Steering Wheel Hand Sensor Shielding for Signal Crosstalk Isolation
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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 crosstalk 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 as a shield or separately, with distinct power sources for heating and shielding functions, along with metallic or dielectric conduits to isolate sensor return wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the sensor mat is disposed close to the steering wheel frame for compact design, then the device complexity is reduced, 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 between the sensor mat and the metal steering wheel frame. The shield mat includes conductive loops that generate a counteracting electromagnetic field to cancel out the interference from the metal frame, thereby protecting the sensor signals without requiring increased spatial separation.
Solution Approach 2:
The shielding function is segmented into discrete conductive loops arranged in zones corresponding to the sensing zones. Each conductive loop can be independently controlled to provide targeted shielding where needed, rather than requiring a continuous shield across the entire steering wheel structure.
2Measurement precision
If a shield mat is added between the sensor mat and the steering wheel frame to prevent interference, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The shield mat is designed to serve multiple functions: it provides electromagnetic shielding for the sensor mat, can function as a heater mat for steering wheel heating, and its conductive loops can be selectively activated based on detected hand presence in different zones. This multi-functionality reduces the need for separate components.
Solution Approach 2:
The shielding function is merged with the heating function by using the same conductive loops for both purposes. The conductive loops can operate in shielding mode when hands are detected or in heating mode when hands are absent, eliminating the need for completely separate shielding and heating systems.
3Device complexity
If the heater mat is used as the shield mat to perform both heating and shielding functions, then the device complexity is reduced, but the control complexity increases due to selective current generation
Solution Approach 1:
The conductive loops are designed to dynamically switch between two operational modes: shielding mode (generating counteracting electromagnetic fields) and heating mode (generating thermal energy). The system automatically transitions between modes based on sensor input, with shielding activated when hands are detected and heating activated when hands are absent.
Solution Approach 2:
The system uses feedback from the sensor mat to automatically control the operation of the conductive loops. When the sensor mat detects hands in a particular zone, the corresponding conductive loop is activated for shielding; when no hands are detected, the same loop can be activated for heating, creating a closed-loop control system.
4Device complexity
If sensor return wires from adjacent sensing zones are placed close together for compact wiring, then the device complexity is reduced, but signal crosstalk occurs between adjacent sensing zones
Solution Approach 1:
Metallic or dielectric conduits are introduced as intermediaries to surround and isolate the sensor return wires from adjacent sensing zones. These conduits act as physical barriers that prevent electromagnetic coupling between wires from different zones, eliminating crosstalk while allowing the wires to remain in close proximity for compact wiring.
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 solution effectively shields the sensor mat from the steering wheel frame interference, reduces noisy measurements, and isolates signal return wires, 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 heater mat disposed around the steering wheel frame may be used as the shield mat by selectively generating a heating current for the heater function
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.