Steering Wheel Sensor System for Control State Differentiation
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Solution Overview
Problem
Current steering wheel sensor systems cannot reliably determine how the wheel is being controlled, such as through a grasp, as they lack the capability to differentiate between various control states like holding, tapping, or inadvertent touching.
Innovation Solution
A sensor system utilizing complex impedance sensors, including capacitance and inductance sensors, is integrated into the steering wheel to detect and differentiate control states by measuring impedance changes caused by driver interactions, allowing for the determination of hand grasp, finger contact, and other control scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If simple electric field sensors are used to detect hand placement, then the device complexity is low, but the measurement precision is insufficient to differentiate control states
Solution Approach 1:
The steering wheel is divided into multiple sensor zones (first sensor in front left portion, second sensor in front right portion, third sensor at rear). Each zone independently measures impedance, allowing the system to differentiate control states by comparing patterns across segmented regions rather than relying on a single complex sensor.
Solution Approach 2:
The system measures complex impedance parameters (capacitance and inductance components) that change differently for various control states. By monitoring multiple electrical parameters simultaneously and their rate of change, the system achieves precise control state differentiation using relatively simple sensor elements.
2Measurement precision
If multiple sensors are added to differentiate control states, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The steering wheel circumference is segmented into three distinct sensor regions (front left, front right, rear), with each region containing a simple impedance sensor. This spatial segmentation allows differentiation of control states through pattern recognition across zones rather than using complex single-point sensors.
Solution Approach 2:
Each sensor element serves multiple functions: it detects presence of hand, determines grasp vs. non-grasp states, and contributes to locating the hand position. The same simple impedance measurement mechanism is used across all three sensor locations, providing universal functionality that reduces overall system complexity.
3Measurement precision
If complex impedance sensors measuring capacitance and inductance are used, then the measurement precision for control states improves, but the use of energy increases
Solution Approach 1:
The sensors perform periodic impedance measurements rather than continuous monitoring. The system measures impedance at discrete time points and compares changes between measurements, allowing accurate control state detection while minimizing energy consumption by keeping sensors inactive between measurement cycles.
Solution Approach 2:
The system measures both capacitive and inductive components of impedance, providing comprehensive control state detection. However, it only processes measurements when changes exceed thresholds indicating actual control state changes, avoiding unnecessary energy expenditure on continuous high-precision measurements.
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
The system effectively distinguishes between safe and unsafe driving states, providing alerts when necessary, and estimates the applied steering control force based on hand position and surface area, ensuring reliable detection of driver engagement with the steering wheel.
Implementation Method 1
The complex impedance can be a capacitance, an inductance, a resistance, or a combination thereof
Implementation Method 2
The complex impedance can be a capacitance, an inductance, a resistance, or a combination thereof
Implementation Method 3
Objects within proximity (such as human hands or body parts) tend to redistribute the electric field intensity and phase, resulting in the change of complex impedance as measured within the electric field circuit
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A sensor system for a steering wheel of a vehicle includes a first sensor disposed within a first portion of the steering wheel to detect contact with a front left surface of the steering wheel. The sensor system includes a second sensor disposed within a second portion of the steering wheel separate from the first portion to detect contact with a front right surface of the steering wheel. The sensor system also includes a third sensor disposed within the steering wheel to detect contact with a rear surface of the steering wheel. The first, second and third sensors are configured to respectively detect touching of the front left surface, the front right, and the rear surface of the steering wheel by a hand or a non-hand part of an operator of the vehicle. The first, second and third sensors can be complex impedance sensors.