver fatigue by generating a sum signal or comparing the time profile with a calculated steering angle or angle speed, allowing for reliable detection even without a steering angle sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a steering angle sensor on the steering wheel is used, then measurement precision of steering activity is improved, but device complexity increases
Solution Approach 1:
The patent introduces a steering torque sensor as an intermediary device that indirectly measures steering activity through torque signals rather than directly measuring steering angle. The torque sensor signal serves as a mediator that correlates with steering angle speed, enabling fatigue detection without requiring a steering angle sensor on the steering wheel.
Solution Approach 2:
The patent replaces the mechanical steering angle sensor system with an electrical/electronic solution using a steering torque sensor. Instead of mechanically coupling a sensor to the steering wheel, the system uses electrical signals from the torque sensor that already exists in the steering column, substituting a mechanical measurement approach with an electrical signal-based approach.
2Device complexity
If steering torque sensor signal is used without steering angle sensor, then device complexity is reduced, but measurement precision deteriorates due to elasticity of steering system
Solution Approach 1:
The patent changes the measurement parameter from steering angle to steering torque. Instead of trying to overcome the limitations of torque-based measurement, the invention utilizes the torque signal directly and processes it through specific algorithms that evaluate torque variations over time, transforming the parameter to match the available sensor capability.
Solution Approach 2:
The patent applies preliminary signal processing and evaluation algorithms to the steering torque signal before fatigue assessment. The system pre-processes the torque signal to extract relevant features and patterns that indicate driver fatigue, compensating for the indirect measurement nature of torque-based detection.
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 approach enables rapid and accurate detection of driver fatigue, effectively identifying corrective movements and maintaining the required resolution for fatigue detection, ensuring timely warnings can be issued.
Implementation Method 1
A steering torque sensor for detecting the driver's request is generally provided between the steering wheel and the steering gear of a steering system, which usually detects the twisting of a torsion bar provided in the area of the steering column or steering shaft.
Implementation Method 2
The elasticity of the steering also acts like a low-pass filter, so that frequencies relevant to the detection of the state of fatigue are largely outside the observation range.
Data Source
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Figure 2
AI summary
The method involves capturing an output signal of steering torque sensor (10).The signals are processed and the steering torque sensor is closed on fatigue condition of driver. The signals represent computed steering angle and a composite signal is produced from the output signal of the steering angle sensor. An independent claim is also included for a device for the recognition of a fatigue condition of a motor vehicle driver.