Steering Wheel Gripping Detection with Temperature Compensation
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Solution Overview
Problem
Existing gripping state detection devices for steering wheels face errors in determining whether the driver is gripping the wheel due to temperature-induced changes in electrostatic capacitance, leading to false positives and negatives in determining the gripping state.
Innovation Solution
A gripping state detection device that incorporates an electrostatic capacitance measuring unit, a temperature detector, and a controller to differentiate between gripping states by using threshold values and differential values of electrostatic capacitance, ensuring accurate determination even with temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed threshold value is used for electrostatic capacitance detection, then the device structure is simple, but measurement precision deteriorates due to temperature-induced capacitance changes
Solution Approach 1:
The patent implements dynamic threshold adjustment by introducing a temperature detector that continuously monitors steering wheel temperature and dynamically modifies the electrostatic capacitance threshold accordingly. The controller receives both the electrostatic capacitance sensor output and temperature detector output, then adjusts the threshold value based on the detected temperature to compensate for thermal effects on capacitance measurement.
Solution Approach 2:
The patent changes the detection parameter from a fixed electrostatic capacitance threshold to a temperature-compensated dynamic threshold. By introducing temperature as an additional detection parameter and using it to adjust the capacitance threshold, the system adapts to temperature variations that affect the relative permittivity of materials between the electrode and driver's hand.
2Measurement precision
If temperature compensation is implemented, then measurement precision improves, but device complexity increases due to additional sensors and control logic
Solution Approach 1:
The controller serves multiple functions: it processes the electrostatic capacitance sensor signal, receives temperature detector signals, performs threshold adjustment based on temperature, and determines gripping state. By making the controller multi-functional, the patent avoids adding a separate threshold adjustment device, thereby limiting the increase in overall system complexity.
Solution Approach 2:
The patent introduces temperature as an intermediary parameter that mediates between the physical environment (temperature changes) and the detection system. The temperature detector acts as an intermediary sensor that provides compensation data to the controller, which then uses this information to adjust the detection threshold, effectively mediating the temperature effect on capacitance measurement.
3Speed
If a single threshold value is used, then the detection process is fast, but reliability deteriorates due to erroneous determination under varying temperature conditions
Solution Approach 1:
The system performs preliminary temperature detection and threshold adjustment before the actual gripping state determination. The controller continuously monitors temperature and pre-adjusts the electrostatic capacitance threshold based on current temperature conditions, so that when gripping state detection is needed, the threshold is already optimized for the current thermal environment, maintaining fast response while improving reliability.
Solution Approach 2:
The patent implements a feedback mechanism where the temperature detector continuously provides temperature information to the controller, which then adjusts the electrostatic capacitance threshold in real-time. This closed-loop feedback system ensures that the detection threshold always reflects current temperature conditions, preventing erroneous determinations while maintaining detection speed through continuous adaptation.
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 device reduces erroneous determinations, minimizing unnecessary warnings and ensuring precise detection of the driver's gripping state, thereby enhancing safety and reliability.
Implementation Method 1
an electrostatic capacitance sensor that detects a steering wheel gripping state based on a change in electrostatic capacitance
Implementation Method 2
a temperature detector that detects a temperature of the steering wheel
Implementation Method 3
the measured value (electrostatic capacitance) of the electrostatic capacitance sensor may be changed
Data Source
AI summary
A gripping state detection device includes a steering state determination ECU that determines the gripping state of a driver with respect to the steering wheel of a vehicle. The steering state determination ECU determines which of a first steering state, a second steering state, and a hands-off state has occurred based on the electrostatic capacitance. The steering state determination ECU outputs a first determination result indicating that the steering wheel is gripped by the driver in a case where the determined state is the first steering state or the second steering state, and outputs a second determination result indicating that the steering wheel is not gripped by the driver in a case where the determined state is the hands-off state.