Capacitive Steering Wheel Hand Detection System
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Solution Overview
Problem
Existing safety devices for motor vehicle steering wheels fail to reliably detect the presence of both the driver's hands and distinguish between the driver's hands and those of another person or artificial means, potentially allowing unsafe driving behaviors.
Innovation Solution
A safety device with capacitive sensing areas on the steering wheel rim detects the electrical capacitance between the driver's hands and the vehicle's ground, comparing measured values to stored standards to ensure both hands are present and belong to the driver, activating an alarm if anomalies are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure sensors are used to detect hand presence on the steering wheel, then the detection of hand presence is enabled, but the device cannot distinguish between the driver's hands and those of another person or artificial means
Solution Approach 1:
The patent replaces the mechanical pressure sensing system with a capacitive sensing system. The capacitive sensors detect electrical capacitance characteristics of the driver's hands, which are unique to the driver's body. This substitution enables not only hand presence detection but also hand identity verification, resolving the contradiction between detection capability and identification precision.
Solution Approach 2:
The patent changes the detection parameter from mechanical pressure to electrical capacitance. By measuring the capacitance between the driver's hands and the vehicle ground, the system obtains a parameter that is characteristic of the driver's body. This parameter change enables the system to distinguish the driver's hands from those of other persons or artificial objects, thereby improving both detection reliability and measurement precision.
2Device complexity
If simple pressure detection is implemented, then the device complexity is reduced, but the ability to verify driver identity is lost
Solution Approach 1:
The patent replaces complex mechanical pressure measurement systems with simpler capacitive sensing. The capacitive sensors can be implemented as simple conductive elements connected to the vehicle ground, significantly reducing device complexity while simultaneously enabling driver verification through capacitance measurement. This resolves the contradiction by achieving verification capability through a simpler system.
Solution Approach 2:
The patent introduces the vehicle ground as an intermediary reference point for capacitance measurement. By using the vehicle ground as a common reference, the system can measure the capacitance of the driver's hands without requiring complex isolated measurement systems. This intermediary approach simplifies the device architecture while maintaining reliable driver verification capability.
3Measurement precision
If capacitive sensing areas connected to vehicle ground are used, then the electrical capacitance of the driver's hands can be detected, but additional wiring and connection requirements are introduced
Solution Approach 1:
The patent makes the vehicle ground serve multiple functions: it acts as the reference potential for the vehicle's electrical system and simultaneously serves as the reference for capacitance measurement. This multi-functionality eliminates the need for separate ground connections for the sensing system, reducing device complexity while maintaining precise capacitance measurement capability.
Solution Approach 2:
The vehicle's existing ground infrastructure serves the additional purpose of capacitance measurement reference. The system utilizes the already-present vehicle ground connections without requiring additional dedicated ground paths, allowing the sensing system to leverage the vehicle's own electrical infrastructure for its measurement needs.
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
Ensures that both hands on the steering wheel are confirmed to belong to the driver, preventing distractions and maintaining safe driving conditions by accurately differentiating between the driver's hands and other influences.
Implementation Method 1
two sensing areas 2a and 2b, which are capacitive in nature and are connected to two different potentials, in particular to the potential of the driver's seat and to the potential of the vehicle ground respectively
Implementation Method 2
a microprocessor 7 which is able to set standard values for the capacitance of both arms of the driver, taking as a reference the electrical potential to which the driver's seat and the vehicle ground are held
Data Source
Figure 1~2
Figure 3a~3b
Figure 4~6
AI summary
A safety device against the removal of one or both hands of the driver from the steering wheel of a motor vehicle is described. The safety device comprises two sensing areas (2a, 2b) associated with respective left and right halves of the rim of the steering wheel of the motor vehicle or with portions thereof intended for placing the motor vehicle driver's hands for correctly driving said vehicle. A processing unit (5) compares the detections of said sensing areas (2a, 2b) with stored data in order to verify the simultaneous contact of both of the driver's hands with said sensing areas (2a, 2b) and the correspondence between the detected contacts and data indicative of the driver's identity. An alarm device (6) is activated in the event of disagreement with the stored data. (Fig. 1)