Steering Wheel Hand Sensor Shielding With Dual-Use Heater Mat
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Solution Overview
Problem
Current steering wheel designs face interference issues due to the metal frame affecting the electrical signals of the sensor mat, leading to noisy or 'shorted' measurements, and signal interference between adjacent sensing zones.
Innovation Solution
A shield mat is introduced between the sensor mat and the steering wheel frame, powered to generate a shielding voltage signal to prevent interference, and a heater mat can be used for both heating and shielding purposes, with separate power sources for heating and shielding functions, and dielectric or metallic conduits to isolate sensor return wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sensor mat is disposed between the outer skin and the steering wheel frame to detect hand presence, then hand detection function is achieved, but the metal frame causes interference with the electrical signals leading to noisy or shorted measurements
Solution Approach 1:
A shield mat is introduced as an intermediary component disposed between the sensor mat and the metal frame. The shield mat includes conductive loops that generate a counteracting electrical field to cancel out the interference from the metal frame, thereby protecting the sensor signals without requiring changes to the sensor mat or frame themselves.
Solution Approach 2:
The shield mat is activated to generate a preliminary counteracting electrical field before the interference adversely affects the sensor measurements. By proactively creating an opposing field that neutralizes the frame's interference, the system prevents noisy or shorted measurements rather than attempting to correct them afterward.
2Area of stationary object
If multiple sensing zones are provided in the sensor mat, then hand detection coverage is improved, but sensor return wires from adjacent zones interfere with each other's signals
Solution Approach 1:
Dielectric conduits are used as intermediaries to physically separate and insulate the return wires from adjacent sensing zones. These conduits prevent capacitive coupling and electrical interference between wires carrying signals from different zones, allowing multiple zones to operate simultaneously without signal contamination.
Solution Approach 2:
The shield mat is divided into multiple conductive loops, each corresponding to a specific sensing zone. Each loop provides localized shielding tailored to its adjacent sensing zone, allowing independent optimization of signal isolation for each zone while maintaining overall system performance.
3Ease of operation
If a heater mat is added for heating function, then driver comfort is improved, but the device complexity and power source requirements increase
Solution Approach 1:
The heater mat is designed to serve dual functions: heating the steering wheel for driver comfort and acting as a shield mat for electrical interference protection. By configuring the heater mat's conductive loops to operate in shielding mode when heating is not required, the system eliminates the need for a separate shield mat and reduces overall device complexity.
Solution Approach 2:
The system dynamically reconfigures the heater mat's function based on operational requirements. The control unit switches the heater mat between heating mode (high current for thermal comfort) and shielding mode (low current for electrical interference protection), allowing a single component to adapt to different functional demands without requiring permanent dual-component architecture.
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 solution effectively shields the sensor mat from the steering wheel frame interference, reduces noisy measurements, and isolates signals between sensing zones, enhancing the accuracy of hand detection systems.
Implementation Method 1
a shield mat that is disposed between the sensor mat and the frame of the steering wheel. A power source is configured for providing a current to the shield mat, which prevents interference between the steering wheel frame and the sensor mat
Implementation Method 2
A power source is configured for selectively generating a heating current for the heater mat for heating the steering wheel
Data Source
AI summary
Systems and methods of shielding a hand sensor system in a steering wheel are disclosed herein. An exemplary hand sensor system includes a sensor mat and a heater mat that is disposed between the sensor mat and a frame of the steering wheel. A power source selectively provides a heating current to the heater mat to provide heat to the steering wheel and a shielding voltage signal to the heater mat to provide electrical shielding for the sensor mat when heating is not needed or when sensing takes priority over heating. Alternatively, the system may include a shield mat that is separate from the heater mat and is disposed between the sensor mat and the heater mat. In addition, to isolate the signal carried by individual sensor return wires, a metallic or insulating covering or conduit may be provided around the wires or portions thereof.