Steering Wheel Grip Sensor Reference Setting for Accurate Hand Detection
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Solution Overview
Problem
Conventional grip sensors for steering wheels face errors in measuring capacitance changes due to initial reference values being set when a hand is already in contact, leading to inaccurate detection.
Innovation Solution
The grip sensor employs multiple capacitive detectors and a controller that determines a reference value by excluding outputs above a threshold, using values below the threshold or their average to minimize errors, and adjusts sensitivity based on output values to prevent incorrect trouble determinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reference value is set at initial startup, then the system can perform capacitance measurements, but the reference value may be inaccurate if a hand is already in contact with the steering wheel
Solution Approach 1:
The system performs preliminary measurements at startup to determine an initial reference value, then continues to monitor and update this reference value during operation. By establishing a baseline measurement before normal operation and maintaining the ability to update it, the system ensures accurate reference values even when hands are in contact with the steering wheel.
Solution Approach 2:
The controller continuously monitors capacitance values from multiple detectors and uses this feedback to determine whether hands are in contact with the steering wheel. Based on this feedback, the system can adjust or update the reference value to maintain measurement accuracy throughout operation.
2Reliability
If multiple capacitive detectors are used to improve detection reliability, then the system can identify contact more accurately, but the complexity of determining a reliable reference value increases
Solution Approach 1:
The steering wheel is divided into multiple detection zones with separate capacitive detectors positioned at different locations. Each detector independently monitors its specific zone, allowing the system to segment the detection task and identify hand contact more reliably without requiring a single complex measurement system.
Solution Approach 2:
The controller combines measurements from multiple capacitive detectors to determine hand contact status and reference values. By merging data from multiple sources, the system achieves more reliable detection while managing complexity through centralized processing that synthesizes information from all detectors.
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 configuration reduces the likelihood of errors in detecting hand contact and improves the accuracy of capacitance measurements by setting a reliable reference value and adjusting sensitivity, ensuring precise detection even when hands are in contact with capacitive detectors.
Implementation Method 1
a grip sensor for a steering wheel, which detects contact of a human body, based on a change in capacitance
Data Source
AI summary
A grip sensor includes: a plurality of capacitive detectors which are disposed in a grip of a steering wheel of a vehicle, and output values which vary according to whether a human body is in contact; and a controller which determines, at a preset timing, a reference value to be subtracted from the values output from the plurality of capacitive detectors, to determine whether the human body is in contact, wherein the controller identifies, from among values output from the plurality of capacitive detectors at the preset timing, one or more values each having an absolute value smaller than a first threshold, and determines, as the reference value, one of the one or more values identified or an average of the one or more values identified.