Steering Wheel Grip Detection Using Capacitance and Torque
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Solution Overview
Problem
Existing steering devices face challenges in accurately detecting whether a driver is gripping the rim part due to low electrostatic capacitance changes and interference from parasitic capacitance caused by internal heaters, especially when the driver rests an elbow on the armrest, leading to inaccurate detection using electrostatic capacitance and steering torque methods.
Innovation Solution
A gripping determination system and method that combines electrostatic capacitance detection using electrodes on the steering device's spoke parts and steering torque detection, determining the gripping state based on the integrated results from both methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conductive layer is arranged in the rim part so that the distance to the driver's hand is increased, then the structural integrity and insulation are improved, but the change in electrostatic capacitance becomes small and detection becomes difficult
Solution Approach 1:
The patent transitions from a single-dimension detection approach (electrostatic capacitance only) to a multi-dimensional approach by combining electrostatic capacitance detection with steering torque detection. This dimensional expansion in detection methodology allows the system to overcome the limitation of small capacitance changes caused by increased distance, as torque detection provides an alternative measurement dimension that remains effective even when capacitance signals are weak.
Solution Approach 2:
The patent merges two different detection methods (electrostatic capacitance detection and steering torque detection) into a unified gripping state determination system. By combining these detection modalities, the system leverages the strengths of both methods to achieve accurate gripping state detection, compensating for the weaknesses of each individual method when used alone.
2Ease of operation
If an internal heater is provided in the steering device, then the comfort and temperature control are improved, but the detection accuracy of the electrostatic capacitance detection method deteriorates due to parasitic capacitance
Solution Approach 1:
The patent introduces steering torque detection as an intermediary measurement method that is not affected by the parasitic capacitance generated by the internal heater. While electrostatic capacitance detection remains susceptible to heater interference, the torque detection mechanism serves as an alternative pathway that bypasses this interference, allowing the system to maintain accurate gripping state detection despite the presence of the heater.
Solution Approach 2:
The patent changes the detection parameter from solely electrostatic capacitance to a combination of electrostatic capacitance and steering torque. This parameter diversification allows the system to overcome the limitation imposed by the internal heater, as torque is a mechanical parameter that remains unaffected by the electrical parasitic effects generated by the heater.
3Ease of operation
If the driver grips the steering device at positions corresponding to the 3 o'clock direction and the 9 o'clock direction, then the driving control is improved, but the detection accuracy of steering torque deteriorates because the driver rests an elbow on an armrest
Solution Approach 1:
The patent transitions from relying solely on torque detection to a multi-dimensional detection approach that includes both electrostatic capacitance detection and torque detection. When the driver rests their elbow on the armrest at 3 or 9 o'clock positions, torque detection accuracy deteriorates, but electrostatic capacitance detection provides an alternative measurement dimension that remains effective, as it detects the electrical properties of the hand gripping the rim rather than relying on mechanical torque transmission.
Solution Approach 2:
The patent merges electrostatic capacitance detection and steering torque detection into a comprehensive gripping state determination system. This combination allows the system to leverage electrostatic capacitance detection as a complementary method that remains accurate even when torque detection is compromised by elbow rest on armrests, ensuring reliable gripping state detection across all driving positions.
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
Enhances the accuracy of detecting whether a driver is gripping the steering device by utilizing electrostatic capacitance and steering torque sensors, providing a more reliable determination even when the driver positions their elbow on the armrest.
Implementation Method 1
a first detecting part for detecting electrostatic capacitance at the electrode
Implementation Method 2
a second detecting part for detecting steering torque of the steering wheel shaft
Data Source
AI summary
Providing of a gripping determination system and gripping determination method enabling detecting whether or not the driver is gripping the steering device with higher accuracy.A gripping determination system that determines a gripping state of a steering device having an electrode on a part of a steering device of a vehicle, includes:an electrostatic capacitance detecting part that detects electrostatic capacitance of the electrode,a steering torque sensor that detects steering torque of the steering wheel shaft, anda determining part that determines whether or not the steering device is being gripped based on detection results of the electrostatic capacitance detecting part and the steering torque sensor.