Steering Wheel Grip Detection With Concentric Hub Electrode
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Solution Overview
Problem
Existing steering devices struggle to accurately determine the presence/absence of driver gripping on the steering wheel due to varying electrostatic capacitance measurements caused by non-uniform electrode placement, leading to inconsistent detection based on grip location.
Innovation Solution
The steering device features an arc-shaped electrode provided on the outer circumferential edge of the hub, concentrically arranged with the annular rim, ensuring equal radial distances to grip portions, and incorporates a torque sensor for accurate detection, even in dead band regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the electrode is provided along the outer circumferential edge of the spokes, then the electrode structure is simple, but the measurement value of electrostatic capacitance varies according to the location at which the driver grips
Solution Approach 1:
The electrode is positioned asymmetrically on the hub rather than on the spokes, and arranged concentrically with the rim. This asymmetric positioning on a different component (hub vs. spoke) creates uniform radial distance to all grip portions, resolving the measurement variation problem while keeping the electrode structure simple
Solution Approach 2:
The concentric arrangement of the electrode on the hub creates equipotential conditions relative to all portions of the rim. By positioning the electrode such that the radial distance to upper grip portions and lower grip portions is equal, the electrostatic capacitance measurement becomes consistent regardless of where the driver grips the rim
2Measurement precision
If the electrode is positioned to cover the entire outer circumferential edge of the hub, then measurement accuracy is improved, but material usage and manufacturing complexity increase
Solution Approach 1:
The electrode is strategically positioned only on the outer circumferential edge of the hub, which is the critical location for detecting grip through the rim. This localized positioning provides sufficient measurement accuracy without the need to cover the entire hub surface, thereby reducing material usage and simplifying manufacturing
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 allows precise determination of gripping presence/absence, reduces material usage, and simplifies manufacturing and maintenance, while maintaining accuracy across different grip locations.
Implementation Method 1
a sensor device which measures electrostatic capacitance of the electrode device (4), and determines presence/absence of gripping of the steering wheel (2) based on a measurement result of the electrostatic capacitance
Data Source
AI summary
A steering device (1) includes: a steering wheel (2) which accepts a steering operation by a driver; an electrode device (4) provided to the steering wheel (2); and a steering controller (7) which measures electrostatic capacitance of the electrode device (4), and determines the presence/absence of gripping of the steering wheel (2) based on a measurement result of the electrostatic capacitance, in which the steering wheel (2) includes: an annular rim (20), a columnar hub (23) provided at an inner side of the rim (20); and spokes (25L, 25R, 25D) which connects the hub (23) and rim (20), in which the electrode device (4) includes an arc-shaped electrode 41 provided at an outer circumferential edge 26 of the hub (23) opposing the rim (20), and in which the electrode (41) and rim (20) are arranged concentrically viewing from the driver.