Capacitive Sensor Heater Assembly for Steering Wheel Hand Detection
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Solution Overview
Problem
Autonomous vehicles face challenges in determining whether a driver's hands are on the steering wheel, especially during transitions from autonomous to manual control, requiring effective sensing technologies to ensure safe operation.
Innovation Solution
A capacitive sensing and heating system is integrated into the steering wheel and seat, using a sensor/heater assembly with a measurement circuit to detect the presence of body parts by measuring capacitance changes caused by the driver's hands, with a controller managing various operational modes for accurate detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitive sensing system is integrated into the steering wheel to detect hand presence, then the reliability of autonomous vehicle control is improved, but the device complexity increases due to integration of sensor assemblies and measurement circuits
Solution Approach 1:
The patent combines the heating element and capacitive sensor into a single integrated sensor/heater assembly. The sensor is positioned on one surface of a substrate while the heater is positioned on the opposite surface, creating a compact dual-functional component that reduces overall system complexity while maintaining reliable hand presence detection capability
Solution Approach 2:
The sensor/heater assembly performs multiple functions simultaneously - it provides both heating functionality and capacitive sensing for hand presence detection. This multi-functional design eliminates the need for separate heating and sensing systems, thereby improving reliability without proportionally increasing device complexity
2Manufacturing precision
If a sensor and heater are arranged on opposite surfaces of a substrate, then the manufacturing precision is improved through standardized assembly, but the device complexity increases due to multi-layer construction
Solution Approach 1:
The patent embeds both the sensor and heater within a multi-layer substrate structure. The sensor is arranged on one surface of the substrate and the heater on the opposite surface, with both components nested within the same structural assembly. This nesting approach provides precise alignment through the substrate while containing the complexity within a unified manufacturing process
3Stability of the object's composition
If the heater wire spacing is reduced to less than or equal to 4 mm, then the heating uniformity is improved, but the manufacturing complexity increases due to tighter spacing requirements
Solution Approach 1:
The patent specifies a maximum wire spacing of 4 mm (with optional tighter spacing of 3 mm or 2 mm) for the heater wires arranged in a predetermined pattern. This parameter optimization ensures sufficient heating uniformity while maintaining manufacturability - the spacing is tight enough to provide consistent heat distribution but not so tight as to make manufacturing impractical
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 reliably determines the presence of a driver's hands on the steering wheel, enabling safe transitions between autonomous and manual driving modes and optimizing the use of safety restraints like airbags and seatbelts.
Implementation Method 1
measure a resonant frequency of the measurement circuit and the sensor/heater assembly in response to the excitation signal; determine at least one capacitance value based on the resonant frequency
Implementation Method 2
measure a resonant frequency of the measurement circuit and the sensor/heater assembly in response to the excitation signal
Implementation Method 3
a sensor/heater assembly is arranged in at least one of a seat or a steering wheel of a vehicle and includes a sensor and a heater arranged adjacent to the sensor
Data Source
AI summary
A system including an assembly arranged in at least one of a seat and a steering wheel of a vehicle and a measurement circuit. The assembly includes a sensor and a heater arranged adjacent to the sensor. The measurement circuit is configured to output an excitation signal to the measurement circuit and the assembly and measure a resonant frequency of the measurement circuit and the assembly in response to the excitation signal. The measurement circuit is configured to determine a capacitance value based on the resonant frequency and determine whether a body part is in proximity to the sensor based on the capacitance value.