Steering Wheel Electrostatic Capacitance Sensor Noise Suppression

Solution Overview

Problem

Conventional steering wheel grip detection systems face challenges in accurately detecting driver grip while minimizing the influence of electromagnetic noise, which can affect the reliability of the system.

Innovation Solution

The proposed steering apparatus includes a sensor unit with an electrode in the steering wheel, a measuring device to detect electrostatic capacitance, and a switching element that grounds the electrode, allowing it to switch between grounded and ungrounded states to manage electromagnetic noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the electrode is kept ungrounded to detect electrostatic capacitance changes for grip detection, then grip detection capability is improved, but electromagnetic noise from the heater wire affects measurement accuracy

Engineering Contradiction:

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The switching element grounds the electrode in advance before heater wire operation to prevent electromagnetic noise accumulation, then switches to ungrounded state for measurement. This preliminary grounding action eliminates noise before it can interfere with the sensitive capacitance detection.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The switching element periodically alternates the electrode between grounded and ungrounded states. During heater operation, the electrode is periodically grounded to discharge accumulated noise; during measurement phases, it is ungrounded for detection. This periodic switching rhythmically removes electromagnetic noise while preserving detection capability.

Inventive Principle:

Principle #19Periodic action

2Object-affected harmful factors

If the electrode is grounded to suppress electromagnetic noise, then noise suppression is improved, but grip detection capability deteriorates

Engineering Contradiction:

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The electrode's grounding state is dynamically changed based on operational requirements. The switching element enables the electrode to transition between grounded (for noise suppression) and ungrounded (for detection) states, making the system adaptive rather than static. This dynamic control allows optimal performance in different operational phases.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The electrical state parameter of the electrode is changed from fixed to variable. By controlling the switching element, the electrode's potential state (grounded or floating) is adjusted according to whether the system needs noise suppression or detection capability, optimizing performance for each operational condition.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If conventional continuous grounding is used to suppress electromagnetic noise, then noise suppression is improved, but detection sensitivity is reduced

Engineering Contradiction:

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The harmful grounding connection is extracted and removed during detection phases. Instead of continuous grounding, the switching element disconnects the electrode from ground during measurement, allowing high detection sensitivity. Grounding is only applied when needed for noise suppression, separating the conflicting requirements in time.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The switching element applies preliminary anti-action by grounding the electrode before electromagnetic noise can significantly accumulate during heater operation. This preemptive grounding prevents noise buildup that would otherwise degrade detection sensitivity, then removes the grounding for sensitive measurement phases.

Inventive Principle:

Principle #9Preliminary anti-action

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 effectively detects the driver's grip on the steering wheel while suppressing the impact of electromagnetic noise, thereby enhancing traffic safety and contributing to the development of sustainable transportation systems.

Implementation Method 1

a measuring device configured to measure an electrostatic capacitance of the electrode

Methodology Applied

Scientific EffectElectrostatic capacitance: Capacitance

Implementation Method 2

a switching element configured to switch the electrode between a first state in which the electrode is grounded and a second state in which the electrode is not grounded

Methodology Applied

Scientific EffectGrounding: Earthing

Data Source

PatentUS20250147198A1Steering apparatus

Publication Date: 2025.05.08

AI summary

A steering apparatus includes: a steering wheel, and a sensor unit configured to detect contact or close proximity of a human body to the steering wheel. The sensor unit includes: an electrode provided in the steering wheel, a measuring device configured to measure an electrostatic capacitance of the electrode, and a switching element configured to switch the electrode between a first state in which the electrode is grounded and a second state in which the electrode is not grounded.