Seat Occupancy Sensor Mat With Environmental Capacitance Correction
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Solution Overview
Problem
Capacitance values measured by interdigital capacitive sensors in vehicle seat occupancy detection mats are prone to errors that vary by sensor, seat, and vehicle, and require time-consuming and labor-intensive recalibration, especially when the sensor mat or seat is replaced or the controller is reset.
Innovation Solution
A system with conductive tracks and a calculation unit that measures and subtracts environmental capacitance from the sensor capacitance to improve accuracy, using a flexible support with interdigital capacitive sensors and conductive tracks connected to a connection box and calculation unit to determine the actual capacitance of the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitance measurements are performed manually in the factory or dealership to record correction values, then measurement precision is improved, but loss of time and productivity deteriorate due to time-consuming and labor-intensive adjustment
Solution Approach 1:
The system automatically performs capacitance measurements and generates correction values without human intervention. The control unit autonomously measures capacitance values from interdigital capacitive sensors, determines correction values, and stores them in memory, eliminating the need for manual factory or dealership adjustment while maintaining high measurement precision
2Measurement precision
If manual capacitance measurement and correction value recording is performed, then measurement precision is improved, but device complexity increases due to additional adjustment procedures
Solution Approach 1:
The control unit automatically executes the entire capacitance measurement and correction value determination process without requiring manual adjustment procedures. The system self-calibrates by measuring capacitance values, calculating correction values, and storing them in memory, thereby maintaining high measurement precision while eliminating complex adjustment procedures
Solution Approach 2:
The system performs capacitance measurements and correction value determination automatically during initial system setup or when needed, preparing the measurement system in advance without requiring subsequent manual adjustment. This preliminary automated action ensures measurement precision is achieved without complex ongoing adjustment procedures
3Measurement precision
If frequent recalibration is performed to maintain accuracy, then measurement precision is improved, but productivity deteriorates due to repeated adjustment requirements
Solution Approach 1:
The control unit automatically performs capacitance measurements and updates correction values as needed without requiring manual recalibration operations. The system autonomously maintains measurement precision by periodically or event-driven recalibrating itself, eliminating productivity losses associated with frequent manual recalibration while sustaining high measurement accuracy
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
Enhances the accuracy of occupant presence and position detection by reducing environmental noise, maintaining precision over time, and reducing the need for frequent recalibration.
Implementation Method 1
The capacitance values measured at the terminals of the interdigital capacitive sensors of an occupancy detection mat are generally affected by an error
Implementation Method 2
a calculation unit configured to determine a first capacitance at one end of the at least one first electrical cable and a second capacitance at one end of the at least one second electrical cable
Data Source
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AI summary
The invention relates to a seat occupancy detection mat for a motor vehicle, comprising a flexible support (4), an interdigitated capacitive sensor (6) carried by the flexible support, a first conductive track (8) carried by the flexible support, the first conductive track (8) having a first end (16) connected to the interdigitated capacitive sensor (6) and a second end (18) for connection to a processing unit, a second conductive track (10) carried by the support, the second conductive track having a first free end (20) and a second end (22) for connection to said processing unit. The invention also relates to a system for determining capacity, a method for determining the capacity or occupancy status of a seat, and a method for detecting rotation of a part of the torso of an occupant seated in a seat.