Capacitive Sensor Connection Diagnostics for Stable Vehicle Distance Sensing
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Solution Overview
Problem
Existing capacitive sensor arrangements in motor vehicles require multiple connections to check the electrical connection status, which can lead to incorrect distance value determination due to high contact resistances or electrical interruptions, and are affected by temperature drift.
Innovation Solution
A method that uses a single connecting line to check the connection state by measuring the input capacitance or input impedance relative to the reference potential, with a reference circuit designed to compensate for temperature drift, allowing for error detection and compensation without the need for multiple connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple connecting lines are used to check the electrical connection state, then the detection reliability is improved, but the device complexity increases
Solution Approach 1:
The patent extracts the ground connection from the diagnostic measurement, using it as a reference potential instead of requiring a separate diagnostic path. This allows connection state verification through a single connecting line between the control unit and electrode, while the ground connection serves dual purposes for both sensor operation and diagnostic reference.
Solution Approach 2:
The ground connection arrangement serves multiple functions: it provides the reference potential for capacitive sensing, establishes the return path for measurement currents, and simultaneously serves as the reference for diagnostic impedance measurements. This multi-functionality eliminates the need for separate diagnostic connections.
2Measurement precision
If the connection state is checked with multiple connecting lines, then the measurement precision is improved, but the ease of operation deteriorates
Solution Approach 1:
The patent extracts the ground connection from the diagnostic measurement, using it as a reference potential instead of requiring a separate diagnostic path. This allows connection state verification through a single connecting line between the control unit and electrode, while the ground connection serves dual purposes for both sensor operation and diagnostic reference.
Solution Approach 2:
The system uses its own ground connection arrangement to provide the reference potential for diagnostic measurements, making the diagnostic function self-sufficient without requiring external reference connections or additional wiring infrastructure.
3Measurement precision
If temperature drift is compensated using a reference circuit, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent combines the temperature compensation function with the existing ground connection arrangement. The reference circuit uses the same ground connection that serves the capacitive sensor, merging temperature reference and sensor operation into a single infrastructure, thereby avoiding additional wiring complexity.
Solution Approach 2:
The ground connection arrangement serves multiple functions: it provides the reference potential for capacitive sensing, establishes the return path for measurement currents, and simultaneously serves as the reference for diagnostic impedance measurements. This multi-functionality eliminates the need for separate diagnostic connections.
4Ease of operation
If a single connecting line is used for diagnostic measurement, then the ease of operation is improved, but the reliability of connection state detection deteriorates
Solution Approach 1:
The patent extracts the ground connection from the diagnostic measurement, using it as a reference potential instead of requiring a separate diagnostic path. This allows connection state verification through a single connecting line between the control unit and electrode, while the ground connection serves dual purposes for both sensor operation and diagnostic reference.
Solution Approach 2:
The ground connection acts as an intermediary reference that enables the single connecting line to carry diagnostic information. By measuring the impedance through this single line relative to the ground reference, the system can detect connection faults without requiring multiple independent connection paths.
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 approach simplifies the diagnostic routine for capacitive sensor arrangements, enabling accurate detection of connection errors and temperature drift, ensuring reliable distance value determination with reduced complexity and increased accuracy.
Implementation Method 1
the verification of the connection state of the respective electrode is simplified by the fact that the input capacitance and thus the connection status can be checked with just a single connection line, since the input capacitance or input impedance is relative to the reference potential
Implementation Method 2
a faulty electrical connection can cause the supply line to the input capacitance to exhibit increased ohmic resistance, which affects the charging behavior of the input capacitance
Implementation Method 3
the above problem is solved in a method according to the preamble of claim 1 by the features of the characterizing part of claim 1
Data Source
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AI summary
The invention relates to a method for operating a capacitive sensor arrangement (1) of a motor vehicle (2) to determine a distance (3) from a measurement object (B), a control unit (7) being provided for actuating the sensor arrangement (1), wherein the sensor arrangement (1) has at least one electrode (9) and a connection arrangement (10) assigned to the electrode (9) with a connecting line (11) and thereon a connection (12) on the electrode side and a connection (13) on the control unit side, wherein within the framework of a measuring routine by means of the control unit (7), the electrode (9) is controlled and the resulting distance values are determined as a function of a measuring capacitance (14) formed by the electrode (9) in relation to a reference potential, in particular in relation to ground potential (M), with the frame a diagnostic routine by means of the control unit (7) the electrical connection status of the electrode (9) with regard to the connection to the controller unit (7) is checked. It is proposed that the connection status based on the input capacitance (15) between the connection (13) on the control unit side and the reference potential is checked as part of the diagnostic routine using the control unit (7).