Steering Wheel Capacitive Sensor Calibration for Detection Accuracy
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Solution Overview
Problem
Existing vehicle control systems face challenges in accurately determining whether the steering wheel is grasped, as sensor detection values can be affected by secular deterioration and environmental changes, leading to false readings even when the wheel is not grasped.
Innovation Solution
A computer program and control device that utilize a capacitive sensor to detect electrostatic capacitance, calibrate detection values, and differentiate between grasped and non-grasped states by setting a reference value based on threshold differences, while also considering the power mode of in-vehicle devices and door operations to ensure accurate user presence detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitive sensor is used to detect steering wheel contact, then the ability to detect user presence is improved, but the accuracy deteriorates due to sensor deterioration and environmental changes causing false readings
Solution Approach 1:
The system performs preliminary calibration by detecting the baseline capacitance value when the driver's seat is empty (before the driver arrives). This preliminary detection establishes a reference value that accounts for environmental factors and sensor characteristics, enabling accurate subsequent measurements of driver presence and steering wheel contact.
Solution Approach 2:
The system dynamically adjusts the reference capacitance value based on detected environmental changes and sensor deterioration. By continuously updating the reference parameter rather than using a fixed threshold, the system adapts to changing conditions and maintains detection accuracy despite sensor aging or environmental variations.
2Reliability
If continuous sensor monitoring is performed to ensure accurate detection, then the reliability of driving support intervention is improved, but the power consumption increases
Solution Approach 1:
The control device performs sensor calibration and detection at periodic intervals rather than continuously. Specifically, it calibrates the reference value when the driver's seat is detected as empty, and then uses this reference for subsequent detection until the next calibration cycle, thereby reducing power consumption while maintaining detection reliability.
Solution Approach 2:
The system automatically performs calibration routines and reference value updates without requiring manual intervention. The control device autonomously detects when calibration is needed (when seat is empty) and executes the calibration process, eliminating the need for manual sensor adjustment while maintaining accurate detection.
3Measurement precision
If the system calibrates reference values frequently to account for sensor deterioration, then the measurement precision is improved, but the loss of time increases due to repeated calibration processes
Solution Approach 1:
The system performs calibration in advance when the driver's seat is detected as empty, before the driver needs to use the vehicle. By completing the time-consuming calibration process during periods when the vehicle is not in use, the system ensures accurate reference values are ready when needed without causing time loss during actual driving operations.
Solution Approach 2:
The system rapidly executes calibration routines when conditions permit (empty seat detected), minimizing the time spent on calibration. The control device efficiently processes the calibration data and updates reference values quickly, reducing the impact on overall system operation time.
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 calibrates sensor detection values to accurately determine user presence, reducing false positives and ensuring reliable operation of driving support systems by accounting for sensor degradation and environmental factors.
Implementation Method 1
a sensor that converts contact with a steering wheel into an electric signal for detection
Implementation Method 2
acquiring, from a sensor that converts contact with a steering wheel into an electric signal for detection, a detection value of a detected electric signal
Data Source
AI summary
A program and a control device capable of calibrating a detection value of a sensor that detects contact with a steering wheel are provided. The program in accordance with the present invention is characterized by causing a computer to execute processing of distinguishing whether or not a user is on a driver's seat of a vehicle; acquiring, from a sensor (21) that converts contact with a steering wheel (2) into an electric signal for detection, a detection value of the detected electric signal; determining whether or not a difference between the detection value acquired when it has been distinguished that the user is not on the driver's seat, and a reference value is equal to or larger than a threshold value; and setting the detection value as the reference value when it has been determined that the difference is not equal to or larger than the threshold value.