Capacitive Positioning Device with Automatic Calibration
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Solution Overview
Problem
Capacitive detectors for locating objects within a medium require manual calibration to account for ambient and environmental factors, which complicates the detection process and reduces measurement accuracy.
Innovation Solution
A capacitive locating appliance with a push-pull measurement bridge and electrode arrangement that includes a measurement electrode, a reference electrode, and a reception electrode, using phase-shifted AC voltages and a control device to compensate for interference factors, and a guard electrode for shielding, allowing for automatic calibration and improved detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual calibration is performed to account for ambient conditions and electrical properties, then measurement accuracy is improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The locating appliance performs automatic calibration without user intervention. The control device automatically determines calibration values by evaluating capacitance measurements at different frequencies and storing these values for subsequent measurements, eliminating the need for manual calibration while maintaining high measurement accuracy
Solution Approach 2:
The system changes measurement parameters by performing capacitance measurements at multiple different frequencies. This allows the control device to calculate calibration values that account for frequency-dependent effects, improving measurement accuracy across different operating conditions without requiring manual intervention
2Measurement precision
If manual calibration is performed to account for ambient conditions and electrical properties, then measurement accuracy is improved, but ease of operation deteriorates
Solution Approach 1:
The locating appliance performs automatic calibration without user intervention. The control device automatically determines calibration values by evaluating capacitance measurements at different frequencies and storing these values for subsequent measurements, eliminating the need for manual calibration while maintaining high measurement accuracy
3Reliability
If electrode capacitance is made sensitive to ambient conditions for detection, then detection capability is improved, but reliability deteriorates due to false readings
Solution Approach 1:
The control device uses feedback from capacitance measurements at different frequencies to automatically determine calibration values. These calibration values are then applied to compensate for ambient condition effects during actual object detection, improving detection reliability by eliminating false readings caused by temperature, humidity, and other environmental factors
Solution Approach 2:
The system changes measurement parameters by performing capacitance measurements at multiple different frequencies. This allows the control device to calculate calibration values that account for frequency-dependent effects and ambient conditions, improving measurement accuracy across different operating conditions without requiring manual intervention
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 enables accurate detection of objects within a medium without manual calibration, reducing the influence of ambient and environmental factors, and enhancing the sensitivity and reliability of the measurement process.
Implementation Method 1
the measurement electrode forms, with the reception electrode, a measurement capacitance that can be influenced by the object, and the reference electrode forms, with the reception electrode, a reference capacitance that cannot be influenced by the object
Implementation Method 2
an oscillator for supplying the measurement capacitance and the reference capacitance with phase-shifted AC voltages
Implementation Method 3
a control device for controlling amplitudes of at least one of the AC voltages in order to match the influences of electrical fields from the measurement electrode or the reference electrode on the reception electrode to one another
Data Source
AI summary
A positioning device for capacitively detecting an object enclosed in a medium includes a measuring electrode, a reference electrode, and a receiving electrode. The measuring electrode with the receiving electrode forms a measuring capacitance, which can be influenced by the object. The reference electrode with the receiving electrode forms a reference capacitance, which cannot be influenced by the object. The positioning device further includes an oscillator configured to supply the measuring capacitance and the reference capacitance with phase-shifted AC voltages and a control device configured to control amplitudes of at least one of the AC voltages, in order to adapt effects of electrical fields of the measuring electrode or of the reference electrode on the receiving electrode to one another. The measuring, reference, and receiving electrodes are planarly formed. The measuring electrode has a larger surface area than the reference electrode.