Steering Wheel Contact Detection via Capacitance Summation
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Solution Overview
Problem
Existing steering wheel systems with multiple electrostatic capacitance type contact sensors face challenges in accurately determining passenger contact due to dispersed electrical charges, which can result in incorrect contact state assessments when comparing individual sensor values against a threshold.
Innovation Solution
A steering wheel unit with a contact determination device that sums all electrostatic capacitance values from multiple sensors and compares the total against a threshold value, or adjusts threshold values based on detected capacitance levels, to accurately determine passenger contact, regardless of the number of sensors engaged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple contact sensors are provided for the steering wheel to improve detection coverage, then the ability to detect passenger contact is improved, but the electrostatic capacitance values of individual sensors decrease due to charge dispersion, making accurate contact determination difficult
Solution Approach 1:
The patent combines the electrostatic capacitance values from multiple contact sensors into a total value by summation. This merging approach allows the system to maintain accurate contact determination even when individual sensor values decrease due to charge dispersion across multiple sensors. The total value compensates for the distributed charge effect.
Solution Approach 2:
The patent changes the evaluation parameter from individual sensor capacitance values to the sum of all sensor capacitance values. This parameter transformation enables accurate contact state determination regardless of how the charge is distributed among individual sensors, resolving the measurement precision issue while maintaining reliability.
2Ease of operation
If a threshold value close to the electrostatic capacitance value when one sensor is contacted is used, then contact determination is simple, but it becomes impossible to properly determine contact state when multiple sensors are contacted due to charge dispersion
Solution Approach 1:
The patent transforms the determination parameter from individual sensor values to the sum of all sensor values. This allows the use of a simple threshold comparison method while maintaining accuracy, because the total capacitance value reflects the overall contact state regardless of charge distribution across multiple sensors.
Solution Approach 2:
The patent creates a universal determination method that works for both single-sensor and multi-sensor contact scenarios. By using the sum of all sensor values, the same threshold-based determination logic applies universally, simplifying the system while maintaining reliability across different contact conditions.
3Device complexity
If individual electrostatic capacitance values are compared against a threshold, then the determination process is straightforward, but incorrect contact state assessment occurs when charges are dispersed across multiple sensors
Solution Approach 1:
The patent merges the evaluation of multiple individual sensor readings into a single total capacitance value. This combining approach maintains procedural simplicity while eliminating the measurement precision errors that occur when individual sensor values are evaluated separately under charge dispersion conditions.
Solution Approach 2:
The patent changes the determination parameter from individual sensor capacitance values to the aggregate total capacitance value. This single parameter approach simplifies the determination process while ensuring accurate contact state assessment regardless of charge distribution patterns across the sensor array.
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 ensures proper contact state determination even when multiple sensors are used, allowing for accurate assessment of passenger interaction with the steering wheel, including scenarios where individual sensor values are decreased, and enables quick contact detection when only one sensor is engaged.
Implementation Method 1
a plurality of electrostatic capacitance type contact sensors provided for a steering wheel
Implementation Method 2
electrostatic capacitance values (hereinafter also referred to as the "electrostatic capacitance values of the contact sensors") produced between the contact sensors and the passenger
Data Source
AI summary
Each of detection units detects electrostatic capacitance values Cc, Cr, Cl produced between sensors and a passenger H, based on electrical signals Sc, Sr, Sl outputted from the sensors, respectively. A total value calculation unit sums electrostatic capacitance values Cc, Cr, Cl to calculate a total value Ct of the electrostatic capacitance values Cc, Cr, Cl. A comparison determination unit compares the total value Ct with a first threshold value Cth1 to make a contact determination of whether the passenger H is in contact with a steering wheel.